CN111433703A

CN111433703A - Rotation control device, moving body, and transfer robot

Info

Publication number: CN111433703A
Application number: CN201880078352.5A
Authority: CN
Inventors: 山本惇史
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-12-05
Filing date: 2018-11-16
Publication date: 2020-07-17
Also published as: JPWO2019111671A1; WO2019111671A1

Abstract

The invention provides a rotation control device, a moving body and a transfer robot, which can restrain the deformation of the posture and the movement even if the control of a rotating body is disturbed. The rotation control device includes: a 1 st controller that controls a rotational speed of the 1 st rotating body to a 1 st target rotational speed; and a 2 nd controller that controls a rotation speed of the 2 nd rotating body to a 2 nd rotation speed of the target, the rotation control device selectively executing: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of a rotation state of the 1 st rotating body and a 2 nd measurement value of a rotation state of the 2 nd rotating body, calculates correction control for bringing a relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

Description

Rotation control device, moving body, and transfer robot

Technical Field

The present invention relates to a rotation control device that controls a rotation state of a rotating body, a moving body, and a transfer robot.

Background

Conventionally, for example, the following techniques are known: a moving body such as a transfer robot, an articulated robot, or the like includes a plurality of rotating bodies such as wheels and joints, and the attitude and the operation of the moving body or the robot are controlled by driving each rotating body with each motor and individually controlling the rotation state of each rotating body.

For example, patent document 1 discloses a technique of performing phase difference synchronization (P LL) control on a reference signal indicating a rotation reference of a motor and a rotation angle detected for the motor.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-78374

Disclosure of Invention

Problems to be solved by the invention

However, even when the respective rotation states of the plurality of rotating bodies are synchronized with the reference signal, if the control of the rotating bodies is disturbed due to signal delay, noise, or the like, the synchronization between the rotating bodies is disturbed, and the posture and the operation of the moving body are deformed.

Therefore, an object of the present invention is to provide a rotation control device, a moving body, and a transfer robot capable of suppressing deformation of a posture and a motion even when disturbance occurs in control of a rotating body.

Means for solving the problems

A rotation control device according to an aspect of the present invention includes: a 1 st controller that controls a rotational speed of the 1 st rotating body to a 1 st target rotational speed; and a 2 nd controller that controls a rotation speed of the 2 nd rotating body to a 2 nd rotation speed of the target, the rotation control device selectively executing: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of a rotation state of the 1 st rotating body and a 2 nd measurement value of a rotation state of the 2 nd rotating body, calculates correction control for bringing a relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

A moving body according to one embodiment of the present invention includes: a base; a 1 st wheel for moving the base; a 2 nd wheel for moving the base; a 1 st driver for rotationally driving the 1 st wheel; a 2 nd driver for rotationally driving the 2 nd wheel; a 1 st controller that controls a 1 st rotation speed of a 1 st rotation body, which is one of the 1 st wheel and the 1 st actuator, to a target 1 st rotation speed; and a 2 nd controller that controls a rotation speed of a 2 nd rotating body that is one of the 2 nd wheel and the 2 nd driver to a target 2 nd rotation speed, the moving body selectively performing: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of a rotation state of the 1 st rotating body and a 2 nd measurement value of a rotation state of the 2 nd rotating body, calculates correction control for bringing a relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

A transfer robot according to an aspect of the present invention includes: a base having a mounting table on which a transported object is mounted; a 1 st wheel for moving the base; a 2 nd wheel for moving the base; a 1 st driver for rotationally driving the 1 st wheel; a 2 nd driver for rotationally driving the 2 nd wheel; a 1 st controller that controls a 1 st rotation speed of a 1 st rotation body, which is one of the 1 st wheel and the 1 st actuator, to a target 1 st rotation speed; and a 2 nd controller that controls a rotation speed of a 2 nd rotating body that is one of the 2 nd wheel and the 2 nd actuator to a target 2 nd rotation speed, the transfer robot selectively executing: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of a rotation state of the 1 st rotating body and a 2 nd measurement value of a rotation state of the 2 nd rotating body, calculates correction control for bringing a relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of a rotation state of the 1 st rotating body and a 2 nd measurement value of a rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, even when a disturbance occurs in the control of the rotating bodies, one of the 1 st rotating body and the 2 nd rotating body rotates following the other, and therefore, the posture and the motion of the moving body and the robot on which the 1 st rotating body and the 2 nd rotating body are mounted can be suppressed from being distorted.

Drawings

Fig. 1 is a perspective view showing one embodiment of a transfer robot according to the present invention.

