Moving device, and control method and control program for moving device

Abstract

A traveling robot 10 comprises: a plurality of wheels 16 that are rotatably supported by a frame 20; and a control part 37. The control part 37 detects derailment of the wheels 16. When a derailment of one of the wheels 16 has been detected, the control part controls the operation of wheels 16 excluding the one wheel 16 that has derailed, among the plurality of wheels 16, and brings said one derailed wheel into contact with the ground.

Description

Mobile device, mobile device control method and control program

[0001] The present invention relates to a mobile device, a control method for a mobile device, and a control program.

[0002] Patent Document 1 discloses a mobile device that can travel along a wall while magnetically adhering its four wheels to the wall. This type of mobile device uses a back-drive motor to drive the magnets built into the wheels, allowing the magnets to passively adhere to the magnetic surface on which the device is running.

[0003] International Publication No. 2021 / 247275

[0004] The conventional transport device described above has difficulty continuing to travel if the wheels come off the road surface. An object of the present invention is to enable the wheels to return to their original position in an appropriate manner after coming off the road surface.

[0005] The moving device of the present invention comprises a plurality of wheels journalled on a vehicle body, a detection unit that detects when any of the wheels has come off the ground, and a control unit that, when the detection unit detects when one of the wheels has come off the ground, controls the operation of the wheels of the plurality of wheels excluding the one wheel, thereby causing the one wheel to touch the ground.

[0006] According to the present invention, the wheel can be suitably returned from being off the track.

[0007] 1 is a plan view of a running robot according to an embodiment. FIG. 2 is a perspective view of a running robot according to an embodiment. FIG. 3 is a cross-sectional view perpendicular to the Y direction showing the structure of a wheel according to an embodiment. FIG. 4 is a cross-sectional view perpendicular to the X direction showing the structure of a wheel according to an embodiment. FIG. 5 is a block diagram showing an outline of the control configuration of a running robot according to an embodiment. FIG. 6 is a flowchart showing the procedure of a wheel-fall recovery process according to an embodiment. FIG. 7 is a view showing an example of change in wheel speed when a wheel falls off. FIG. 8 is a view showing an example of change in current value of a wheel drive unit when a wheel falls off. FIG. 9 is a view showing an example of change in angle of a magnet when a wheel falls off. FIG. 10 is a view for explaining operation pattern A of a wheel-fall recovery operation according to an embodiment. FIG. 11 is a view for explaining operation pattern A of a wheel-fall recovery operation according to an embodiment. FIG. 12 is a view for explaining operation pattern A of a wheel-fall recovery operation according to an embodiment. FIG. 13 is a view for explaining operation pattern B of a wheel-fall recovery operation according to an embodiment. FIG. 14 is a view for explaining operation pattern B of a wheel-fall recovery operation according to an embodiment. FIG. 15 is a view for explaining a method of selecting a wheel-fall recovery operation pattern according to an embodiment. FIG. 16 is a view for explaining a method of selecting a wheel-fall recovery operation pattern according to an embodiment. FIG. 17 is a view for explaining the operation of a running robot when a wheel that has returned from a wheel-falling state is moved backward while touching the ground in the wheel-fall recovery process according to an embodiment. 1 is a diagram for explaining the operation of a traveling robot when moving backward while a wheel that has returned from a wheel drop is in contact with the ground in a wheel drop return process according to an embodiment. FIG. ... wheel drop return when the suspension mechanism is configured to function around the roll axis. FIG. 1 is a diagram for explaining the operation of a wheel drop return when the suspension mechanism is configured to function around the roll axis. FIG. 1 is a diagram for explaining the operation of a wheel drop return when the suspension mechanism is configured to function around the roll axis. FIG. 1 is a diagram for explaining the operation of a wheel drop return when a six-wheel rocker bogie system. FIG. 1 is a diagram for explaining the operation of a wheel drop return when a six-wheel rocker bogie system.It is a diagram for explaining the wheel-falling return operation in a six-wheel rocker bogie system. It is a diagram for explaining the wheel-falling return operation in a six-wheel rocker bogie system. It is a diagram for explaining the wheel-falling return operation in a six-wheel rocker bogie system. It is a diagram for explaining the wheel-falling return operation in a structure in which four-wheel units are connected by a universal joint.

