JP6693291B2 - Mobile robot movement route planning method - Google Patents

Description

  The present invention relates to a moving route planning method for a mobile robot.

  A mobile robot that autonomously moves to a target point is known. The mobile robot determines a route to the target point using the environment map and moves along the route. For example, Patent Literature 1 discloses a technique for evaluating the possibility of colliding with an obstacle on a moving route.

JP, 2009-291540, A

  When a mobile robot grips a conveyed object and tries to move to a target point, the method of deciding the movement path that does not contact the obstacle after recognizing the outer shape including the conveyed object requires a large amount of calculation. In other words, it is a cause of hindering smooth movement. On the other hand, the method of sweeping the circle circumscribing the projection of the mobile robot holding the conveyed object on the environment map to determine the movement route that does not contact the obstacle has a small amount of calculation but many obstacles. In the environment, sometimes it was not possible to find a route to move.

  The present invention has been made to solve such a problem, and provides a technique for planning a travel route for autonomous movement by searching a travel route that does not come into contact with an obstacle while suppressing the amount of calculation. Is provided.

A travel route planning method according to an aspect of the present invention is a mobile robot having a movable gripping unit and a storage unit that stores an environment map, and a projection of the mobile robot on the environment map in a state where a conveyed object is not gripped. It is equipped with the step of searching for the route to the target point on the environment map by sweeping the reference circle circumscribing to the Therefore, it is determined whether the gripping part or the conveyed object protrudes from the reference circle when the conveyed object is grasped, and if it protrudes, the judgment circle circumscribing the projection of the mobile robot including the protruding grasping part or the conveyed object. To determine whether there is a contact point where the judgment circle touches an obstacle when the judgment circle is swept along the path, and to identify the contact point. If, and a step of developing the avoidance operation to avoid the obstacle by at least changing one of the orientation of the orientation and mobile robot gripper.
With this configuration, if the movement route can be determined by the reference circle or the determination circle, the amount of calculation for route search is small and smooth autonomous movement can be realized. In this case, since it is not necessary to consider a change in posture during movement, traveling control is easy. On the other hand, if the movement path cannot be determined even by sweeping the judgment circle, the contact point on the path is identified and contact with obstacles is avoided by changing the posture while gripping the conveyed object. The route can also be passed. Further, the posture change at the contact point is calculated by using the actual shape of the outer shape of the mobile robot, so the amount of calculation is increased, but the amount of calculation is smaller than when the entire movement path is calculated using the actual shape. be able to.

  According to the present invention, the mobile robot can smoothly search for a moving route that does not come into contact with obstacles in a short time even in an environment with many obstacles and smoothly move.

FIG. 3 is an external perspective view of a mobile robot according to this embodiment. It is a control block diagram of a mobile robot. It is a figure explaining the reference circle in the case where a conveyed article is not gripped. It is a figure explaining the relationship with a reference circle when a conveyed article is grasped. It is a figure explaining the judgment circle at the time of grasping the conveyed thing. It is a figure which shows the example of the environment map to hold | maintain. It is a figure explaining the route search to a reference circle. It is a figure explaining the route search to a judgment circle. It is a figure explaining the environment in which the route for the judgment circle cannot be generated. It is a figure explaining the search of the movement course accompanying a posture change. It is a figure explaining operation which avoids an obstacle by posture change. It is a figure explaining contact determination after a posture change. It is a flow figure showing a processing procedure of a mobile robot.

  Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. In addition, not all of the configurations described in the embodiments are essential as means for solving the problem.

  FIG. 1 is an external perspective view of a mobile robot 100 according to this embodiment. The mobile robot 100 is roughly divided into a carriage 110 and a grip 120.

  The dolly unit 110 mainly includes a base 111, two drive wheels 112 attached to the base 111, and one caster 113. The two drive wheels 112 are arranged on opposite sides of the base 111 such that the axes of rotation are aligned. Each drive wheel 112 is independently rotationally driven by a motor (not shown). The caster 113 is a driven wheel, and a turning shaft extending in the vertical direction from the base 111 is provided so as to pivotally support the wheel apart from the rotation axis of the wheel, and follows the moving direction of the carriage 110. .. The mobile robot 100 goes straight if, for example, the two drive wheels 112 are rotated in the same direction at the same rotation speed, and turns around the vertical axis passing through the center of gravity if they are rotated in the opposite direction at the same rotation speed. That is, the mobile robot 100 can move forward, reverse, or turn by controlling the rotation direction and rotation speed of the two drive wheels 112, respectively.

