JP2008234400A - Mobile robot and robot movement control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile robot and a robot movement control method that can naturally follow a moving target. <P>SOLUTION: The robot movement control method controls the mobile robot configured to follow a target while maintaining a predetermined relative position. A dead area A in which a follow-up motion is stopped in a traveling direction and a dead area B in which the follow-up motion in a lateral direction perpendicular to the traveling direction is stopped are set first. Whether the target 2 is within the dead area A and dead area B is determined. The follow-up motion in the traveling direction is executed if the target 2 is outside the dead area A, and turns if the target 2 is outside the dead area B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mobile robot and a robot movement control method, and more particularly to movement control of a mobile robot that moves following a tracking target.

  The mobile robot can move according to a predetermined movement route or a movement route that is corrected in real time. In such a mobile robot, there has been proposed a mobile robot that performs movement control following the movement of a tracking target such as a human. For example, this mobile robot is applied as a shopping cart type robot or a stroller type robot that follows a human.

  FIG. 8 is a schematic view of a mobile robot having such a function and a person who is a follow target as seen from above. The mobile robot 1 is controlled so as to be always located at a predetermined relative position on the right front side of the tracking target 2. In FIG. 8, the moving direction of the person is represented by an x direction, and a direction perpendicular to the x direction is represented by an xy coordinate system. Then, the mobile robot 1 acquires the position coordinates of the tracking target 2 and creates a movement path so as to maintain a self-position that has a predetermined relative positional relationship with the position coordinates.

  As one of the following movement algorithms, there is “turn is prioritized and moves back and forth only when turning is not necessary”. As shown in FIG. 8, when the mobile robot 1 moves following this tracking movement algorithm so that the relative position between the mobile robot 1 and the tracking target 2 is maintained, the movement of the tracking target 2 is small. In response, a useless turning operation continues, and the following operation of the mobile robot 1 becomes unnatural. Furthermore, since the mobile robot 1 cannot move back and forth, the distance between the mobile robot 1 and the tracking target 2 increases, and the relative position of the mobile robot 1 and the tracking target 2 is determined in advance. There was a problem that it was significantly different from the target value.

Patent Document 1 discloses a robot that receives a work instruction from a predetermined IC tag and moves toward another IC tag that should be directed to the next. However, the IC tag to which the robot moves in Patent Document 1 is affixed to the floor surface and does not move itself.
JP 2004-108782 A

  As described above, according to the conventional tracking algorithm, there is a problem in that the useless turning motion increases and the robot tracking motion becomes unnatural.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a mobile robot and a robot movement control method that can naturally follow a moving follow target.

  A mobile robot according to the present invention is a mobile robot that performs a tracking operation while maintaining a predetermined position relative to a moving tracking target, the first insensitive region that stops the tracking operation in the front-rear direction, Setting means for setting a second dead area for stopping the follow-up operation in the lateral direction perpendicular to the front-rear direction, and whether the follow target is inside the first dead area and the second dead area And a determination means for determining whether or not the tracking target is not inside the second dead area as a result of the determination, and then the turning operation is performed, and then the tracking target is not inside the first dead area In some cases, it is provided with an operation determining means for executing the front-rear operation.

  Here, the mobile robot is preferably a wheeled mobile robot.

  The first insensitive area includes a target position that is the relative predetermined position where the follow target is to be located, and is in a right and left direction with a certain width in a direction perpendicular to the traveling direction of the follow target. It is desirable that the second dead area includes the target position and extends in the front-rear direction with a certain width in the direction of travel of the tracking target.

  Furthermore, the first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be located, and extends in both directions with a certain width in an arc shape around the current position of the mobile robot. Preferably, the second insensitive area includes the target position, and extends in the direction of the current position and in the opposite direction with a certain width in a line direction connecting the target position and the current position. .

  A robot movement control method according to the present invention is a robot movement control method for controlling movement of a mobile robot that performs a tracking operation while maintaining a predetermined position relative to a moving tracking target. Setting a first insensitive area for stopping the operation and a second insensitive area for stopping the follow-up operation in the lateral direction perpendicular to the front-rear direction; and the follow-up target is the first insensitive area and A step of determining whether or not the object is inside the second dead area; and as a result of the determination, if the follow target is not inside the second dead area, a turning operation is performed, and then the follow target is And a step of performing a back-and-forth operation when not inside the first insensitive area.

