Walking robot

Abstract

To provide a walking robot that can walk stably even with large strides. [Solution] A walking robot 100 comprising a pair of bases 110 that move relative to each other, a plurality of legs 130 attached to each base 110, a leg drive device 140 that moves the plurality of legs 130 individually in the vertical direction relative to the base 110, a base drive device 150 that moves the pair of bases 110 relative to each other, weights 160, 170 provided corresponding to each base 110 and that move relative to the base 110, weight drive devices 161, 171 that move the weights 160, 170, and a control device 190, wherein the control device 190 moves the weights 160, 170 in a direction that minimizes the change in the overall center of gravity of the walking robot 100 due to the movement of the base 110 on the side to which the legs 130 that are free legs (away from the ground 10) are attached.

Description

Technical Field

[0001] The present invention relates to a walking robot, and more particularly to a walking robot having a plurality of legs.

Background Art

[0002] Patent Document 1 discloses a robot that moves by raising and lowering six legs. The robot disclosed in Patent Document 1 has three legs in one set, and two such sets are provided. The three legs constituting one set are integrated. The integrated three legs can move up and down, can move horizontally by a feed mechanism, and can rotate by a rotation mechanism. The robot disclosed in Patent Document 1 walks by moving the legs with the center of gravity within a polygon formed by connecting the tips of the legs. The description of the prior art document is incorporated herein by reference as an explanation of the technical elements in this specification.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the robot disclosed in Patent Document 1, when attempting to walk stably, it is preferable that the center of gravity is as close as possible to the center of the polygon even within the polygon formed by connecting the tips of the legs. Therefore, when the robot disclosed in Patent Document 1 attempts to walk stably, it is difficult to move with a large stride.

[0005] The present disclosure has been made based on this situation, and an object thereof is to provide a walking robot that can walk stably even with a large stride.

Means for Solving the Problems

[0006] The above objectives are achieved by combinations of features described in the independent claims, and the subordinate claims provide further advantageous specific examples. The reference numerals in parentheses in the claims indicate a correspondence with specific embodiments described later as one aspect, and do not limit the disclosed technical scope.

[0007] One disclosure for achieving the above objective is a pair of bases (110) that move relative to each other, Each base has multiple legs (130) attached to it, A leg drive device (140) that moves multiple legs individually in the vertical direction relative to the base, A base drive device (150) for moving a pair of bases relative to each other, Each base has corresponding weights (160, 170, 270) that move relative to the base, Weight drive devices (161, 171) for moving the weights, A walking robot comprising a control device (190) that controls a leg drive device, a base drive device, and a weight drive device, The control device moves the weights in a direction that minimizes the change in the overall center of gravity of the walking robot caused by the movement of the base on the side to which the free leg (the leg that is off the ground) is attached.

[0008] This walking robot is equipped with weights that move relative to its base, and these weights are moved in a direction that minimizes the movement of the center of gravity caused by the movement of the swing leg. As a result, the movement of the robot's overall center of gravity is minimized even when taking large strides. Therefore, it can walk stably even when taking large strides. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram showing the walking robot of the first embodiment from a direction horizontal to the ground. [Figure 2]View of the walking robot from above. [Figure 3] Diagram for explaining the walking motion in the case of the comparative example. [Figure 4] Diagram for explaining the walking motion of the walking robot of the first embodiment. [Figure 5] Diagram for explaining the walking motion in the case of the comparative example. [Figure 6] Diagram for explaining the walking motion of the walking robot of the first embodiment. [Figure 7] Flowchart showing the processes executed by the control device when the walking robot walks. [Figure 8] Diagram for explaining the forces generated by the movement of the base and the movement of the weight. [Figure 9] Diagram showing an example of suppressing a fall by controlling the leg drive device. [Figure 10] Diagram showing an example of suppressing a fall by controlling the weight control device. [Figure 11] Diagram showing an example of suppressing a fall by controlling the base drive device. [Figure 12] Diagram showing the walking robot of the second embodiment. [Figure 13] Diagram showing the walking robot of the third embodiment. [Figure 14] Diagram for explaining the coordinates used in Equation 1. [Figure 15] Diagram for explaining α used in Equation 1. [Figure 16] Diagram showing the processes executed by the control device in the fourth embodiment. [Figure 17] Diagram showing the walking robot of the seventh embodiment. [Figure 18] Diagram showing the planar shapes of the upper housing and the lower housing. [Figure 19] Diagram showing the processes executed by the control device in the seventh embodiment. [Figure 20] Diagram showing the walking robot of the seventh embodiment in a fallen state. [Figure 21] Diagram showing the walking robot of the seventh embodiment returning from the fallen state. [Figure 22]Figure showing the state where the lower housing of the walking robot of the seventh embodiment is in contact with the ground. [Figure 23] Figure showing the processing executed by the control device in the eighth embodiment. [Figure 24] Figure showing the walking robot of the ninth embodiment. [Figure 25] Figure showing the state where the walking robot of the ninth embodiment is standing on its own. [Figure 26] Figure showing the state where the walking robot of the ninth embodiment has fallen over. [Figure 27] Figure showing the state where the walking robot of the ninth embodiment is recovering from the fallen state. [Figure 28] Figure showing the processing executed by the control device in the tenth embodiment. [Figure 29] Figure showing the state where the walking robot of the tenth embodiment has fallen over. [Figure 30] Figure showing the state where the walking robot of the tenth embodiment has recovered from the fallen state. [Figure 31] Figure showing the housing of the eleventh embodiment. [Figure 32] Figure showing the housing of the twelfth embodiment. [Figure 33] Figure showing the walking robot of the thirteenth embodiment. [Figure 34] Figure showing the state where the walking robot of the thirteenth embodiment is standing on its own. [Figure 35] Figure showing the state where the walking robot of the thirteenth embodiment is upside down. [Figure 36] Figure showing the state where the walking robot of the thirteenth embodiment resumes walking while upside down. [Figure 37] Figure showing the processing executed by the control device in the thirteenth embodiment.

Mode for Carrying Out the Invention

[0010] <First Embodiment> The embodiments will be described below with reference to the drawings. Figure 1 is a view of the walking robot 100 of the first embodiment from a direction horizontal to the ground 10. Figure 2 is a view of the walking robot 100 from above.

[0011] As shown in Figures 1 and 2, the walking robot 100 is equipped with a pair of bases 110. The upper base 110 of the pair is designated as the upper base 111, and the lower base 110 is designated as the lower base 112. The upper base 111 and the lower base 112 are identical in shape, being flat and triangular in plan view.

[0012] Legs 130 are attached to the vertices of the upper base 111 and the lower base 112, respectively. Since the upper base 111 and the lower base 112 are triangular in shape, the walking robot 100 has a total of six legs 130.

[0013] The leg 130 attached to the upper base 111 is designated as leg 131, and the leg 130 attached to the lower base is designated as leg 132. A leg drive device 140 is attached to each leg 130. The leg drive device 140 moves the leg 130 in the vertical direction. A linear actuator can be used as the leg drive device 140.

[0014] The leg drive unit 140 causes the leg 131 to move vertically relative to the upper base 111, that is, perpendicular to the upper base 111, and the leg 132 to move vertically relative to the lower base 112, that is, perpendicular to the lower base 112.

[0015] The upper base 111 and the lower base 112 are connected by two base drive units 150. The base drive units 150 include a base drive unit 151 attached to the upper base 111 and a base drive unit 152 attached to the lower base 112. The base drive units 151 and 152 are coupled to each other, and the base drive unit 151 moves the upper base 111 and the lower base 112 relative to each other in a linear direction along the plate surfaces of the upper base 111 and the lower base 112. The base drive unit 152 moves the upper base 111 and the lower base 112 relative to each other in a direction perpendicular to the driving direction of the base drive unit 151, along the plate surfaces of the upper base 111 and the lower base 112.