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0009] [Configuration of Running Robot] Figures 1A and 1B are a plan view and a perspective view of a running robot 10 according to this embodiment. As shown in Figures 1A and 1B, the running robot 10 is an example of a mobile device according to the present invention, and is a robot that can run on a floor, wall, ceiling, or other surface by attaching wheels 16 to these surfaces. The running robot 10 is remotely controlled by, for example, an operator, or runs autonomously based on a predetermined running program. In the following description, the mutually orthogonal X, Y, and Z directions are set as shown in the figures. In this embodiment, the XY plane is the horizontal plane, and the Z direction is the vertical direction.

[0010] Specifically, the traveling robot 10 includes a plurality of wheels 16 and a frame 20 (car body) that supports (pivots) the plurality of wheels 16 .

[0011] Each of the four wheels 16 is supported rotatably about a first rotation axis Ax1 that lies along the X direction. Each wheel 16 is spherical (spherical shell-shaped) and configured to be able to transmit driving force to a traveling surface in various orientations. Note that the wheels 16 do not necessarily have to be spherical; they may have any shape, such as a roller shape, as long as the wheels 16 can follow a traveling surface in various orientations and transmit driving force to the traveling surface.

[0012] The frame 20 includes a first frame 20a and a second frame 20b arranged side by side in the X direction. Each of the first frame 20a and the second frame 20b supports two wheels 16 arranged side by side in the Y direction so that the wheels 16 are rotatable about a first rotation axis Ax1.

[0013] The first frame 20a and the second frame 20b are connected via a suspension mechanism 14. The suspension mechanism 14 is a mechanism that can change the relative position of the first frame 20a and the second frame 20b in a torsional direction At. The torsional direction At is the direction of rotation about a suspension axis A14 that extends in the direction in which the first frame 20a and the second frame 20b are aligned (the X direction). This mechanism is also called a rocker suspension mechanism. The suspension mechanism 14 can change the relative position of the first frame 20a and the second frame 20b in the torsional direction At, allowing the four wheels 16 to contact curved surfaces of various shapes. The suspension mechanism 14 is also provided with a measuring device 141, such as an encoder, that measures the degree of deformation.

[0014] 2A and 2B are cross-sectional views showing the structure of the wheels 16. FIG. 2A is a cross-sectional view perpendicular to the Y direction, and FIG. 2B is a cross-sectional view perpendicular to the X direction. As shown in FIGS. 2A and 2B , each wheel 16 contains a magnet 19 and a link mechanism 192 that supports the magnet 19 so that it can be displaced. The link mechanism 192 supports the magnet 19 so that it can rotate about a first rotation axis Ax1 and a second rotation axis Ax2 that intersects (e.g., is perpendicular to) the first rotation axis Ax1. The magnet 19 may be a permanent magnet or an electromagnet. With this configuration, when the wheel 16 is grounded on a magnetic material such as iron, the magnet is attracted to the ground surface, causing the wheel 16 to adhere to the ground surface. Therefore, the running robot 10 can adhere to walls, ceilings, and other surfaces against gravity and run on the surface. Furthermore, even when the wheel 16 touches down on a surface of various orientations, the link mechanism 192 allows the magnet 19 to flexibly change direction independently of the wheel 16 to face the ground surface, thereby generating a strong attraction force to the ground surface.

[0015] Each wheel 16 is provided with a wheel driver 21 that drives the wheel 16 to rotate and a magnet driver 191 that drives the magnet 19 to rotate. The wheel driver 21 is a motor (e.g., a gear motor) capable of controlling the amount of rotation or the rotational speed, and rotates the wheel 16 coaxially with the first rotation axis Ax1. The amount of rotation or the rotational speed of the wheel 16 is detected by a first encoder 34 (see FIG. 3). The magnet driver 191 (magnet motor) is a motor (e.g., a gear motor) capable of controlling the amount of rotation or the rotational speed, and rotates the first rotation axis Ax1 that supports the magnet 19. The current value of the magnet driver 191 is detected by a current detector 193 (see FIG. 3). The orientation (direction) of the magnet 19 is detected by a second encoder 35 (see FIG. 3), which is, for example, a two-axis encoder. The magnet driver 191 is capable of backdriving when the torque output is turned off.