  The trolley unit 110 is provided with various sensors for detecting obstacles and recognizing the surrounding environment. The camera 114 is one of the sensors and is arranged at the four corners of the base 111. The camera 114 includes, for example, a CMOS image sensor, and transmits a captured image signal to a control unit described later. If two adjacent cameras 114 capture the same subject, a parallax image can be acquired and the distance to the subject can also be calculated.

  The grip 120 is mainly composed of a plurality of arms 121, 122, 123 and a hand 124. The arm 121 has one end pivotally supported by the base 111 so as to be rotatable around a vertical axis. The arm 122 has one end pivotally supported by the other end of the arm 121 so as to be rotatable around a horizontal axis. The arm 123 is rotatably in the radial direction at the other end of the arm 122, and has one end pivotally supported by the other end of the arm 122. The hand 124 is rotatably supported on the other end of the arm 123 so as to be rotatable about a central axis parallel to the extending direction of the arm 123. Further, the hand 124 is provided with a gripping mechanism so that the conveyed object can be gripped. The arms 121, 122, 123 and the hand 124 are driven by a motor (not shown) to take a predetermined posture or hold a conveyed object.

  FIG. 2 is a control block diagram of the mobile robot 100. The control unit 200 is, for example, a CPU, and is provided in the carriage unit 110. The drive wheel unit 210 includes a drive circuit and a motor for driving the drive wheels 112, and is provided in the carriage unit 110. The control unit 200 controls the rotation of the drive wheels 112 by sending a drive signal to the drive wheel unit 210.

  The arm unit 220 includes a drive circuit and a motor for driving the arms 121, 122, 123 and the hand 124, and is provided in the grip section 120. The control unit 200 sends a drive signal to the arm unit 220 to execute posture control and grip control of the grip unit 120.

  The sensor unit 230 includes various sensors for searching the surrounding environment and monitoring the posture of the grip 120, and is arranged in a distributed manner in the carriage 110 and the grip 120. The control unit 200 sends a control signal to the sensor unit 230 to drive various sensors and obtain their outputs. The camera 114 is included in the sensor unit 230 and executes a shooting operation according to a control signal.

  The memory 240 is a non-volatile storage medium, and for example, a solid state drive is used. The memory 240 stores not only a control program for controlling the mobile robot 100, but also various parameter values, functions, lookup tables, and the like used for control. The memory 240 includes an environment map DB 241 that stores an environment map expressing the environment in which the mobile robot 100 autonomously travels.

  The control unit 200 also plays a role as a function calculation unit that executes various calculations related to control by transmitting and receiving information to and from the drive wheel unit 210, the arm unit 220, the sensor unit 230, and the memory 240. The contact determination unit 201 uses the environment map read from the environment map DB 241 to determine whether the mobile robot 100 contacts an obstacle when the mobile robot 100 autonomously travels. The route planning unit 202 uses the environment map read from the environment map DB 241 to plan a route for the mobile robot 100 to autonomously travel. The conveyed object recognition unit 203 photographs the conveyed object held by the hand 124 with the camera 114, and recognizes the size and position of the conveyed object using the image data. The posture planning unit 204 plans how to change the orientation of the carriage unit 110 and the posture of the gripping unit 120 to travel at a specific position on the movement route. The specific contents of each calculation will be described in detail in order.

FIG. 3 is a diagram illustrating the reference circle 501 when the conveyed object is not gripped. The reference circle 501 is a circle that surrounds the meshed area in the figure. Specifically, the reference circle 501 is a circle circumscribing the projection (shadow projected on the traveling surface from the vertical direction) of the mobile robot 100 in a state where the conveyed object is not gripped. When the gripping part 120 forms a part of the projection, the gripping part 120 takes a posture so that the entire projection is as small as possible. The diameter of the reference circle 501 defined in this way is defined as R ₀ . Since R ₀ is a constant determined by the structure of the mobile robot 100, its value is stored in the memory 240 in advance.