  Here, the mobile robot is preferably a wheeled mobile robot.

  The first insensitive area includes a target position that is the relative predetermined position where the follow target is to be located, and is in a right and left direction with a certain width in a direction perpendicular to the traveling direction of the follow target. It is desirable that the second dead area includes the target position and extends in the front-rear direction with a certain width in the direction of travel of the tracking target.

  Furthermore, the first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be located, and extends in both directions with a certain width in an arc shape around the current position of the mobile robot. Preferably, the second insensitive area includes the target position, and extends in the direction of the current position and in the opposite direction with a certain width in a line direction connecting the target position and the current position. .

  According to the present invention, it is possible to provide a mobile robot and a robot movement control method that can naturally follow a moving follow target.

Embodiment 1 of the Invention
A robot movement control method according to the first embodiment will be described with reference to FIGS. As shown in FIG. 1, the mobile robot 1 acquires the position coordinates of the tracking target 2 and creates a movement path so as to maintain a self-position having a predetermined relative positional relationship with the position coordinates. A specific configuration of the mobile robot 1 in FIG. 1 will be described in detail later. The mobile robot 1 is typically a non-holonomic wheel-type robot that cannot move sideways, but may be an autonomous walking robot. The follow target 2 has a function of moving by itself and is typically a person, but may be another robot or vehicle.

  As shown in FIG. 1, the mobile robot 1 creates a movement path so as to maintain a predetermined position (here, a position advanced by xt forward and yt in the horizontal direction) diagonally right before the tracking target 2. The movement is controlled. In FIG. 1, P1 indicates the current position of the mobile robot 1, and P2 indicates a target position that is a predetermined relative position. The target position P2 is (xt, yt) when the current position P1 is the origin (0, 0) in the xy coordinate system.

  In this example, a dead area A and a dead area B are provided. The insensitive area A is an area serving as a reference for determining whether the mobile robot 1 performs a follow-up operation in the front-rear direction. Specifically, when the follow target 2 is located in the dead area A, the mobile robot 1 does not perform the follow-up operation in the front-rear direction, and when the follow target 2 is located outside the dead area A. The mobile robot 1 performs a follow-up operation in the front-rear direction. The dead area A includes a target position P2 of the tracking target 2 that is a target determined to maintain a predetermined relative positional relationship with the current position P1 of the mobile robot 1, and the target position P2 of the tracking target 2 from the target position P2 It has a rectangular range provided with a predetermined width by a predetermined distance in the left-right direction perpendicular to the traveling direction. In this example, the insensitive area A is provided with the same distance from the target position P2 in the left-right direction.

  The insensitive area B is an area serving as a reference for determining whether or not the mobile robot 1 performs the horizontal lateral tracking operation. Specifically, when the tracking target 2 is located in the insensitive area B, the mobile robot 1 does not perform a lateral tracking operation, and the tracking target 2 is positioned outside the insensitive area B. The mobile robot 1 performs a lateral tracking operation. The insensitive area B includes a target position P2 of the tracking target 2 that is a target determined so as to maintain a predetermined relative positional relationship with the current position P1 of the mobile robot 1. It has a rectangular range provided with a constant width by a predetermined distance with respect to the traveling direction. In this example, the insensitive area B is provided with the same distance from the target position P2 in the front-rear direction.

  When the tracking target 2 is located in a common area included in both the insensitive area A and the insensitive area B, the mobile robot 1 does not perform front / rear / right / left tracking operations (that is, the mobile robot 1 does not perform any tracking operation). ). Therefore, as long as the tracking target 2 exists in the common area, even if the tracking target 2 moves in the common area, the mobile robot 1 does not perform the tracking operation and thus does not move at all.

