A backhoe is an excavator generally hinged vertically to the rear of some wheeled or tracked vehicle which often has other functions. It comprises, articulated together, a swing frame, an elongated boom, and elongated dipper, and a bucket, and is generally powered by double-acting hydraulic actuators. A typical example referred to hereinafter is the Wheeled Tractor Loader Backhoe, a machine in which the vehicle is a wheeled tractor that is support for a loader in the front and a backhoe in the rear. Backhoes are versatile tools and are generally successful and ubiquitous machines. However, the vehicle supporting the backhoe suffers from several drawbacks, which restrict the field of use of the backhoe itself.
During operation of the backhoe, the vehicle needs to be immobilized by a pair of hydraulically actuated stabilizers, and eventually, a lowered loader or other implement in the front, to create and expand its stability base both in the transversal and the longitudinal direction. This is to help prevent roll-over of the machine, and to offer a non-compliant base for the precise operation of the backhoe, as low-pressure tractor tires, for example, yield significantly under load (Caterpillar 1992). These stabilizers increase the bulkiness of the machine and reduce the lateral clearance available for swinging the backhoe. They increase the complexity of the machine and require their own hydraulic controls. Operationally, they need to be retracted and reextended every time the operator wants to move the vehicle to a better working position for the backhoe.
A backhoe vehicle is severely limited by the slope of the terrain it is moving on. Slope, both in the longitudinal and the transversal direction, has generally to be less than 10x for safe operation of a backhoe on a wheeled vehicle. Even stopped and with stabilizers deployed, some operating precautions are necessary on hillsides to increase stability, such as maintaining a full bucket close to the ground to keep the overall center of mass as low as possible, or dumping spoil dirt on the uphill side of a trench. The tipping over of a backhoe vehicle on a slope or some unstable terrain is a damaging and dangerous event, even with a Roll Over Protecting Structure for the operator. Some backhoe vehicles, manufactured for example by Caterpillar and JCB Inc., have four-wheel steering and provision for rolling slightly crabwise, which can somewhat compensate for sliding down slopes laterally.
Typical backhoe vehicles contain not only hydraulic pumps and associated controls for the backhoe and other implements, but also a number of clutches, gearboxes, transmissions, directional and powered wheels or tracks, brakes, and all other numerous mechanical parts necessary for the locomotion of the vehicle itself. This adds to the complexity of the machine as a whole, and as a consequence leads to a higher manufacturing cost. The reduced reliability of complex machines in general also leads to a higher maintenance and operational cost.
To compensate for the weight of the backhoe and its loads, the backhoe vehicle is not only built without much weight-saving concern, but often built heavy on purpose. All the above- mentioned mechanical parts used exclusively for locomotion add significantly to the total weight. Also, substantial counterweights have often to be attached to a vehicle location as far as practically possible from the backhoe itself, for example to a front axle, to increase longitudinal stability. Having to carry any form of deadweight is not energetically efficient, especially in hilly areas.
In off-road locations, the churning of the top soil and its vegetation by the wheels and tracks of heavy vehicles damages the work site. In case of rain, the ground quickly becomes muddy to the point of making further work at this location more difficult and more hazardous, or else impossible for long periods of time. The disturbed ground is then also vulnerable to erosion, especially in hilly areas. This environmental damage has to be repaired, sometimes at great cost.
Because its overall center of mass has to be kept low for stability, the wheeled or tracked vehicle supporting the backhoe has a small ground clearance for its size and weight. The low ground clearance restricts access to rugged environments, where backhoes would be just the tools needed by their versatility for a number of tasks. As a result, the ground often has to be planed or roads have to be built and surfaced prior to backhoe activity. This often requires specific earthmoving equipment to do so, extra time, extra labor, and a possible increase of abovementioned environmental damage. The same can be said for the few existing walking machines, which often offer little clearance advantage over the use of wheels or tracks.
The need to operate on moderately steep slopes such as canal banks has led to the development of so-called "mobile walking excavators", for example the HSM 41 manufactured by Schaeff (1996). This kind of vehicle can lift its wheels from the ground and rest on its body and on long telescopic outriggers that increase greatly its overall stability. Their limiting slope reaches about 45deg longitudinally and about 35deg transversally. However, "walking" may be a misleading word to describe the motion of such an excavator. Its outriggers are in fact overdimensioned stabilizers with three degrees of freedom, that is, not only vertical, but lateral and telescopic. By the reach of their extension, they allow the excavator to be somewhat repositioned without jeopardizing stability. The motion of these outriggers cannot be compared to the agility of the leg of even a simple insect, or for that matter, to the agility of the excavator it helps stabilize. Also in this "mobile walking excavator" category are US Patents 4,049,070 (Soyland 1977), 4,395,191 (Kaiser 1983), and 4,482,287 (Menzi 1984).
Todd (1985) enunciates the idea that in walking machines "the legs themselves can have functions other than walking, such as digging or manipulation. This has hardly ever been tried". This latter remark is presumably because a leg able to perform those functions and able to withstand the loads of walking has hitherto not been formally identified. A leg with full load- bearing ability is generally ill-designed for digging or manipulating and vice-versa. As a result, the idea has not materialized into a viable machine, and legs are designed as just legs, that is to bear the weight of the machine and to propel it in some direction. A concept drawing of a possible excavator truly walking on four legs appears in the same Todd (1985). A number of walking machines have been built over the last few decades. Some exist in the form of a patent, for example US Patents 4,202,423 (Soto 1980) or 5,040,626 (Paynter 1991). Most seem never to reach beyond experimental status either within the settings of a University or a research environment (Rosheim 1994). Very few reach the commercial market, for example the hydraulically powered six-legged walking Forest Harvester, with a boom and dipper terminated by a band saw and forestry implements, developed by Plustech Oy (1997).
A further limitation of the walking machines of the prior art stems from that abovementioned fact that generally their legs are designed only to walk. That is, the legs themselves become a significant deadweight in regard of any payload the machine can carry for some other task than just walking. As a result, only light payloads are generally possible, such as cameras and other sensors for a reconnaissance legged robot, for example. This explains in part why only very few walking machines are commercially available, and even so, only for very limited applications. Another limitation of walking machines of the prior art (Rosheim 1994) is that their legs do not have a large volume of possible motions relative to the size of the walking machine they support. As a result, using such legs provides only a marginal advantage over using very large diameter wheels, for example. Also, many walking machines of the prior art (Rosheim 1994) have a relatively narrow polygon of stability that exposes them to catastrophic roll-overs just as their wheeled and tracked counterparts.
If there are few walking machines, there are fewer that possess both legs and wheels, but there is a number of wheeled vehicles that possess legs. Apart some of the "mobile walking excavators" mentioned hereinbefore, US Patents 4,265,326 (Lauber 1981), 4,482,287 (Menzi 1984) and 5,513,716 (Kumar 1996) are such examples. However, legs of those machines are not their primary means of locomotion.
Backhoes instrumented with position and load transducers and controlled by a computer system operating electric valves have been built successfully by researchers, and some have been patented, such as US Patent 4,288,196 (Sutton II 1981). However, a competent human operator can use a backhoe quite efficiently with only manual controls, which makes a computer controlling system unnecessary for a single backhoe. This probably explains the quasi-absence of such backhoes in the commercial arena. However, a computer controlling system is required for the walking machine of the present invention because of the plurality of its legs. Even operating a four-legged machine necessitates too many simultaneous operations of valve controls to be executed efficiently by a human operator (Rosheim 1994). The presence of a computer, in turn, opens many possibilities beyond just the several algorithms that exist for the coordination of walking. For example, depending on which of different operating modes is selected, the same joystick inputs from the operator can either drive the machine, or operate a leg-backhoe as a standard backhoe, or even control any of the abovementioned tools, all with the same wiring and piping. The computer system also opens new possibilities of cooperative work between two leg-backhoes of the same machine. This flexibility adds greatly to the versatility of the machine.