FIG. 4 is a diagram illustrating a relationship with the reference circle 501 when the conveyed object 301 is gripped. When the transport object 301 to be transported by the mobile robot 100 is relatively small, the projection of the transport object 301 falls within the reference circle 501 by devising the posture of the grip portion 120 even when the transport object 301 is gripped. In this way, if the projection of the mobile robot 100 holding the conveyed object 301 falls within the reference circle 501, the route planning unit 202 can search for the movement route based on the width R ₀ .

  The control unit 200 determines whether or not the projection of the mobile robot 100 holding the conveyed object 301 falls within the reference circle 501 after the conveyed object recognition unit 203 recognizes the size and position of the conveyed object. When the conveyed object recognition unit 203 recognizes that the tip of the conveyed object 301 in a certain gripping state is inside the virtual cylinder formed by the reference circle 501, it determines that the conveyed object 301 is within the reference circle 501. Even when it is recognized that it is projected from the virtual cylinder, it is calculated whether the posture of the gripping portion 120 is changed to change the gripped state of the conveyed object 301 so that the conveyed object 301 can be present inside the cylinder. Specifically, the conveyed object 301 is virtually arranged at various positions inside the cylinder in various postures, and whether or not there is a solution in the posture of the gripping portion 120 that grasps the conveyed substance 301 at the position and the posture. Calculate using kinematics. If a solution exists, the control unit 200 changes the gripping unit 120 to the posture according to the solution.

FIG. 5 is a diagram illustrating the determination circle 502 when the conveyed object 303 is gripped. When the conveyed object 303, which is an object to be conveyed, is relatively large, the projection of the state in which the conveyed object 303 is grasped does not fall within the reference circle 501, even if the posture of the grip portion 120 is devised. In this case, a determination circle 502 circumscribing the projection of the mobile robot 100 including the conveyed object 303 in a state where the conveyed object 303 is held is defined. At this time, it is preferable that the gripping part 120 has a posture such that the entire projection is as small as possible. For example, the control unit 200 variously changes the posture of the gripping unit 120 and recognizes the front end position of the conveyed product 303 by the conveyed product recognition unit 203 to find a posture in which the entire projection is as small as possible. The diameter of the judgment circle 502 defined in this way is defined as R ₁ . R ₁ is a value determined through the processing of the conveyed object recognition unit 203. The route planning unit 202 searches for a movement route based on the width R ₁ .

  Next, the search for the moving route will be described. FIG. 6 is a diagram showing an example of the environment map stored. The illustrated environment map 601 is one of the environment maps stored in the environment map DB 241. The environment map 601 is a map generated so as to project the actual environment on a plane at a predetermined scale, and specifically, is described so that the size and position of the fixed object can be mainly grasped. The example in the figure represents a substantially square room, which is surrounded by a wall 621. An open door 622 exists near the entrance, and a desk 624 is arranged in the center of the room. A sofa 625 and a television stand 626 are arranged so as to sandwich the desk 624. In such an environment, the control unit 200 defines a starting point 611 near the entrance and a target point 612 that should be reached by autonomous traveling.

FIG. 7 is a diagram for explaining the route search for the reference circle 501. As described with reference to FIG. 4, when it is determined that the projection falls within the reference circle 501 even if the conveyed object is grasped, the route planning unit 202 sets the width R _{0 from} the starting point 611 to the target point 612. Search for a route that can be established. Specifically, on the environment map 601, it is tried whether the circle having the diameter R ₀ can be swept from the starting point 611 to the target point 612. In the environment of the environment map 601, the route planning unit 202, as shown in FIG. 7A, the first route 631 along the two walls on the right side and the back side, and as shown in FIG. Two paths of travel can be found, passing between 624 and the television stand 626 and a second path 632 along the left wall. When a plurality of movement routes can be found in this way, the route planning unit 202 selects one according to a predetermined evaluation standard and determines the movement route of the mobile robot 100. As the evaluation standard, whether the distance between the route and the obstacle is long, the traveling distance to the target point 612 is short, or the like can be adopted.

FIG. 8 is a diagram illustrating a route search for the determination circle 502. As described with reference to FIG. 5, when it is determined that the projection when the conveyed object is gripped does not fit in the reference circle 501 and the determination circle 502 larger than the reference circle 501 fits, the route planning unit 202 searches for it can establish a travel route from the starting point 611 with a width _{R 1} to the target point 612. Specifically, on the environment map 601, it is tried whether the circle of the diameter R ₁ can be swept from the starting point 611 to the target point 612. In the environment of the environment map 601, the route planning unit 202 can find the movement route of the first route 641 along the two walls on the right side and the back side as illustrated. The route planning unit 202 determines the first route 641 as the moving route of the mobile robot 100. When a plurality of movement routes can be found, one may be selected according to a predetermined evaluation standard, as in the example of FIG. 7.

