JP7069703B2 - Autonomous mobile robot - Google Patents

Description

The present invention relates to an autonomous mobile robot that pulls an object to be transported and autonomously moves while acquiring information on the surrounding environment.

Conventionally, a technique for transporting an object to be transported by an autonomous mobile robot has been known.
For example, Non-Patent Document 1 discloses a robot that automatically travels while towing a trolley on which an article is placed. This robot has two left and right drive wheels, and by controlling the rotation speeds of these left and right drive wheels, it moves while following the magnetic rail.

Further, Patent Document 1 discloses an autonomous moving body that prevents an object to be transported connected to the own machine from interfering with the surrounding environment when avoiding obstacles. In this autonomous moving body, a connecting portion that connects the own machine and the object to be transported is fixed, and the front direction of the own machine is controlled so as to match the direction of the movement path.

When an article is placed on a trolley and transported, there is a risk that the trolley may tilt or the article may fall when turning, depending on the position on which the article is placed. Therefore, Patent Document 2 discloses a robot that arranges a heavier article among a plurality of articles closer to a presumed turning center of a carriage as compared with other articles.

Gen Aoyama, Kazuyoshi Ishikawa, Junya Seki, Saori Ishimura, Yuichi Satsumi, Shuji Hashigadani, Yoshiaki Oishi, "Consolidated Pharmaceutical Container Exchange Robot", January 2009, Journal of the Robotics Society of Japan, Vol. 27, No. 1, pp. 39-40, 2009

Japanese Patent No. 5337408 Japanese Unexamined Patent Publication No. 2016-1240336

As described above, since the robot described in Non-Patent Document 1 moves with two left and right drive wheels, the center of the left and right drive wheels (the center of the axle) follows the path when performing path tracking control (the center of the axle). It becomes a control point). Therefore, the distance from the control point to the center of gravity of the connected object to be transported is long, and the inertial force applied to the object to be transported during turning becomes large. This inertial force becomes even larger when the weight of the transported object is heavy. As a result, the transported object may be shaken greatly and interfere with the surrounding environment.

Therefore, in Patent Document 1, in order to prevent the transported object from being shaken during turning and interfering with the surrounding environment, the connecting portion between the own machine and the transported object is fixed, and the front direction and the movement path of the own machine are fixed. Matches the orientation of. However, in the autonomous moving body of Patent Document 1, in order to maintain the front direction, it may not be possible to pass through a narrow crank path.

The present invention has been made in view of such a problem, and an object of the present invention is to prevent interference between the transported object and the surrounding environment during turning and to enable passage in a narrow place. It is to provide an autonomous mobile robot that pulls and transports a transported object.

The autonomous mobile robot according to one aspect of the present invention is an autonomous mobile robot that pulls and transports an object to be transported, and manages a physical quantity for obtaining the position of the center of gravity of the entire transport system including the autonomous mobile robot and the object to be transported. A unit and a movement control unit that performs route tracking control by setting a point to follow the path at the position of the center of gravity are provided.

According to the present invention, it is possible to provide an autonomous mobile robot that pulls and transports a transported object, which prevents interference between the transported object and the surrounding environment during turning and enables passage in a narrow space. ..

It is a figure which shows the whole structure of the autonomous mobile robot of an embodiment. It is a block diagram which shows the functional structure of the control device of the autonomous mobile robot of embodiment. It is a figure explaining the position of the center of gravity of the whole transfer system including the autonomous mobile robot of embodiment, and the object to be conveyed. It is a figure explaining the path-following operation of the autonomous mobile robot of embodiment. It is a figure which shows the runout amount of the to-be-behaved object by the path-following operation of the autonomous mobile robot of embodiment. It is a figure explaining the crank path passage operation of the autonomous mobile robot of embodiment. It is a figure which shows an example of the physical quantity management part of the autonomous mobile robot of embodiment. It is a figure which shows the runout amount of the to-be-behaved object by the path-following operation of the transfer robot of the comparative example. It is a figure explaining the crank path passage operation of the transfer robot of the comparative example.

The present invention relates to an autonomous mobile robot that pulls an object to be transported and autonomously moves while acquiring information on the surrounding environment. The autonomous mobile robot according to the embodiment obtains the position of the center of gravity of the entire transport system including the autonomous mobile robot and the object to be transported, and sets a point to follow the path when performing path tracking control at the center of gravity position. It is characterized by.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Equivalent components in each figure are designated by the same reference numerals, and duplicate description is omitted.

Embodiment 1
1 and 2 are diagrams showing a configuration of an autonomous mobile robot according to the first embodiment. Examples of the autonomous mobile robot include HSR (Human Support Robot). As shown in FIGS. 1 and 2, the autonomous mobile robot 10 includes an omnidirectional moving mechanism 11, a connecting portion 12, and a control device 30. The object to be transported 20 is connected to the rear portion of the autonomous mobile robot 10 via the connecting portion 12. The connecting portion 12 integrally fixes and connects the autonomous mobile robot 10 and the object to be transported 20. The autonomous mobile robot 10 pulls and transports the connected object 20 to be transported.