Using backhoes as legs for a walking machine presents significant cost advantages. Backhoes are already manufactured in large quantities, by several manufacturers. Using components from an existing production line is much more economical than manufacturing totally new ones. The necessary modifications to convert a backhoe into a leg-backhoe are additions, for example of transducers, after it is built, and therefore do not require any expensive modification of the line of production of standard backhoes. Furthermore, if all legs use identical backhoe components, it creates a further reduction of any inventory of spare parts. This is especially significant when managing a fleet of both standard and walking backhoes.
The propulsive energy of the walking machine of the present invention relies only on hydraulic pumps and actuators, and those are of well-known technology and mass-produced. The walking machine of the present invention does not require clutches, gearboxes, transmissions, torque converters, wheels, tracks, steering wheels, or brake systems to move about. The walking machine also dispenses with the weight and hindrance of stabilizers. Its construction is therefore much simpler, less costly, and of lower maintenance. These attributes are most important in the developing, tropical, or rugged countries likely to use them, which may be limited by both initial acquisition costs and spare parts logistics.
The stability of the walking machine of the present invention is due to the wide base of the stability polygon provided by its legs, not to the ponderous stability of some centrally supporting structure. No counterweights and other deadweights are required, therefore increasing the power to weight ratio and the overall energetic efficiency. The body of the walking machine can also be lowered to the ground also as a support, with the leg-backhoes diagonally opposed to the working ones extended to act as counterweights, if necessary. Heavy loads or bulky loads, such as containers or trees, can be carried attached under the body, and in that case actually increase stability. Similarly, the body can be direct support for a tool, such as a fork lift, a drilling machine, dozer blade, or agricultural implements.
As opposed to wheels and tracks that constantly create ruts and try to roll out of them, the legs of the walking machine of the present invention exert mostly vertical punctual forces on the ground. Also, feet can be especially designed to reduce local churning torques applied to the surface of the ground. These properties make the machine less aggressive on the environment, especially on slopes where ruts are the source of particularly damaging erosion. Furthermore, less dependence on planed ground and roads to go to and return from a work site also reduces the environmental impact.
About 50% of emerged land on Earth is not accessible to wheeled or tracked vehicles, and yet most of it is accessible to legged animals. The food requirements of the ever-increasing world population is starting to push agriculture more and more up the slopes. However, current agricultural equipment is not well suited to working on slopes. For example, the leading cause of farm-related deaths even in a flat country such as Illinois is tractor roll-over accidents. The wide stability base of the walking machine of the present invention allows it to tackle slopes not accessible to a tractor. Also, the reduced churning of the ground by walking machines is a significant factor in erosion control in cultivated fields. The walking machine of the present invention can perform many tasks in a safer manner for both humans and the environment, on terrains that previously would not have been considered for agriculture.
A backhoe is originally designed to dig deep trenches and can extend down steeply from its support vehicle. The converse is that a backhoe used as a leg can elevate the body of the walking machine of the present invention to great heights, many times the ground clearance of the same backhoe installed on a wheeled or tracked tractor. Available ground clearance of the walking machine of the present invention for its size is also significantly larger than in most existing legged machines (Rosheim 1994). Some backhoes possess a telescopic dipper that could increase ground clearance even further. This high ground clearance opens new terrains previously inaccessible to backhoes. These can be rugged irregular surfaces, or comprise large obstacles such as boulders or fallen trees, encountered for example, in mining and logging activities. The high ground clearance also allows the walking machine of the present invention to wade in significant depths of water. This can simplify levee, ditch and canal maintenance, for example. Furthermore, the high ground clearance provided by using backhoes as legs opens the possibility of carrying bulky payloads such as containers under the body of the machine, thereby simplifying pick, carry, and place operations of such cargoes.
Locomotion of ground-based machines on solid horizontal terrain is likely to always be the domain of wheeled and tracked vehicles. The walking machine of the present invention not only can be moved about passively on a wheeled trailer but can be docked onto a wheeled or tracked cart, to retain advantages of wheeled locomotion when suitable. When connected to a simple tracked cart, the walking machine has the ability to be self- propelled by legs, or by tracks, or by both. This cart add-on confers to the walking machine of the present invention a greatly increased range of activity on terrains both flat and rugged.
Another novel advantage of the walking machine of the present invention is the possible cooperation between leg- backhoes for other tasks than walking, thanks to the natural agility of backhoes. Cooperation is made possible by the computer system control, as the direct coordination of even simple tasks would be beyond the capacities of a human operator. For instance, a grapple attachment on one leg could guide a post into a hole previously dug by an auger attachment on another leg, or two leg-backhoes could be connected in parallel to a same wide bucket to act as a single loader, or two adjacent leg-backhoes could hold against one another two pipes to be welded together.
Backhoes are commonly submitted to loads several times their own weight and are robust by design, so they are well suited to encounter the loads legs have to bear. Actually, operation manuals of backhoe vehicles state that on level terrain, after raising the stabilizers, the vehicle can be moved by pushing it with the backhoe against the ground (John Deere 1982). Also, savvy operators of tracked excavators use boom, dipper and bucket assembly as a prop to partially lift and quickly reposition their tracks, reducing churning of the ground at that location. The design of most backhoes is such that even in the harsh working conditions of digging a deep trench, for example, hydraulic cylinders, pipes, hoses, pivot pins, and other crucial parts are well protected against ground contact, which is an advantage for legs in harsh environments as well.
Standard backhoe hydraulic systems are as little compliant as possible, to allow precision in its operation. However, the impact of each step of a leg-backhoe walking on a solid rocky terrain could briefly raise the pressure in its hydraulic system beyond nominal limits. The addition of hydraulic accumulators tapped in the hydraulic lines dampens such hydraulic pressure spikes. Each accumulator can be isolated from its hydraulic line by a damping valve under the control of the computer system, and ultimately, the operator, in a manner similar to that of Caterpillar (1992). Damping valves closed, the leg-backhoe behaves as rigidly as a standard backhoe, and damping valves open, the same leg-backhoe behaves with some mushiness and compliance that is beneficial to legs in general. This system increases further the adaptability of leg-backhoes of the present invention.
The number of leg-backhoes in the walking machine of the present invention offers a natural redundancy. If for some reason a leg-backhoe cannot perform a task, another may. For example, in case of leg damage in a particularly dangerous area, the damaged leg-backhoe can be removed altogether by an adjacent leg-backhoe acting as a crane, without the help of another machine nearby. If at least four legs are intact, the walking machine of the present invention can still walk back to safety, albeit with reduced performance, and replace the missing leg with a spare one by an operation inverse of the one described above.
Backhoes possess a wide variety of working configurations and have a surprisingly powerful reach for their size. As a result, leg-backhoes are naturally agile appendages, especially under computer control. A wide variety of walking gaits is possible, from moving one leg at a time to the full alternating tripod gait, as used by Sutherland in his hexapod (1983). The walking direction can be straight ahead, or fully crabwise, or any angle in between. The walking machine can turn on the spot without churning the ground under itself. Thanks to the reach of leg-backhoes, the machine can perform complex maneuvers such as turning right while crabbing left, for example. Also, while using one leg-backhoe as a backhoe, the other leg-backhoes acting as legs can shift position without lifting any foot from the ground, to help the operation of the backhoe. In the walking machine of the present invention, the agility of backhoes is simply transferred in the agility of legs.