  Subsequently, the movement control of the mobile robot according to the first embodiment will be described with reference to FIG. The follow-up algorithm in the movement control according to the first embodiment is “prioritizing the turning movement for adjusting to a desired direction, and moves back and forth only when turning is not necessary”.

  FIG. 2A shows an initial state. In this state, since the mobile robot 1 and the tracking target 2 have a predetermined relative positional relationship, the tracking target 2 is in the common area of the insensitive area A and the insensitive area B. For this reason, the mobile robot 1 does not perform the following operation.

  FIG. 2B shows a state in which the tracking target 2 has left the insensitive area A because the moving speed of the tracking target 2 is faster than that of the mobile robot 1. On the other hand, the tracking target 2 is in the insensitive area B. In such a case, the mobile robot 1 starts follow-up control in the front-rear direction. Specifically, the mobile robot 1 increases the speed in the forward direction, the distance to the tracking target 2 is shortened, and the mobile robot 1 moves so that the tracking target 2 enters the insensitive area A. Note that when the tracking target 2 is shifted backward from the insensitive area A, the mobile robot 1 moves so that the tracking target 2 moves relatively forward.

  FIG. 2C shows a state in which the follow target 2 has moved to the left side and has left the insensitive area B. On the other hand, the tracking target 2 is in the insensitive area A. In such a case, the mobile robot 1 performs a clockwise turning operation. Note that when the follow target 2 moves to the right and exits from the insensitive area B, the mobile robot 1 performs a counterclockwise turning operation.

The insensitive area A and the insensitive area B are also rotated at the same time by the turning operation, and the follow target 2 enters the insensitive area B, but goes out of the insensitive area A. This state is shown in FIG. By such a turning operation, the relative positional relationship between the mobile robot 1 and the tracking target 2 is in a state that matches only in the lateral direction and is in a state of being shifted in the front-rear direction. For this reason, the mobile robot 1 starts a follow-up operation in the front-rear direction and starts moving in the rear direction. The mobile robot 1 moves backward until the tracking target 2 is located in the insensitive area A.
Here, when the tracking target 2 comes out of the insensitive area B, the tracking target 2 enters the insensitive area B by moving the mobile robot 1 in the horizontal direction without performing the turning motion. Is also possible. However, since the mobile robot 1 is a wheel-type robot that cannot move in the lateral direction, in order to move in the lateral direction, it is necessary to turn 90 degrees and then go straight, and to rotate greatly. On the other hand, in the present invention, although the turning operation is performed, the tracking target 2 is performed until it enters the insensitive area B, and thereafter, the turning operation is stopped and the operation proceeds to the front-rear operation. Follow-up action.

  Here, a configuration example of the mobile robot according to the first embodiment will be described. As shown in FIG. 3, the mobile robot 1 is a two-wheeled mobile robot having a box-shaped main body 1a, a pair of opposing wheels 11a and 11b, and a caster 12, and these wheels 11a and 11b. The caster 12 supports the main body 1a horizontally. Further, in the main body 1a, drive units (motors) 13a and 13b for driving the wheels 11a and 11b, a counter 14 for detecting the rotation speed of the wheels, and a control signal for driving the wheels are created. And the calculating part 15 which transmits the control signal to the drive parts 13a and 13b is provided.

  In this example, the arithmetic unit 15 calculates the front / rear motion output and the turning motion output according to the follow-up algorithm, and creates a control signal including an operation output value so that the motion according to these is executed. A program for controlling the moving speed, moving direction, moving distance, etc. of the vehicle 10 based on the control signal is recorded in a storage area 15a such as a memory provided as a storage unit provided inside the calculation unit 15. Yes. The moving speed, the moving distance, and the like are obtained based on the number of rotations of the wheels 11a and 11b detected by the counter 14.

