JP2663416B2 - Material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a motor driven material testing machine. <Conventional Technology> As a control method of a DC servomotor that drives a material testing machine, there is pulse-wide control. This is a method in which a pulse having a constant period is applied to a motor, and the power supplied to the motor is controlled by changing the pulse width. In the closed loop control system for controlling the DC servo motor by the pulse wide control, when the error signal becomes small, the pulse width becomes small and the power supplied to the motor decreases as shown in FIG. 3 (a). On the other hand, when the error signal increases, as shown in FIG. 3B, the pulse width increases and the power supplied to the motor increases. <Problems to be Solved by the Invention> As described above, in the related art, the pulse width is reduced as the error signal decreases, but when the error signal is extremely small, the pulse width to the motor is set to the minimum pulse width. The supply power will be large. For this reason, when the error signal is small, as shown in FIG. 4, it is repeated to output two or three pulses and then output two or three pulses again after a fixed pause period. A method is adopted, but in this case, rotation unevenness of the motor occurs. When the rotation unevenness occurs in the DC servo motor that drives the material testing machine in this way, there occurs a problem that the speed of the material test becomes uneven and the test result is greatly affected. <Means for Solving the Problems> The present invention relates to a motor-driven material testing machine having a control system for controlling the power supplied to a DC servomotor by changing the width of a pulse supplied to the DC servomotor. And a reference wave generating means for generating a reference wave having a plurality of peak values, and a comparing means for comparing the error signal with the reference wave and outputting a pulse having a pulse width corresponding to the comparison operation. In which the period of the pulse supplied to the DC servomotor is changed according to <Example> An example of the present invention will be described below. FIG. 1 shows the configuration of a control device for a DC servomotor.
The DC servo motor 1 drives a material testing machine (not shown). The output of the DC power supply 2 is converted into a pulse by the motor drive power pulsing unit 3 and supplied to the DC servo motor 1. A displacement detector of a material testing machine (not shown), a computing device (not shown) for calculating a deviation between a displacement signal from the displacement detector and a displacement set value from a displacement setter (not shown) and providing an error signal to an error signal input unit 4 , Comparators 5 and 6 and motor drive power pulsing unit 3 constitute a closed loop control system. The error signal provided to the error signal input unit 4 is input to the comparator 6 via the comparator 5 and the inverter 7. The reference wave generator 8 outputs a triangular wave of a negative voltage as shown in FIG. The triangular waves alternately have different peak values, and the peak value a is larger than the peak value b. This triangle wave is a comparator
Entered in 5,6. The output signals of the comparators 5 and 6 are input to the motor drive power pulsing unit 3. The comparator 5 compares the error signal with the triangular wave from the reference wave generator 8, and outputs a normal rotation control pulse corresponding to the magnitude of the error signal when the error signal is negative.
The comparator 6 compares the inverted signal of the error signal from the inverter 7 with the triangular wave from the reference wave generator 8, and outputs a reverse control pulse according to the magnitude of the error signal when the error signal is positive. I do. Motor drive power pulsing unit 3
Converts the DC power from the DC power supply 2 into a pulse adjusted to a required pulse width in accordance with the forward control pulse from the comparator 5 or the reverse control pulse from the comparator 6. Then, the motor driving power pulsing unit 3
Is supplied to the DC servomotor 1. When the error signal is large, the comparator 5 or 6 generates an output for both the triangular wave having the peak value a and the triangular wave having the peak value b, and outputs a forward control pulse or a reverse control pulse having a large pulse width. You. At this time, the DC power supplied to DC servo motor 1 is large. On the other hand, when the error signal decreases and approaches Ov, the comparator 5 or the comparator 6 outputs only the triangular wave having the peak value a, and the forward control pulse having a small pulse width and a large cycle or A reverse control pulse is output. The forward control pulse or the reverse control pulse has a cycle longer than the cycle of the forward control pulse or the reverse control pulse when the error signal is large, and has a small pulse width and is continuously output. . Therefore, the pulse supplied from the motor drive power pulsing unit 3 to the DC servo motor 1 has a large period, a small pulse width, and is supplied continuously. As a result, even when the error signal is small, smooth rotation of the DC servo motor 1 can be obtained. <Effects> As described above, according to the material testing machine of the present invention,
Since the pulse period is changed together with the pulse width to be supplied to the DC servomotor in accordance with the magnitude of the error signal, the pulse can be continuously supplied to the DC servomotor even when the error signal is small, thereby always As a result of smooth rotation, material testing can be performed with high precision.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block circuit diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a triangular waveform of the embodiment of the present invention, FIG. 3 and FIG.
FIG. 2 is a diagram showing a pulse waveform in a conventional pulse width control. 1 DC servo motor 3 Motor drive power pulsing unit 4 Error signal input unit 5, 6 Comparator 7 Inverter 8 Reference wave generator

Claims (1)

(57) [Claims] A reference for generating a reference wave having a plurality of peak values in a motor driven material testing machine having a control system for controlling the power supplied to the DC servomotor by changing the width of a pulse supplied to the DC servomotor Wave generating means, and comparing means for comparing the error signal and the reference wave and outputting a pulse having a pulse width corresponding to the comparison operation,
A material testing machine wherein a cycle of a pulse supplied to the DC servomotor is changed according to the error signal.