The walking machine using backhoes as legs represents a novel form of machine which does not compete with backhoes and excavators supported by wheels or tracks; they complement them by opening new grounds, new possibilities, and new modes of operation. In particular, they can go perform a pinpoint task in some forbidding terrain, in and out with a minimum of logistics. Still further objects and advantages rest on the novel arrangement and combination of several leg-backhoes on a same chassis, a novel method of walking, and will become apparent from a consideration of the ensuing drawings, the detailed description and operation, and the appended claims.
10 walking machine 11 chassis 12 leg-backhoe 13 end implement 14 operator's cab 15 machinery compartment 16 end implement storage area 17 bracket 18 swing pivot 19 bucket 20 rigid foot implement 21 swing frame 22 boom 23 dipper 24 swing rods 25 swing cylinders 26 boom pivot 27 boom rod 28 boom cylinder 29 dipper pivot 30 dipper rod 31 dipper cylinder 32 bucket pivot 33 bucket rod 34 bucket cylinder 35 floating knee 36 guide links 37 guide link pivot 38 bucket links 39 strap 40 bumper 41 hemispheric cup 42 foot brackets 43 pins 44 cotter pins 45 ankled foot implement 46 circular plate 47 ball & 48 socket 49 upper spring mount 50 lower spring rim 51 compression spring 52 accessory hole 53 tooth 54 cart 55 cart chassis 56 track 57 wheels
FIG. 1. Perspective view of hexapod walking machine standing up on its feet. For clarity, booms are represented as U cross-section channels, hydraulic actuators are not drawn, and volumes of occupancy of foot end implements are spheric.
Referring to FIG. 1, a hexapod walking machine generally designated by the numeral 10 comprises a rigid chassis 11 and attached to it six identical "leg-backhoes" 12, which are terminated by interchangeable end implements 13. All implements 13 illustrated in FIG. 1 are spherical feet that will be described hereinafter, which the walking machine is shown standing on, in a stopped condition. Walking machine 10 illustrated in FIG. 1 could be named "backhoe hexapod", "walker backhoe", "sixhoe", or "hexhoe".
Chassis 11 has a generally rectangular shape approximately twice as long as wide and is analogous to the body, or more precisely, to the thorax of an arthropod. The center front area of chassis 11 is support for an operator's cab 14 and a computer system, not shown. A machinery compartment 15 for engines and hydraulic pumps is located in the center area of the middle and rear of chassis 11. Finally, backhoe tool storage areas 16 are located on chassis 11 on either side of machinery compartment 15.
FIG. 2. Front view of the two front leg-backhoes of the walking machine partially resting on front right leg and on a chassis bumper, and engaged in some earth-moving activity. The front right leg-backhoe is terminated by a hemispheric foot, and the front left one being terminated by a tool, namely, a bucket. For clarity, hydraulic pipes, transducers, and middle & rear legs are not drawn.
Referring to FIG. 1, and to FIG. 2 for details, six pairs of vertically spaced upper and lower brackets 17 protrude laterally at a front, middle, and rear location of the right and left sides of chassis 11. In each pair of brackets, pivots 18 define a generally vertical hinge axis. In a typical configuration, the middle vertical axes are laterally spaced approximately 2.1 m (7 feet) apart, the front or rear axes are laterally spaced approximately 1.5 m (5 feet) apart, and front, middle, and rear axes are longitudinally spaced approximately 1.8 m (6 feet) apart.
Leg-backhoe 12 is a backhoe terminated by a removable end implement 13. In a standard backhoe, and in the front left leg- backhoe of the walking machine in FIG. 2, this end implement is a bucket 19. In the front right leg-backhoe of the same machine of FIG. 2, this end implement is a foot 20. The standard backhoes mentioned herein are backhoes, truckhoes(R), or compact excavators currently manufactured by companies bearing the names of Case, Caterpillar, Charles Machine Works, Darby Industries, Ford New Holland, JCB, John Deere, Kubota, Master Craft, Melroe Ingersoll-Rand, Terramite, or other. The geometry, kinematics, and performance of the leg-backhoe represented in the drawings are modelled after the backhoe of model 580L of the Case Corporation, but they would essentially be similar when using models from other manufacturers. Backhoes are also described in US Patents 3,376,984 (Long 1968), 4,039,095 (Long 1977), 4,122,959 (Stedman 1978), 4,358,240 (Shumaker 1982), 4,715,771 (Hanson 1987), or 5,176,491 (Houkom 1993). As a result, leg- backhoe 12 will not be described in detail, but mostly in how it differs from a standard backhoe.
Referring now to FIG. 2, each leg-backhoe 12 comprises a swing frame 21, also called swing tower or king post, analogous to the coxa of an arthropod, a generally elongated boom 22, analogous to the femur of an arthropod, a generally elongated dipper 23, also called dipper arm, dipperstick, or crowd, analogous to the tibia of an arthropod, which are all elements of standard backhoes. Backhoe booms 22 can sometimes be angled, as for instance in some Caterpillar and Kubota designs (US Patent 4,961,371 Takashima 1990). As shown in FIG. 2, end implement 13 of the front right leg-backhoe is rigid foot 20, and end implement 13 of the front left leg-backhoe is bucket 19. Feet, buckets, and other end implements are removable and freely interchangeable on any of the six leg-backhoes of walking machine 10. However, tool implements are preferably installed on the front leg-backhoes to be more visible during their operation from operator's cab 14, and for tool storage reasons that will be addressed in the operation section hereinafter.
For each leg-backhoe, swing frame 21 is hinged vertically to chassis 11 through brackets 17 and pivots 18, as the thoraco- coxal joint of an arthropod. The chassis-swing frame angle depends on the extension of swing rods 24 in hydraulic swing cylinders 25. Swing frame actuation system represented in FIG. 2 is that of US Patent 4,039,095 (Long 1977). The front direction being defined 0deg by convention, the chassis-swing frame angle of the front and middle leg-backhoes can externally swing an arc approximately from 0deg to 180deg. The chassis-swing frame angle of the rear leg-backhoes can externally swing an arc approximately from 45deg to 225deg for reasons of clearance of the backhoe tool storage area (FIG. 1). When the all swing frames are oriented either 0deg or 180deg, the total width of walking machine 10 does not exceed the width limitation of about 2.4 m (8') set by the US Department of Transportation for roads.
Boom 22 is hinged horizontally to a bottom pivot 26 of swing frame 21, as the coxo-femoral joint of an arthropod. The swing frame-boom angle depends on the extension of a boom rod 27 in an hydraulic boom cylinder 28. The horizontal direction being defined 0deg by convention, the swing frame-boom angle can vary approximately from 100deg up to -60deg down. The swing-over of boom 22 past a neutral up position is made possible by the backhoe arrangement and operation of US 3,376,984 (Long 1968) or its variants.
Dipper 23 is hinged horizontally to a pivot 29 at the distal end of boom 22, as the femoro-tibial joint angle of an arthropod. The boom-dipper angle depends on the extension of a dipper rod 30 in an hydraulic dipper cylinder 31. The fully extended direction being defined 180deg by convention, the boom-dipper angle can vary approximately from 40deg to 155deg.
