JPS6023368B2 - Actuator abnormality detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to detection of abnormal operation of an actuator that is controlled on-off.

Regarding actuators operated by continuous signals in a servo system, abnormalities can be easily detected by monitoring a control deviation between a displacement command, which is a target value, and a displacement, which is a controlled amount.

However, an abnormality detection technology for actuators that are controlled on and off in an open loop by intermittent signals, such as actuators that are a combination of a solenoid valve and a cylinder, has not yet been established. Therefore, the present invention seeks to provide an effective method for detecting abnormalities in actuators that are controlled on and off.

The feature of the present invention is to detect abnormal operation of the actuator from the deviation between the level of the displacement signal of the actuator and the level obtained by sampling and holding this displacement signal at regular time intervals. The present invention will be specifically described below with reference to the accompanying drawings.

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
It is a time chart of signals of each part in the figure.

In FIG. 1, A is an abnormality detection device, B is an actuator that is controlled on and off by an open signal e and a close signal e2, and C is a displacement detector that detects the displacement of actuator B.

In addition, 1 is a sample hold circuit that samples and holds the displacement signal e6 at a sampling time interval T2, 2 is a level comparator that checks the deviation e5 between the displacement signal e6 and the sample hold level, and 3 is a delay time T, (where T .<T2); 4 is a pulse generator that outputs a timing signal e4 at a period of the sample time interval T2; 5 and 6 are inverters;
7 and 8 are or gates, and 9 is an and gate. Next, the operation when the open signal e is issued will be explained with reference to FIG.

When the open signal e is issued at time t, the abnormality detection signal e3
That is, since the output signal of the timer 3 is not output, the open signal e activates the pulse generator 4 through the OR gate 7 and the AND gate 9, and generates the timing signal e4 with a period of [2] as shown.

If actuator B operates normally, the level of displacement signal e6 increases at a constant slope as shown. The sample hold circuit 1 is reset at the falling time of the timing signal e4, , t3, and is reset at the rising time of the timing signal e4.
Sample and hold. Therefore, the sample hold level follows the displacement signal e6 and rises in a stepwise manner as shown in the figure. In Figure 2, day is in hold mode,
T is close value mode (sample/hold operation is canceled,
This is a mode in which e6 is output as is. As a result, the deviation e5 between the hold level and the displacement signal e6 is at time t, . Then, before time T has elapsed since t3, the set level (10L) of the comparator 2 is exceeded, so the output e9 of the comparator 2 rises, and the OR gate 8 outputs the reset signal e7. The timer 3 starts operating at the rising edge of the timing signal e4, but it does not turn on because it is reset by the reset signal e7 before the delay time T.
Its output, that is, the abnormality detection signal e3 does not rise. However, if an abnormality occurs in the actuator B and the operation stops after time t, the deviation e5 remains at the set level of the comparator 2 (10L) even after time T has elapsed from time t3 as shown in the figure.
) is not exceeded, so reset signal history 7 is not issued,
The timer 3 outputs an abnormality detection signal e3 at time t4.

Note that the operation when the close signal e2 is issued is based on the displacement signal e.
Since it can be explained in exactly the same way except that the level of 6 decreases over time, it will not be explained in detail.

The role of the isoverter 5 is to ensure that the timer is initially reset when the actuator starts driving.

That is, during the falling period of the timing signal pole 4, the inverter 5
The output e3 becomes high, and by resetting the timer 3, the delay time of the timer 3 is initialized to be reliably T, based on the rise time of the timing signal collar 4 at the start of actuator drive. It will be possible. As is clear from the above detailed description, according to the method of the present invention, abnormalities in the actuator can be reliably detected.

In addition, although the above-mentioned embodiment detects the stop of the actuator or the decrease in the displacement amount, the invention is not limited to this, and abnormally rapid actuation of the actuator can be detected from the deviation between the displacement signal and the sample hold level. will also be easy to understand.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the same embodiment. A: Abnormality detection device, B: Actuator, C: Displacement detector, 1: Sample hold circuit, 2: Comparator, 3: Delay on timer, 4...Pulse generator. Figure 2 of the ship

Claims (1)

[Claims] 1 An abnormality detection method for an actuator that is controlled on and off in an open loop by an on and off control signal of an intermittent signal, which outputs a displacement signal at a level proportional to the displacement of the actuator that is controlled on and off. a displacement detector, a pulse generator that is driven by the on/off control signal of the actuator and generates pulses at regular time intervals, and samples the displacement signal using the pulse signal output from the pulse generator. a sample and hold circuit that holds the sample and hold circuit; a circuit that calculates the deviation between the hold level of the sample and hold circuit and the level of the displacement signal, compares the deviation with a preset value, and outputs a comparison result signal; and a timer circuit that is activated by a pulse signal output from a generator and reset by a comparison result signal output when the deviation exceeds a preset value, and the timer circuit is activated after a predetermined period of time has elapsed. An abnormality detection method for an actuator, characterized in that an abnormality in the operation of the actuator is detected when the actuator times out without being reset.