The object to be transported 20 includes a wagon 21 and a load 22 mounted on the wagon 21. For example, the wagon 21 can be fixedly connected by grasping the wagon 21 using the arm and gripper of the HSR. Wheels 23 are attached to the lower part of the wagon 21. When the autonomous mobile robot 10 pulls the wagon 21, the wheels 23 rotate and the load 22 is moved. In the example shown in FIG. 1, the transported object 20 is arranged on the back side of the autonomous mobile robot 10, but the transported object 20 may be arranged on the front side of the autonomous mobile robot 10. The object to be transported 20 is arranged on at least one of the back side and the front side of the autonomous mobile robot 10.

The omnidirectional movement mechanism 11 includes a wheel for moving the autonomous mobile robot 10, a drive device for driving the wheel, and the like. The omnidirectional movement mechanism 11 realizes control (omnidirectional movement control) in which the autonomous mobile robot 10 is moved in an arbitrary posture in an arbitrary direction according to a movement command given from the control device 30.

The control device 30 controls the autonomous movement of the autonomous mobile robot 10. As shown in FIG. 2, the control device 30 includes a route calculation unit 31, a physical quantity management unit 32, and a movement control unit 33. For example, the control device 30 is a CPU (Central Processing Unit) that realizes path tracking control of the autonomous mobile robot 10 of the present embodiment by executing a control program.

Each element shown in the drawing as a functional block that performs various processing can be configured by a CPU, a memory, and other circuits in terms of hardware, and a program loaded in the memory in terms of software. Realized by. It is understood by those skilled in the art that these functional blocks can be realized in various ways by hardware only, software only, or a combination thereof, and is not limited to any of them. It is assumed that all or part of the components of the autonomous mobile robot 10, the route calculation unit 31, the physical quantity management unit 32, and the movement control unit 33, are processed by a computer for the cloud.

The route calculation unit 31 calculates the target route to be followed by the autonomous mobile robot 10. The route calculation unit 31 performs, for example, the shortest route search using a grid map. The physical quantity management unit 32 obtains the position of the center of gravity of the entire transport system including the autonomous mobile robot 10 and the object to be transported 20. FIG. 3 is a diagram illustrating the position of the center of gravity of the entire transfer system including the autonomous mobile robot 10 and the object to be transported 20.

As shown in FIG. 3, the origin of the robot coordinate system (xy coordinate system) is set at the position of the center of gravity of the autonomous mobile robot 10. Let m be the mass of the autonomous mobile robot 10, and M be the mass of the transported object 20 (the total mass of the wagon 21 and the mounted object 22). Assuming that the distance from the origin of the coordinate system of the autonomous mobile robot 10 to the center of gravity of the object to be transported 20 is L, the position D of the center of gravity of the entire transfer system including the autonomous mobile robot 10 and the object to be transported 20 is expressed by the following equation ( Obtained in 1).
D = ML / (M + m) ... (1)
The mass of the autonomous mobile robot 10, the mass of the object to be transported 20, and the position of the center of gravity can be manually input to the physical quantity management unit 32.

The movement control unit 33 sets the position D of the center of gravity of the entire transport system including the autonomous mobile robot 10 and the object to be transported 20 obtained by the physical quantity management unit 32 at a point (control point) to follow the target path, and sets the route. Follow-up control (for example, PD control) is performed. That is, the turning center of the transport system including the autonomous mobile robot 10 and the transported object 20 is changed from the center of the autonomous mobile robot 10 to the transported object 20 side according to the weight of the transported object 20.

FIG. 4 is a diagram illustrating a path following operation of the autonomous mobile robot 10. As shown in FIG. 4, the movement control unit 33 generates a movement command so that the center of gravity position D, which is a control point, moves to the target position on the target path, and the autonomous mobile robot 10 takes the target posture, and omnidirectionally. It is transmitted to the moving mechanism 11. As a result, the autonomous mobile robot 10 moves so that the center of gravity position D comes to the target position according to the movement command, and rotates around the center of gravity position D so as to take the target posture and changes its direction.

Here, the problems of the transfer robot of the comparative example will be described. FIG. 8 is a diagram showing the amount of runout of the transported object 2 due to the path following operation of the transport robot 1 of the comparative example. The transfer robot 1 of FIG. 8 has two independent drive wheels on the left and right as in Non-Patent Document 1, and the control point for path follow-up control is the center of the left and right drive wheels (axle center C). be. As shown in FIG. 8, when the route follow-up control is performed with the axle center C as the control point, the distance from the control point to the center of gravity of the connected object 2 is long, and the inertial force applied to the object 2 during turning is applied. growing. In particular, especially when the object to be transported is a heavy object, the moment of inertia becomes large, and there is a risk that the object to be transported 2 is shaken greatly and interferes with the surrounding environment, or the loaded object falls.