Referring to the front left leg-backhoe used as a backhoe in FIG. 2, the generally cusplike bucket 19 is hinged horizontally to a bucket pivot 32 at the distal end of dipper 23. The dipper- bucket angle depends on the extension of a bucket rod 33 in a hydraulic bucket cylinder 34, through the action of a floating knee pivot 35, guide links 36, a guide link pivot 37, and bucket links 38, constituting a typical four-bar linkage very often associated with backhoe buckets.
Referring now to the front right leg-backhoe used as a leg in FIG. 2, rigid foot 20, that will be described hereinafter, is attached to the distal end of dipper 23 by the means of pins in bucket pivot hole 32 and guide link pivot hole 37. Bucket rod 33 is retracted in hydraulic bucket cylinder 34, and the latter is secured to the dipper by a strap 39. Optionally, cylinder 34 can be altogether removed, for example in a leg that is fitted infrequently with tool implements, such as a rear leg. Rigid foot 20 is shown resting on the ground, bearing part of the total weight of walking machine 10.
Chassis 11 is able to rest permanently or drag occasionally on the ground, by its own structure or by protective elements such as shock absorbers, skids, springs, strike plates, bumpers, rollers, small wheels, or swivel wheels. Two bumpers 40 are shown in FIG. 2; front right bumper 40 does not touch the ground and front left bumper 40 is bearing part of the total weight of walking machine 10. Middle and rear legs not visible in FIG. 2 also participate in bearing the total weight. Referring to FIG. 3A, rigid foot 20 comprises a generally hemispheric metal cup 41, of which the convexity is meant to contact the ground, and two metal brackets 42. These brackets extend approximately parallel to one another from the rim of cup 41 at diagonally opposed locations. The distance between the two brackets 42 is equal to the width of dipper 23. Each bracket is perforated by two holes, a lower hole with the same diameter as that of bucket pivot hole 32, and an upper hole with the same diameter as that of guide link pivot hole 37. Both upper and lower holes are located so as to be aligned with pivot holes 32 and 37, respectively, and such that the axis of symmetry of cusp 41 is approximately collinear with the longitudinal axis of dipper 23. Removable means of attachments such as pins 43 secured by cotter pins 44, as shown, or screws and nuts, not shown, hold firmly dipper 23 sandwiched between brackets 42 through holes 32 and 37. As a result, foot 20 is a rigid extension of dipper 23.
FIG. 3. Isometric views of foot end implements and their attachment to a dipper; A, rigid hemispheric foot; B, ankled ball & socket self-centering foot.
Rigid foot 20 described hereinabove is a simple example of general purpose foot end implement 13. The versatility of backhoes is naturally expanded in the field of leg-backhoes, by having different types of feet available for them. A particular type of foot is selected according to the type of ground the walking machine is called to tread on. An ankled foot 45 is described herein as another example of end implement 13. It is similar and yet different from that of the Walking Beam Machine developed by Martin Marietta Astronautics (Rosheim 1994) and from that of US Patent 5,421,426 (de Beaucourt 1995).
Referring to FIG. 3B, ankled foot 45 comprises a generally circular metal plate 46, of which the underside is meant to contact the ground, a ball 47 and socket 48 coupling, two metal brackets 42, a spring mount 49, a spring containment rim 50 and a helical compression spring 51. Ball 47 is fixed rigidly to the center of upper side of plate 46. Brackets 42 extend approximately parallel to one another from the convexity and at diagonally opposed locations of socket 48. Otherwise, brackets 42 are identical to the ones described hereinbefore for rigid foot 20 in FIG. 3A. Inner diameter of helical spring 51 is larger than the diameter of socket 48 and its bracket extensions 42. Lower end of spring 51 rests on plate 46 within rim 50, and the upper end rests against spring mount 49 fixed around brackets 42, as shown in FIG. 3B.
The length and the strength of spring 51 is such that when plate 46 is not contacting the ground, it is pushed by spring 51 to a position approximately perpendicular to the longitudinal axis of dipper 23, and when plate is contacting the ground, it will tend to follow the local contour of the ground under it. In other words, the combination of ball 47 and socket 48 coupling and helical spring 51 constitutes an unpowered self-centering ankle. It is also possible to dispense with spring 51 and let plate 46 dangle horizontally under socket 48 by the action of gravity. The three degrees of freedom conferred to ankled foot 45 by the ball and socket coupling locally reduce the possible churning of the ground, and yet spread loads on a larger surface than that of rigid foot 20 in FIG. 3A. Plate 46 is perforated by a plurality of holes 52 that allow the bolting of accessories such as metal teeth, wooden boards, or rubberlike bumpers, depending of the nature and the vulnerability of the terrain expected to be encountered. For illustration, a conical metal tooth 53 is shown bolted through one of holes 52 in FIG. 3B.
Added to each leg-backhoe as described hereinbefore are a number of sensory transducers. Among those, position transducers encode the chassis-swing frame angle, the swing frame-boom angle, and the boom-dipper angle. These transducers can be of a linear type, for example installed alongside hydraulic cylinders and rods, or embedded in the cylinder itself, or of a rotary type, centered on pivots 18, 26, and 29 of each leg-backhoe. Examples can be found in US Patents 4,202,423 (Soto 1980) or 4,288,196 (Sutton II 1981). Also, pressure transducers encode the fluid pressure in the hydraulic lines leading to cylinders 25, 28, and 31 (Rosheim 1994). This and other sensory information, for example from foot contact sensors, foot strain sensors, or chassis orientation sensors, is sent to the computer system.
The flow of hydraulic fluid in and out of the hydraulic actuators in standard backhoes is controlled by manual valves, for example in US Patents 4,007,845 (Worback 1977) or 4,961,371 (Takashima 1990). In the walking machine of the present invention, this flow is controlled by the computer system, either by electrically operated valves or by electrically controlled variable-displacement pumps (Rosheim 1994). Another difference with standard backhoes is that hydraulic accumulators are tapped in the hydraulic lines leading to cylinders 25, 28, and 31, through electrically operated damping valves also controlled by signals sent by computer system. Finally, the chambers of swing cylinders 25 can be interconnected by electrically operated and computer controlled bypass valves, so that the swing frame can coast passively about its swing axis when these bypass valves are open.
A human operator, by means of a computer-human interface comprising displays, joysticks, keyboards, switches, and pedals, instructs the computer system as to which of several modes it is to be in (Rosheim 1994), which tasks are to be performed, and how those tasks are to be performed. The different modes comprise walking by stepping one leg at a time, walking in an alternating tripod gait (Sutherland 1983), and other statically stable gaits, operating a leg-backhoe as a standard backhoe, and others, some described hereinafter in the Operation section. The computer system is also running a collision-avoidance algorithm responsible for respecting clearance of the segments 21, 22, 23, and end implements 13 with chassis 11 and with segments or end implements of other legs. However, in the design of hexapod walking machine 10 illustrated, the general hardware limitations of standard backhoes prevent the invasion of operator's cab 14 by any parts of leg-backhoes 12, in the event of a computer or hydraulic system failure.