Fig. 2 is a block diagram of a control system including a transfer robot according to an embodiment of the present invention.

Fig. 3 is a diagram showing an operation sequence of the external computer and 2 motor units.

Fig. 4 is a diagram showing an example of the format of the control command.

Fig. 5 is a diagram showing an example of the rotation speed of the wheel motor in the 2 nd motor unit.

Fig. 6 is a diagram showing an example of the format of the measurement command.

Fig. 7 is a diagram showing an example of a format of a status report of the 2 nd motor unit.

Fig. 8 is a diagram showing the follow-up control executed by the 1 st main control unit.

Fig. 9 is a diagram showing an example of the rotation speed of the wheel motor in the 1 st motor unit.

Fig. 10 is a diagram illustrating the follow-up control during the turning operation.

Fig. 11 is a diagram showing another example of the follow-up control 1.

Fig. 12 is a diagram showing another example of the follow-up control 2.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

< transfer robot >

The transfer robot 1 of the present embodiment also corresponds to one embodiment of the moving body of the present invention. The transfer robot 1 is used for transferring materials in a factory, for example.

The transfer robot 1 includes a vehicle body (base) 2, and 2

wheels

4A and 4B supported by the vehicle body 2 and rotating. The vehicle body 2 is a substantially horizontal frame provided below the transfer robot 1. The

wheels

4A, 4B are identical in shape and size and are arranged concentrically.

The vehicle body 2 is mounted with 2

wheel motors

6A and 6B for driving the

wheels

4A and 4B, respectively. A battery case 8 that houses a battery as a power source for driving the

wheel motors

6A and 6B is mounted on the vehicle body 2. Printed

boards

10A, 10B, 12A, and 12B for driving the

wheel motors

6A and 6B are mounted on the vehicle body 2. Here, the printed

boards

10A and 10B include a drive circuit including an inverter and a motor driver, and the printed

boards

12A and 12B include a main control circuit including a microcomputer board.

In fig. 1, the printed

boards

10A, 10B, 12A, and 12B are shown as being mounted on shelves, but the printed

boards

10A, 10B, 12A, and 12B themselves may be shelves.

A plurality of support columns 14 are attached to the vehicle body 2, and the support columns 14 support the stage 16.

< control System >

Fig. 2 is a block diagram of a control system including the transfer robot 1 according to the embodiment of the present invention. The transfer robot 1 can communicate with an external computer (external control device) 40 that remotely operates the transfer robot 1 by wireless communication. The manner of wireless communication includes, but is not limited to, Wi-Fi (registered trademark).

The transfer robot 1 has 2 motor units, i.e., a 1 st motor unit 42A and a 2 nd motor unit 42B. These 2

motor units

42A, 42B correspond one-to-one to the 2

wheels

4A, 4B shown in fig. 1, and the 2

motor units

42A, 42B include

wheel motors

6A, 6B for driving the

corresponding wheels

4A, 4B, respectively. In the following description, when the elements corresponding to the 1 st motor unit 42A and the 2 nd motor unit 42B are distinguished, the elements may be distinguished using expressions of "1 st" and "2 nd".

The

motor units

42A, 42B are supplied with power by a power supply 43. The power supply 43 is a battery housed in the battery case 8 (see fig. 1).

In the present embodiment, the 2

motor units

42A, 42B have the same configuration as each other as hardware, and include

wheel motors

6A, 6B, wireless communication circuits 44A, 44B,

main control units

46A, 46B,

memories

48A, 48B, motor

drive control units

50A, 50B,

drive circuits

52A, 52B, and

speed sensors

54A, 54B, respectively.

The wireless communication circuit 44A, the main control unit 46A, the memory 48A, the motor drive control unit 50A, and the drive circuit 52A of the 1 st motor unit 42A are mounted as hardware on 2 printed boards, respectively, and are mounted on 2 printed

boards

10A, 12A on the 1 st wheel 4A side among the 4 printed

boards

10A, 10B, 12A, 12B shown in fig. 1. Specifically, the wireless communication circuit 44A, the main control unit 46A, the memory 48A, and the motor drive control unit 50A are mounted on the lower printed circuit board 12A, and the drive circuit 52A is mounted on the upper printed circuit board 10A.

Similarly, the wireless communication circuit 44B, the main control unit 46B, the memory 48B, the motor drive control unit 50B, and the drive circuit 52B of the 2 nd motor unit 42B are mounted on 2 printed boards as hardware, respectively, and are mounted on 2 printed

boards

10B, 12B on the 2 nd wheel 4B side among the 4 printed

boards

10A, 10B, 12A, 12B shown in fig. 1. Specifically, the wireless communication circuit 44B, the main control unit 46B, the memory 48B, and the motor drive control unit 50B are mounted on the lower printed circuit board 12B, and the drive circuit 52B is mounted on the upper printed circuit board 10B.