[0016] The weight 160 is positioned below the lower base 112. The weight 160 is provided in correspondence with the lower base 112. The weight 160 is fixed below the lower base 112 via a weight drive unit 161. The weight 160 is moved by the weight drive unit 161 and moves relative to the lower base 112. The weight drive unit 161 moves the weight 160 in a direction parallel to the direction of relative movement between the upper base 111 and the lower base 112 by the base drive unit 152. A linear actuator can be used as the weight drive unit 161.

[0017] The imaging device, camera 170, is positioned above the upper base 111. The camera 170 is fixed to the upper base 111 via a camera drive unit 171. The camera 170 is moved by the camera drive unit 171 and moves relative to the upper base 111. The camera drive unit 171 moves the camera 170 in a direction parallel to the relative movement direction of the upper base 111 and lower base 112 by the base drive unit 151. A linear actuator can be used as the camera drive unit 171. In this embodiment, the camera 170 is also used as a weight. Therefore, the camera drive unit 171 is also a weight drive unit. The camera 170 is a weight provided in correspondence with the upper base 111. Note that in Figures 1 and 2, the base drive unit 150, weight drive unit 161, and camera drive unit 171 are simplified.

[0018] The posture estimation device 180 is mounted between the base drive unit 151 and the base drive unit 152 and estimates the posture of the walking robot 100. The posture of the walking robot 100 can also be described as the tilt of the walking robot 100. The tilt of the walking robot 100 refers to the tilt of the upper base 111 and the lower base 112. The posture estimation device 180 can also be called a tilt estimation device. An inertial measurement unit can be used as the posture estimation device 180. The inertial measurement unit is equipped with a 3-axis angular velocity sensor, a 3-axis acceleration sensor, and a temperature sensor.

[0019] The control device 190 is a device that controls the walking of the walking robot 100. In Figure 1, the control device 190 is assumed to be located in the same position as the posture estimation device 180. In Figure 1, the positions of the posture estimation device 180 and the control device 190 are near the center of the walking robot 100. However, the position of the control device 190 is not limited to this position. There are no particular restrictions on the position of the control device 190.

[0020] The control device 190 makes the walking robot 100 walk by controlling the leg drive unit 140 and the base drive unit 150. The control device 190 also suppresses changes in the walking robot 100's center of gravity by controlling the weight drive unit 161 and the camera drive unit 171 while acquiring the inclination of the upper base 111 and lower base 112 estimated by the posture estimation device 180. The control device 190 may be equipped with a wireless communication function so that an external operator can input instructions to the control device 190.

[0021] [Description of the walking motion of walking robot 100] The walking motion of walking robot 100 will be explained in comparison with walking robot 100a, which lacks weights, as a comparative example. Walking robot 100a is the same as walking robot 100 except that it lacks weights.

[0022] Figure 3 illustrates the walking motion in the case of a comparative example, specifically when walking in a direction perpendicular to one side of the lower base 112. As this is a diagram illustrating walking motion, the walking robot 100a is shown in a simplified form. In Figures 3 to 6, black circles represent the stance leg and white circles represent the swing leg. The stance leg refers to the leg 130 that is in contact with the ground 10, and the swing leg refers to the leg 130 that is away from the ground 10.

[0023] Let time t0 be the initial state. At time t0, leg 131 of the upper base 111 is the standing leg, and leg 132 of the lower base 112 is the free leg. The position of the center of gravity of the lower base 112 (hereinafter, lower base center of gravity) GL is the same as the position of the center of gravity of the upper base 111 (hereinafter, upper base center of gravity) GU. As a result, the overall center of gravity of the walking robot 100a (hereinafter, overall center of gravity) Gt is also at the same position as the lower base center of gravity GL and the upper base center of gravity GU. The stability margin M is the distance between the edge of the base 110 to which the standing leg is attached that is closest to the overall center of gravity Gt and the overall center of gravity Gt. The shorter the stability margin M, the more unstable the walking robot 100a is. If the stability margin M is zero, that is, if the overall center of gravity Gt is located outside the base 110 to which the standing leg is attached, the walking robot 100a will fall over.

[0024] Time t1 represents the state in which the base drive unit 152 is driven from the state at time t0. Since the leg 132 attached to the lower base 112 is a free leg, when the base drive unit 152 is driven, the position of the upper base 111 does not change, and the lower base 112 moves to the right in Figure 3, as shown at time t1. The movement of the lower base 112 also moves the center of gravity GL of the lower base. The movement of the center of gravity GL of the lower base also moves the overall center of gravity Gt to the right in Figure 3. As a result, the stability margin M is very small.

[0025] At time t2, the swing leg and stance leg have been swapped. That is, the state of the walking robot 100a at time t2 is that, from the state at time t1, the leg 132 attached to the lower base 112 has been moved downward to make contact with the ground 10, and then the leg 131 attached to the upper base 111 has been moved upward. Since only the swing leg and stance leg have been swapped, the position of the overall center of gravity Gt at time t2 has not changed from the position of the overall center of gravity Gt at time t1.

[0026] As the supporting leg changes to the leg 132 of the lower base 112, the stability margin M changes to a length based on the lower base 112. However, the size of the stability margin M is the same as at time t1, and the stability margin M is very small.

[0027] At time t3, the base drive unit 152 is being driven. Since the leg 131 attached to the upper base 111 is in a free-moving position, the drive of the base drive unit 152 causes the upper base 111 to move to the right in Figure 3.

[0028] At time t4, the stance leg and free-floating leg have been swapped from the state at time t3. The state of walking robot 100a at time t4 is almost the same as the state of walking robot 100a at time t0. Therefore, it can be seen that by repeating the above-described operation, walking robot 100a can move to the right in Figure 3. However, looking at the state at time t1 and time t2, it can be seen that the stability margin M is small and the robot becomes unstable during movement.

[0029] Figure 4 illustrates the walking motion of the walking robot 100 according to the first embodiment. At time t0, similar to time t0 in Figure 3, the leg 131 of the upper base 111 is in the standing position, the leg 132 of the lower base 112 is in the free position, and the position of the center of gravity GL of the lower base coincides with the position of the center of gravity GU of the upper base. Figure 4 also shows the center of gravity Gw of the weight. The center of gravity Gw of the weight is the center of gravity of the weight. Here, the weight includes not only the weight 160 but also the camera 170.

[0030] Assume that the weight is adjusted so that the gravitational force acting on the weight's center of gravity Gw is the same as the gravitational force acting on the upper base center of gravity GU by the components of the walking robot 100 excluding the weight when leg 131 is in a free-floating position. Note that the gravitational force acting on the upper base center of gravity GU by the components of the walking robot 100 excluding the weight when leg 131 is in a free-floating position is the same as the gravitational force acting on the lower base center of gravity GL by the components of the walking robot 100 excluding the weight when leg 132 is in a free-floating position.

[0031] The position of the weight center of gravity Gw also coincides with the positions of the lower base center of gravity GL and the upper base center of gravity GU. Therefore, the overall center of gravity Gt of the walking robot 100 is also in the same position as the lower base center of gravity GL, the upper base center of gravity GU, and the weight center of gravity Gw.

[0032] At time t1, similar to time t1 in Figure 3, the base drive unit 152 is driven to move the lower base 112 to the right in Figure 3. In addition, the weight 160 is moved so that the weight's center of gravity Gw is in a position symmetric to the lower base's center of gravity GL with respect to the upper base's center of gravity GU. As a result, as shown at time t1, the overall center of gravity Gt coincides with the geometric center of gravity of the upper base 111 to which the support legs are attached, and the maximum value of the stability margin M is maintained.

[0033] At time t2, the swing leg and stance leg are swapped, similar to time t2 in Figure 3. First, the leg 132 attached to the lower base 112 is moved downward to make contact with the ground 10. Then, the weight 160 is moved so that the weight's center of gravity Gw is point-symmetric with respect to the upper base's center of gravity GU, with respect to the lower base's center of gravity GL. Next, the leg 131 attached to the upper base 111 is moved upward to become the swing leg. As the leg 131 becomes the swing leg, the overall center of gravity Gt shifts. Before the leg 131 becomes the swing leg, the weight's center of gravity Gw was moved so that it is point-symmetric with respect to the upper base's center of gravity GU, with respect to the lower base's center of gravity GL. Therefore, the stability margin M is maintained at its maximum value.

