JPH05346812A - Abnormality detector - Google Patents

Abstract

PURPOSE:To provide an abnormality detector which extremely easily detects the presence or absence of the abnormality of a servo system generated when a belt driving the arm of an industrial robot or the like is cut without using an auxiliary facility such as a limit switch. CONSTITUTION:A detector 6 outputting a speed feedback signal, and a detector 8 outputting position feedback signal are directly connected with a servo motor 5 rockingly driving an arm 1 through a pulley 2, belt 3, and pulley 4. The feedback of each feedback signal to a driving device 10 driving the servo motor 5 based on a command signal from a controller 9 is operated. Then, when a torque command signal to the driving device 10 is processed in integration and the time until it is turned into a saturated state is longer than a prescribed time, the cutting of a belt 3 is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for detecting the presence / absence of abnormality in a servo system driven by a servo actuator such as a servo motor.

[0002]

BACKGROUND OF THE INVENTION In an industrial robot, for example, when each arm is swung, it is driven and controlled by a servomotor or the like via a transmission mechanism including belts, pulleys or the like, or a speed reducer. From the viewpoint of avoiding the occurrence of various control problems, it is general to add a function of detecting whether or not the belt is cut. As an example,
Touch the limit switch to the tensioned belt,
It is known that the disconnection is detected based on the change in the state of the output from the limit switch when the belt is disconnected. However, the above-mentioned conventional techniques involve various troubles such as the setting of the limit switch, the manufacturing of the mounting jig for the limit switch, and the wiring work accompanying it. Therefore, the present invention has been devised in view of the above circumstances, and for example, whether or not there is an abnormality in the servo system that occurs when the drive belt or the like is cut off can be performed very simply without using auxiliary equipment such as a limit switch. An object of the present invention is to provide an abnormality detection device that can detect the abnormality.

[0003]

In order to achieve the above object, the main means adopted by the present invention, which is the gist of the invention, is driven by a servo actuator which is feedback-controlled by a control device via a drive device. A device for detecting the presence / absence of an abnormality in the servo system, which integrates the command signal to the drive device after feedback and detects the presence / absence of an abnormality in the servo system based on the degree of change in the data. It is an abnormality detection device concerning a point.

[0004]

[Operation] For example, when the torque command signal from the servo actuator to the drive device after feedback is integrated,
There is a change in the data when the load is applied to the servo actuator and when it is not. That is, by catching this change, for example, the cut state of the belt is detected.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not of the nature to limit the technical scope of the present invention. 1 is a circuit diagram of an abnormality detecting device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of a servo system to which the above abnormality detecting device can be applied, and FIG. 3 is a torque command to a driving device. It is a graph which shows the relationship between a signal and its integrated output. In an industrial robot to which the abnormality detecting device (see FIG. 1) according to this embodiment can be applied, as shown in FIG. 2, an arm 1 pivotally supported is provided with a pulley 2, a belt 3, and a pulley 4. It is connected to a servomotor 5 for driving the arm 1 via. A detector 6, which outputs a speed feedback signal, a speed reducer 7, and a detector 8, which detects a swing angle of the arm 1 and outputs a position feedback signal, are directly connected to the servo motor 5. Then, the speed feedback signal and the position feedback signal are fed back to the driving device 10 that drives the servo motor 5 based on the command signal from the control device 9.

In the abnormality detecting device, for example, the torque command signal to the driving device 10 after the feedback is integrated, and the presence or absence of an abnormality in the servo system is detected based on the degree of change of the data. That is, the drive device 1
A torque command signal to 0 is input to the abnormality detection device and integrated. The counter output resets each time the negative side or the positive side is saturated. The time until the above integrated output is saturated and reset is measured, and this measured time is compared with a preset reference value. If the time until saturation is longer than the reference value, it is determined that the belt 3 has been cut (Fig. 3 (a)).
Error) is output. On the other hand, when the time until saturation is shorter than the reference value, it is determined that the belt 3 has not been cut (see FIG. 3B). this is,
The focus is on the fact that the feedback signal also changes as the load on the servomotor 5 changes. Since the abnormality detection device according to the present embodiment is configured as described above, whether or not there is an abnormality in the servo system that occurs when the belt 3 is cut is extremely simple and easy without using auxiliary equipment such as limit switches. It can be reliably detected. In the above embodiment, the case of using the belt has been described as an example, but the abnormality detecting device is also applied to a servo system having a transmission mechanism including a chain, a link, a gear or the like instead of the belt. It is possible.

[0007]

As described above, the present invention is an apparatus for detecting the presence or absence of an abnormality in a servo system driven by a servo actuator which is feedback-controlled by a control apparatus via a drive apparatus. Since the command signal to the drive device is integrated, the presence or absence of an abnormality in the servo system is detected based on the degree of change of the data.
For example, the presence or absence of an abnormality in the servo system that occurs when the drive belt or the like is cut can be detected very simply without using auxiliary equipment such as limit switches.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an abnormality detection device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a servo system to which the abnormality detection device can be applied.

FIG. 3 is a graph showing the relationship between a torque command signal to a drive device and its integrated output.

[Explanation of symbols]

 1 ... Arm 2,4 ... Pulley 3 ... Belt 5 ... Servomotor 6,8 ... Detector 7 ... Reducer 9 ... Control device 10 ... Drive device

Claims (1)

[Claims] 1. A device for detecting the presence / absence of an abnormality in a servo system driven by a servo actuator feedback-controlled by a control device via a drive device, wherein the command signal to the drive device after feedback processing is integrated. An abnormality detecting device is characterized in that the presence or absence of abnormality in the servo system is detected based on the degree of change of the data.