Each of the 2 wireless communication circuits 44A and 44B has a function of performing wireless communication with the external computer 40. In the present embodiment, the 1 st wireless communication circuit 44A is normally used for wireless communication with the external computer 40, and the 2 nd wireless communication circuit 44B is used as a backup when a communication failure occurs due to, for example, a failure of the 1 st wireless communication circuit 44A. In addition, the 2 nd wireless communication circuit 44B may also serve as an auxiliary of the 1 st wireless communication circuit 44A. For example, the 1 st wireless communication circuit 44A may be used for receiving from the external computer 40 and the 2 nd wireless communication circuit 44B may be used for transmitting to the external computer 40.

In the present embodiment, each of the

main control units

46A and 46B is, for example, a processor, and each reads and executes a program stored in a recording medium (not shown), whereby a combination of 2

main control units

46A and 46B operates as one embodiment of the rotation control device of the present invention. Therefore, in the present embodiment, the program (program code) itself read from the recording medium realizes the functions of the

main control units

46A and 46B. In addition, a recording medium on which the program is recorded can constitute an embodiment of the present invention.

The 1 st main control unit 46A performs wireless communication with the external computer 40 by using the wireless communication circuit 44A. The 1 st main control unit 46A controls the motor drive control unit 50A to control the drive of the wheel motor 6A. The 1 st main control unit 46A and the 2 nd main control unit 46B are connected by wire so as to be able to communicate with each other.

The 2 nd main control unit 46B also controls the driving of the wheel motor 6B by controlling the motor drive control unit 50B. When a communication failure occurs in the 1 st main controller 46A, the 2 nd main controller 46B performs wireless communication with the external computer 40 using the wireless communication circuit 44B instead of the 1 st main controller 46A.

The

memories

48A and 48B store data necessary for the

main control units

46A and 46B to perform processing, respectively. The

main control units

46A and 46B read necessary data from the

memories

48A and 48B, respectively. The

memories

48A and 48B in the present embodiment are volatile memories (e.g., SRAM), but may be nonvolatile memories (e.g., flash memories). Each of the

memories

48A and 48B may include both a volatile memory and a nonvolatile memory.

The motor

drive control units

50A and 50B control the drive (e.g., the rotation speed) of the

wheel motors

6A and 6B in accordance with instructions from the

main control units

46A and 46B. Each of the motor

drive control units

50A and 50B can perform PID (Proportional-Integral-derivative) control and vector control, for example, and is a microprocessor, an ASIC (Application Specific Integrated Circuit), or a DSP (digital signal Processor), for example.

The

drive circuits

52A, 52B drive the

wheel motors

6A, 6B under the control of the motor

drive control units

50A, 50B, respectively.

The

speed sensors

54A, 54B output electric signals indicating the rotational speeds of the

wheel motors

6A, 6B, respectively. Each of the

speed sensors

54A and 54B is, for example, a hall sensor mounted inside the

wheel motor

6A or 6B, and converts a magnetic field into an electric signal. The motor

drive control units

50A, 50B calculate the rotation speeds of the

wheel motors

6A, 6B based on the output signals of the

speed sensors

54A, 54B, respectively. That is, the motor

drive control units

50A and 50B measure the rotational speeds of the

corresponding wheel motors

6A and 6B, respectively. The

main control units

46A, 46B are notified of the measured values of the rotational speeds of the

wheel motors

6A, 6B, and the

main control units

46A, 46B give the motor

drive control units

50A, 50B a command for controlling the driving of the

wheel motors

6A, 6B using the values of the rotational speeds of the

wheel motors

6A, 6B.

The motor

drive control units

50A and 50B can calculate the torques of the

wheel motors

6A and 6B by a known calculation method based on the current values of the

drive circuits

52A and 52B, respectively. That is, the

drive circuits

52A and 52B can measure the torque of the

wheel motors

6A and 6B. The

main control units

46A and 46B are notified of the measured values of the torques of the

wheel motors

6A and 6B, and the

main control units

46A and 46B can give commands for controlling the driving of the

wheel motors

6A and 6B to the motor

drive control units

50A and 50B using the values of the torques of the

wheel motors

6A and 6B.

< example of operation of Motor control >

An example of the control operation of the

motor units

42A, 42B to control the

wheel motors

6A, 6B based on a control command from the external computer 40 will be described.