[0034] At time t3, the base drive unit 152 is driven to move the upper base 111, which is the base 110 on the free leg side, to the right in Figure 4. In conjunction with the movement of the upper base 111, i.e., the movement of the upper base's center of gravity GU, the weight 160 is moved so that the center of gravity Gw of the weight moves in the opposite direction to the upper base's center of gravity GU by an amount equal to the movement of the upper base's center of gravity GU. In this way, even while the upper base 111 is moving, the overall center of gravity Gt is maintained at the position of the geometric center of gravity of the lower base 112 to which the standing leg 132 is attached.

[0035] At time t4, the free leg and the standing leg are swapped. First, the leg 131 attached to the upper base 111 is moved downward to make contact with the ground 10. Then, the weight 160 is moved so that the center of gravity Gw is point-symmetric with respect to the center of gravity GL of the lower base, with respect to the center of gravity GU of the upper base. Next, the leg 132 attached to the lower base 112 is moved upward to become the free leg. As the leg 132 becomes the free leg, the overall center of gravity Gt shifts. Before the leg 132 became the free leg, the center of gravity Gw was moved so that it was point-symmetric with respect to the center of gravity GL of the lower base, with respect to the center of gravity GU of the upper base. Therefore, the overall center of gravity Gt after the leg 132 becomes the free leg is at the position of the center of gravity GU of the upper base. Consequently, the maximum value of the stability margin M is maintained.

[0036] Thus, the walking robot 100 of the first embodiment can maintain its maximum stability margin M when moving to the right in Figure 4. Therefore, it can be seen that it can walk stably.

[0037] Figure 5 is another diagram illustrating the walking motion of the comparative example. The difference from Figure 3 is the walking direction. Figure 3 illustrated the walking motion when walking in a direction perpendicular to one side of the lower base 112. Figure 5 illustrates the walking motion when walking in a direction parallel to one side of the lower base 112.

[0038] In Figure 5, the state of the walking robot 100a at time t0 is simply a rotational representation of the state shown at time t0 in Figure 3, and is therefore the same as the state shown at time t0 in Figure 3.

[0039] At time t1, the base drive unit 151 is driven. As can be seen from Figures 1 and 2, the base drive unit 151 moves the upper base 111 and the lower base 112 relative to each other, parallel to one side of the triangle they form. Therefore, the lower base 112 moves in the direction indicated by the arrow at time t1 in Figure 5. As the lower base 112 moves, the center of gravity GL of the lower base also moves, and therefore the overall center of gravity Gt also moves. In the state at t1, the stability margin M is reduced.

[0040] At time t2, the leg 132 attached to the lower base 112 is moved downward from the state at time t1 to become the standing leg, and then the leg 131 attached to the upper base 111 is moved upward to become the free leg. Since the standing leg is now the leg 132 of the lower base 112, the stability margin M also applies to the lower base 112, but the size of the stability margin M is the same as at time t1, and the stability margin M is very small.

[0041] At time t3, the base drive unit 151 is driven. This causes the upper base 111 to move to the right in Figure 5. As the upper base 111 moves, the center of gravity GU of the upper base also moves, and therefore the overall center of gravity Gt also moves. Even in the state at time t3, the stability margin M is small.

[0042] At time t4, the swing leg and stance leg are swapped. As a result, the target of the stability margin M changes to the upper base 111. Even after the target of the stability margin M changes to the upper base 111, the stability margin M remains small.

[0043] Figure 6 illustrates the case where the walking robot 100 performs a walking motion in the same direction as in Figure 5. At time t0, the upper base center of gravity GU, the lower base center of gravity GL, the weight center of gravity Gw, and the overall center of gravity Gt are all located at the position of the geometric center of gravity of the upper base 111.

[0044] At time t1, the base drive unit 151 is driven. This causes the lower base 112 to move in the direction indicated by the arrow at time t1 in Figure 6, and the lower base's center of gravity GL also moves in the direction of that arrow. In conjunction with the movement of the lower base 112, that is, the movement of the lower base's center of gravity GL, the camera 170, which is a weight, is moved so that the weight's center of gravity Gw is point-symmetric with respect to the upper base's center of gravity GL with respect to the upper base's center of gravity GU. In this way, even if the lower base 112 moves, the overall center of gravity Gt remains at the same point as the upper base's center of gravity GU, and the stability margin M maintains its maximum value.

[0045] At time t2, the free leg and the standing leg are swapped. First, the leg 132 attached to the lower base 112 is made the standing leg. Then, the camera 170, which is the weight, is moved so that the weight's center of gravity Gw is point-symmetric with respect to the upper base's center of gravity GU, with respect to the lower base's center of gravity GL. Next, the leg 131 attached to the upper base 111 is made the free leg. Since the weight's center of gravity Gw was moved before the leg 131 became the free leg, the overall center of gravity Gt after the leg 131 becomes the free leg is at the position of the lower base's center of gravity GL. Therefore, the maximum stability margin M is maintained.

[0046] At time t3, the base drive unit 151 is driven again. This time, the upper base 111 moves to the right in Figure 6. In conjunction with the movement of the upper base 111, the camera 170, which is the weight, is moved so that the weight's center of gravity Gw moves in the opposite direction to the upper base's center of gravity GU by the same amount as the movement of the upper base's center of gravity GU. In this way, even while the upper base 111 is moving, the overall center of gravity Gt is maintained at the position of the geometric center of gravity of the lower base 112, which is the base 110 on the support leg side. Therefore, the stability margin M remains large.

[0047] At time t4, the free leg and the standing leg are swapped. First, leg 131, attached to the upper base 111, is made the standing leg. Then, the camera 170, which is the weight, is moved so that the weight's center of gravity Gw is point-symmetric with the lower base's center of gravity GL, with respect to the upper base's center of gravity GU. Next, leg 132, attached to the lower base 112, is made the free leg. Since the weight's center of gravity Gw was moved before leg 132 became the free leg, the overall center of gravity Gt after leg 132 becomes the free leg is at the position of the upper base's center of gravity GU. Therefore, the maximum stability margin M is maintained.

[0048] Figure 7 is a flowchart showing the processes executed by the control device 190 when the walking robot 100 walks. In S1, the base drive unit 151 or base drive unit 152 is controlled to move the base 110 on the swing leg side in the direction of travel. In conjunction with this, the weight drive unit 161 or camera drive unit 171 is controlled to move the weight in the opposite direction. This S1 is executed at times t1 and t3 in Figure 4 and at times t1 and t3 in Figure 6.

[0049] When the base 110 is moved, a force F1 acts on the walking robot 100 in a direction that could cause it to tip over, as shown in Figure 8. However, simultaneously with the movement of the base 110, a force F2 is generated by moving the weight (camera 170 in Figure 8) in the opposite direction to the movement of the base 110. Force F2 can cancel out at least a portion of force F1. Therefore, the walking robot 100 remains stable even while the base 110 is moving. Note that Figure 8 shows the walking robot 100 in a simplified form compared to Figure 1, with the drive mechanism and other components omitted.

[0050] In S2, the leg drive unit 140 that drives the swing leg is controlled to bring the swing leg down. In the following S3, the weight drive unit 161 or camera drive unit 171 is controlled to move the weight of the base 110 on the next stance leg side. In S4, the leg drive unit 140 that drives the next leg to be the swing leg 130 is controlled to raise the next leg to be the swing leg 130. These steps S2, S3, and S4 are executed at times t2 and t4 in Figure 4 and t2 and t4 in Figure 6.

[0051] [Fall prevention control] Next, the fall prevention control performed by the control device 190 will be explained. Fall prevention control is performed when the walking robot 100 is about to fall. The control device 190 determines that the walking robot 100 is about to fall from the tilt of the walking robot 100 which is sequentially estimated by the posture estimation device 180.