As it is the case for many earth-moving pieces of equipment, the walking machine is brought as close as possible to the work site on a standard flatbed truck or trailer. On the flatbed, the walking machine rests on its chassis and has its leg-backhoes in a folded transport configuration, as shown in FIG. 4. Booms 22 are secured here in an overcenter configuration, as for example in US Patents 3,376,984 (Long 1968) or 5,176,491 (Houkom 1993) but do not need to be. In this configuration, walking machine 10 has overall dimensions of 5.5 m (18") length, 2.4 m (8') width, and 3 m (10') height. On site, the operator activates the walking machine and has it extend its legs to the ground, feet well clear of the lateral edges of the trailer. The operator then has the machine lift its chassis from the flatbed, in a disposition similar to that of FIG. 1, straddling the flatbed, and has the flatbed driven away from under the walking machine standing still on its legs. This is not a critical maneuver, as a road-legal flatbed is about 2.4 m (8') wide and the the clear span of walking machine 10 can reach about 7 m (23') with dippers vertical. Naturally, the walking machine could also walk away from the flatbed.
FIG. 4. Perspective view of walking machine resting on its chassis with all leg-backhoes folded here in an overcenter stowed position. Same conventions as in FIG. 1.
Before detailing the method of walking, an important remark has to be made on the general design of backhoes. Standard backhoes, and therefore leg-backhoes, are designed to exert and withstand large forces within the plane of motion of their dipper relative to their boom, not in the plane of motion of their swing frame. In a backhoe, the bucket digging force, by action of cylinder 34, and the dipper ripping force, by action of cylinder 31, are generally advertised numbers that help to select a particular backhoe for a given task. For example, in the front right leg-backhoe depicted in FIG. 2, with dipper 23 vertical and boom 22 approximately horizontal, foot 20 can exert a force tangential to the ground of about 35 kN (8000 lb) inwards and 26 kN (6000 lb) outwards, by action of dipper cylinder 31. However, in the same configuration, foot 20 can exert a forward or backwards propulsive force tangential to the ground of only about 7 kN (1600 lb), by action of swing frame hydraulic cylinders 25. This limitation of the swing force, 4 to 5 times smaller than the dipperstick force, is due not so much to the bore of swing cylinders 25 than to the stress and strain acceptable in the structure of the leg-backhoe itself. It is therefore apparent that a leg-backhoe is ill-designed to strongly propel a walking machine by using swing frame actuators, for example with the leg disposition of FIG. 5B and the machine walking forward. In other words, just using a backhoe as a leg is not sufficient to make a good leg out of it.
This significant limitation of leg-backhoes now leads to a novel method of walking, controlled by the computer system taking consideration of overall stability, current configuration, operator's commands, and other constraints, described as follows. (a) Any leg-backhoe 12 bearing some weight on the ground with its boom 22 generally aligned with the intended direction of motion of its chassis-swing frame pivot 18 will use its dipper cylinder 31 as primary propulsive force generator. (b) Any leg-backhoe 12 bearing some weight on the ground with its boom 22 generally perpendicular with the intended direction of motion of its chassis-swing frame pivot 18 will use its swing cylinders 25 as accessory propulsive force generator, or not use them at all, so as to be in a propulsory passive yet load-bearing coasting mode. (c) Any leg-backhoe in contact with the ground and not generally in configuration (a) or (b) will be lifted up and aligned so that when it is lowered to the ground it will then be in configuration if possible (a) or else (b) above. This novel walking method enables a walking machine to employ backhoes as efficient legs.
As a result, for hexapod walking machine 10 walking forward, this method of walking leads to the somewhat unconventional leg disposition shown in FIG. 5A, where the front and rear legs provide most of the propulsive forces, and the load-bearing middle legs mostly provide lateral stability, as mobile outriggers. At the extreme, the middle legs on the ground can just coast by opening the bypass valves, or equivalent, of their swing frame actuators. This leg disposition also avoids problems of mutual leg clearance by naturally spacing the leg-backhoes away from one another. For example, if all leg-backhoes were all offset on either side, in a similar configuration to that shown in FIG. 5B, but during forward walking instead of crabwise, a rearward moving leg on the ground would conflict with the leg that follows it when the latter is off the ground and moving forward in search of a foothold. This clearance problem can be especially acute in an alternating tripod gait (Sutherland 1983). Now, for the same walking machine 10 walking this time crabwise, this method of walking leads to the leg disposition shown in FIG. 5B, where all the legs participate to provide propulsive forces, and mutual leg clearances are not a problem.
FIG. 5. Perspective views of machine walking; A, forward in an open space; B, crabwise; C, forward in a narrow space. Same conventions as in FIG. 1.
As walking machines are intended to walk on slopes, some performance estimations to do so are provided, with the same propulsive force values given hereinbefore. The propulsive force F necessary for a machine of total weight W to climb a slope ` is given by the simple formula F = W sin(`). In the case of climbing forward with the leg disposition of FIG. 5A, with 1 leg up, 2 middle legs down coasting, and 3 legs down providing a propulsive force F = 87 kN (20,000 lb), walking machine 10 can theoretically weigh up to W = 174 kN (40,000 lb) and climb or descend a slope ` = 30deg. By comparison, in the case of climbing crabwise with the leg disposition of FIG. 5B, with 1 leg up and 5 legs down providing a propulsive force F = 148 kN (34,000 lb), walking machine 10 can now theoretically weigh up to W = 296 kN (68,000 lb) and climb or descend the same slope ` = 30deg.
The walking machine walks to pick up some cargo, in this example a utility pole 8 m (26') long and 0.23 m (9") diameter weighing 3200 N (720 lb). "Utility pole" is herein meant equally to be telephone pole, electrical pole, antenna, microwave relay tower, tree trunk, or any similar elongated structure. Either by first walking to some pole storage area and straddling one, or by standing still and having a pole carrier driven under it, the utility pole is secured by appropriate means of attachment, described hereinafter, under the chassis of walking machine, so that the pole is located axially between the two front and the two rear legs. In this case the pole actually does not extend beyond the overall length of about 9 m (30') of walking machine 10 having front and rear leg-backhoe booms horizontal and dippers vertical, in a leg disposition similar to that of FIG. 5A.
The walking machine proceeds to walk uphill. If the terrain is very steep or rugged, or if the cargo exceptionally heavy, walking machine 10 steps only one leg at a time for better load- bearing and climbing ability, as shown hereinbefore. At a first difficult location, lateral clearance between two trees is too narrow for machine 10 to keep the leg disposition of FIG. 5A. In this case, a leg disposition depicted in FIG. 5C is adopted until the narrow area is passed. The middle leg booms can be both swung forward, or both rearward, or as shown. These leg dispositions also increase available longitudinal pulling force, had walking machine 10 to tow the utility pole skidding on the ground. At a second difficult location, walking machine 10 encounters a 1.8 m (6') diameter boulder right in its path. In that case, walking machine elevates itself until it can walk over the obstacle while straddling it, as the clearance under the chassis of walking machine 10 can exceed 2.7 m (9') with still good stability. At a third difficult location, the ground is too steep to climb in a forward walking mode depicted in FIG. 5A, or the utility pole conflicts with some fold in the terrain. In that case, walking machine 10 walks crabwise as depicted in FIG. 5B, for reasons hereinbefore explained. The flexibility of these walking modes is enhanced by the agility of the leg-backhoes used as legs; for example, walking machine 10 can turn right while crabbing left and being in a pitched up, rolled right, elevated configuration.
FIG. 6. Perspective view of walking machine resting on the ground and in the process of exchanging front right foot implement for a tool implement, namely, a bucket, in the implement storage area. Same conventions as in FIG. 1.