FIG. 9 is a diagram illustrating an environment in which a route for the determination circle 502 cannot be generated. The environment shown in FIG. 9 differs from the example in FIG. 6 in that there is a pillar 627 protruding from the wall 621 to the side of the desk 624. The distance between the desk 624 and the pillar 627 is R ′, which is smaller than R ₁ and further smaller than R ₀ . In the environment map 602 showing this environment, it is not possible to sweep the circle having the diameter R ₁ from the starting point 611 to the target point 612. That is, the first route 641 in FIG. 8 cannot be established. In such an environment, the mobile robot 100 that is determined that the projection when the conveyed object is gripped does not fall within the reference circle 501 and falls within the reference circle 501 if the decision circle 502 is larger than the reference point 501 is changed from the starting point 611 to the target point. The case of traveling up to 612 will be described.

FIG. 10 is a diagram for explaining a search for a moving route involving a change in posture. The illustrated environment is the same as the environment of FIG. 9 and is represented by an environment map 602. In the environment map 602, the second route 632 shown in FIG. 7B swept by the reference circle 501 can establish the route from the starting point 611 to the target point 612. However, since the width of the second path 632 is R ₀ , when the determination circle 502 having a diameter of R ₁ is swept along this path, it comes into contact with the obstacle at any point. The contact determination unit 201 identifies a contact point where the determination circle 502 contacts an obstacle when the determination circle 502 is swept along the second path 632. In the illustrated example, the decision circle 502 contacts the desk 624 at point P _S. Therefore, the contact determination unit 201 identifies the point P _S as the first contact point.

In addition, the contact determination unit 201 identifies a departure point at which the determination circle 502 does not come into contact with an obstacle when the determination circle 502 is swept along the second path 632. In the illustrated example, the judgment circle 502 contacts the desk 624 up to the point P _E. Therefore, the contact determination unit 201 identifies the point P _E as the departure point. Then, the contact determination unit 201 can identify the section D ₁ sandwiched between the contact point P _S and the departure point P _E as the contact section. When the contact section is identified, first, in the section other than the contact section, it is guaranteed that the mobile robot 100 holding the conveyed object 303 can travel without contacting the obstacle.

The posture planning unit 204 takes over the information of the contact section D ₁ from the contact determination unit 201, and whether or not the mobile robot 100 can pass through this section by changing the orientation of the trolley unit 110 and the attitude of the gripping unit 120. Is calculated. In the following description, changing the orientation of the carriage 110 and the attitude of the grip 120 may be simply referred to as attitude change.

  FIG. 11 is a diagram illustrating an operation of avoiding an obstacle by changing the posture. As shown in FIG. 11A, in a situation where the conveyed object 304 does not fit within the reference circle 501 because it protrudes in a direction orthogonal to the traveling direction, if the mobile robot 100 goes straight ahead, the conveyed object 304 will be a desk. Contact 624. The posture planning unit 204 grasps this situation and calculates whether or not contact with the desk 624 can be avoided due to a change in posture. As described above, the posture planning unit 204 considers a change in the orientation of the carriage unit 110 and a change in the posture of the gripping unit 120 as the posture change for avoiding an obstacle. In the situation of FIG. 11A, if the direction of the carriage 110 is changed, the traveling direction and the direction of the carriage 110 do not match, which is disadvantageous from the viewpoint of traveling control. Therefore, the posture planning unit 204 gives priority to changing the posture of the gripping unit 120 rather than changing the orientation of the carriage unit 110.

In the situation of FIG. 11A, the posture planning unit 204 finds a posture change of the gripping unit 120 in which the conveyed object 304 does not contact the desk 624. One of the solutions is a posture change to FIG. 11 (b). As shown in FIG. 11B, if the posture of the gripping part 120 is changed so that the conveyed object 304 is located rearward in the traveling direction, even if the mobile robot 100 advances from the contact point P _{S in a} minute section, the mobile robot 100 can move to the desk 624. It can be calculated that they do not touch. Here, the contact determination as to whether or not the mobile robot 100 contacts the obstacle when the mobile robot 100 is advanced in a minute section is determined as the obstacle described in the environment map 602 when the inclusion contour 510 shown in FIG. 12 is moved. It is geometrically determined whether they overlap.