[0052] If the control device 190 determines that the walking robot 100 is about to fall, it controls at least one of the leg drive unit 140, base drive unit 150, weight drive unit 161, and camera drive unit 171 so that the tilt estimated by the posture estimation device 180 approaches horizontal.

[0053] Figure 9 shows an example of controlling the leg drive unit 140 to suppress falls. When the control device 190 determines that the walking robot 100 is about to fall, it controls the leg drive unit 140 that controls the standing leg in the direction of the fall, so that the part of the standing leg below the base 110 becomes longer. As a result, the standing leg receives a reaction force pushing from the ground 10, as shown by the upward arrow in Figure 9. Consequently, the tilt estimated by the posture estimation device 180 approaches horizontal. In addition, the leg 130, which is originally a standing leg but has come off the ground 10 due to the walking robot 100's tilt, can be moved towards the ground 10.

[0054] Figure 10 shows an example of controlling the camera drive unit 171, which is a weight control device, to move the camera 170, which is a weight, in order to suppress a fall. Suppose the control device 190 determines that the walking robot 100 is about to fall. At this time, a force F3 is generated on the walking robot 100. When the control device 190 makes the above determination, it controls the camera drive unit 171 so that the camera 170 moves in the direction of the fall, as shown by arrow D1. Due to the reaction force of the movement of the camera 170, a force F4 is generated on the walking robot 100. Due to force F4, a force F5 is generated on the standing leg in the direction of the fall. Forces F4 and F5 suppress the walking robot 100 from falling.

[0055] Figure 11 shows an example of controlling the base drive unit 150 to suppress tipping. When the control device 190 determines that the walking robot 100 is about to tip over, it controls the base drive unit 150 to move the base 110 to which the support legs are attached in the direction of the tipping, as shown by arrow D2. This generates a force F6 on the support legs in the direction of the tipping. Due to the reaction force of force F6, a force F7 acts on the walking robot 100 in the opposite direction to the tipping direction. Force F7 suppresses the tipping of the walking robot 100.

[0056] [Summary of the First Embodiment] As described above, the first embodiment includes a weight 160 that moves relative to the base 110 and a camera 170, and moves the weight in a direction that reduces the movement of the upper base center of gravity GU or the lower base center of gravity GL caused by the movement of the swing leg. As a result, the movement of the overall center of gravity Gt is reduced even when moving with a large stride. Therefore, stable walking is possible even when moving with a large stride.

[0057] Furthermore, the walking robot 100 is designed so that the camera 170 can be moved by the camera drive unit 171, and the camera 170 is used as a weight. This reduces the number of components in the walking robot 100 compared to having two weights 160. Note that camera 170 is just one example of a sensor, and if the walking robot 100 is equipped with sensors other than camera 170, those sensors may be used as weights in place of camera 170, or in addition to camera 170. The walking robot 100 may also be equipped with a battery. This battery may be used as a weight in place of the above-mentioned sensor, or in addition to the above-mentioned sensor. The weight here may be a weight that moves in the same direction as camera 170, or it may be a weight 160 that intersects the direction of movement of camera 170.

[0058] Furthermore, the weight drive unit 161 moves the weight 160 parallel to the relative movement direction of the upper base 111 and lower base 112 by the base drive unit 152, and the camera drive unit 171 moves the camera 170, which is a weight, parallel to the relative movement direction of the upper base 111 and lower base 112 by the base drive unit 151. In this way, the change in the position of the overall center of gravity Gt due to the movement of the lower base center of gravity GL or the upper base center of gravity GU can be effectively suppressed by the movement of the weight center of gravity Gw.

[0059] Furthermore, if the control device 190 determines that the walking robot 100 is about to fall over based on the tilt sequentially estimated by the posture estimation device 180, it controls at least one of the leg drive unit 140, base drive unit 150, weight drive unit 161, and camera drive unit 171 to bring the tilt closer to horizontal. In this way, the walking robot 100 can be prevented from falling over.

[0060] <Second Embodiment> Next, a second embodiment will be described. In this second embodiment and subsequent descriptions, elements having the same reference numerals as those used up to that point are identical to the elements with the same reference numerals in the previous embodiments, unless otherwise specified. Also, when only a part of the configuration is described, the previously described embodiments can be applied to the other parts of the configuration.

[0061] Figure 12 shows a walking robot 200 according to a second embodiment. As shown in Figure 12, the walking robot 200 is equipped with a camera 271. In addition to the camera 271, it is also equipped with a weight 270. Thus, the camera 271 may be provided separately from the weight 270. The camera 271 is fixed to the upper part of the weight 270. Therefore, the weight 270 and the camera 271 move together. The weight 270 moves in the direction shown by the dashed line in Figure 12 by a weight drive device similar to the camera drive device 171.

[0062] The effects of this second embodiment will now be explained. Since the camera 271 is movable by the weight drive device, the position of the camera 271 can be moved and photographs taken of the area around the walking robot 200 can be taken without the need for a separate camera drive device. Photography is possible both when the walking robot 200 is walking and when it is stopped.

[0063] Furthermore, when the walking robot 200 is stationary, the camera 271 can also be moved up and down by raising and lowering the base 110 to which the three supporting legs 130 are attached. The base 110 to which the three supporting legs 130 are attached can be raised and lowered by controlling the leg drive unit 140 that drives those legs 130.

[0064] According to this second embodiment of the walking robot 200, it is possible to take photographs while moving the camera 271 to various positions. This walking robot 200 is useful when used in Structure from Motion (SfM), a technique for calculating a 3D model from multiple photographs. SfM requires taking multiple photographs from different locations, and these photographs must overlap. By using the walking robot 200, multiple overlapping photographs can be taken in a stable manner, thus improving the accuracy of SfM.

[0065] Furthermore, the walking robot 100 of the first embodiment, in which the camera 170 also serves as a weight, is one configuration in which the camera 170 moves integrally with the weight. Therefore, the walking robot 100 also achieves the effects of the second embodiment described above.

[0066] <Third Embodiment> Figure 13 shows a walking robot 300 according to a third embodiment. The walking robot 300 is equipped with three cameras 371. These three cameras 371 are each fixed to the top of three legs 130 that are attached to the same base 110. In Figure 13, the three cameras 371 are each fixed to the top of three legs 131 of the upper base 111. However, the three cameras 371 may also be fixed to three legs 132 of the lower base 112.

[0067] Furthermore, the camera 371 may be fixed not only to the tops of the three legs 131 of the upper base 111, but also to the tops of the three legs 132 of the lower base 112. However, as explained using Figures 4 and 6, the free leg and the standing leg can be swapped at the same position. Therefore, it is sufficient for the camera 371 to be fixed to only one of the legs 130 of the base 110.

[0068] In this walking robot 300, since the camera 371 is fixed to the top of the leg 130, the position of the camera 371 can be changed significantly in the vertical direction. Therefore, it is possible to take many pictures at different heights while maintaining the same horizontal position, which improves the 3D accuracy of horizontally extending objects such as branches in SfM.

[0069] Furthermore, the camera 371 does not need to be fixed to all of the legs 130 attached to a single base 110. It is sufficient for it to be fixed to one or more of the legs 130.

[0070] <Fourth Embodiment> In the fourth embodiment, the control device 190 estimates the shape of the ground 10 and determines the height coordinate (i.e., z coordinate) of the lower end of the leg 130 when the leg 130 is in a free-swinging position. In this embodiment, the z coordinate of the leg 130 in a free-swinging position is determined from the following equation 1. Equation 1 is an equation that estimates the inclination of the ground 10 as the shape of the ground 10, assuming the ground 10 is a plane, and represents a plane that is higher than that plane by a margin α.