Upon reaching the implantation site, the operator lowers the walking machine and detaches the utility pole close to the intended ground location, and proceeds to replace the right front foot with a pole digging auger. To do so, chassis is lowered to the ground and that front leg is brought aft to the tool right storage location 16, as shown in FIG. 6. By simply removing a number of pins and washers, the foot is disconnected from the dipper and secured at one location of storage area 16. The distal end of the dipper is then brought to a hydraulically powered helical auger which was stowed in the tool storage area, and connected to it, also with washers and pins. This leg- backhoe is brought forward and under control of the operator its auger end attachment digs a hole for the utility pole. The foot is then reattached to the dipper, by a procedure inverse of the above. In the similar way, the left front leg-backhoe can be fitted with an end implement stowed in the left tool storage area, such as a truss boom crane or a pole grapple, not shown, to insert the utility pole into the hole previously dug out by the auger. To increase the field of action of a leg-backhoe and its tool implement, the chassis can be lifted from the ground by the other leg-backhoes on foot end implements and these legs can be actuated to change the position of the chassis for a more advantageous orientation.
There is no need to exchange a tool implement for a foot implement every time walking machine 10 is to move about short distances at a work site. Statically stable walking with 5 or even 4 feet is possible by lifting only one leg at a time, albeit with reduced performance. Also, some tool implements such as hammers or breakers can be tread on without much risk of damage. In case of damage to a leg-backhoe, walking machine 10 is not immobilized in some terrain unreachable by repair vehicles. The damaged leg-backhoe is disconnected from the chassis by an adjacent leg-backhoe used as a crane, in a method similar to that depicted in FIG. 6, and the walking machine limps back to a more convenient or accessible terrain.
After the pole implantation work is completed, walking machine 10 proceeds back to its original starting point by a shorter but more rugged route. At one difficult location, even using all available ground clearance, the chassis happens to contact the ground and drags on it. This is done without damage because of bumpers 40. Furthermore, a leg-backhoe happens to contact and apply load-bearing force on a protuberance of the ground not under its foot, but under its boom. This is done without other damage than paint wear and tear because of the ruggedness of backhoes in general. The central computer will note this unconventional state by its monitoring of hydraulic pressures, whereas foot sensors only, such as in US Patent 5,421,426 (de Beaucourt 1995) could erroneously make it believe that the leg is up in the air. Many walking machines are designed for ground contact only at the feet; the walking machine of the present invention can contact the ground by its chassis and other parts of its leg-backhoes, as many living reptiles and arthropods actually do. Finally, the operator lowers walking machine 10 onto the flatbed it originated from, and folds the legs in the configuration of FIG. 4 to be driveable to some other location.
The hydraulic system of standard backhoes is designed to be as little compliant as possible, to allow precision and repeatability in the operation of the backhoe. However, walking on a hard unyielding surface such as a solid rock bed can create potentially damaging pressure spikes in the hydraulic system of leg-backhoes. In the walking modes described hereinbefore, the described damping valves will generally be open to let hydraulic lines communicate with hydraulic accumulators, as means to dampen those spikes. Also, when these damping valves are open and walking machine 10 has more than 3 leg-backhoes bearing weight, this weight tends to be more equally spread among the feet. When its damping valves are closed, on the contrary, a leg-backhoe regains the rigidity of the standard backhoe it is derived from. The hereinbefore described operations where a leg-backhoe is used for other functions than walking are generally done with damping valves closed. In any case, the operator retains ultimate control of the state of all damping valves.
The hereinbefore utility pole scenario is only an example, but it shows not only that some rugged terrain previously not accessible to wheeled or tracked vehicles can be reached by a land machine, but also a new mode of operation, in great part thanks to the choice of backhoes as legs. Minimal logistic support is needed, in the form of a flatbed vehicle. A complex and varied task is accomplished by a single walking machine. The task can be controlled and executed by a single operator. As a result, this work can be uncommonly planned as a solo "in and out" operation. In this example, the cost of the implantation is cheaper than that of airlifting a "utility pole" slung under a helicopter, as it is sometimes done, and one of the reasons why those "utility poles" usually follow roads.
The walking machine 10 described hereinbefore can carry some payload, generally tool and foot end implements, in storage areas 16, and bulkier payloads attached under the chassis by means hitherto undescribed. The underside of the chassis of walking machine 10 possesses means of external payload attachment such as rings, hooks, tongues & grooves, pins, holes, clevises, bolts, and latches, as well as the usual securing and tow shackles generally found on earth moving equipment. These means of attachment secure removable external payloads snugly so that the payload does not sway during walking. For example, the "utility pole" described hereinbefore is secured to the chassis by these means of attachment through straps and cables. Provided they fit in these means of attachment, payloads can thereby be picked up, transported by walking, and released by walking machine 10 used as a walking crane. These payloads comprise passive payloads such as containers or tools, or active payloads such as hydraulically powered equipment. In this latter description, chassis 11 becomes direct support for equipment, and is equipped with power transmission devices such as Power Take Offs (PTO) common on agricultural tractors, or quick-connect hydraulic couplings tapping in the pressurized hydraulic fluid generated in machinery compartment 15.
Referring to FIG. 7, a removable tracked cart 54 is attached as an addition to walking machine 10. Cart 54 comprises a chassis 55 which is connected by the means of attachment described hereinbefore to the underside of chassis 11 of walking machine 10, and which is equipped with right and left tracks 56 guided and propelled by wheels 57. Hydraulic motors power the wheels that entrain the tracks. Total width of cart 54 and its tracks does not exceed that of walking machine 10 in its stowed configuration. Pressurized hydraulic fluid is provided to the hydraulic motors via quick-connect couplings between chassis 11 and 55. The velocity and direction of the hydraulic motors and thereby of the tracks is controllable by the operator in cab 14. In FIG. 7 the middle and rear legs are in the same configuration as in FIG. 4, but booms 22 of the front legs are lowered to offer a better field of view to the operator in cab 14. The feet implements illustrated in FIG. 7 are springless variants of ankled feet 45 of FIG. 3B, and the front feet are shown resting onto storage areas 16. Unlike what was described previously, walking machine 10 can now be considered itself as a payload for tracked cart 54.
FIG. 7. Side view of walking machine with leg-backhoes in a stowed configuration, docked onto a tracked chassis standing with its tracks on the ground.
Operation of walking machine 10 with its tracked cart 54 addition is as follows. With its leg-backhoes configurated as shown in FIG. 7, walking machine can be driven in a self- propelled way on existing roads and on terrain tractable by the tracks of chassis 55, at a greater speed than would be possible by walking. At a location selected by the operator, motion is stopped, and the hydraulic couplings and the means of attachment between chassis 11 and 55 are disconnected. Uncoupled walking machine 10 is now operable just as described hereinbefore from the flatbed trailer. The inverse operation consists in docking walking machine 10 to cart 54, securing them together by the mentioned means of attachment, and connecting the quick-connect couplings.
Operation of walking machine 10 coupled with cart 54 was described with legs in a stowed position. However, leg-backhoes are free to move even when chassis 55 is attached to chassis 11. Operator can unfold and use the legs to help the tracks pull out of a sand or mud pit, for example. As chassis 55 only supports a pair of tracks and a few hydraulic motors, cart 54 is light enough to be lifted altogether by walking machine 10 standing on its leg-backhoes, and repositioned in a more suitable area. Again using their duality of function, the leg-backhoes of walking machine 10 docked to cart 54 can be used as backhoes in all the ways described hereinbefore, further extending their adaptability. Cart 54 is to be considered as yet another attachment for walking machine 10, although the combination of chassis 11 and 55 creates a novel kind of versatile legged and tracked machine.
