JPS623308A - Industrial robot runaway prevention device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a runaway prevention device for an industrial robot.

Conventional technology In recent years, the spread of industrial robots has been reported, but the reason why they have not seen rapid growth is not only due to cost and performance, but also to safety issues. , a conventional safety device for industrial robots will be explained.

FIG. 6 is a block diagram of a safety circuit of a conventional control device. In FIG. 5, 21a is a control unit that outputs a position command value Pc, 21b is a position error register that is an error amplifier for the position command value Pc and position feedback value Pf, and 26 is a power supply for the servo amplifier system 27. , power supply control means for controlling off, 28 is an actuator, 2
9 is a position detector coupled to the actuator.

Regarding the safety circuit of the control device configured as above,
The operation will be explained below.

First, FIGS. 6 and 7 are timing diagrams of position feed panoch pulses when the actuator moves CW or CCW.

A position command Pc is output from the control section 21a to the position deviation register. The amount of deviation between the position command Pc and the position feedback value Pf is output to the servo amplifier system 27 as a speed command value Vc. Then, the actuator 28 moves in the CW force direction or in the CCW direction. Furthermore, the A phase and B phase as shown in FIG. 6 or 7 are output from the position detector 29 coupled to the actuator 28, and the position pulse generating means 22 generates position feedback as shown in FIG. 6 or 7. Generates a CW pulse or CCW pulse for pulse creation, and uses the difference between the CW pulse and CCW pulse as position feedback Pf to register the position error register 2.
Output to 1b. Here, the position deviation register 21b amplifies the deviation between the position command value Pc and the position feedback value Pf, and outputs it to the servo amplifier system 27 as a speed command value Vc. Repeat the above operations to position it at a predetermined position.

Here, the position deviation register 21b has a position command value Pc
When the error between the position feedback value Pf and the position feedback value Pf (hereinafter referred to as position deviation) reaches a constant value, the servo amplifier system 2
7 and the actuator 2B and the position detector 29, the power supply for driving the actuator 28, which is supplied to the servo amplifier system via the power supply control means 26, is cut off to ensure safety.

(For example, Patent Publication No. 49-31056 Safety circuit of control device) Problems to be solved by the invention However, in the above configuration, until the positional deviation reaches a value Pe greater than a certain value, it takes a certain period of time according to the Pe O value. The problem is that detection of abnormalities, disconnections, and poor connections in the position detector is delayed, resulting in unavoidable runaway for a certain period of time.

In view of the above-mentioned problems, the present invention provides an industrial robot runaway prevention device that detects abnormality, disconnection, or poor contact of a position detector without delay and prevents the industrial robot from running out of control. It is.

Means for Solving the Problems In order to solve the above problems, the industrial robot of the present invention includes a phase movement detection means for detecting phase movement of a two-phase signal generated by a position detector, and the phase movement detection means. The current phase detected by the phase movement detection means is compared with the previous phase stored in the phase movement storage means, and an abnormality is detected. The present invention is equipped with phase movement comparison means for detecting the presence or absence of phase movement, and power supply control means for controlling on/off of the power supplied to the actuator. By taking advantage of the fact that the phase movement has a certain regularity, it is possible to detect an increase in wiring impedance due to disconnection or poor contact, or a decrease in signal amplitude due to deterioration of elements inside the encoder, and to prevent runaway due to sensor abnormality. can be prevented.

EXAMPLE Hereinafter, a runaway prevention device for an industrial robot according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of the industrial robot runaway prevention device according to the first embodiment of the present invention, FIGS. 2 and 3 are timing diagrams of the phase movement detection means, and FIG. 8 is the judgment of the opponent's hand size. The flowchart is shown below. In FIG. 1, 11 is a control section, 1o is a disconnection detection timing generation means, 13 is a phase shift detection means, 14 is a phase shift storage means, 16 is a phase shift comparison means, and 16 is a power supply control means.

In Figures 2 and 3, 1, 2, 3, 4°5.6,
7.8 is the phase number.

The operation of the runaway prevention device for an industrial robot constructed as described above will be explained below with reference to FIGS. 1, 2, 3, 4, and 8.

First, FIGS. 2 and 3 are timing diagrams of the phase movement detection means. When the actuator 18 is driven by the servo amplifier system 17, a two-phase signal (A phase and B phase) as shown in FIG. 2 is output from the position detector 19 depending on the direction of movement.