[0016] The running robot 10 configured as described above can move in various directions, such as turning around, turning left, turning right, and moving straight, by controlling the amount of rotation of each of the four wheels 16. Furthermore, the suspension mechanism 14 allows the running robot 10 to run with all four wheels 16 in contact with the running surface, even if the running surface is curved.

[0017] 3 is a block diagram showing a schematic control configuration of the traveling robot 10. As shown in this figure, the traveling robot 10 includes an imaging camera 31, a posture sensor 32, a communication unit 33, a storage unit 36, and a control unit 37 in addition to the above configuration.

[0018] The imaging camera 31 is mounted on the frame 20 and captures an image of, for example, the area ahead in the direction of travel and stores the image in the storage unit 36. It is desirable that the imaging camera 31 also acquires distance information by employing, for example, 3D-LiDAR (Light Detection and Ranging). The attitude sensor 32 is mounted on the frame 20 and measures the three-dimensional acceleration and angular velocity of the frame 20 and outputs the measured values ​​to the control unit 37. The attitude sensor 32 is, for example, an IMU (Inertial Measurement Unit). The communication unit 33 transmits and receives various information to and from the operator's operation terminal 40, etc., via a predetermined communication network, etc., based on a predetermined wireless communication standard.

[0019] The storage unit 36 ​​is a memory configured, for example, by RAM (Random Access Memory) or ROM (Read Only Memory), and stores various programs and data, and also functions as a work area for the control unit 37. The control unit 37 is configured, for example, by a CPU (Central Processing Unit), and controls the operation of each part of the traveling robot 10. Specifically, the control unit 37 operates the wheel drive unit 21 and the magnet drive unit 191 based on operation commands from the operator via the communication unit 33, and loads programs stored in advance in the storage unit 36 ​​and executes various processes in cooperation with the loaded programs.

[0020] [Wheel Detachment Recovery Process] Next, a wheel detachment recovery process for recovering the wheel 16 from a detachment state will be described. FIG. 4 is a flowchart illustrating the procedure for the wheel detachment recovery process. FIGS. 5A, 5B, and 5C are diagrams illustrating examples of changes in the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19 when the wheel 16 detachs. FIGS. 6A, 6B, and 6C are diagrams illustrating operation pattern A of the wheel detachment recovery operation. FIGS. 7A, 7B, and 7C are diagrams illustrating operation pattern B of the wheel detachment recovery operation. FIGS. 8A and 8B are diagrams illustrating a method for selecting a wheel detachment recovery operation pattern. FIGS. 9A, 9B, and 9C are diagrams illustrating the operation of the traveling robot 10 when the wheel 16, which has recovered from the detachment state, moves backward while keeping the wheel 16 on the ground. Note that in FIG. 6A and subsequent figures, the detached wheel 16 is illustrated with a light dot pattern.

[0021] The wheel-off recovery process is a process for bringing one of the wheels 16 back into contact with the road surface when it has become "off-road" and is in a "wheel-off" state. The control unit 37 executes the wheel-off recovery process by reading and executing a corresponding program from the storage unit 36. Here, a case will be described in which the traveling robot 10 is traveling on, for example, a wall W (road surface) (see FIG. 6A , etc.). The wall W is made of a magnetic material except for a non-magnetic portion NM, which will be described later, and is attracted by the magnet 19. In the following, unless otherwise specified, the traveling robot 10 is assumed to travel in the Y direction, with the first frame 20a located on the left side and the second frame 20b located on the right side as viewed forward in the traveling direction. Furthermore, the four wheels 16 may be identified by adding a symbol "F" to the wheel on the front side in the traveling direction (Y direction), a symbol "B" to the wheel on the rear side, a symbol "L" to the wheel on the left side as viewed forward in the traveling direction, and a symbol "R" to the wheel on the right side as viewed forward in the traveling direction. For example, the left front wheel facing forward in the direction of travel may be referred to as the "wheel 16FL," and the right rear wheel may be referred to as the "wheel 16BR." In addition, in this embodiment, it is assumed that two or more wheels 16 will not simultaneously derail.