Fig. 3 is a diagram showing an operation sequence of the external computer 40 and the 2

motor units

42A and 42B. The operations of the

motor units

42A and 42B are represented by

communication threads

61A and 61B and control threads 62A and 62B.

In order to cause the transfer robot 1 to draw a predetermined trajectory, the external computer 40 calculates target speeds of the 2-

wheel motors

6A and 6B of the transfer robot 1, and transmits a control command indicating the target speeds to the transfer robot 1 through wireless communication. In the transfer robot 1, the 1 st motor unit 42A normally receives a control command.

Fig. 4 is a diagram showing an example of the format of the control command.

As shown in fig. 4, an example of the format of the control command has a field indicating the command type, a field indicating the target achievement time (Duration), a field indicating the 1 st device ID (device ID of the 1 st motor unit 42A), a field indicating the target speed of the 1 st wheel motor 6A, a field indicating the 2 nd device ID (device ID of the 2 nd motor unit 42B), and a field indicating the target speed of the 2 nd wheel motor 6B.

The field indicating the command type contains a bit string indicating that the transmitted command is a control command to set the target speed. The field indicating the target achievement time includes a bit string indicating the time until the

wheel motors

6A, 6B reach the target speed after receiving the control command. The field indicating the device ID contains a bit string indicating the ID of the motor unit having the wheel motor to be controlled by the control command. That is, the 2 fields indicating the device ID each contain a bit string indicating the device ID of the 1 st motor unit 42A or a bit string indicating the device ID of the 2 nd motor unit 42B. The field indicating the target speed immediately after the field indicating the device ID of the 1 st motor unit 42A contains a bit string indicating the target speed of the 1 st wheel motor 6A. The field indicating the target speed immediately following the field indicating the device ID of the 2 nd motor unit 42B contains a bit string indicating the target speed of the 2 nd wheel motor 6B.

In this control command, for example, it is assumed that the target achievement time is designated 100ms, the target speed of the 1 st wheel motor 6A is designated 100rpm, and the target speed of the 2 nd wheel motor 6B is designated 200 rpm. In this case, the control command means that the 1 st motor unit 42A should control the rotation speed of the wheel motor 6A to 100rpm and the 2 nd motor unit 42B should control the rotation speed of the wheel motor 6B to 200rpm within 100ms after the control command is received.

Returning to fig. 3, when the wireless communication circuit 44A receives a control command in the 1 st motor unit 42A, the main control unit 46A compares the target speeds of the 2

wheel motors

6A and 6B, and determines whether the operation of the transfer robot 1 is a straight-ahead operation or a turning operation. That is, when the 2 target speeds are equal, it is determined as a straight-traveling operation, and when the 2 target speeds are different, it is determined as a turning operation.

In addition, a control command indicating the target speed of the 2 nd wheel motor 6B is sent from the 1 st motor unit 42A to the 2 nd motor unit 42B through wired communication. The format of the control command is a format in which the device ID and the target speed for the 1 st motor unit 42A are deleted from the format shown in fig. 4.

< acceleration control >

The

motor units

42A, 42B, which are instructed to the target speed by the control command, respectively make control plans for reaching the target speed within the target achievement time. That is, the

main control units

46A and 46B determine the instantaneous target speeds of the

wheel motors

6A and 6B at respective moments of time up to the target achievement time. The instants are instants separated by a fixed control period. The instantaneous target speed is determined by interpolation based on, for example, the current rotational speed of each motor, the target speed of the motor specified in the control command, and the target achievement time specified in the control command.

Specifically, when both of the 2

wheel motors

6A and 6B stop (when the rotation speed is 0 rpm) at the time when the control command of the above-described assumed example is received, the 1 st main control unit 46A determines the instantaneous target speed at each moment every 1ms so as to increase the rotation speed of the 1 st wheel motor 6A by 1rpm every 1ms, for example. The 2 nd main control unit 46B determines the instantaneous target speed at each moment of 1ms so as to increase the rotation speed of the 2 nd wheel motor 6B by 2rpm every 1ms, for example. Thus, after 100ms has elapsed, the rotation speed of the 1 st wheel motor 6A reaches 100rpm, and the rotation speed of the 2 nd wheel motor 6B reaches 200 rpm. In this example, the

main control units

46A and 46B determine the instantaneous target speed by, for example, linear interpolation, but other interpolation algorithms may be used.

As described above, the

main control units

46A, 46B that determine the instantaneous target speeds of the

wheel motors

6A, 6B store the instantaneous target speeds of the

wheel motors

6A, 6B in the

memories

48A, 48B.