Further, an obstacle detection means 16 such as a camera for recognizing an obstacle appearing in the moving direction is fixed on the front surface of the main body 1a. An image of the obstacle recognized by the obstacle detection means 16 is fixed. And information such as video are input to the calculation unit 15. An antenna 17 for recognizing the self position is provided on the upper surface of the main body 1a. For example, position information from a GPS or the like (not shown) is received, and the position information is analyzed by the calculation unit 15 to detect the self position. Can be accurately recognized. As a result, the moving direction and speed of the vehicle are determined according to the program.
Further, a tracking target detection unit 18 such as a camera for recognizing the tracking target 2 is fixed on the rear surface of the main body 1a, and information such as an image and a video of the tracking target 2 recognized by the tracking target detection unit 18 is provided. Is input to the calculation unit 15. The calculation unit 15 can perform analysis based on information such as images and videos of the tracking target 2 and accurately recognize the relative positions of the tracking target 2 and the mobile robot 1.

  When an ultrasonic tag is attached to the tracking target 2, the tracking target detection means 19 corresponds to a receiving device that receives an ultrasonic signal transmitted from the ultrasonic tag.

  Next, the flow of movement control according to the first embodiment will be described using the flowchart of FIG.

  First, in the mobile robot 1, the position of the tracking target 2 is measured by the tracking target detection means 18, and the calculation unit 15 that has acquired this position information calculates a deviation (Δx, Δy) on the xy coordinates, and outputs the longitudinal motion. And the turning motion output are calculated respectively (S101). Here, the deviation (Δx, Δy) is a value representing a deviation between a target position where the tracking target 2 should be positioned with respect to the mobile robot 1 and an actual position of the tracking target 2 in xy coordinates. The back-and-forth motion output and the turning motion output are values that can move the mobile robot 1 so that the deviation (Δx, Δy) becomes zero.

  Next, the computing unit 15 of the mobile robot 1 determines whether or not the follow target 2 is located inside the insensitive area B with respect to the y direction (S102). As a result of the determination, when it is determined that the tracking target 2 is located inside the insensitive region B with respect to the y direction, the calculation unit 15 determines that the turning motion is not necessary, and sets the value 0 to the turning motion output. (S103). On the other hand, as a result of the determination, when it is determined that the tracking target 2 is not located inside the insensitive region B with respect to the y direction, that is, located outside, the calculation unit 15 determines that the front-rear operation is unnecessary. Then, the value 0 is set to the front-rear operation output (S104).

  Next, when the value 0 is set for the turning motion output in step S103, the calculation unit 15 of the mobile robot 1 further determines whether or not the follow target 2 is located inside the insensitive area A in the x direction. (S105). As a result of the determination, when it is determined that the tracking target 2 is located inside the insensitive area A with respect to the x direction, the calculation unit 15 determines that the front / rear operation is unnecessary, and sets a value of 0 for the front / rear operation output. (S106). On the other hand, as a result of the determination, when it is determined that the follow target 2 is not located inside the insensitive area A with respect to the x direction, that is, located outside, the calculation unit 15 determines that the turning motion is unnecessary. Then, the value 0 is set to the turning operation output (S107).

  Thereafter, the calculation unit 15 updates the operation output value (S108).

  Next, an example different from FIG. 4 will be described with respect to the flow of movement control according to the first embodiment, using the flowchart of FIG.

  First, in the mobile robot 1, the position of the tracking target 2 is measured by the tracking target detection means 18, and the calculation unit 15 that has acquired this position information calculates a deviation (Δx, Δy) on the xy coordinates, and outputs the longitudinal motion. And the turning motion output are respectively calculated (S201).

  Next, the computing unit 15 of the mobile robot 1 determines whether or not the follow target 2 is located inside the insensitive area B in the y direction (S202). As a result of the determination, when it is determined that the tracking target 2 is located inside the insensitive region B with respect to the y direction, the calculation unit 15 determines that the turning motion is not necessary, and sets the value 0 to the turning motion output. (S203). On the other hand, as a result of the determination, when it is determined that the tracking target 2 is not located inside the insensitive region B with respect to the y direction, that is, located outside, the calculation unit 15 reduces the front-rear motion output, It is determined that the front / rear operation is not necessary, and the value 0 is set to the front / rear operation output (S204).