[0022] As shown in FIG. 4 , when the wheel recovery process is executed and the traveling robot 10 starts a predetermined autonomous travel based on, for example, a travel start command from the operation terminal 40, the control unit 37 detects wheel derailment (step S1). Here, the control unit 37 detects wheel derailment of a wheel 16 based on the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19. Specifically, the control unit 37 determines that a wheel 16 has derailed when the following three conditions are simultaneously satisfied for a certain wheel 16: Condition 1: The speed of the wheel 16 is equal to or greater than a first threshold (or a speed command is present); Condition 2: The current value of the wheel drive unit 21 is equal to or less than a second threshold; and Condition 3: The difference between the angle of the magnet 19 around the first rotation axis Ax1 and the average of the same angles for the other three wheels is equal to or greater than a third threshold. For example, when the data shown in FIGS. 5A , 5B , and 5C are obtained, it can be determined that the left front wheel 16FL, indicated by the dashed line in the figures, has derailed. However, it is not necessary to use all three parameters, namely, the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19. If at least one of the current value of the wheel drive unit 21 and the angle of the magnet 19 is used, it is possible to suitably detect the wheel 16 coming off the track.

[0023] The method for detecting wheel derailment is not limited to the above. For example, the presence or absence of wheel derailment may be determined by statistical processing, such as using a learning model generated in advance by machine learning based on the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19. Alternatively, the frictional force of the wheel 16 may be estimated from a dynamic model of the traveling robot 10 using, for example, an observer, and the like, and the wheel 16 may be determined to be derailed. In this case, the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19 may be input into a dynamic model estimator created in advance to estimate the frictional force generated in the wheel 16. Furthermore, in addition to the three parameters of the speed of the wheel 16, the current value of the wheel drive unit 21, and the angle of the magnet 19, the rotational angle of the suspension axis A14 measured by the measuring instrument 141 and the frame attitude information measured by the attitude sensor 32 may also be used. This improves the accuracy of wheel derailment detection.

[0024] Next, the control unit 37 determines whether or not any wheel 16 has derailed based on the detection result of step S1 (step S2). If it determines that no wheel 16 has derailed (step S2; No), the control unit 37 proceeds to the process of step S1.

[0025] On the other hand, if it is determined in step S2 that a wheel 16 has come off (step S2; Yes), the control unit 37 stops the traveling of the traveling robot 10 (step S3).

[0026] Next, the control unit 37 determines whether a command to execute a wheel recovery operation has been input (step S4). During the wheel recovery operation, the traveling robot 10 may move in a manner not anticipated by the operator or may result in an unexpected outcome. Therefore, in this step, the control unit 37 asks the operator for confirmation of the execution of the wheel recovery operation. The operator may refrain from executing the wheel recovery operation if, for example, there is limited space around the traveling robot 10 and the operator does not want to move the traveling robot 10 carelessly. Specifically, in this step, the control unit 37 notifies the operator that a wheel has fallen off and prompts the operator to input whether or not to execute the wheel recovery operation. For example, the control unit 37 may cause the display unit of the operation terminal 40 to display a message such as "Perform wheel recovery operation? (Yes / No)" and then accept the operator's input in response to this message. If the control unit 37 determines that a command to execute a wheel recovery operation has not been input (step S4; No), the control unit 37 proceeds to another process. In this case, the control unit 37 may, for example, continue traveling on the three wheels that are not off the road, based on the operator's operation.

[0027] On the other hand, if it is determined that a command to execute the wheel recovery operation has been input (step S4; Yes), the control unit 37 selects a wheel recovery operation pattern to execute (step S5). Here, the control unit 37 selects the safer of the two wheel recovery operation patterns, operation pattern A and operation pattern B.