Thereafter, the

main control units

46A and 46B control the motor

drive control units

50A and 50B according to the control schedule to accelerate the rotation speed of the

wheel motors

6A and 6B. That is, the

main control units

46A and 46B read the instantaneous target speeds of the

wheel motors

6A and 6B from the

memories

48A and 48B at each instant, and repeatedly control the motor

drive control units

50A and 50B at a fixed control cycle so that the rotational speeds of the

wheel motors

6A and 6B become the instantaneous target speeds. In the above example, the control cycle of each motor is 1ms, but the control cycle is not limited to 1ms, and may be 5ms, for example.

< constant speed control >

When the

wheel motors

6A and 6B reach the target speed by the acceleration control described above, the main control portion 46B performs constant speed control for maintaining the rotation speed of the wheel motor 6B of the 2 nd motor unit 42B at the target speed.

Fig. 5 is a diagram showing an example of the rotation speed of the wheel motor 6B in the 2 nd motor unit 42B. In fig. 5, the horizontal axis represents elapsed time, and the vertical axis represents the rotation speed of the wheel motor 6B.

The motor 6B for the 2 nd wheel reaches the target speed during the target achievement time (Duration) by the acceleration control. Thereafter, the constant speed control is performed to maintain the rotation speed of the 2 nd wheel motor 6B at the target speed.

However, when a disturbance such as noise occurs, for example, the control in the motor unit 42B may be disturbed, and the rotation speed of the wheel motor 6B may deviate from the target speed. In the present embodiment, the 2 nd motor unit 42B receives the control command from the 1 st motor unit 42A by wired communication, and therefore, the disturbance of the control due to the communication delay of the control command can be suppressed by utilizing the robustness of wired communication, but when the 2 nd motor unit 42B receives the control command from the external computer 40 in parallel with the 1 st motor unit 42A by wireless communication, the communication delay or the like may become a cause of the above-described interference.

< tracking control >

In the present embodiment, as shown in fig. 3, the follow-up control is executed in the 1 st motor unit 42A so that the transfer robot 1 can draw a predetermined trajectory even when such a disturbance occurs in the 2 nd motor unit 42B.

When the follow-up control is started, the 1 st main control unit 46A transmits a measurement command requesting motor information to the 2 nd main control unit 46B by wired communication.

As shown in fig. 6, an example of the format of the measurement command includes a field indicating the type of the command, a field indicating the start time of the status measurement, a field indicating the report duration, and a field indicating the period of the report (the period of measurement). The field indicating the type of command contains a bit string indicating that the transmitted command is a measurement command.

In the 2 nd motor unit 42B, the main control unit 46B that has received the measurement command stores the measurement command in the memory 48B. The main control unit 46B performs the state measurement at the time when the state measurement designated by the measurement command is started. Specifically, the main control unit 46B causes the motor drive control unit 50B to measure the rotation speed and the torque of the 2 nd wheel motor 6B and obtains the measured values of the rotation speed and the torque from the motor drive control unit 50B. After the measurement is completed, the main control portion 46B transmits a status report indicating the measurement result to the 1 st motor unit 42A as motor information of the 2 nd motor unit 42B by wired communication.

Fig. 7 is a diagram showing an example of the format of the status report of the 2 nd motor unit 42B.

As shown in fig. 7, an example of the format of the status report has a field indicating the report type, a field indicating the speed, and a field indicating the torque. The field for the report type contains a bit string indicating that the report is a status report for the 2 nd motor unit 42B. The field of the velocity contains a bit string representing the measured value of the velocity. The field of the torque contains a bit string representing the measured value of the torque.

Upon receiving the status report of the 2 nd motor unit 42B, the main control unit 46A of the 1 st motor unit 42A executes follow-up control (described later) for causing the rotation state of the 1 st wheel motor 6A to follow the rotation state of the 2 nd wheel motor 6B indicated by the status report.

Thereafter, the main control unit 46B of the 2 nd motor unit 42B performs status measurement in accordance with the report cycle (measured cycle) designated by the measurement command and transmits the status report of the 2 nd motor unit 42B to the 1 st motor unit 42A by wired communication. Such measurement and reporting are repeated until a report duration specified by the measurement order has elapsed. When the report duration elapses, the 2 nd motor unit 42B ends the state measurement and the transmission of the state report. In addition, there is a case where an indefinite period is designated as a report continuation period, and in this case, measurement and report are repeated until a measurement stop command is received.

Fig. 8 is a diagram showing the follow-up control executed by the 1 st main control unit 46A.

