JPH0425495B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a speed and position detector for a rotating body,
More specifically, the speed of the servo system, the speed of the position detector and rotating body, the speed with an abnormality detection function used as an interface with the position control device,
The present invention relates to a position detection device.

[Prior art] The speed of the AC servo system, the speed of the position detector and the rotating body (electric motor), and the interface section of the position control device are connected to the speed and position detector side using a differential line (balanced transmission) for noise countermeasures. The operating line driver is interfaced by a differential line receiver or photocoupler on the speed and position controller side. This speed and position detection device becomes a current transmission path and detects pulses in the current direction, but since current flows to the speed and position detection device except for breaks in the transmission path itself, the control device side detects pulses in the current direction. It was difficult to detect abnormalities in the speed and position detector itself. In other words, even though the transmission line is not disconnected in response to the speed command from the speed and position control device, if an abnormality occurs in the speed detector system and pulses are not output to the transmission line, the transmission line An incorrect current flows through the Therefore, the control device side detects this as one pulse of feedback pulse being applied, and the rotating body whose speed is controlled by pulse application naturally shows a deviation from the speed command pulse that is properly applied. becomes larger, and the rotating body, which is rotating at the actual commanded speed, is commanded to further increase its speed. This causes the rotating body to rotate at high speed, causing abnormal movements in machine tools, robots, etc. that are driven by this rotating body, which not only makes it impossible to control rotation with high reliability, but also causes major damage in some cases. This could have led to an accident.

On the other hand, the circuit for detecting disconnection in the signal transmission system is currently not built into the rotation speed detector but is provided on the speed control circuit side, so the protection function of the rotation speed detector cannot be used. Upgrading requires changes to the software and hardware of the control device itself, which poses the problem of being extremely large-scale.

[Object of the Invention] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is capable of detecting an abnormal state on the speed detector side and notifying the control device of the abnormal state without imposing a burden on the control device. The present invention provides a highly reliable rotation speed and position detection device that can notify the rotation speed and position.

[Summary of the Invention] The present invention provides a waveform shaping circuit that outputs binary signals A and B by shaping the output of a sensor that outputs a two-phase signal whose phase changes depending on the rotation direction of a rotating body, and a waveform shaping circuit that outputs binary signals A and B;
a first flip-flop that samples and holds the signal at the rising edge of the B signal; a second flip-flop that samples and holds the A signal at the falling edge of the B signal; and a third flip-flop that samples and holds the B signal at the rising edge of the A signal; a fourth flip-flop that samples and holds the B signal at the falling edge of the A signal;
a first logical means for calculating an exclusive OR of the flip-flop and the second flip-flop;
a second logical means for calculating the exclusive OR of the flip-flop and the fourth flip-flop; a third logical means for calculating the AND of the first and second logical means; and an output of the third logical means, The present invention is characterized in that a self-diagnosis function is added that outputs that the sensor is malfunctioning when one of the second signals is indicated.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a control block diagram of the rotational speed and position detection device, in which 11 is a rotational speed detection sensor of a rotating body (not shown), 12, 13, and 14 are waveform shaping circuits for the minute voltage detected by the sensor 11, 15,
16 and 17 are gate circuits, 18 is an abnormality detection circuit provided at the output section of each leaf shape shaping circuit 12, 13, and 14, and 19 is a speed control device for a rotating body (not shown).

According to the same circuit configuration, the minute voltage detected by the speed detection sensor 11 is transmitted to the waveform shaping circuit sections 12 and 1.
At steps 3 and 14, the signal is shaped to a logic level and transmitted as a feedback pulse to the speed control device via gate circuits 15, 16, and 17. At this time, the abnormality detection circuit 18 constantly monitors the pulse state, and when an abnormality is detected, the gate circuits 15, 16,
17 performs control to prevent malfunction on the speed control device 19 side by making the output signal of the gate circuit a high impedance output regardless of the outputs of the waveform shaping circuits 12, 13, and 14.

In such a rotational speed detection control system for a rotating body, TTL level A phase, A phase, B phase, B phase, Z phase, and Z phase, such as the pulse waves shown in FIG. 2, are transmitted to the speed control device 19. shall be taken as a thing. And phase A, B
The phase difference between the phases is ±90°, and whether the rotating body rotates forward or backward can be determined by the sign of the phase difference. The speed control device uses the A-phase and B-phase pulse numbers as feedback pulses and compares them with the speed command value, detects the deviation, and performs speed detection.