[0028] The two wheel recovery operation patterns (operation patterns) are operations for restoring the wheel 16 that has come off the ground by controlling the posture of the traveling robot 10. Each operation pattern controls the posture of the traveling robot 10 by controlling the operation of at least one of the three wheels 16 that have not come off the ground.

[0029] Of the two operation patterns, operation pattern A moves the other wheel 16 on the same frame (vehicle body) side in the forward / backward direction away from the derailed wheel 16. For example, as shown in Figures 6A and 6B, if the left front wheel 16FL derails forward in the direction of travel, operation pattern A moves the left rear wheel 16BL backward. This applies a forward torque around the suspension axis A14 to the left first frame 20a, causing the derailed wheel 16FL to return to the ground as shown in Figure 6C.

[0030] In operation pattern B, at least one wheel 16 on a different frame (vehicle body) is moved forward or backward toward the derailed wheel 16. For example, as shown in Figures 7A and 7B, if the left front wheel 16FL derails forward in the direction of travel, operation pattern B moves the two right wheels 16FR, 16BR forward. This applies a forward force to the left first frame 20a via the suspension axis A14, causing the derailed wheel 16FL to return to the ground as shown in Figure 7C.

[0031] Specifically, in step S5, the control unit 37 determines whether operation pattern A or operation pattern B is safer based on the traveling direction of the traveling robot 10 immediately before the wheel derailment. Because the road surface FT (see FIGS. 8A and 8B ) on the side of the road surface FT on which the traveling robot 10 traveled immediately before the wheel derailment has been used and is considered to be reattachable, it can be determined that the operation pattern of returning to the same side of the road surface FT on which the traveling robot 10 traveled is safer. That is, in step S5, the control unit 37 selects an operation pattern in which the direction of movement of the wheels 16 executed during the operation pattern is opposite to the traveling direction of the traveling robot 10 immediately before the wheel derailment. For example, as shown in FIG. 8A , if the front wheels 16 derailed relative to the traveling direction TD immediately before the wheel derailment, operation pattern A is selected, which moves the wheels 16 in the direction opposite to the traveling direction TD. On the other hand, as shown in FIG. 8B , if the rear wheels 16 derailed relative to the traveling direction TD immediately before the wheel derailment, operation pattern B is selected, which moves the wheels 16 in the direction opposite to the traveling direction TD.

[0032] Next, the control unit 37 executes the wheel recovery operation using the operation pattern selected in step S4 (step S6), thereby causing the wheel 16 that has come off the ground to return to the ground.

[0033] Next, the control unit 37 determines whether the wheel 16 that has returned from being off the road generates an appropriate adhesive force with respect to the road surface (step S7). That is, an adhesive determination is performed to determine whether the adhesive state of the wheel 16 is good or bad.

[0034] In this adhesion determination, the control unit 37 first swings (rotates) the magnet 19 of the wheel 16 being determined within a range in which the magnet 19 will not come off, and detects the current value of the magnet drive unit 191 at the maximum swing position at that time. The "range in which the magnet 19 will not come off" is the range in which the magnet 19 will not release its magnetic attraction to the road surface. The control unit 37 then determines whether the current value (absolute value) of the magnet drive unit 191 at the detected maximum swing position exceeds a predetermined threshold, and if it determines that it does exceed the threshold, it determines that the wheel 16 is exerting an appropriate adhesive force on the road surface.

[0035] In step S7, if it is determined that the wheel 16 that has returned from being off the road generates an appropriate adhesive force to the road surface (step S7; Yes), the control unit 37 proceeds to step S10, which will be described later. In this case, since it can be determined that the magnet 19 of the wheel 16 is properly attached to the adhesive surface (wall surface W), the control unit 37 turns off the output of the magnet driving unit 191.