FIG. 12 is a diagram illustrating the contact determination after the posture change. Subsumption contour illustrated 510, the reference circle 501 having a diameter of R _0, is obtained by adding the projection of the contour of the portion projecting from the diameter R _0. That is, by expressing the protruding portion with an actual geometrical shape, the relative position with respect to the obstacle can be strictly determined.

The posture planning unit 204 divides the contact section D ₁ into minute sections, and determines for each section whether the inclusion contour 510 does not contact the obstacle. When it is determined that the obstacle is contacted in a certain section, it is tried to avoid the obstacle by changing the posture again at the start point of the minute section. By repeating this calculation, it is determined whether or not the contact section D ₁ can be passed if the posture is changed.

Then, when it is determined that the vehicle can pass, what kind of posture change is to be executed at which point, and this is defined as an avoidance operation for avoiding an obstacle accompanying the traveling control of the bogie. If such an avoiding action can be formulated in the contact section, the control unit 200 can determine that the mobile robot 100 can reach the target point 612 in combination with the travel plan of the section other than the contact section in which the posture is not changed. .. In the above example, one contact section D ₁ exists on the route from the starting point 611 to the target point 612, but two or more contact sections may exist. In that case, try to determine whether the avoidance action can be formulated for each section.

  Further, in the above example, the straight section is introduced as an example of the contact section, but the contact section may of course include a right turn portion, a left turn portion, a curved section, and the like. When the traveling direction changes, it may be easier to avoid contact with an obstacle by changing the orientation of the trolley unit 110 rather than changing the posture of the grip unit 120. The posture planning unit 204 may formulate the avoidance motion in consideration of the traveling control.

  Next, a process from generation to execution of the movement plan of the mobile robot 100 will be described. FIG. 13 is a flowchart showing the processing procedure of the mobile robot 100. The flow starts when the mobile robot 100 is stopped at the starting point.

In step S101, the route planning unit 202 reads the environment map from the environment map DB 241, reads the diameter R _{0 of the} reference circle from the memory 240, and determines whether a movement route to reach the target point can be established with the width R ₀ as a reference. Explore. If it is determined that the movement route cannot be established, the target point cannot be reached even if the transported object is not gripped in the first place, so the process proceeds to step S102 and a notification that the destination cannot be reached is issued. The unreachability notification may be, for example, a voice notification or an image displayed on the terminal owned by the user. The mobile robot 100 ends the series of processes without starting the movement when the unreachability notification is made.

  When it is determined that the movement route can be established in step S101, the process proceeds to step S103, and the control unit 200 holds the conveyed object via the arm unit 220. Then, the conveyed product recognition unit 203 executes outer shape recognition such as the size and position of the conveyed product via the sensor unit 230.

In step S104, the control unit 200 determines whether or not the projection is within the radius R _{0 of the} reference circle with the gripping unit 120 gripping the conveyed object. When it is determined that the width is within the range, the process proceeds to step S105, and the movement route with the width R ₀ is determined. In addition, as described above, when a plurality of movement routes having the width R ₀ are found, one route is determined according to the evaluation standard. When the moving route is determined, the process proceeds to step S106, the vehicle moves along the route, and when the target point is reached, the series of processes is ended.

When it is determined in step S104 that the radius does not fall within the radius R ₀ , the conveyed object recognition unit 203 determines the determination circle and its diameter R ₁ while changing the posture of the gripping unit 120 in step S107. It should be noted that this process may be collectively performed at the stage of step S103.

In step S108, the route planning unit 202 refers to the environment map and searches for a movement route that reaches the target point based on the width R ₁ as a reference. When the movement route can be established, the process proceeds to step S109, and the movement route with the width R ₁ is determined. In addition, when a plurality of movement routes having the width R ₁ are found, one route is determined according to the evaluation standard. When the moving route is determined, the process proceeds to step S106, the vehicle moves along the route, and when the target point is reached, the series of processes is ended.