  Subsequent to step S203 and step S204, the computing unit 15 of the mobile robot 1 determines whether or not the tracking target 2 is located inside the dead area A with respect to the x direction (S205). As a result of the determination, when it is determined that the tracking target 2 is located inside the insensitive area A with respect to the x direction, the calculation unit 15 determines that the front / rear operation is unnecessary, and sets a value of 0 for the front / rear operation output. (S206). On the other hand, as a result of the determination, if it is determined that the follow target 2 is not located inside the insensitive area A with respect to the x direction, that is, located outside, the calculation unit 15 reduces the turning operation output. Then, it is determined that the turning motion is unnecessary, and the value 0 is set to the turning motion output (S207).

  Thereafter, the calculation unit 15 updates the operation output value (S208).

  As described above, in the mobile robot according to the first embodiment, a dead zone is set, and as long as the follow target is located in the dead zone, the follow operation is not performed, and thus a useless turn occurs. In addition, there is an effect that the tracking target can be tracked by natural movement. In addition, when the subject to be tracked is shifted laterally beyond the dead area with respect to the mobile robot, the robot does not start moving in the horizontal direction but performs a turning operation, and then moves back and forth. Therefore, there is an effect that the tracking target can be tracked by a more natural movement.

Embodiment 2 of the Invention
Also in the movement control method according to the second embodiment, as in the first embodiment of the invention, the mobile robot 1 acquires the position coordinates of the tracking target 2 and has a predetermined relative positional relationship with the position coordinates. Create a movement path to keep a certain position.

  As shown in FIG. 6A, the mobile robot 1 creates a movement path so as to maintain a predetermined position diagonally in front of the tracking target 2 and is controlled for movement. In FIG. 1, P1 indicates the current position of the mobile robot 1, and P2 indicates a target position that is a predetermined relative position. In the movement control method according to the second embodiment, the position of the target position P2 is specified by the distance d from the current position P1 and the angle θ with respect to the line extending from the current position P1 in the front-rear direction.

  In this example, a dead area C and a dead area D are provided. The insensitive area C is an area serving as a reference for determining whether or not the mobile robot 1 performs the front-rear tracking operation. In the second embodiment, the front-rear direction is on a line connecting the current position P1 of the mobile robot 1 and the target position P2 of the tracking target 2. Specifically, when the follow target 2 is located in the dead area C, the mobile robot 1 does not perform the follow-up operation in the front-rear direction, and when the follow target 2 is located outside the dead area C. The mobile robot 1 performs a follow-up operation in the front-rear direction.

  The dead area C has a range extending by rotating a predetermined width including the target position P2 of the tracking target 2 in both directions by a predetermined angle in an arc shape around the current position P1. In this example, the insensitive area C is provided with the same angle on both sides from the target position P2.

  The insensitive area D is an area that serves as a reference for determining whether the mobile robot 1 performs the horizontal lateral tracking operation. Here, the left and right lateral directions are directions perpendicular to the front-rear direction. Specifically, when the tracking target 2 is located in the insensitive area D, the mobile robot 1 does not perform a lateral tracking operation, and the tracking target 2 is positioned outside the insensitive area D. The mobile robot 1 performs a lateral tracking operation. The dead area D includes the target position P2 of the tracking target 2, connects P1 and P2, and is a line obtained by rotating a line segment extending beyond P2 clockwise and counterclockwise by a predetermined angle around P1. It has a range of isosceles triangles with the hypotenuse as the minute. At this time, the base of the isosceles triangle may be a part of an arc having the same distance from the current position 1 of the mobile robot 1. In other words, the insensitive region D extends in the direction of P1 and the opposite direction with a certain width in the line direction connecting P1 and P2.

  When the tracking target 2 is located in a common area included in both the insensitive area C and the insensitive area D, the mobile robot 1 does not perform front / rear / right / left tracking operations (that is, the mobile robot 1 does not perform any tracking operation). ). Therefore, as long as the tracking target 2 exists in the common area, even if the tracking target 2 moves in the common area, the mobile robot 1 does not perform the tracking operation and thus does not move at all.

  The robot movement control method according to the second embodiment is a flowchart in which the insensitive area A is replaced with the insensitive area C and the insensitive area B is replaced with the insensitive area D in the control flow in the first embodiment shown in FIGS. 4 and 5. Is feasible. Note that the front-rear direction in this example is a direction connecting the current position of the mobile robot 1 and the target position of the tracking target 2 to the current position from the tracking target 2 and the opposite direction.