[0036] On the other hand, if it is determined in step S7 that the wheel 16 that has returned from wheel derailment is not exerting an appropriate adhesive force on the road surface (step S7; No), the control unit 37 determines, based on the operator's operation, whether to return to the position immediately before wheel derailment where the adhesive force was being exerted (step S8). If the adhesive force between the wheel 16 and the road surface cannot be confirmed, the road surface may be a non-magnetic portion NM. In this case, there is a risk of the wheel derailment occurring again if the vehicle continues traveling. Therefore, it is safe to return to the position immediately before wheel derailment after obtaining the operator's confirmation. Therefore, in this step, the control unit 37 notifies the operator that the wheel 16 is not exerting an appropriate adhesive force and prompts the operator to input whether or not to return to the position immediately before wheel derailment. For example, the control unit 37 causes the display unit of the operation terminal 40 to display a message such as "Do you want to move to the previous position where adhesive force is available? (Yes / No)" and accepts the operator's input in response to this message. If it is determined that the wheel 16 will not return to the position immediately before wheel derailment (step S8; No), the control unit 37 proceeds to another process. In this case, the control unit 37 may, for example, continue traveling with the three wheels that are not off the road, based on the operation of the operator.

[0037] On the other hand, if it is determined in step S8 that the traveling robot 10 will return to the position immediately before the wheel 16 derailed (step S8; Yes), the control unit 37 moves the wheel 16 back to the position where the wheel 16 was attached while maintaining the wheel 16's contact with the ground (step S9). Specifically, as shown in FIGS. 9A and 9B , the control unit 37 moves the other wheel 16 on the same frame as the wheel 16 that derailed and has returned to the ground in the forward / backward direction opposite the wheel 16 that derailed, with a relatively greater output than the wheel 16 on the other frame. In the illustrated example, the left rear wheel 16BL is moved backward with a greater output than the combined output of the two right wheels 16FR and 16BR. As a result, as shown in FIG. 9C , the traveling robot 10 moves backward diagonally while dragging the wheel 16 on the other frame, while maintaining the wheel 16's contact with the ground. If a cable, such as for a power supply, is routed around the traveling robot 10, the output of each wheel 16 is set taking into account the tension of the cable. Additionally, a search for an attractive surface to which the wheel 16 (magnet 19) can be attached may be performed in conjunction with the movement of the traveling robot 10. In searching for an attractive surface, the magnet 19 is rotated in one direction within an angle range that includes the angle at which the wheel 16 is detached from the current traveling surface, and the angle at which the current value of the magnet driving unit 191 first becomes zero toward the negative angle from the angle of the magnet 19 at which the current value is the largest is set as the direction of a new attractive surface. This makes it possible to deal with cases where it is unknown where the wheel 16 was attached just before it came off the track.

[0038] Next, the control unit 37 determines whether or not to terminate the wheel-fall recovery process (step S10), and if it determines not to terminate it (step S10; No), the control unit 37 proceeds to the above-mentioned step S1. Then, if it determines to terminate the wheel-fall recovery process, for example, due to the completion of movement to the target position (step S10; Yes), the control unit 37 terminates the wheel-fall recovery process.

[0039] [Technical Effects of the Present Embodiment] As described above, according to the present embodiment, when it is detected that one of the wheels 16 has come off the track, the operations of the wheels 16 other than the wheel 16 that has come off the track are controlled, and the wheel 16 that has come off the track is returned to the ground. This allows the wheel 16 to be suitably returned from the wheel-off state.

[0040] Furthermore, according to this embodiment, the wheel drive units 21 that individually drive the four wheels are controlled, and torque acts on the first frame 20a or the second frame 20b in a direction that causes the off-wheel wheel 16 to return to the ground. This allows the first frame 20a or the second frame 20b that supports the wheel 16 to rotate appropriately, and the wheel 16 to return to the ground after off-wheel driving.

[0041] Furthermore, according to this embodiment, the first frame 20a and the second frame 20b are connected via the suspension mechanism 14 that can change the relative position of the first frame 20a and the second frame 20b in the torsional direction. Therefore, the relative position of the first frame 20a and the second frame 20b can be changed in the torsional direction by the suspension mechanism 14, and the wheel 16 can be suitably returned from a wheel-off state.

[0042] Furthermore, according to this embodiment, the movement pattern of the wheels 16 other than the wheel 16 that has come off the road is selected based on the traveling direction TD of the traveling robot 10 immediately before the wheel 16 came off the road. This allows the wheel return operation to be performed on a road surface that has been used before. Ultimately, the wheel return operation can be performed more safely.