Furthermore, the Z phase outputs one pulse per rotation of the rotating body, and is used for positioning NC machine tools and the like.

The output pulses from the rotational speed detector 11, which are necessary for speed control as described above, may deteriorate as shown in Fig. 3 due to deterioration of the detector itself due to aging, temperature changes, etc.
~d may be output as pulses, but even in this case, the speed control device 19 has a signal that is difficult to detect unless the output becomes high impedance due to a break in the transmission line. Become.

The present invention solves such problems, and an abnormality detection circuit based on the circuit of FIG. 1 is shown in FIG. 4 and will be explained. In Figure 4, A, B, and Z are A
These are the outputs of the phase, B phase, and Z phase, which are the outputs of the waveform shaping circuits 12, 13, and 14 shown in FIG. 1, respectively. A first flip-flop 33 samples and holds the A signal at the rising edge of the B signal, and a second flip-flop 34 samples and holds the A signal at the rising edge of the output of the inverter 44 (that is, the falling edge of the B signal).

A third flip-flop 31 samples and holds the B signal at the rising edge of the A signal, and a fourth flip-flop 32 samples and holds the B signal at the rising edge of the output of the inverter 43 (ie, the falling edge of the A signal).

The first logic means 39 calculates the exclusive OR of the outputs of the first flip-flop 33 and the second flip-flop.
Calculate with.

The second logic means 38 calculates the exclusive OR of the outputs of the third flip-flop 31 and the fourth flip-flop.
Calculate with.

In the third logic means 42, the first logic means 39 and the second logic means 42
The logical product of the logic means 38 is calculated.

This embodiment further includes the following circuit to detect a Z-phase failure. In other words, the fifth flip-flop 35 inverts its output with the Z-phase signal,
It is configured to be reset at the rising edge of the output of the first OR circuit 45.

The output of the fifth flip-flop 35 and the Z-phase output are subjected to an OR operation in a second OR circuit 40. Furthermore, the sixth flip-flop is Z
The seventh flip-flop 37 is configured to sample and hold the output of the sixth flip-flop 36 at the rising edge of the output of the OR circuit 46. It's getting old. The outputs of the sixth and seventh flip-flops 36 and 37 are
A logical operation is performed in the NAND circuit 41, and the outputs of the second OR circuit 40 and the NAND circuit 41 are
The third logic means 42 is configured to perform an OR operation together with the outputs of the second logic means 39 and 38. The output of the third logic means 42 is the abnormality detection circuit 18
This is the output of

First, as shown in the second pulse waveform diagram, during normal operation, the state of the A phase rises and the state of the B phase at the time of the A phase rise are OV (hereinafter referred to as L level) and 5V (hereinafter referred to as H level), respectively. ).
Now, in the circuit shown in FIG. 4, if the pulse signals input to the A and B phases are as shown in FIG. The output of the flip-flop 32 is continuously held at H. These outputs are output as H level by exclusive OR circuit 38. Similarly, the rising edge of the B-phase pulse causes the A-phase pulse state to be output from the flip-flops 33 and 34, and similarly, the exclusive OR circuit 39 outputs the A-phase pulse state to an H level.
Output as level.

That is, when the pulse input is normal, the outputs of the exclusive OR circuits 38 and 39 are output as H level. However, as shown in Figure 3a,
If the B-phase input pulse remains at H level (or remains at L level), A,
Since the B-phase pulse states are the same at the rising edge of the A-phase pulse, the outputs of the flip-flops 31 and 32 are the same, and the output of the exclusive OR circuit becomes L level.

On the other hand, in the case as shown in FIG. 3c, the rise of the pulses of the A, A, B, and B phases as described above disappears, so that the abnormality cannot be detected. However, as shown in FIG. 3C, it is rare for both A and B phase signals to become inactive at the same time or within a very short period of time, except when a disconnection occurs. As mentioned above, wire breakage can be conventionally detected by known means.

Furthermore, as shown in Figure 3d, the Z-phase signal may not be output normally, but if only the rotational speed and direction are to be detected, this Z-phase is not necessary;
Even if a phase does not operate properly, there is little worry that the rotating body will run out of control. Therefore, the measures against these are:
This is not essential to the invention. However, in this embodiment, countermeasures are taken against these problems.

As a countermeasure for the problem shown in FIG. 3C, the abnormality is detected by the flip-flop 35 and the OR circuit 40 shown in FIG.