In the example shown in fig. 8, the follow-up control is executed using the measured value of the speed and the measured value of the torque, which are included in the status report transmitted from the 2 nd motor unit 42B. When it is determined that the vehicle is traveling straight in the speed determination, the follow-up control shown in fig. 8 is executed.

In the follow-up control, the 1 st main control unit 46A causes the motor drive control unit 50B to measure the speed of the 1 st wheel motor 6A, and the measured value θ of the rotation speed of the 2 nd wheel motor 6B obtained by the 2 nd motor unit 42B is used as the measured value₂Divided by a measured value theta of the rotational speed obtained by the measurement₁. Thereby, the rotational speed difference between the 2

wheel motors

6A and 6B is calculated.

The 1 st main control portion 46A calculates a proportional action 71 and an integral action 72 in the PI control based on the rotation speed difference. This PI control is correction control for correcting the rotation speed of the 1 st wheel motor 6A so that the rotation speed difference approaches zero. The 1 st main control portion 46A calculates a corrected target speed by adding the component of the correction control to the target speed given to the 1 st wheel motor 6A by the control command. Then, the 1 st main control unit 46A controls the motor drive control unit 50A so that the 1 st wheel motor 6A becomes the corrected target speed.

Fig. 9 is a diagram showing an example of the rotation speed of the wheel motor 6A in the 1 st motor unit 42A. In fig. 9, the horizontal axis represents elapsed time, and the vertical axis represents the rotation speed of the wheel motor. In fig. 9, an example of the rotation speed of the 1 st wheel motor 6A is shown by a solid line, and an example of the rotation speed of the 2 nd wheel motor 6B is shown by a broken line.

The rotation speed of the 1 st wheel motor 6A reaches the target speed for the target achievement time (Duration) by the same acceleration control as the 2 nd wheel motor 6B. Then, by performing the follow-up control shown in fig. 8, the rotation speed of the 1 st wheel motor 6A follows the rotation speed of the 2 nd wheel motor 6B. That is, the rotation speed of the 1 st wheel motor 6A is the same as the rotation speed of the 2 nd wheel motor 6B, regardless of whether the rotation speed of the 2 nd wheel motor 6B is kept at the target speed or the disturbance occurs as described above. As a result, even when the interference occurs in the 2 nd motor unit 42B, the transfer robot 1 keeps the straight-traveling operation.

However, disturbance due to noise or the like may also occur in the 1 st motor unit 42A. Therefore, in the present embodiment, a threshold value is set for the target speed, and the 1 st main control unit 46A compares the threshold value with the rotation speed to detect the occurrence of disturbance. That is, when the measured value of the rotation speed of the 1 st wheel motor 6A deviates from the target speed and exceeds the threshold value, it is considered that the disturbance occurs in the 1 st motor unit 42A. However, when the measured value of the rotation speed of the 2 nd wheel motor 6B exceeds the threshold value first, the rotation speed of the 1 st wheel motor 6A exceeds the threshold value in accordance with the follow-up control, and therefore it is not considered that the disturbance occurs in the 1 st motor unit 42A.

As shown in fig. 3, in stage 1 from the end of the acceleration control to the detection of the occurrence of disturbance in the 1 st motor unit 42A, the constant speed control is executed in the 2 nd motor unit 42B, and the follow-up control is executed in the 1 st motor unit 42A. In phase 2 after the occurrence of disturbance in the 1 st motor unit 42A is detected, constant speed control is executed in the 1 st motor unit 42A, and follow-up control is executed in the 2 nd motor unit 42B. That is, the 1 st motor unit 42A and the 2 nd motor unit 42B alternately perform control operations. In the alternation of such control operations, a control command requesting to stop the report motor information is transmitted from the 1 st motor unit 42A to the 2 nd motor unit 42B, and a control command requesting to start the follow-up control is also transmitted. After transmitting these control commands, the 1 st motor unit 42A executes constant speed control, and periodically reports motor information to the 2 nd motor unit 42B. Then, the 2 nd motor unit 42B that has received the control command executes follow-up control for causing the rotation speed of the 2 nd wheel motor 6B to follow the rotation speed of the 1 st wheel motor 6A.

In the constant speed control in phase 2, when the rotation speed in the 1 st wheel motor 6A returns to within the threshold range, it is regarded that the disturbance in the 1 st motor unit 42A ends. In phase 3 after the end of the disturbance, the control operation is again alternated in the 1 st motor unit 42A and the 2 nd motor unit 42B, the constant speed control is executed in the 2 nd motor unit 42B, and the follow-up control is executed in the 1 st motor unit 42A.