  As described above, in the mobile robot according to the second embodiment, as in the first embodiment, the insensitive area is set, and the tracking operation is not performed as long as the tracking target is located in the insensitive area. There is an effect that a tracking target can be tracked by natural movement without causing unnecessary turning. In addition, when the subject to be tracked is shifted laterally beyond the dead area with respect to the mobile robot, the robot does not start moving in the horizontal direction but performs a turning operation, and then moves back and forth. Therefore, there is an effect that the tracking target can be tracked by a more natural movement.

Other embodiments.
The shape of the insensitive area may be a circle or an ellipse like the insensitive area E shown in FIG.

It is explanatory drawing for demonstrating the robot movement control method concerning this invention. It is explanatory drawing for demonstrating the robot movement control method concerning this invention. It is a schematic block diagram which shows the structural example of the mobile robot concerning this invention. It is a flowchart which shows the flow of control in the robot movement control method concerning this invention. It is a flowchart which shows the flow of control in the robot movement control method concerning this invention. It is explanatory drawing for demonstrating the robot movement control method concerning this invention. It is explanatory drawing for demonstrating the robot movement control method concerning this invention. It is explanatory drawing for demonstrating the conventional robot movement control method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile robot 2 Tracking object 1a Main body 11a, 11b Wheel 12 Caster 13a, 13b Drive part 14 Counter 15 Calculation part 16 Obstacle detection means 17 Antenna 18 Tracking object detection means

Claims (8)

A mobile robot that performs a tracking operation while maintaining a predetermined position relative to a moving tracking target,
Setting means for setting a first insensitive area for stopping the follow-up operation in the front-rear direction and a second insensitive area for stopping the follow-up action in the lateral direction perpendicular to the front-rear direction;
Determination means for determining whether the follow target is inside the first dead area and the second dead area;
As a result of the determination, if the follow target is not inside the second dead area, a turning motion is executed, and if the follow target is not inside the first dead area, a back and forth action is executed thereafter. A mobile robot comprising movement determining means.   The mobile robot according to claim 1, wherein the mobile robot is a wheeled mobile robot. The first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be positioned, and extends in both left and right directions with a certain width in a direction perpendicular to the traveling direction of the tracking target. And
3. The mobile robot according to claim 1, wherein the second insensitive area includes the target position and extends in the front-rear direction with a certain width in the direction of travel of the tracking target. The first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be located, and extends in both directions with a certain width in an arc shape around the current position of the mobile robot,
The second insensitive area includes the target position, and extends in the direction of the current position and in the opposite direction with a certain width in a line direction connecting the target position and the current position. The mobile robot according to claim 1 or 2. A robot movement control method for controlling movement of a mobile robot that performs a tracking operation while maintaining a predetermined position relative to a moving tracking target,
Setting a first insensitive region for stopping the follow-up operation in the front-rear direction and a second insensitive region for stopping the follow-up operation in the lateral direction perpendicular to the front-rear direction;
Determining whether the tracking target is inside the first dead area and the second dead area;
As a result of the determination, if the follow target is not inside the second dead area, a turning motion is executed, and if the follow target is not inside the first dead area, a back and forth action is executed thereafter. And a robot movement control method.   6. The robot movement control method according to claim 5, wherein the mobile robot is a wheel type mobile robot. The first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be positioned, and extends in both left and right directions with a certain width in a direction perpendicular to the traveling direction of the tracking target. And
7. The robot movement control according to claim 5, wherein the second insensitive area includes the target position and extends in the front-rear direction with a certain width in the direction of travel of the follow target. Method. The first insensitive area includes a target position that is the relative predetermined position where the tracking target is to be located, and extends in both directions with a certain width in an arc shape around the current position of the mobile robot,
The second insensitive area includes the target position, and extends in the direction of the current position and in the opposite direction with a certain width in a line direction connecting the target position and the current position. The robot movement control method according to claim 5 or 6.

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