A first type of octopod is a hexapod walking machine 10, where the middle leg-backhoes are duplicated into twins, with their swing frames relatively close to one another in the longitudinal direction. In this arrangement, these twin middle leg-backhoes on each side move generally in synchrony during walking. A natural example can be found in millipedes, who possess two pairs of legs per body segment. If the twin middle legs are functionally used as a single one during walking, this octopod can adopt the standard alternating tripod gait of a hexapod, yet in a more powerful way.
A second type of octopod is also a hexapod walking machine 10, where the middle leg-backhoes are also duplicated, but with their swing frames well separated from one another in the longitudinal direction, until they are relatively close to the front and rear leg-backhoes. In this arrangement, during walking, these duplicated middle leg-backhoes generally alternate with one another, and also alternate with their immediate neighboring front or rear leg-backhoe, resulting in a form of alternating tetrapod gait, with the same load-bearing advantages aforementioned.
The walking machines described possess six or eight leg- backhoes, but can possess a different number, either odd or even. In an extreme design, the chassis itself could be articulated in jointed segments, as in US Patent 4,122,959 (Stedman 1978), with one pair of leg-backhoes per chassis segment. A natural example can be found in centipedes, who also possess one pair of legs per body segment.
The swing frame of the leg-backhoe is swung by hydraulic cylinders in hereinbefore embodiments, for example as in US patent 4,039,095 (Long 1977). However, they can be swung with fluid motors, for example as in US Patent 3,968,731 (Myers 1976) or 4,122,959 (Stedman 1978). These motors offer a gain of space that can allow the swing frames to be closer to one another, and can offer greater swing angle, especially for the front legs.
The number and the geometric arrangement of hydraulic cylinders or motors on the backhoe used as leg in the preferred embodiment varies with manufacturers. Some backhoes have telescopic dippers; a leg-backhoe can have the same. Some booms and some dippers have supplemental pivots further increasing their agility, or some booms have extended reach, for example as in US Patent 4,715,771 (Hanson 1987); a leg-backhoe can have the same as well. Sensor and valve arrangement would be modified accordingly.
The bore of hydraulic cylinders and therefore the force they can generate, can be increased if necessary. In particular the bore of boom cylinder 28 can be increased by a relatively small fraction and the load that leg-backhoe can bear is significantly increased, and yet the backhoe retains all its backhoe functions. Hydraulic cylinder actuators are often interchangeable between manufacturers.
Finally, all the dimensions given hereinbefore are only one example. In particular, the width in the folded configuration of FIG. 4 can be much wider or narrower than the 2.4 m (8') example which was selected as a maximum allowable on roads as per Department of Transportation regulations.
Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.
It is claimed: 1. A walking machine comprising: (a) a chassis support for an engine connected to means for providing pressurized hydraulic fluid, (b) a plurality of vertically spaced groups of brackets protruding outwards on the periphery of said chassis, with pivot holes in said brackets defining through each group a generally vertical swing axis, (c) a plurality of commercially manufactured backhoes, that is excavators, each comprising the jointed members of, namely, a swing frame pivoting proximally about said swing axis on said chassis, a boom pivoting at its proximal end about a horizontal pivot axis in said swing frame, an elongated dipper pivoting in the vicinity of its proximal end about a horizontal pivot axis at the distal end of said boom and possessing means for attachment of a removable bucket at its distal end, as well as actuators selected from the group consisting of hydraulic cylinders and hydraulic motors as means for pivoting said swing frame about said chassis, said boom about said swing frame, and said dipper about said boom, (d) a plurality of removable foot end implements, means for supporting a fraction of the weight and loads of said walking machine and to protect the distal end of said dippers when contacting the ground, with means for attachment of said foot end implements to the distal end of any one of said dippers, (e) a plurality of removable tool end implements selected from the group consisting of buckets, rippers, teeth, breakers, grinders, impactors, augers, drills, shears, claws, grapples, hammers, saws, harvesters, limbing heads, feller-bunchers, and truss booms, with means for attachment of said tool end implements to the distal end of any one of said dippers not terminated by one of said foot end implements, (f) throttle means for controlling hydraulic fluid flow and pressure in hydraulic lines to or from said actuators, selected from the group consisting of electrically operated valves and electrically controlled variable displacement hydraulic pumps, (g) position sensors, means for encoding in each of said backhoes the angle of said swing frame relative to said chassis, of said boom relative to said swing frame, and of said dipper relative to said boom, (h) a computer system collecting sensory signals from said sensors and sending appropriate command signals to said throttle means, so that backhoes terminated by foot end implements are coordinated for walking and so that backhoes terminated by tool end implements are usable as tools, (i) a walking method in which said computer system coordinates said actuators so that propulsive force is provided primarily by the actuators moving said dippers relative to said booms and only accessorily by the actuators moving said swing frames relative to said chassis, whereby said walking machine will be able to walk on said backhoes terminated by said foot implements, and to use as tools said backhoes terminated by said tool implements, thereby providing a machine combining the functions of both walking machines and backhoes. 2. The walking machine of claim 1, further including hydraulic accumulators connected to said hydraulic lines between said throttle means and said actuators, whereby damping hydraulic fluid pressure surges and providing a more even spread of ground forces when more than 3 feet are simultaneously on the ground. 3. The walking machine of claim 2, further including valves between said hydraulic accumulators and said hydraulic lines, with said valves generally opened during walking and generally closed during backhoe operations requiring precision or rigidity, whereby providing a commutable compliance. 4. The walking machine of claim 1, wherein the underside of said chassis is equipped with replacable protective elements selected from the group of shock absorbers, skids, springs, strike plates, bumpers, rollers, wheels, and swivel wheels, whereby easing the interaction of said chassis with obstacles in case of occasional contact with them. 5. The walking machine of claim 1, wherein the underside of said chassis possesses means for attaching external payloads, whereby said walking machine will be able to pick, carry, and release said external payloads. 6. The walking machine of claim 1, wherein the underside of said chassis possesses means for securing said chassis to a removable cart bearing axle-based locomotion devices selected from the group consisting of wheels and tracks, whereby the walking machine without any of its backhoes touching the ground will be a payload of said cart. 7. The walking machine of claim 6, wherein said axle- based locomotion devices in said cart are powered by hydraulic motors connected via hydraulic couplings to said means for providing pressurized hydraulic fluid in said walking machine, whereby a hybrid self-propelled vehicle will be created. 8. The walking machine of claim 1, wherein one of said tool implements is also able to perform the functions of a foot, whereby said walking machine can essentially walk on tools. 9. The walking machine of claim 1, further including means for said swing frames to pivot passively about their respective swing axes, whereby said backhoes can coast while still bearing weight. 