[0043] Furthermore, according to this embodiment, the wheel 16 is detected to have come off the track based on at least one of the angle (direction) of the magnet 19 around the first rotation axis Ax1 and the output of the wheel drive unit 21. This allows the internal sensor built into the traveling robot 10 to suitably detect the wheel coming off the track.

[0044] Furthermore, according to this embodiment, when a wheel 16 is detected to have come off the ground, the operator is notified of the wheel 16. Then, based on an execution command from the operator, control is executed to return the wheel 16 to the ground. This prevents the traveling robot 10 from falling into a state unexpected by the operator due to the wheel return operation.

[0045] [Variation 1] In the above embodiment, the suspension axis A14 is arranged along the left-right direction perpendicular to the traveling direction, i.e., the suspension mechanism 14 functions around the pitch axis. However, even if the suspension mechanism 14 functions around the roll axis, it is possible to preferably recover from a wheel drop by applying, for example, the following wheel drop recovery operation pattern. In this wheel drop recovery operation pattern, of the two wheels 16 on a different frame (vehicle body) from the wheel 16 that has dropped off, the wheel 16 on the same left-right side as the wheel 16 that has dropped off is moved forward in the front-rear direction away from the wheel 16, and the wheel 16 on the different left-right side from the wheel 16 that has dropped off is moved forward in the front-rear direction toward the wheel 16 that has dropped off. For example, as shown in Figures 10A and 10B , if the left front wheel 16FL drops off toward the traveling direction, the left rear wheel 16BL is moved backward, and the right rear wheel 16BR is moved forward. This applies a leftward force to the front first frame 20a via the suspension axis A14, causing the wheel 16FL that has come off the ground to return to the ground, as shown in Figure 10C. This wheel return operation pattern can be executed in step S6 of the wheel return process. In this case, step S5 can be omitted.

[0046] [Variation 2] In the above embodiment, the case where the number of wheels 16 is four has been described. However, the present invention can also be suitably applied to cases where the number of wheels is other than four. For example, a case where a suspension mechanism for a six-wheel rocker bogie system (three wheels on each side) is applied will be described. In a six-wheel rocker bogie system, as shown in FIG. 11A , a first wheel 16 a and a second wheel 16 b are supported at both ends of a bogie arm 25. One end of a rocker arm 26 is connected to the bogie arm 25 via a passive joint 27, and a third wheel 16 c is supported at the other end of the rocker arm 26. The frame 20 is connected to the rocker arm 26. In such a six-wheel rocker bogie system, if the first wheel 16 a derails, the second wheel 16 b is moved away from the first wheel 16 a as shown in FIG. 11A , or the third wheel 16 c is moved toward the first wheel 16 a as shown in FIG. 11B . When the second wheel 16b goes off the track, the first wheel 16a is moved away from the second wheel 16b as shown in Fig. 11C, or the third wheel 16c is moved away from the second wheel 16b as shown in Fig. 11D. When the third wheel 16c goes off the track as shown in Fig. 11E, the first wheel 16a and the second wheel 16b can be replaced with a single imaginary wheel 16d as shown in Fig. 11F, and the situation can be considered similar to the four-wheel case. Therefore, in this case, the above-mentioned operation pattern A or operation pattern B can be applied.

[0047] In addition, in the case of an eight-wheel (four wheels on each side) rocker bogie system, there are two sets of two wheels 16 connected by a bogie arm, and the two sets of bogie arms can be considered to be connected by a rocker arm, and the above-mentioned wheel recovery operation can be expanded and applied.

[0048] 12, in the case of a structure in which multiple units of a four-wheeled traveling robot 10 are connected by universal joints 28, the unit in which the wheel has come off performs a wheel-recovery operation using all four wheels, similar to the wheel-recovery process described above. The other units in which the wheel has not come off perform operations in coordination with the wheel-recovery operation so that the constraint (connection) of the universal joints 28 does not interfere with the recovery operation of the unit in question. For example, wheel-recovery may be performed while controlling torque using compliance control.

