JP2007072870A - Control system for automated guided vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide steering control upon an emergency stop without requiring extra circuits and extra electrical energy. <P>SOLUTION: A control system, when an emergency stop button 5 is pushed, stops an automated guided vehicle by turning off a main circuit contactor MC to shut off power supply from a power supply part 1 to a driving motor drive device 2 and a steering motor drive device 3. When the emergency stop button 5 is pushed, a driving motor M1 is regeneratively operated, and electrical energy generated by the regenerative operation is supplied to the steering motor drive device 3 to continue operating a steering motor M2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an automatic guided vehicle, and more particularly to control of a motor at an emergency stop.

  An automated guided vehicle is a guided vehicle that travels autonomously along a taxiway laid on the floor of a warehouse or the like. Such an automatic guided vehicle is equipped with a travel motor for traveling the vehicle body and a steering motor for turning the vehicle body, and is provided with a motor drive device for driving each motor. . In addition, emergency stop means such as an emergency stop button is provided for emergency stop of the vehicle body when an abnormality occurs.

  FIG. 3 is a circuit diagram illustrating an example of a control device in an automatic guided vehicle having an emergency stop function. 1 is a power supply unit including a battery, 2 is a travel motor drive device that receives power supply from the power supply unit 1, M1 is a travel motor driven by the travel motor drive device 2, and 3 is a steering motor that receives power supply from the power supply unit 1. Drive device, M2 is a steering motor driven by the steering motor drive device 3, MC is a main circuit contactor provided between the power supply unit 1, the traveling motor drive device 2 and the steering motor drive device 3, and D is a main circuit contactor Diodes connected to both ends of the MC, 4 is a control unit composed of a CPU, a memory and the like for controlling the operation of the traveling motor drive device 2 and the steering motor drive device 3, and 5 is an emergency stop provided on the side of the vehicle body, for example Button. Each of the traveling motor drive device 2 and the steering motor drive device 3 includes a known motor drive circuit including a PWM (Pulse Width Modulation) circuit and a power transistor.

  During normal operation, the main circuit contactor MC is in an ON state, and power is supplied from the power supply unit 1 to the traveling motor drive device 2 and the steering motor drive device 3 via the main circuit contactor MC. Then, based on a control signal from the control unit 4, the traveling motor drive device 2 rotates the traveling motor M1, and the steering motor drive device 3 rotates the steering motor M2, so that the automatic guided vehicle travels and turns. When the emergency stop button 5 is pressed during an emergency stop, the main circuit contactor MC is turned off in conjunction with this (the state shown in FIG. 3). For this reason, the power supply from the power supply unit 1 to the traveling motor drive device 2 and the steering motor drive device 3 is cut off, the traveling motor M1 and the steering motor M2 are stopped, and the automatic guided vehicle is stopped.

  FIG. 4 is a flowchart showing the operation of the control device of FIG. This procedure is executed by the CPU of the control unit 4. In step S11, it is monitored whether or not the emergency stop button 5 is pressed. If the emergency stop button 5 is not pressed (step S11: NO), the normal operation described above is performed (step S12). When the emergency stop button 5 is pressed (step S11: YES), the control unit 4 receives an emergency stop command from the emergency stop button 5 and turns off the main circuit contactor MC (step S13). Further, the control unit 4 deactivates the traveling motor drive device 2 and stops the traveling motor M1 (step S14), deactivates the steering motor drive device 3 and stops the steering motor M2 (step S14). S15).

For example, the following patent documents are given as prior art documents relating to control during emergency stop of an automatic guided vehicle.
Japanese Patent Laid-Open No. 1-287712 JP-A-11-231936 JP 2001-344020 A

  In the conventional control device shown in FIGS. 3 and 4, when the emergency stop button 5 is pushed, both the travel motor drive device 2 and the steering motor drive device 3 are inactivated, and together with the travel motor M1. The steering motor M2 is also stopped. However, when the steering motor M2 stops, the steering control of the vehicle body becomes impossible, and the vehicle stops with the vehicle body tilted, stops when the vehicle body deviates from the taxiway and cannot be restarted, or collides with surrounding equipment. Or other problems occur.

  Therefore, as a method for solving this problem, in Patent Documents 1 to 3 described above, steering control can be performed by setting the steering motor drive device in an operating state for a certain period of time after the emergency stop signal is issued. To prevent derailment of the car body. However, in Patent Documents 1 to 3, a control circuit for supplying power to the steering motor drive device for a certain period of time is required in order to enable steering control during an emergency stop. Further, during operation of the steering motor drive device, the power of the power source is consumed, which is uneconomical.