As described above, as shown in fig. 9, by alternately controlling the operation of the 1 st motor unit 42A and the 2 nd motor unit 42B in response to the occurrence and the end of the detection disturbance, when the disturbance occurs in either of the

motor units

42A and 42B (that is, at any stage), the rotational speeds of the 2 nd wheel motor 6B and the 1 st wheel motor 6A both follow each other and maintain the straight-ahead operation.

< follow-up control in turning action >

Next, the following control in the turning operation will be described. Although the above-described control operations are alternated during the turning operation, for convenience of explanation, the following description will be given by taking as an example a case where the 1 st motor unit 42A performs the follow-up control.

During the turning operation, the rotation speed of the 1 st wheel motor 6A and the rotation speed of the 2 nd wheel motor 6B are maintained at a ratio corresponding to a predetermined turning radius. That is, when it is determined that the turning motion is performed in the speed determination, the ratio γ of the target speed is obtained, and the rotation speed of the 1 st wheel motor 6A is controlled so as to maintain the ratio γ in the follow-up control.

Specifically, the 1 st main control unit 46A causes the motor drive control unit 50B to measure the speed of the 1 st wheel motor 6A. The 1 st main control unit 46A also calculates a measured value θ of the rotation speed of the 2 nd wheel motor 6B obtained from the 2 nd motor unit 42B₂Multiplied by the ratio gamma of the target speed and derived therefromThe result is divided by the measured value theta of the speed of the 1 st wheel motor 6A₁。

Thus, the difference between the rotation speed of the 1 st wheel motor 6A, at which the ratio of the rotation speeds of the 2

wheel motors

6A and 6B is maintained at the target speed ratio γ, and the measured rotation speed of the 1 st wheel motor 6A is obtained.

The 1 st main control portion 46A calculates a proportional action 71 and an integral action 72 in the PI control based on the difference. The PI control is correction control for correcting the rotation speed of the 1 st wheel motor 6A so that the difference approaches zero and the ratio of the rotation speeds of the 2

wheel motors

6A and 6B approaches the ratio γ. The 1 st main control portion 46A calculates a corrected target speed by adding the component of the correction control to the target speed given to the 1 st wheel motor 6A by the control command. Then, the 1 st main control unit 46A controls the motor drive control unit 50A so that the 1 st wheel motor 6A becomes the corrected target speed.

As a result of the follow-up control, the ratio of the rotational speeds of the 2

wheel motors

6A and 6B is maintained at the ratio γ of the target speeds, and even when disturbance occurs, the transfer robot 1 maintains a predetermined turning motion.

< Another example of the follow-up control >

Next, another follow-up control that can be executed instead of the above-described follow-up control will be described. However, the follow-up control during the straight traveling operation will be described, and the description of the follow-up control during the turning operation will be omitted. The following control is performed in the 1 st motor unit 42A as an example.

Fig. 11 is a diagram showing another example of the follow-up control 1.

The following control shown in fig. 11 uses PID control, as opposed to PI control for the following control shown in fig. 8. That is, the 1 st main control unit 46A calculates the proportional action 71, the integral action 72, and the derivative action 73 in the PID control based on the rotation speed difference in the 2

wheel motors

6A, 6B calculated in the same manner as the follow-up control shown in fig. 8. This PID control is a correction control for correcting the rotation speed of the 1 st wheel motor 6A so that the rotation speed difference approaches zero, as in the PI control, but since the differentiation action 73 is added, rapid correction is achieved even when a sharp disturbance occurs. Since both the PI control and the PID control are highly accurate control with simple logic, high-speed and highly accurate control can be realized by using the PI control and the PID control.

The 1 st main control unit 46A adds the component of the correction control to the target speed given to the 1 st wheel motor 6A by the control command, and controls the motor drive control unit 50A so that the 1 st wheel motor 6A becomes the corrected target speed.

Fig. 12 is a diagram showing another example of the follow-up control 2.

As shown in fig. 12, in another example 2 of the follow-up control, a measured value θ of the rotation speed of the 2 nd wheel motor 6B obtained from the 2 nd motor unit 42B is used instead of the target speed given by the control command₂. That is, the 1 st main control section 46A compares the component of the correction control by the PI control with the measurement value θ₂The rotational speeds shown are added to calculate a corrected target speed. Then, the 1 st main control unit 46A controls the motor drive control unit 50A so that the 1 st wheel motor 6A becomes the corrected target speed.

According to such follow-up control, for example, even when a persistent control deviation or the like occurs between the 1 st motor unit 42A and the 2 nd motor unit 42B, the rotation speed of the 1 st wheel motor 6A follows the rotation speed of the 2 nd wheel motor 6B.