[0049] [Others] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, a motor may be installed to drive the suspension axis A14, and in the wheel return operation after the wheel has come off, the angle of the suspension axis A14 may be controlled in addition to the control of the wheels 16 that have not come off the wheel.

[0050] In addition, the imaging camera 31 may detect the situation around the traveling robot 10, and the traveling robot 10 may perform a wheel recovery operation within an operable range based on the detection results.

[0051] In addition, in the wheel recovery operation after a wheel has come off, the operation of the wheels 16 may be set in advance (for example, a specific wheel 16 may be rotated 60 degrees), or each wheel 16 may be controlled so that the rotation angle of the suspension axis A14 detected by the measuring device 141 (the relative angle between the two frames) approaches zero. Alternatively, a movement pattern may be generated by reinforcement learning.

[0052] Furthermore, the mobile device according to the present invention may be applied to, for example, a mobile robot that moves between various parts of a steel structure in the fields of shipbuilding and heavy industry, architecture and construction, infrastructure inspection and maintenance, etc. In addition, the details shown in the above embodiment may be modified as appropriate without departing from the spirit of the invention.

[0053] INDUSTRIAL APPLICABILITY As described above, the present invention is useful for suitably returning a wheel from a wheel-off position.

[0054] 10 Traveling robot (mobile device) 14 Suspension mechanism 16 Wheel 16FL Left front wheel 16FR Right front wheel 16BL Left rear wheel 16BR Left front wheel 16a First wheel 16b Second wheel 16c Third wheel 16d Virtual wheel 19 Magnet 20 Frame (vehicle body) 20a First frame (first vehicle body) 20b Second frame (second vehicle body) 21 Wheel drive unit 32 Attitude sensor 37 Control unit (detection unit, notification unit) 141 Measuring instrument 191 Magnet drive unit A14 Suspension axis At Twist direction FT Road surface (road surface on the side that the vehicle traveled just before the wheel derailed) NM Non-magnetic portion TD Direction of travel just before the wheel derailed W Wall surface (road surface)

Claims

1. A mobile device comprising: a plurality of wheels journalled on a vehicle body; a detection unit which detects when any of the wheels come off the road; and a control unit which, when the detection unit detects when one of the wheels has come off the road, controls the operation of all of the wheels except for the one wheel, thereby causing the one wheel to come off the road and touch the ground.

2. The moving device according to claim 1, wherein the control unit controls a wheel drive unit that drives the plurality of wheels individually, and applies a torque to the vehicle body in a direction that causes the one wheel to contact the ground.

3. The moving device according to claim 1, wherein the vehicle body includes a first vehicle body and a second vehicle body which individually support wheels, and the first vehicle body and the second vehicle body are connected via a suspension mechanism which can change the relative position of the first vehicle body and the second vehicle body in a torsional direction.

4. The moving device according to claim 1, wherein the control unit selects the motion pattern of the wheels other than the one wheel based on the traveling direction of the moving device immediately before the one wheel derails.

5. A mobility device as described in claim 1, comprising: a magnet built into each of the plurality of wheels and supported rotatably about a rotation axis; and a wheel drive unit that drives the plurality of wheels individually, wherein the detection unit detects the wheel coming off based on at least one of the angle of the magnet about the rotation axis and the output of the wheel drive unit.

6. A moving device as described in claim 1, further comprising an alarm unit that, when the detection unit detects that one of the wheels has come off the ground, notifies an operator of the come off, and the control unit executes control to cause the one of the wheels to touch the ground based on an execution command from the operator.

7. A control method for a mobile device having a plurality of wheels journalled on a vehicle body, the control unit of the mobile device executing the steps of: detecting a wheel coming off; and, if a wheel coming off of one of the wheels is detected in the step, controlling the operation of all wheels of the plurality of wheels excluding the one wheel, thereby causing the one wheel to contact the ground.

8. A control program for a mobile device that causes a computer of the mobile device having multiple wheels journalled on the vehicle body to function as: a detection unit that detects when one of the wheels has come off; and a control unit that, when the detection unit detects when one of the wheels has come off, controls the operation of all of the wheels except for the one wheel, thereby causing the one wheel to touch the ground.

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