If the movement route based on the width R ₁ cannot be established in step S108, the process proceeds to step S110, and the contact determination unit 201 determines the movement route based on the width R ₀ searched by the route planning unit 202 in step S101. Select one for verification. If there is only one, the movement route is subject to verification. Then, in step S111, as described with reference to FIG. 10, the determination circle having the diameter R ₁ is swept along the movement path to be verified to identify the contact point and the contact section with the obstacle. The contact determination unit 201 proceeds to step S112, and tries whether or not the contact point and each point obtained by dividing the contact section into minute sections can avoid a collision with an obstacle due to a change in posture. When it is determined that it cannot be avoided, the process proceeds to step S113, and the contact determination unit 201 confirms whether the route planning unit 202 has verified all the moving routes based on the width R ₀ searched in step S101. If all have not been verified yet, the process returns to step S110 and steps S110 to S112 are repeated. On the other hand, when all the verifications have been completed, the process proceeds to step S102, the notification of unreachability is given as described above, and the series of processes is ended.

  When it is determined in step S112 that the contact with the obstacle can be avoided, the process proceeds to step S114 to determine what kind of posture change is to be performed at which point and formulate the avoidance operation for avoiding the obstacle. Then, the process proceeds to step S115, in which the control unit 200 moves along the movement route while changing the posture according to the avoidance motion determined in the contact section, and ends the series of processes when reaching the target point.

  As described above, when the mobile robot 100 autonomously moves to carry a conveyed object to a target point, if the movement route can be determined by the reference circle or the determination circle formed from the projection of the mobile robot 100, the route search is performed. There is little calculation amount for, and smooth autonomous movement can be realized. In this case, since it is not necessary to consider a change in posture during movement, traveling control is easy. On the other hand, if the movement path cannot be determined even by sweeping the judgment circle, the contact point on the path is identified and contact with obstacles is avoided by changing the posture while gripping the conveyed object. The route can also be passed. That is, even if the movement route cannot be searched for by sweeping the circle, the route to the target point can be secured. Further, since the posture change at the contact point is calculated by using the actual shape of the outer shape of the mobile robot 100, the amount of calculation is increased, but the amount of calculation is smaller than that when the entire movement path is calculated using the actual shape. Become. If the amount of calculation can be reduced, movement stop for calculation can be suppressed or the moving speed can be improved, especially when a target point is continuously set and moving a long distance.

  The execution order of each process such as the operation, procedure, step, and stage in the devices, systems, programs, and methods shown in the above-described embodiments is explicitly stated as "prior to", "prior to", or the like. It can be realized in any order unless the output of the previous process is used in the subsequent process. Even if “first,” “next,” and the like are used for convenience, it does not mean that it is essential to carry out in this order.

100 mobile robot, 110 trolley part, 111 base, 112 drive wheel, 113 caster, 114 camera, 120 gripping part, 121, 122, 123 arm, 124 hand, 200 control part, 201 contact determination part, 202 route planning part, 203 Transport object recognition unit, 204 posture planning unit, 210 drive wheel unit, 220 arm unit, 230 sensor unit, 240 memory, 241 environment map DB, 301 transport object, 303 transport object, 501 reference circle, 502 judgment circle, 510 inclusion contour , 601, 602 Environmental Map, 611 Starting Point, 612 Target Point, 621 Wall, 622 Door, 623 Floor, 624 Desk, 625 Sofa, 626 TV Stand, 627 Pillar, 631 1st Route, 632 2nd Route, 641 4th 1 route

Claims (1)

A mobile robot having a movable gripper and a storage that stores an environment map, and sweeping a reference circle circumscribing the projection of the mobile robot that is not gripping the transported object on the environment map. According to the present invention, there is provided a step of searching for a route to a target point on the environment map, wherein the gripper holds a conveyed object to plan a movement route to the target point.
When gripping the conveyed object, it is determined whether the gripping portion or the conveyed object protrudes from the reference circle, and when protruding, the projection of the mobile robot including the protruding gripping portion or the conveyed object. Creating a circumscribing decision circle,
When the determination circle is swept along the path, the determination circle determines whether or not there is a contact point in contact with an obstacle, and the step of identifying the contact point,
When the contact point exists, a step of formulating an avoidance operation for avoiding the obstacle by changing at least one of the attitude of the grip section and the attitude of the mobile robot, is provided.

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