[0071]

number

[0072] The coordinates x and y can be determined based on the coordinates determined by the GNSS positioning device, which is installed on the walking robot, and the relative coordinates between the GNSS positioning device and the leg 130. Alternatively, the coordinates x and y may be determined based on the distance and direction of movement from the point where the robot starts walking or a reference point (x,y)=(0,0). The coordinates z1, z2, and z3 can be determined based on the z coordinate determined by the GNSS positioning device and the amount of movement of the leg 130 by the leg drive device 140. Alternatively, the coordinates z1, z2, and z3 may be expressed as relative coordinates of the z coordinate of the lower end of the stance leg. In the case of relative coordinates, the coordinates z1, z2, and z3 can be determined by the length below the base 110 for each stance leg. In the case of relative coordinates, any one of the coordinates z1, z2, and z3 can be set to zero.

[0073] L is the distance between the legs 130. α is the clearance between the lower end of the leg 130 and the ground 10. The clearance α is also shown in Figure 15. The clearance α can also be described as the amount by which the leg 130 is lifted from the ground 10. The clearance α is a value that is added to account for the error between the actual height of the ground 10 and the calculated height of the ground 10. The clearance α is a constant.

[0074] The margin α may be sequentially changed based on the forest environment that can be estimated at the time of operation when this walking robot is operating in a forest. For example, if, when actually walking, the z calculated by Equation 1 causes the lower end of the swing leg to come into contact with the ground 10 when the base 110 moves, α may be increased. Also, if the forest conditions are checked in advance before operating the walking robot in the forest, α may be set according to the results of that check.

[0075] In equation 1, x and y are given by x = x n +X, y=y n It is +Y. n is one of 1, 2, or 3. Also, X and Y are the amount of movement of base 110, in other words, the stride length of the walking robot. The direction and amount of movement of base 110 is set in advance or each time by the person operating the walking robot.

[0076] From the above, since numerical values ​​can be substituted for the variables on the right side of Equation 1, the z on the left side can be calculated. When leg 130 is used as a free leg, the lower end of leg 130 is raised to the z calculated in this way.

[0077] Furthermore, in this embodiment, when calculating z when the leading standing leg in the direction of movement of the walking robot is considered the swing leg, the margin α in Equation 1 is replaced with a margin β. As shown in Figure 15, the margin β is the value obtained by adding δ to α. δ is a value greater than 0. Therefore, the margin β is a value greater than the margin α.

[0078] Figure 16 shows the process that the control device 190 performs during walking in the fourth embodiment. In S11, the stroke amount of the supporting leg 130 is obtained from the leg drive device 140. This stroke amount is a value that indicates the relative position between the base 110 to which the supporting leg 130 is attached and the leg 130. Based on this stroke amount, the length of the leg 130 located below the base 110 can be determined. Therefore, z1, z2, and z3 shown in Figure 14 can be determined.

[0079] In S12, it is determined whether the base 110 to which the supporting leg 130 is attached is the lead-moving base. The lead-moving base is the base 110 of a pair of bases 110 that moves first in the direction of movement of the walking robot. For example, in the examples in Figures 4 and 6, the lower base 112 is the lead-moving base. If the result of the determination in S12 is YES, the process proceeds to S13.

[0080] In S13, for the leading leg in the walking robot's direction of movement, the height coordinate z for the swing leg is calculated by replacing α with β in Equation 1. For the remaining legs, the height coordinate z for the swing leg is calculated using Equation 1. If the result of the judgment in S12 is NO, proceed to S14. In S14, the height coordinate z for the swing leg is calculated for all legs using Equation 1.

[0081] After executing S13 or S14, proceed to S15. In S15, the leg 130 is raised to the height coordinate z determined in S13 or S14 to become the free leg. Note that the leg 130 attached to the other base 110 becomes the standing leg when S15 is executed, as described in S19. S11 to S15 correspond to S4 in Figure 7.

[0082] In the following step S16, the base 110 to which the free-moving leg 130 is attached is moved. Step S17 is performed while the base 110 is moving. In step S17, it is determined whether or not an obstacle has come into contact with the tip of the leg. Here, an obstacle means an obstacle that is large enough to hinder the movement of the base 110. Therefore, the determination in S17 can be made by determining whether or not the base 110 has moved the predetermined amount. Whether or not the base 110 has moved the predetermined amount can be determined, for example, by the change in the amount of current generated in the base drive unit 150. Alternatively, pressure sensors or contact sensors may be attached to the tip or side of the leg 130, and the determination can be made based on the sensor values. If the result of the determination in S17 is YES, the process proceeds to S18.

[0083] In S18, the stroke amount of the target leg 130 is adjusted. The target leg 130 is the free leg. The stroke amount to be adjusted is, for example, the stroke amount to adjust the height coordinate z calculated by adding a constant value to α and β, replacing α in Equation 1. After executing S18, return to S17. If the result of the judgment in S17 is NO, proceed to S19. S16 to S18 correspond to S1 in Figure 7.

[0084] In S19, the three free legs are brought into contact with the ground 10. S19 corresponds to S2 in Figure 7. In S20, weight 160 or weight 270 is moved so that the overall center of gravity Gt is closer to the center of the walking robot. S20 corresponds to S3 in Figure 7.

[0085] According to this fourth embodiment, the height coordinate z of the lower end of the leg 130 when it is a free-floating leg is determined based on Equation 1, which estimates the shape of the ground 10. If the shape of the ground 10 is not estimated, regardless of the shape of the ground 10, the lower end of the leg 130 would need to be raised higher than necessary to prevent the free-floating leg from contacting the ground 10 while the base 110 is moving. In contrast, according to this fourth embodiment, it is possible to suppress raising the leg 130 higher than necessary. As a result, the power consumption required to raise and lower the leg 130 can be reduced.

[0086] In addition, if the walking robot becomes unstable, and the free leg is to be brought into contact with the ground to stabilize it, the leg 130 is not raised very high, allowing the free leg to quickly make contact with the ground and stabilize the walking robot quickly.

[0087] Furthermore, among the support legs attached to the front base, the support leg at the front of the walking robot's direction of movement, when used as a free leg, is the leg furthest forward in the direction of the walking robot's movement among the multiple legs 130 provided by the walking robot. Therefore, the ground 10 may be higher than expected. Accordingly, in this embodiment, for the support leg at the front of the walking robot's direction of movement, among the support legs attached to the front base, a larger margin β is used than for the other support legs to calculate the height coordinate z of the lower end of the leg 130 when it is used as a free leg. By doing so, even if the ground 10 is higher than expected, it is possible to suppress the leading free leg from coming into contact with the ground 10.

[0088] <Fifth Embodiment> The fifth embodiment is a modified version of the fourth embodiment. In the fifth embodiment, the margin α in Equation 1 is determined based on the shape of the ground 10 or the margin α estimated during a previous walk.

[0089] [Memory of the estimated shape of the ground 10 or margin α] To achieve the above, the control device 190, for example in Figure 16, stores the position of the walking robot and the margin amount α in a predetermined storage device after executing S19. The storage device may be provided by the control device 190, or it may be provided separately by the walking robot. Alternatively, the storage device may be located outside the walking robot and connected by wireless communication. The control device 190 obtains the position of the walking robot from a position determination device such as a GNSS positioning device.

[0090] The margin α is the adjusted margin α when S18 is executed. The adjusted margin α can be said to reflect the shape of the ground 10. Alternatively, instead of the margin α, the coordinates of the legs 130 obtained sequentially by walking may be stored as the shape of the ground 10. If the position estimation accuracy of the walking robot is sufficiently high, the coordinates of the legs 130 obtained sequentially by walking may be stored directly as the shape of the ground 10. Alternatively, based on the coordinates of the legs 130 obtained sequentially by walking, the degree of unevenness of the ground 10 may be estimated and stored as the shape of the ground 10 for each certain area.

[0091] [Determination of the margin α this time] Next, we will explain how the margin α is determined in this case. When S13 and S14 in Figure 16 are executed, the control device 190 obtains the current position from the position determination device. Then, based on the obtained current position and the walking plan of the walking robot, it checks whether the shape of the ground 10 or the margin α corresponding to the next position that the walking robot's legs 130 will move to is stored in the memory device.

