JPS62160006A - Controlling method for dead slow speed of unmanned conveying vehicle - Google Patents

Abstract

PURPOSE:To smoothly move an unmanned conveying vehicle by increasing a current flowing to a motor when judging that the vehicle is in a stopped state. CONSTITUTION:A speed controller 3 compares a speed command 1 with the output of an encoder 9 and outputs a current command. A current controller 5 compares the current command with a current signal detected by a current detector 8, and applies a control signal to a converter 6. A vehicle stop detector 10 calculates the output of the encoder 9, and when the detector 10 detects the stop of the vehicle, it outputs a motor current rise command to a comparator 4. Thus, it can prevent the vehicle from stopping in a recessed terrain or a slope and can travel the vehicle smoothly on a flat road.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a slow speed control method for an automatic guided vehicle.

[Prior art]

The conventional speed control method for automatic guided vehicles is explained using Figure 1. Four types of speed command signals are provided: high speed, medium speed, low speed, and slow speed, and the vehicle speed is detected and compared using an encoder for each speed command. Proportional control is performed by comparing the output with the output of the current detector, and the output is sent to the converter to control the speed of the motor.

[Problems to be solved]

Automated guided vehicles usually do not require much speed accuracy, so proportional control, which is easy to adjust as described above, is adopted. Therefore, since the difference between the speed command and the vehicle speed detection value becomes the current command, the current does not flow up to the maximum controllable current value of the converter when the slow speed command is given.

Furthermore, the environment in which automatic guided vehicles are used may include potholes and slopes on the road surface, and the above-mentioned control may cause the vehicles to stop.

In such cases, the proportional control gain was increased, but the control became less smooth and sometimes hunting occurred.

Means for Solving Problem C] The present invention provides an automatic guided vehicle that performs feedback speed control using a speed signal and a current signal. When it is determined that the automatic guided vehicle is in a stopped state, it issues a motor current command signal that increases the current flowing to the motor to ensure smooth operation of the automatic guided vehicle.

〔Example〕

An embodiment of the present invention will be explained based on FIG. 2. ■ is a speed command, 2 is a comparator, 3 is a speed control circuit, 4 is a comparator,
5 is a current control circuit, 6 is a converter, 7 is a motor, 8 is a current detector, 9 is an encoder connected to the motor 7, 10 is a stop detector for the encoder 9, and the comparator 2 has a speed command 1 and an encoder. A signal obtained by detecting the current flowing through the motor 7 by a current detector 8 and a signal from a stop detector 10 are applied to the comparator 4.

〔motion〕

The speed command 1 and the output of the encoder 9 are compared by a comparator 2, the output is calculated by the speed control circuit 3, and the result and the output of a current detector 8 that detects the current flowing through the motor 7 are compared by the comparator 4. compare. Here, a stop detector 10 calculates the output of the encoder 9, and outputs a motor current increase command to the comparator 4 when a stop is detected.

A current control circuit 5 calculates the output of the comparator 4, gives a command to a converter 6, and controls the speed of the motor 7.

〔effect〕

As explained above, if the automatic guided vehicle stops despite the speed command signal being output, the stop detector 10 outputs a motor current increase command to prevent it from stopping in a pothole or on a slope. , and enables smooth driving on flat roads.

[Brief explanation of drawings]

FIG. 1 is a control block diagram of a conventional automatic guided vehicle. FIG. 2 is a control block diagram of the automatic guided vehicle of the present invention. 1...Speed command, 2...Comparator.

Claims (1)

[Claims] In an automatic guided vehicle that performs feedback speed control using speed signals and current signals, a stop detector determines that the automatic guided vehicle is in a stopped state based on the speed command signal and a signal from an encoder connected to the motor of the automatic guided vehicle. A slow speed control method for automatic guided vehicles that issues a motor current command signal that increases the current flowing through the motor.