Although the above description has exemplified the conveyance system having 1 conveyance robot, the present invention can be applied to a conveyance system in which 1 pallet or the like is conveyed by a plurality of conveyance robots, for example.

In the above description, the wheels and the motor that move the moving body have been exemplified as the rotating body whose rotation speed is controlled by the rotation control device, but the rotation control device of the present invention may control the rotation speed of the joints of the robot, a series of conveying rollers that convey sheets that are linked together in a factory, or the like.

In addition, although the above description has described an example in which the relative relationship of the rotational speeds is maintained in the follow-up control, in the present invention, the relative relationship of the torques may be maintained instead of the rotational speeds, or the relative relationship of the rotational angles may be maintained.

Description of the reference numerals

1 … mobile body (robot), 2 … vehicle body (support), 6A, 6B … wheel motor, 40 … external computer (external control device), 42A … 1 st motor unit, 42B … 2 nd motor unit, 44a … wireless communication circuit, 46A, 46B … main control unit, 50A, 50B … motor drive control unit, 52A, 52B … drive circuit.

Claims

1. A rotation control device is characterized by comprising:

a 1 st controller that controls a rotational speed of the 1 st rotating body to a 1 st target rotational speed; and

a 2 nd controller that controls a rotation speed of the 2 nd rotating body to a target 2 nd rotation speed,

the rotation control device selectively performs: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, calculates correction control for bringing the relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

2. The rotating control device according to claim 1,

selecting the 2 nd control mode when the rotation speed of the 1 st rotating body deviates from the 1 st rotation speed by a predetermined degree,

the 1 st control mode is selected when the rotational speed of the 1 st rotating body is within a predetermined range from the 1 st rotational speed.

3. The rotation control apparatus according to claim 1 or 2,

at least one of the 1 st controller and the 2 nd controller determines the relative relationship of the targets based on the 1 st rotational speed and the 2 nd rotational speed externally given.

4. The rotating control device according to any one of claims 1 to 3,

the 1 st controller uses a rotation speed obtained from a 2 nd measurement value of a rotation state of the 2 nd rotating body as the target rotation speed of the 1 st rotating body instead of the 1 st rotation speed in the 1 st control mode,

the 2 nd controller uses a rotation speed obtained from a 1 st measurement value of a rotation state of the 1 st rotating body as the target rotation speed of the 2 nd rotating body instead of the 2 nd rotating speed in the 2 nd control mode.

5. The rotating control device according to any one of claims 1 to 4,

the 1 st controller and the 2 nd controller use at least one of PI control and PID control as the correction control.

6. The rotating control device according to any one of claims 1 to 5,

at least one of the 1 st controller and the 2 nd controller acquires the 1 st rotation speed and the 2 nd rotation speed from the outside via wireless communication,

the rotation speed used by the other of the 1 st rotation speed and the 2 nd rotation speed is given to the other of the one and the other via wired communication.

7. The rotating control device according to claim 6,

both of the 1 st controller and the 2 nd controller have a function of performing wireless communication with the outside,

switching between the 1 st controller and the 2 nd controller a task of acquiring the 1 st rotation speed and the 2 nd rotation speed from the outside according to a communication state.

8. A moving body is characterized by comprising:

a base;

a 1 st wheel for moving the base;

a 2 nd wheel for moving the base;

a 1 st driver for rotationally driving the 1 st wheel;

a 2 nd driver for rotationally driving the 2 nd wheel;

a 1 st controller that controls a 1 st rotation speed of a 1 st rotation body, which is one of the 1 st wheel and the 1 st actuator, to a target 1 st rotation speed; and

a 2 nd controller that controls a rotation speed of a 2 nd rotating body that is one of the 2 nd wheel and the 2 nd driver to a target 2 nd rotation speed,

the mobile body selectively performs: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, calculates correction control for bringing the relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.

9. A transfer robot is characterized by comprising:

a base having a mounting table on which a transported object is mounted;

a 1 st wheel for moving the base;

a 2 nd wheel for moving the base;

a 1 st driver for rotationally driving the 1 st wheel;

a 2 nd driver for rotationally driving the 2 nd wheel;

the transfer robot selectively performs: a 1 st control mode in which the 1 st controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, calculates correction control for bringing the relative relationship between the 1 st measurement value and the 2 nd measurement value close to a target relative relationship, and applies the correction control to the 1 st rotating body; and a 2 nd control mode in which the 2 nd controller acquires a 1 st measurement value of the rotation state of the 1 st rotating body and a 2 nd measurement value of the rotation state of the 2 nd rotating body, and applies the correction control to the 2 nd rotating body.