[0092] If the memory device stores the coordinates of the ground surface 10 corresponding to the next position the walking robot's legs 130 will move to, the margin α is determined so that the height coordinate z calculated from Equation 1 is higher than the ground surface determined by those coordinates. If the memory device stores the degree of unevenness in the area corresponding to the next position the walking robot's legs 130 will move to, the greater the degree of unevenness, the larger the margin α should be. If the memory device stores the margin α associated with the next position the walking robot's legs 130 will move to, that margin α is used as is.

[0093] In the fifth embodiment described above, when the walking robot walks, the control device 190 stores the estimated ground shape or margin α along with the position of the walking robot. Then, when the control device 190 determines the height coordinate z of the lower end of the swing leg, if the estimated ground shape or margin α is stored for the current position of the walking robot, it determines the margin α to be used based on the stored ground shape or margin α. In this way, it is suppressed that the height coordinate z calculated from Equation 1 becomes too high or too low.

[0094] <Sixth Embodiment> The sixth embodiment is also a modified embodiment of the fourth embodiment. In the sixth embodiment, when moving the rear-moving base, the margin amount α used in Equation 1 is determined based on the shape of the ground 10 estimated when the front-moving base was moved or the margin amount α used when the front-moving base was moved. The rear-moving base is the base 110 of a pair of bases 110 that is not the front-moving base. In the examples of Figures 4 and 6, the upper base 111 is the rear-moving base.

[0095] The control device 190 stores the estimated ground shape or margin α at the position where the leading base is located in a memory device after the leading base has finished moving and before the trailing base moves. The location of the memory device is the same as in the fifth embodiment. As the estimated ground shape, the coordinates of the lower ends of the three legs 130 attached to the leading base can be used. These coordinates represent the coordinates of the ground 10. Also, the margin α is the adjusted margin α if S18 is performed, as in the fifth embodiment.

[0096] Next, we will explain how to determine the margin α used in Equation 1 when moving the rear-moving base. Since we are moving the rear-moving base, we will perform S14 in Figure 16. At this time, if the coordinates of the ground 10 are stored in the memory device, we will determine the margin α such that the height coordinate z calculated from Equation 1 is higher than the ground surface indicated by those coordinates. If the margin α is stored in the memory device, we will use that margin α as is.

[0097] In the sixth embodiment described above, when the front base is moved, the estimated ground shape or margin α at the position where the front base is located is stored. Then, when the leg 130 attached to the rear base is set as a free leg, the margin α used in Equation 1 is determined based on the estimated ground shape or margin α stored in the memory device (S14). The position of the rear base after movement is approximately the same as the position of the front base. Therefore, by doing so, when moving the rear base, it is suppressed that the height coordinate z calculated from Equation 1 becomes too high or too low.

[0098] <Seventh Embodiment> Figure 17 shows a walking robot 400 according to the seventh embodiment. The walking robot 400 includes a housing 410 that houses the base 110. The walking robot 400 is the same as the walking robot 200 but with the housing 410 added.

[0099] The housing 410 comprises an upper housing 411 that houses the upper base 111 and a lower housing 412 that houses the lower base 112. The upper housing 411 also houses the weight 270. The lower base 112 also houses the weight 160. The housing 410 can be made of a metal such as aluminum or a high-strength resin. The housing 410 is a plate-like body, but may be made of a mesh if the strength allows.

[0100] Figure 18 shows the planar shapes of the upper housing 411 and the lower housing 412. As can be seen from Figures 17 and 18, the upper housing 411 is cylindrical. On the other hand, the lower housing 412 is a bottomed body with an open top. The lower housing 412 comprises a cylindrical part 413 and a bottom part 414. The bottom part 414 is disc-shaped, and the lower surface 414a of the bottom part 414 is flat. As can be seen from Figure 17, this lower surface 414a faces the ground 10 when the walking robot 400 is standing upright.

[0101] The bottom 414 side of the cylindrical portion 413 becomes smaller in diameter towards the bottom 414, and the end of the cylindrical portion 413 on the bottom 414 side is connected to the bottom 414. The opening side of the cylindrical portion 413 is cylindrical in shape. The outer surface of the cylindrical portion 413 is the side surface 415 of the lower housing 412. The side surface 415 of the cylindrical portion 413 that becomes smaller in diameter towards the bottom 414 is an inclined surface portion 415a. As shown in Figure 17, the inclined surface portion 415a is a convex curved surface that is convex downwards when the walking robot 400 is in an autonomous state. Therefore, the inclined surface portion 415a protrudes horizontally from the bottom surface 414a as it extends upwards from the part that is in contact with the bottom surface 414a.

[0102] In the walking robot 400, the control device 190 periodically performs the process shown in Figure 19 to determine if the robot is in a fallen state and to recover, separate from the control for walking. In S31, the attitude angle is acquired. The attitude angle refers to the inclination of the object with respect to the horizontal plane. The attitude angle is measured by the attitude estimation device 180. In S32, it is determined whether the walking robot 400 is in a fallen state based on the attitude angle acquired in S31. If the result of the determination in S32 is NO, the process returns to S31. On the other hand, if the result of the determination in S32 is YES, the process proceeds to S33.

[0103] In S33, the posture angle is acquired sequentially to determine whether the walking robot 400 is stationary or not. This is to avoid executing S34 and subsequent steps immediately after a fall. If the result of the S33 decision is NO, the decision in S33 is repeated. On the other hand, if the result of the S33 decision is YES, the process proceeds to S34.

[0104] In S34, the legs 130 are shortened. Shortening the legs 130 means reducing the length that the legs 130 protrude from the lower housing 412. The degree of shortening is a fixed amount. Figure 20 illustrates a walking robot 400 in a fallen state. In the example in Figure 20, a portion of the legs 130 and the inclined surface portion 415a of the lower housing 412 are in contact with the ground 10. If the length that the legs 130 protrude from the lower housing 412 is shortened by a fixed amount from this state, the distance between the part of the inclined surface portion 415a of the lower housing 412 that is in contact with the ground 10 and the tip of the leg 130 that is in contact with the ground 10 becomes shorter. As a result, the walking robot 400 may rotate counterclockwise in Figure 20.

[0105] In S35, it is determined whether the robot is stationary or not. This is because the operation in S34 may change the posture of the walking robot 400, so the robot waits while the posture is changing. If the result of the determination in S35 is YES, the process proceeds to S36. In S36, it is determined again whether the walking robot 400 is in a fallen state or not. If the result of the determination in S36 is YES, the process returns to S34 and the legs 130 are further retracted.

[0106] Figure 21 shows the state in which the lower ends of all legs 130 have moved to a position where none of the lower ends protrude from the lower housing 412. In reality, the posture of the walking robot 400 changes before reaching the state shown in Figure 21, but this state is shown for illustrative purposes.

[0107] In Figure 21, only the inclined surface 415a is in contact with the ground 10. As a result, the inclination of the inclined surface 415a causes the walking robot 400 to rotate in the direction indicated by the arrow in Figure 21. Figure 22 shows the state after the walking robot 400 has rotated from the state in Figure 21 in the direction indicated by the arrow in Figure 21. Since the bottom surface 414a of the housing 410 of the walking robot 400 is flat, as shown in Figure 22, the posture of the walking robot 400 is stabilized when the bottom surface 414a contacts the ground 10. As a result, the judgment result of S35 becomes YES and the judgment result of S36 becomes NO. After the judgment result of S36 becomes NO, the walking robot 400 can resume walking by extending its legs 130.

[0108] The walking robot 400 of this seventh embodiment is equipped with a posture estimation device 180, and the control device 190 can determine whether or not it is in a fallen state based on the signal from the posture estimation device 180. In addition, the walking robot 400 has an inclined surface portion 415a formed on the side surface 415 of the lower housing 412, which protrudes horizontally from the lower surface 414a upwards from the lower surface 414a. Based on the control device 190's determination that the walking robot 400 is in a fallen state, it controls the leg drive device 140 to shorten the length of the legs 130 protruding from the lower housing 412 (S34). As a result, the walking robot 400 may be able to recover from the fallen state.