Here, as shown in FIG. 2, when the actuator moves in the CW direction, the rising and falling timings of the A phase and B phase are 1.2, 3, 4. and the phase number. In addition, as shown in Fig. 3, when the actuator moves in the CCW direction, the timing of the rise and fall of the A and B phases is 5.6,
7.8 Assign phase numbers. When the actuator repeats movement in the CW force direction, the group numbers of the A phase and B phase change from 1 → 2 → 3 →
4 → 1 → 2 → 3 is repeated. On the other hand, when the actuator repeats movement in the CCW direction, the set numbers of the A phase and B phase are repeated in the order of 8→7→6→5→8→7→6→5→8. Further, as shown in FIG. 4, when the moving direction of the actuator is changed from CW to CCW at the time of group number 1, the group numbers of the A phase and B phase will be 1→2→3→4→1→5. →8
→7→6→6→8→7.

The phase movement detection means 13 creates a number determined as the current set number in FIGS. 2 and 3. The phase movement storage means 14 is
The set number detected by the phase movement detecting means 13 one time before is stored. The phase movement comparison means 15 is the phase movement detection means 13
The current group number determined in step 1 and the previous group number stored in the phase movement storage means 14 are compared each time the phase movement detection means 13 detects a phase movement. In cases other than the correct phase movement determined in the table below, the servo power can be shut off via the power supply control means 16 as an error to prevent the industrial robot from running out of control.

In the margin below the table in Figure 2, if phase B is not input due to disconnection, poor contact, or abnormality in the position detector 19, the group number is 1.
→3, and the phase movement detection means 13 is detected by the phase movement comparison means.
An error is determined when phase movement number 3 is detected. Further, in FIG. 3, if the A phase is not input, the group number changes from 8 to 6, and when the phase movement comparing means detects the phase movement number 6 in the phase movement detecting means 13, an error is determined.

Further, if the position deviation value Pe is other than 0, the disconnection detection timing means 1o is always activated, and if no phase movement occurs in the phase movement detection means 13 after a certain period of time, the phase movement detection means 13 detects the phase movement. The comparison means 16 is caused to start comparison, and a case where both the human face and the B phase are abnormal is detected.

As described above, according to this embodiment, the phase shift detecting means 13 sets a set number for the two-phase signal output from the phase detector, and the phase shift storage means 14 stores the previous set number. and,
The current group number set by the phase movement detection means 13 is detected every time a phase movement is detected by the phase movement detection means 13, or even if the disconnection detection timing generation means 1o is activated and a certain period of time has elapsed. By comparing when no phase movement is detected by the means 13, it is possible to detect wire breakage, poor contact, or abnormality in the position detector, and by cutting off the actuator drive power by the servo power control means 16, it is possible to prevent the industrial robot from running out of control. It can be prevented.

Effects of the Invention As described above, the present invention provides a phase shift detection means, a phase shift storage means, a phase shift comparison means, and a power supply control means, thereby preventing disconnection, contact failure, and contact failure of two-phase signals output from a position detector. It is possible to detect abnormalities in the position detector without any delay time, and prevent the robot from running out of control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the industrial robot runaway prevention device according to the first embodiment of the present invention, and FIG. 2 shows the set number set when the actuator moves in the CW force direction using the phase movement detection means of FIG. In the explanatory diagram and Figure 3, the actuator is CC.
Explanatory diagram of phase numbers set when moving in the W direction, 4th
The figure is an explanatory diagram showing the movement of phase numbers when the actuator changes from the CW force direction to the CCW direction, Figure 5 is a block diagram of the safety circuit of a conventional control device, and Figures 6 and 7 are Figure 5. FIG. 8 is a timing diagram of position feedback pulses in FIG. 8, which is an operation flow diagram of an embodiment of the present invention. 10...Disconnection detection timing generation means, 11.
. . . Control unit, 13 . . . Phase movement detection means, 1
4... Phase movement storage means, 16... Phase movement comparison means, 16... Power supply control means. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (1)

[Claims] An industrial robot comprising a shaft, an actuator for driving the shaft, and a position detector for the shaft, comprising: a phase shift detection means for detecting phase shift of a two-phase signal generated by the position detector; A phase movement storage means for storing the phase detected by the phase movement storage means compares the current phase detected by the phase movement detection means with the previous phase stored in the phase movement storage means; A phase shift comparison means that outputs an output when the previous phase and the current phase are in a predetermined combination, and the phase shift comparison means is operated by the output of the phase shift comparison means to control turning on and off of the power supplied to the actuator. An industrial robot runaway prevention device equipped with a power supply control means.