  The present invention solves the above-described problems, and an object of the present invention is to enable steering control during emergency stop without requiring an extra circuit or extra electric energy.

  The present invention includes a power supply unit, a travel motor drive device that receives power supply from the power supply unit, a travel motor that is driven by the travel motor drive device, a steering motor drive device that receives power supply from the power supply unit, A steering motor driven by the steering motor drive device, a contactor provided between the power supply unit, the travel motor drive device and the steering motor drive device, and emergency stop means for emergency stop of the automatic guided vehicle, When the emergency stop means outputs an emergency stop command, the contactor is turned off, and the automatic guided vehicle that stops the automatic guided vehicle by stopping the power supply from the power source to the traveling motor drive device and the steering motor drive device. In the control device, the emergency stop means is emergency When outputting stopping instruction, a travel motor and a regenerative operation, by supplying electric energy generated by the regenerative operation to the steering motor drive, in which so as to continue the operation of the steering motor.

  In the present invention, after the emergency stop command is output, the steering motor drive device is driven using electric energy generated by regenerative operation of the travel motor. For this reason, the steering motor continues to operate with regenerative energy until the travel motor stops. Therefore, steering control at the time of emergency stop can be performed without providing a control circuit for supplying power to the steering motor drive device for a certain period of time, and derailment of the vehicle body can be prevented. Further, in the present invention, since the steering motor drive device is driven by the regenerative energy of the travel motor, the power of the power supply unit is not consumed excessively and is economical.

  In the present invention, it is preferable to connect a diode to both ends of the contactor so that a part of the electric energy generated by the regenerative operation is returned to the power supply unit via the diode during the regenerative operation of the traveling motor. According to this, after the emergency stop signal is output, the responsiveness to the stop of the travel motor can be satisfactorily maintained while enabling the steering control.

  According to the present invention, after the emergency stop command is output, the traveling motor is regeneratively operated to supply power to the steering motor drive device, so that no extra circuitry or extra electrical energy is required. It is possible to perform steering control during emergency stop.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an example of a control device according to the present invention. 1 is a power supply unit including a battery, 2 is a travel motor drive device that receives power supply from the power supply unit 1, M1 is a travel motor driven by the travel motor drive device 2, and 3 is a steering motor that receives power supply from the power supply unit 1. Drive device, M2 is a steering motor driven by the steering motor drive device 3, MC is a main circuit contactor provided between the power supply unit 1, the traveling motor drive device 2 and the steering motor drive device 3, and D is a main circuit contactor Diodes connected to both ends of the MC, 4 is a control unit composed of a CPU, a memory and the like for controlling the operation of the traveling motor drive device 2 and the steering motor drive device 3, and 5 is an emergency stop provided on the side of the vehicle body, for example Button. Each of the traveling motor drive device 2 and the steering motor drive device 3 includes a known motor drive circuit including a PWM (Pulse Width Modulation) circuit and a power transistor. The above configuration itself is the same as that shown in FIG.

  During normal operation, the main circuit contactor MC is in an ON state, and power is supplied from the power supply unit 1 to the traveling motor drive device 2 and the steering motor drive device 3 via the main circuit contactor MC. Then, based on a control signal from the control unit 4, the traveling motor drive device 2 rotates the traveling motor M1, and the steering motor drive device 3 rotates the steering motor M2, so that the automatic guided vehicle travels and turns. The operation so far is the same as that described in FIG.

  When the emergency stop button 5 is pressed during an emergency stop, the main circuit contactor MC is turned off in conjunction with this (state shown in FIG. 1). Therefore, the power supply from the power supply unit 1 to the traveling motor drive device 2 and the steering motor drive device 3 is cut off. At this time, based on the control signal from the control unit 4 to the traveling motor drive device 2, the traveling motor M1 Is regeneratively operated. Then, electric energy (regenerative current) generated by this regenerative operation is supplied to the steering motor drive device 3. As a result, the steering motor drive device 3 maintains the operating state, and performs the steering control of the steering motor M2 based on the control signal from the control unit 4. Thereafter, when the traveling motor M1 stops after a certain period of time, the electric energy due to regeneration is lost, the steering motor drive device 3 becomes inoperative, and the steering motor M2 stops. A part of the electric energy generated by the regenerative operation of the traveling motor M1 is returned to the power supply unit 1 through the diode D. The dashed arrows in FIG. 1 indicate the path of the regenerative current.