[0109] Furthermore, because the lower surface 414a is flat, when the walking robot 400 rotates by shortening the length of the legs 130 protruding from the lower housing 412, the walking robot 400 can be stabilized with the lower surface 414a in contact with the ground 10. Once the walking robot 400 is stabilized in this state, it can then resume walking by extending the legs 130.

[0110] <Eighth Embodiment> In the eighth embodiment, the control device 190 of the walking robot 400 also controls the weights 160 and 270 to attempt to recover from the fallen state. In the eighth embodiment, the control device 190 executes the process shown in Figure 23 instead of the process shown in Figure 19.

[0111] The process shown in Figure 23 differs from the process shown in Figure 19 in that S33-1 is executed between S33 and S34. After determining in S32 that the vehicle is in an overturned state and in S33 that it is in a stationary state, in S33-1 the weight drive device is controlled to move the weights 160 and 270 that are movable upward as far upward as possible. After that, the process proceeds to S34, similar to the seventh embodiment.

[0112] When the weight moves upward by executing S33-1, it often moves diagonally upward rather than directly upward, as illustrated in Figure 20. When the weight moves diagonally upward, the center of gravity of the walking robot 400 moves in the direction in which the walking robot 400 rotates. Therefore, it is easier to recover the walking robot 400 from a fallen state than simply retracting the legs 130 in S34.

[0113] <Ninth Embodiment> Figure 24 shows a walking robot 500 according to the ninth embodiment. The walking robot 500 includes a housing 510. The housing 510 houses the upper base 111 and the lower base 112 together. The housing 510 is connected to the upper base 111 and the lower base 112 by a plurality of connecting columns 511. The connecting columns 511 are made movable relative to the housing 510 in the direction of movement of the upper base 111 and the lower base 112 by rails or the like. In addition, slits are formed on the lower surface 512 and the upper surface 514 of the housing 510 to allow the legs 130 to move in conjunction with the movement of the upper base 111 and the lower base 112. In this way, the upper base 111 and the lower base 112 can be housed in a single housing 510.

[0114] If a camera 271 is provided, the camera 271 may be positioned above the housing 510. Alternatively, while housing the camera 271 in the housing 510, a hole may be provided in the housing 510 so that the camera 271 can capture images of the outside even when it is housed in the housing 510.

[0115] The housing 510 has a flat bottom surface 512 that faces the ground 10 when the walking robot 500 is standing upright. The entire side surface 513 of the housing 510 is an inclined surface portion 513a, and the side surface 513 protrudes horizontally from the bottom surface 512 as it moves upward from the part in contact with the bottom surface 512.

[0116] In the walking robot 500, the control device 190 performs the same control as in the walking robot 400. In Figure 25, the walking robot 500 is standing upright. In Figure 26, the walking robot 500 is lying on its side. Similar to the seventh embodiment, by executing S34 and retracting the legs 130, it rotates under its own weight as shown in Figure 27 and stabilizes with its lower surface 512 in contact with the ground 10. After that, the walking robot 500 can resume walking by extending its legs 130.

[0117] <Tenth Embodiment> In the tenth embodiment, the control device 190 of the walking robot 500 executes the process shown in Figure 28. The process shown in Figure 28 differs from the process shown in Figure 19 in that S34-1 and S34-2 are executed instead of S34.

[0118] In S34-1, the inclination information of the ground 10 is acquired. Specifically, the inclination information of the ground 10 is the angle θ1 between the plane containing the surface of the base 110 and the direction of gravity. This angle θ1 is shown in Figure 29. When the walking robot 500 is standing upright on the horizontal ground 10, the direction of gravity detected by the attitude estimation device 180 is assumed to be perpendicular to the plane containing the surface of the base 110. In this case, if the direction of gravity detected by the attitude estimation device 180 is known, the angle θ1 can be calculated.

[0119] In S34-2, the length of the legs 130 is adjusted using the angle θ1 obtained in S34-1 so that the base 110 becomes horizontal when it recovers from a fallen state. The angle θ1 obtained in S34-1 is the sum of the inclination angle θ2 of the ground 10 and the angle at which the walking robot 500 is tilted relative to the ground 10. When the walking robot 500 is fallen, it is assumed that the most protruding part of the housing 510 and the tip of the leg 130 are in contact with the ground 10. With this assumption, the angle at which the walking robot 500 is tilted relative to the ground 10 can be calculated geometrically. By removing the angle at which the walking robot 500 is tilted relative to the ground 10 from the angle θ1, the inclination angle θ2 of the ground 10 can be calculated.

[0120] The adjustment of the leg length 130 is to shorten the leg 130 that is in contact with the ground 10 by a certain amount so that when the walking robot 500 rotates, the base 110 of the walking robot 500 becomes horizontal, as shown in Figure 30. The leg 130 that is in contact with the ground 10 is designated as the reference leg 130a, and the leg 130 whose length is to be calculated is designated as the target leg 130b. Let c be the horizontal distance between the reference leg 130a and the target leg 130b, let d be the length of the reference leg 130a, and let e be the length of the target leg 130b. As can be seen from Figure 30, ed = ctanθ². At the time of executing S34-2, the legs 130 whose tips are not in contact with the ground 10 are sequentially designated as target legs 130b, and the length of the target legs 130b is calculated. Note that the length refers to the length of the leg 130 that is below the housing 510. The length of all target legs 130b is calculated, and after adjusting the target legs 130b to the calculated length, the leg 130 in contact with the ground 10 is shortened by a certain length. This completes the process of S34-2.

[0121] In this way, as shown in Figure 30, even if the ground 10 is sloped, the walking robot 500 can recover from a fallen state to a horizontal position.

[0122] <Embodiment 11> In the 11th embodiment, the walking robot is equipped with a housing 610 as shown in Figure 31. The housing 610 is provided on the walking robot in place of the lower housing 412 or housing 510. The housing 610 has a rounded rectangular shape when viewed from the side. The bottom surface 612 of the housing 610 is flat. The side surface 613 of the housing 610 is equipped with an inclined surface portion 613a that connects to the bottom surface 612. The inclined surface portion 613a protrudes horizontally from the bottom surface 612 as it extends upward from the portion in contact with the bottom surface 612.

[0123] <Twelfth Embodiment> In the twelfth embodiment, the walking robot is equipped with a housing 710 as shown in Figure 32. The housing 710 is provided on the walking robot in place of the lower housing 412 or housing 510. In side view, the housing 710 has a shape that combines a rectangle and a trapezoid. The bottom surface 712 of the housing 710 is flat. The side surface 713 of the housing 710 is equipped with an inclined surface portion 713a that connects to the bottom surface 712. The inclined surface portion 713a protrudes horizontally from the bottom surface 712 as it extends upward from the portion in contact with the bottom surface 712.

[0124] <13th Embodiment> Figure 33 shows a walking robot 800 according to the 13th embodiment. The walking robot 800 includes a housing 810. The housing 810 houses the upper base 111 and the lower base 112 together. Similar to the connecting columns 511, the housing 810 is connected to the upper base 111 and the lower base 112 by a plurality of connecting columns 811 that can move relative to the housing 810.

[0125] The housing 810 retains the same shape even when inverted. The bottom surface 812 and top surface 814 of the housing 810 are flat. The side surface 813 of the housing 810 has an inclined surface portion 813a that contacts the bottom surface 812 and an inclined surface portion 813b that contacts the top surface 814. The inclined surface portion 813a protrudes horizontally from the bottom surface 812 as it extends upward from the portion in contact with the bottom surface 812. The inclined surface portion 813b protrudes horizontally from the top surface 814 as it extends downward from the portion in contact with the top surface 814. If a camera 271 is provided, a hole is made in the housing 810 so that the camera 271 can photograph the outside.

[0126] Figure 34 shows the normal autonomous state of the walking robot 800. In the normal autonomous state, the upper surface 814 is above the lower surface 812. Figure 35 shows the state in which the walking robot 800 has fallen over from the state shown in Figure 31, and the lower surface 812 is now on top. Figure 36 shows the state in which the legs 130 are extended downwards while the lower surface 812 remains facing upwards. If the walking robot 800 is inverted, it will resume walking while remaining inverted.