10. The walking machine of claim 1, (a) wherein said chassis has a generally rectangular shape approximately twice as long as wide, (b) further including at a front axial location of said chassis, an operator's cab containing a seat for an operator, and containing human-computer interface devices selected from the group consisting of displays, keyboards, joysticks, trackballs, switches, and pedals, connected to said computer system, (c) wherein said engine is located in a machinery compartment at a rear and partially middle axial location of said chassis, (d) further including storage areas for said backhoe end implements in generally horizontal areas on the upperside of said chassis on both sides of said machinery compartment, (e) wherein said plurality of backhoes amounts to 6, namely two front, two middle, and two rear backhoes, with the following geometrical constraints, (i) the distance between swing axes of rear backhoes does not exceed that of the front backhoes, (ii) the distance between swing axes of middle backhoes exceeds that of front backhoes by at least one middle swing frame width, so that the middle backhoes have the ability to swing outwards from front to rear without encountering any parts of the chassis, (iii) each front swing frame has the ability to swing outwards at least from front to rear without encountering any parts of the chassis, so that with front boom elevated for clearance of middle brackets and middle swing frame, a front dipper is able to reach said end implement storage area on its side, (iv) each rear swing frames has the ability to swing outwards at least from 45deg front to fully aft without encountering any parts of the chassis, whereby said hexapod walking machine will be able to walk on said backhoes terminated by said foot implements, to swing a front backhoe to said implement storage area on the same side, to have there its foot implement at the end of the front dipper replaced by one of said tool implements, so as to be able to perform with said front backhoe a task unrelated to walking, and vice-versa, thereby providing a machine which can switch in the field the functions of both walking machines and backhoes. 11. The hexapod walking machine of claim 10, further including pressure sensors, means for encoding the pressure of said hydraulic fluid in said hydraulic lines between said throttle means and said actuators, with resulting pressure information transmitted to said computer system, whereby providing a better picture of the overall state of the walking machine to said computer system. 12. The hexapod walking machine of claim 10, wherein said backhoes to be used for the right and left middle legs are modified by exchanging original boom actuators by actuators of a larger working area, that is in particular a larger bore for a cylinder actuator, whereby enabling the middle legs to bear increased weight. 13. The walking machine of claim 1, wherein said chassis has a generally rectangular shape, and wherein said plurality of backhoes amounts to 8, with swing frames thereof attached in pairs in the vicinity of each corner of said chassis such that: (a) an anterior front left backhoe is able to pivot about 180deg from left to right but generally extends front, (b) a lateral front left backhoe is able to pivot about 180deg from front to rear but generally extends left, (c) an anterior front right backhoe is able pivot about 180deg from left to right but generally extends front, (d) a lateral front right backhoe is able to pivot about 180deg from front to rear but generally extends right, (e) a posterior rear left backhoe is able to pivot about 180deg from left to right but generally extends rear, (f) a lateral rear left backhoe is able to pivot about 180deg from front to rear but generally extends left, (g) a posterior rear right backhoe is able to pivot about 180deg from left to right but generally extends rear, (h) a lateral rear right backhoe is able to pivot about 180deg from front to rear but generally extends right, whereby said walking machine will exhibit the general appearance of a spider and the risk of inter-leg collision legs will be minimized. 14. The walking machine of claim 13, wherein said computer system sends off signals to said throttle means so that; (a) in walking forward, propulsive force is provided primarily by the actuator pivoting the dipper about the end of boom of said legs (a), (c), (e), and (g), and accessorily by the actuators swinging the swing frames of said legs (b), (f), (d), and (h), used as means of supplemental stability, (b) in walking crabwise, propulsive force is provided primarily by the actuator pivoting the dipper about the end of boom of said legs (b), (f), (d), and (h), and accessorily by the actuators swinging the swing frames of said legs (a), (c), (e), and (g), used as means of supplemental stability, whereby said backhoes will be used in a way consistent with their general design. 15. A walking method for walking machines comprising a chassis on the periphery of which is attached a plurality of backhoes each comprising a swing frame pivoting vertically on said chassis, a boom pivoting horizontally on said swing frame, a dipper pivoting horizontally on said boom, and a foot implement attached to the distal end of said dipper, method such that, (a) any backhoe with a foot implement bearing some weight on the ground and with its boom generally aligned with the intended direction of motion of the attachment of said backhoe to said chassis will use the actuators moving its dipper as a primary propulsive force generator, (b) any backhoe with a foot implement bearing some weight on the ground and with its boom generally perpendicular to the intended direction of motion of the attachment of said backhoe to said chassis will use the actuators moving its swing frame as an accessory propulsive force generator, (c) any backhoe in contact with the ground and not generally in configuration (a) or (b) will be lifted up and swung so that when it is lowered to the ground it will then be in configuration if possible (a) or else (b) above, whereby said backhoes will mostly exert forces within the vertical plane of motion of their booms and dippers and not horizontally about their swing axes. 16. The method of claim 15, further including hydraulic fluid bypass means for neutralizing said swing frame actuators when a backhoe is in said situation (b), whereby this backhoe will be able to coast while still bearing weight. 17. A foot implement for a walking machine, comprising two upwardly projecting and generally parallel metal brackets each pierced by two holes, with said brackets separated so as to sandwich the distal end of the dipper of a backhoe of which standard bucket and associated guide links have been removed, with said brackets attached by elongated fasteners, selected from the group consisting of pins and bolts, through said holes and, respectively, the bucket pivot hole and the guide link pivot hole of said dipper, whereby said foot implement effectively transforms said backhoe into a leg to be attached to said walking machine.
3,376,984 1968 Long 214/138 Backhoe. 3,968,731 1975 Myers 91/407 Fluid motor for swinging booms. 4,007,845 1977 Worback 214/138D Swing mechanism. 4,039,095 1977 Long 214/138D Swing mechanism for backhoe. 4,049,070 1977 Soyland 180/8C Excavator having lifting legs and cooperating boom mounted bucket for "walking". 4,122,959 1978 Stedman 314/138R Backhoe with multi-movement capabilities. 4,202,423 1980 Soto 180/8D Land vehicle with articulated legs. 4,265,326 1981 Lauber 180/8R Rolling and stepping vehicle. 4,288,196 1981 Sutton II 414/699 Computer controlled backhoe. 4,358,240 1982 Shumaker 414/694 Asymmetric backhoe. 4,395,191 1983 Kaiser 414/694 Excavator-hoist construction vehicle. 4,482,287 1984 Menzi 414/694 Excavator. 4,715,771 1987 Hanson 414/688 Variable geometry mounting arrangement for backhoe assembly. 4,961,371 1990 Takashima 91/530 Hydraulic circuit for a backhoe. 5,040,626 1991 Paynter 180/8.1 Walking robots having fluid driven twistor pairs as combined joints and motors and method of locomotion. 5,176,491 1993 Houkom 414/694 Overcenter backhoe apparatus. 5,421,426 1995 de Beaucourt 180/8.1 Walking robot foot. 5,513,716 1996 Kumar 180/8.3 Adaptive mobility system.
Caterpillar (1992) Ride Control System. Flyer AEHQ3759 (4-92). John Deere (1982) JD410 Loader Backhoe Operator's Manual TM 5- 2420-222-14 & P1. Headquarters, Department of the Army, Washington D.C. 28 October 1982. Pages 26-27, 241-243. Plustech (1997) A walk in the forest. Popular Science 250:(2)17, February 1997, "Forest Harvester" by Plustech Oy, Lokomonkatu 15, Box 306, 33101 Tampere, Finland. Rosheim, M.E. (1994). Robot Evolution: The Development of Anthrobotics. New York: John Wiley & Sons. Pages 235-251. Schaeff (1996) HSM 41 Mobile Walking Excavator. Flyer 01/96 GB/US. Karl Schaeff GmbH & Co., Maschinenfabrick, Schaefferstrasse 8, D-74595 Langenburg/Wuerttenberg, Germany. Sutherland, I.E. (1983) A Walking Robot (2nd. Ed.). Pittsburgh, PA: Marcian Chronicles, Inc. Pages 103-105 and Figure 11-1. Todd, D.J. (1985) Walking Machines: An Introduction to Legged Robots. London: Kogan Page Ltd. Pages 49-55 and Figure 2-11.