Therefore, even if the configuration of Patent Document 1 is adopted in order to prevent interference with the surrounding environment during turning, the following problems occur. FIG. 9 is a diagram illustrating the crank path passing operation of the transfer robot 3 of the comparative example. The transfer robot 3 of FIG. 9 is an autonomous moving body that can be moved in an arbitrary direction in an arbitrary posture as in Patent Document 1. The connecting portion between the transfer robot 3 and the object to be transported 2 is fixed, and the transfer robot 3 is controlled so that the front direction thereof and the direction of the movement path match. Since the transfer robot 3 always faces the front direction, the total length of the transfer robot 3 and the object to be transported 2 is longer than between the two obstacles in a narrow crankway where the obstacles are in the front right and the rear left. In that case, the transported object 2 comes into contact with the obstacle.

On the other hand, in the autonomous mobile robot 10 of the embodiment, as shown in FIG. 5, the center of gravity position D of the entire transport system including the autonomous mobile robot 10 and the object to be transported 20 is set as a control point. Therefore, since the transport system including the autonomous mobile robot 10 and the transported object 20 rotates around the center of gravity position D, the distance from the center of gravity position D to the center of gravity of the transported object 20 becomes short, and the transported object 20 The amount of runout becomes smaller. This makes it possible to suppress contact with the surrounding environment and drop of the mounted object.

Further, since the center of gravity position D of the entire transport system including the autonomous mobile robot 10 and the object to be transported 20 is the control point, it is possible to travel in a small turn as compared with the transport robot 3 shown in FIG. Therefore, as shown in FIG. 6, even in the crank path where the obstacle is on the right front side and the left rear side, it is possible to rotate around the center of gravity position D between the obstacles and pass while avoiding the obstacles. ..

In the above example, the mass and the position of the center of gravity of the object to be transported 20 are manually input to the physical quantity management unit 32, but the present invention is not limited to this. For example, by attaching a load sensor as a physical quantity management unit 32 to the wagon 21 and measuring the mass and the position of the center of gravity of the mounted object 22, it is possible to measure the mass and the position of the center of gravity of the object to be transported 20. FIG. 7 shows an example of the physical quantity management unit of the autonomous mobile robot of the embodiment. FIG. 7 shows an example in which a load cell is used as a load sensor of the physical quantity management unit 32 and the mass and the position of the center of gravity of the load 22 are obtained.

A plate 24 having substantially the same shape as the wagon 21 is provided on the wagon 21. In FIG. 7, only the plate 24 is shown for the sake of brevity. The four load cells L1 to L4 are located between the wagon 21 and the plate 24, respectively, in the vicinity of the four corners of the plate 24 in a plan view. The plate is supported by the wagon 21 via a load cell.

Let the center of the plate 24 be the origin (0,0) of the xy coordinate system. The positions where the load cells L1 to L4 are arranged are (X1, Y1), (X2, Y2), (X3, Y3), and (X4, Y4), respectively. By measuring the loads (F1 to F4) applied to the load cells L1 to L4, the mass F of the load 22 and the coordinates (Xc, Yc) of the position of the center of gravity can be obtained by the following equations (2) to (4), respectively. can.

F = F1 + F2 + F3 + F4 ... (2)

The number and arrangement of load cells are not limited to the above examples. It is also possible to mount a force sensor on the connecting portion 12 of the transported object 20 and estimate the physical quantity of the transported object 20 using the value of the force sensor. Therefore, the physical quantity management unit 32 can measure and hold not only the position D of the center of gravity of the object to be transported 20 but also the inertial force applied to the object to be transported 20.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit. In the embodiment, the autonomous mobile robot 10 and the object to be transported 20 are integrally fixed and connected, but the present invention is not limited to this. It suffices that the autonomous mobile robot 10 has a function of knowing the relative posture between the autonomous mobile robot 10 and the object to be transported 20. When the relative posture of the autonomous mobile robot 10 and the object to be transported 20 is known, the autonomous mobile robot 10 and the object to be transported 20 may be connected by a deformable articulated connecting portion.

10 Autonomous mobile robot 11 Omnidirectional mobile mechanism 12 Connecting unit 20 Transported object 21 Wagon 22 On-board equipment 23 Wheels 24 Plate 30 Control device 31 Route calculation unit 32 Physical quantity management unit 33 Movement control unit D Center of gravity position L1 to L4 Load cell

Claims (1)

An autonomous mobile robot that pulls and transports objects to be transported.
A physical quantity management unit that obtains the position of the center of gravity of the entire transfer system including the autonomous mobile robot and the object to be transported, and a physical quantity management unit.
A movement control unit that sets a point to follow the path at the position of the center of gravity, controls the path following , and rotates around the position of the center of gravity so as to take a posture along the path .
To prepare
Autonomous mobile robot.

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