  FIG. 2 is a flowchart showing the operation of the control device of FIG. This procedure is executed by the CPU of the control unit 4. In step S1, it is monitored whether or not the emergency stop button 5 is pressed. If the emergency stop button 5 is not pressed (step S1: NO), the normal operation described above is performed (step S2). When the emergency stop button 5 is pressed (step S1: YES), the control unit 4 receives an emergency stop command from the emergency stop button 5 and turns off the main circuit contactor MC (step S3). In addition, the control unit 4 gives the traveling motor drive device 2 a command (RUN signal) for setting the drive device 2 to an operating state and a rotation speed instruction value “0” (rotation stop signal). Thus, the traveling motor M1 is regeneratively operated (step S4). As a result, the motor M1 rotates due to inertia and acts as a generator to generate electrical energy. Then, this electric energy is supplied to the steering motor drive device 3 to maintain the steering motor drive device 3 in an operating state, and the operation of the steering motor M2 is continued. That is, steering control is performed. In the next step S5, it is determined whether or not the traveling motor M1 has stopped. This determination can be made based on the output of an encoder attached to the traveling motor M1, for example. If the traveling motor M1 is not stopped (step S5: NO), the process returns to step S4 and the regenerative operation is continued, and if the traveling motor M1 is stopped (step S5: YES), the steering motor drive device 3 receives electric energy. The supply is lost and the engine becomes inoperative, and the steering motor M2 stops (step S6).

  As described above, in the present embodiment, after the emergency stop button 5 is pressed and the emergency stop command is output, the steering motor drive device uses the electric energy generated by the regenerative operation of the travel motor M1. 3 is driven. For this reason, the steering motor M2 continues to operate with regenerative energy until the travel motor M1 stops. Therefore, steering control at the time of emergency stop can be performed without providing a control circuit for supplying power to the steering motor drive device 3 for a certain period of time, and derailment of the vehicle body can be prevented. Further, since the steering motor drive device 3 is driven by the regenerative energy of the travel motor M1, the power of the power supply unit 1 is not consumed excessively and is economical.

  In the present embodiment, part of the electric energy generated by the regenerative operation is returned to the power supply unit 1 via the diode D during the regenerative operation of the traveling motor M1. The diode D protects the traveling motor drive device 2 by reducing the surge voltage generated in the motor by circulating the motor current to the power supply unit 1 even when the main circuit contactor MC is turned off at the time of emergency stop. Is provided. Therefore, since this diode D can be used as a path for returning a part of the electric energy of the traveling motor M1 to the power supply side, the traveling motor M1 can be stopped as quickly as possible. That is, the electric energy generated by the regenerative operation is distributed to the two systems of the steering motor drive device 3 side and the power supply unit 1 side, so that after the emergency stop signal is output, the steering control can be performed while enabling the steering control. Responsiveness to the stop can be maintained well.

  In the above-described embodiment, the case where the emergency stop button 5 is provided on the vehicle body of the automatic guided vehicle is described as an example. However, the emergency stop button 5 may be provided at a location different from the vehicle body. Further, in the above-described embodiment, the emergency stop button 5 operated by a human is exemplified as the emergency stop means. However, the emergency stop means of the present invention is not limited to this. For example, an emergency stop is automatically detected by detecting an abnormality. It may be a sensor that outputs a command.

It is the circuit diagram which showed an example of the control apparatus which concerns on this invention. It is the flowchart which showed operation | movement of the control apparatus of FIG. It is the circuit diagram which showed an example of the control apparatus in the automatic guided vehicle provided with the emergency stop function. It is the flowchart which showed operation | movement of the control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply part 2 Traveling motor drive device 3 Steering motor drive device 4 Control part 5 Emergency stop button M1 Traveling motor M2 Steering motor MC Main circuit contactor D Diode

Claims (2)

A power supply,
A traveling motor drive device that receives power supply from the power supply unit;
A travel motor driven by the travel motor drive device;
A steering motor drive device that receives power supply from the power supply unit;
A steering motor driven by the steering motor drive device;
A contactor provided between the power supply unit and the travel motor drive device and the steering motor drive device;
Emergency stop means for emergency stop of the automated guided vehicle,
When the emergency stop means outputs an emergency stop command, the contactor is turned off and the automatic guided vehicle is stopped by cutting off the power supply from the power supply unit to the traveling motor drive device and the steering motor drive device. In the control device for automatic guided vehicles,
When the emergency stop means outputs an emergency stop command, the driving motor is regeneratively operated, and the operation of the steering motor is continued by supplying the electric energy generated by the regenerative operation to the steering motor drive device. A control device for an automatic guided vehicle. In the control device of the automatic guided vehicle according to claim 1,
A diode is connected to both ends of the contactor, and part of the electric energy generated by the regenerative operation is returned to the power supply unit via the diode during the regenerative operation of the traveling motor. Control device for transport vehicles.

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