Figure 2 shows the pulse waveform during normal operation, that is,
The timing chart shown is a logical sum of the A and B phase pulse waveforms (Z has no relation to the operation of this embodiment). 35 becomes L, but the logic sum circuit 40 outputs the Z-phase pulse output H level as it is, and the flip-flop 35 is reset by the output of the logic sum circuit 45 based on the logical sum of the A and B phases. The output of the OR circuit 40 becomes H level, and the output of the OR circuit 40 remains at H level. Note that during normal operation, the Z signal remains high until the output of the OR circuit 45 rises.
It is configured to output the level.

However, in the case shown in FIG. 3C, while the Z-phase pulse is at H level, the output of the OR circuit 45 does not go to L level, and even when the Z-phase pulse goes to L level, the output of the flip-flop remains unchanged. Since it is not reset, it remains at L, and the OR circuit 40
The output of is also L.

Further, as shown in FIG. 3d, when the Z phase remains at the H level, an abnormality is detected by the flip-flops 36 and 37, the OR circuit 46, and the NOR circuit 41. At the rising edge of the logical sum of the A phase and B phase, the Z phase output pulse state H is sent to the flip-flop 36.
The level will be memorized as is. If it is a normal Z pulse, it will be at the L level at the next rise of the logical sum of the A phase and the B phase, so the output of the logical sum circuit 41, which is a negative logical sum, will be at the H level, but as shown in FIG. In such a case, the outputs of the flip-flops 36 and 37 are at the H level, so the output of the OR circuit 41 is at the L level.

As mentioned above, under normal conditions, all four inputs of the AND circuit 42 are at H level, so its output is at H level. However, if an abnormality occurs and even one of the four inputs goes to L level, the logic The output of the product circuit 42 becomes L level. That is, the initial objective can be achieved by controlling the output of the gate circuit to high impedance during an abnormality using this signal.

According to the same embodiment, an abnormal state of a detector that detects the rotational speed of a rotating body is immediately detected, and the output of a gate circuit that interfaces with a speed control device is controlled to be high impedance.
Since the speed control device can perform processing control as if it were a disconnection abnormality processing, it is possible to prevent accidents caused by erroneous control of the rotating body.

[Effects of the Invention] As is clear from the above description, according to the present invention, an abnormality detection function is added to the rotation speed and position detection device, so that the burden on the speed control device of the servo system as described above is reduced. It is possible to construct a highly reliable and highly safe system by reducing the weight of the system and quickly taking measures against abnormalities, processing countermeasures, and processing responses.

[Brief explanation of drawings]

The attached drawings are diagrams for explaining the present invention, and
Figure 1 is a control block diagram of the rotation speed and position detection device, Figure 2 is the normal A phase, B phase, B phase, Z phase,
A timing chart of the logical sum of the Z phase and the A and B phases, FIG. 3 is a timing chart explaining that an abnormality has occurred in the A, B, and Z phases, and FIG. 4 is an embodiment of the present invention FIG. 2 is a circuit diagram of an abnormality detection circuit section. 11... Rotation speed detection sensor, 12, 13, 1
4... Waveform shaping circuit, 15, 16, 17... Gate circuit, 18... Abnormality detection circuit, 19... Speed control circuit, 31-37... Flip-flop, 3
8, 39...exclusive OR circuit, 40, 41, 4
5, 46...OR circuit, 42...AND circuit.

Claims (1)

[Claims] 1. A waveform shaping circuit that outputs binary signals A and B by shaping the output of a sensor that outputs a two-phase signal whose phase changes depending on the rotation direction of the rotating body, and a waveform shaping circuit that samples and holds the A signal at the rising edge of the B signal. First thing to do
A flip-flop 33, a second flip-flop 34 which samples and holds the A signal at the falling edge of the B signal, a third flip-flop 31 which samples and holds the B signal at the rising edge of the A signal, and a third flip-flop 31 which samples and holds the B signal at the falling edge of the A signal. a fourth flip-flop 32 for holding the sample at
first logic means 39 for calculating exclusive OR of the first flip-flop and the second flip-flop;
, a second logic means 38 for calculating the exclusive OR of the third flip-flop and the fourth flip-flop, a third logic means 42 for calculating the AND of the first and second logic means, A rotational speed of a rotating body, characterized in that a self-diagnosis function is added that outputs that the sensor is malfunctioning when the output of the three logic means indicates one of the binary signals;
Position detection device.