[0127] Figure 37 shows the process executed by the control device 190 in the walking robot 800. Figure 37 shows the process that is executed in place of the process shown in Figure 19. The process shown in Figure 37 executes S34-3 in place of S34 in Figure 19.

[0128] In S34-3, the leg 130 on the side closer to the ground 10 is shortened. Specifically, it is determined which of the upper surface 814 and the lower surface 812 is closer to the ground 10, and the length of the leg 130 protruding from the surface closer to the ground 10 is shortened by a certain length. In S34-3, if it is determined that the upper surface 814 is the surface closer to the ground 10, the length of the leg 130 protruding from the upper surface 814 is shortened. After executing S34-3, S35 and S36, the same as in Figure 19, are executed. In determining the tipping state in S36, as shown in Figure 35, a state inverted vertically is determined not to be a tipping state.

[0129] Figure 35 shows a state where the robot is completely inverted vertically, but it is also possible that neither the upper surface 814 nor the lower surface 812 is parallel to the ground 10, and that the upper surface 814 is closer to the ground 10 than the lower surface 812. The walking robot 800 has an inclined surface portion 813b on the side 813 on the upper surface 814 side. Therefore, when neither the upper surface 814 nor the lower surface 812 is parallel to the ground 10, and the upper surface 814 is closer to the ground 10 than the lower surface 812, S34-3 is executed. By executing S34-3, the robot can recover from the fallen state, even though it is in an inverted vertical state.

[0130] Although embodiments have been described above, the disclosed technology is not limited to the embodiments described above. The following modifications are also included within the scope of disclosure, and further modifications can be made in various ways without departing from the gist of the invention.

[0131] For example, the shape of base 110 does not have to be a triangle. The shape of base 110 may be a polygon other than a triangle, an ellipse, etc.

[0132] Walking robots from the fourth embodiment onward, excluding the eighth embodiment, do not need to be equipped with weights and weight drive devices.

[0133] In the seventh embodiment, the upper housing 411 may not be provided. [Explanation of Symbols]

[0134] 110...Base, 130...Legs, 140...Leg drive unit, 150...Base drive unit, 160...Weight, 161...Weight drive unit, 170...Camera (weight), 171...Camera drive unit (weight drive unit), 180...Attitude estimation unit (tilt estimation unit), 190...Control device, 271...Camera, 410...Housing, 414a...Bottom, 415...Side, 415a...Inclined surface, 510...Housing, 512...Bottom, 513...Side, 513a...Inclined surface, 610...Housing, 612...Bottom, 613...Side, 613a...Inclined surface, 710...Housing, 712...Bottom, 713...Side, 713a...Inclined surface

Claims

1. A pair of bases (110) that move relative to each other, Multiple legs (130) are attached to each of the aforementioned bases, A leg drive device (140) that moves multiple legs individually in the vertical direction relative to the base, A base drive device (150) for moving a pair of bases relative to each other, Each of the aforementioned bases is provided with a weight (160, 170, 270) that moves relative to the base, A weight drive device (161, 171) for moving the aforementioned weight, A walking robot comprising a control device (190) that controls the leg drive device, the base drive device, and the weight drive device, The control device moves the weight in a direction that minimizes the change in the overall center of gravity of the walking robot caused by the movement of the base on the side to which the leg that is a free leg (away from the ground) is attached. Walking robot.

2. Equipped with sensors and a battery, The weight drive device moves at least one of the sensor and the battery as the weight. The walking robot according to claim 1.

3. The weight drive device moves the weight in a direction parallel to the direction in which the base drive device moves the base relative to it. The walking robot according to claim 1.

4. The system includes a tilt estimation device (180) for estimating the tilt of the base, The control device controls at least one of the leg drive unit, the base drive unit, and the weight drive unit based on the tilt estimated sequentially by the tilt estimation unit, so that the tilt estimated by the tilt estimation unit approaches horizontal. The walking robot according to claim 1.

5. The control device controls the leg drive device to lengthen the portion of the leg that is in contact with the ground in the direction the walking robot is falling, so that the tilt sequentially estimated by the tilt estimation device approaches horizontal. The walking robot according to claim 4.

6. The control device, based on the change in inclination sequentially estimated by the inclination estimation device, determines that the walking robot is about to fall, and controls the weight drive device so that the weight moves in the direction of the fall, thereby generating a force acting on the walking robot in the opposite direction to the direction of the fall. The walking robot according to claim 4.

7. If the control device determines, based on the change in inclination sequentially estimated by the inclination estimation device, that the walking robot is about to fall, it controls the base drive device so that the base to which the support legs, which are in contact with the ground, are attached moves in the direction of the walking robot's fall, thereby generating a force acting on the walking robot in the opposite direction to the direction of the fall. The walking robot according to claim 4.

8. The system includes cameras (170, 271) that move integrally with any of the multiple legs and the multiple weights. The walking robot according to claim 1.

9. The control device is The shape of the ground is estimated based on the relative positions of the base to which the supporting legs, which are the legs that are in contact with the ground, are attached, and the plurality of supporting legs. Based on the estimated shape of the ground, the height of the lower end of the swing leg is determined when the supporting leg is moved upward to become the swing leg. The walking robot according to claim 1.

10. The control device is When the aforementioned support leg is designated as the swing leg, a margin is added to the ground height at the position of the swing leg after the base has moved, and the height of the lower end of the swing leg is determined accordingly. Of the support legs attached to the base that advance in the direction of movement of the walking robot, the support leg at the leading end in the direction of movement of the walking robot shall have a larger margin than the other support legs. The walking robot according to claim 9.

11. The control device is When the aforementioned support leg is designated as the swing leg, a margin is added to the ground height at the position of the swing leg after the base has moved, and the height of the lower end of the swing leg is determined accordingly. When the walking robot walks, the estimated ground shape or the margin amount is stored along with the position of the walking robot. When determining the height of the lower end of the swing leg, if the estimated ground shape or the margin is stored relative to the position of the walking robot, the margin to be used this time is determined based on the stored ground shape or margin. The walking robot according to claim 9.

12. The control device is When the aforementioned support leg is designated as the swing leg, a margin is added to the ground height at the position of the swing leg after the base has moved, and the height of the lower end of the swing leg is determined accordingly. The estimated ground shape or margin amount at the position where the base that has advanced ahead in the direction of the walking robot's movement is located among the pair of bases is stored. The amount of margin used when the multiple legs attached to the base that moves backward in the direction of travel of the walking robot are designated as the free legs is determined based on the stored, estimated shape of the ground or the amount of margin. The walking robot according to claim 9.

13. The system includes a tilt estimation device (180) for estimating the tilt of the base, The system comprises a housing (410, 510, 610, 710) that accommodates the base, The aforementioned enclosure is When the walking robot is standing upright, the lower surface (414a, 512, 612, 712) faces the ground and is flat, It has the aforementioned lower surface in contact with the aforementioned lower surface and, when the walking robot is standing upright, it has sides (415, 513, 613, 713) that extend upward from the aforementioned lower surface, The aforementioned side surface has inclined surface portions (415a, 513a, 613a, 713a) that protrude horizontally from the lower surface as they extend upward from the portion in contact with the lower surface. Based on the tilt estimation device's determination that the walking robot is in a fallen state, the control device controls the leg drive unit to shorten the length of the legs protruding from the lower surface of the housing. The walking robot according to claim 1.

14. Based on the determination that the walking robot is in a fallen state, the control device controls the weight drive device to move the weight upward. The walking robot according to claim 13.

15. Based on its determination that the walking robot is in a fallen state, the control device shortens the length of the leg whose tip is in contact with the ground, extending from the lower surface of the housing, while the length of the leg whose tip is not in contact with the ground is set to the length at which the tip of the leg would be in contact with the ground if the walking robot were in a horizontal position. The walking robot according to claim 13 or 14.

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