JPS6040912A - Fault monitoring circuit of servo system measuring instrument - Google Patents

Abstract

PURPOSE:To simplify the constitution of a fault monitoring device, by providing an input terminal, which introduces a monitoring signal into a servo amplifier or a servo system measuring instrument, in which acceleration is fed back to a pendulum, providing a constant voltage diode pair in parallel with a fed-back element, thereby omitting a monitoring forcer. CONSTITUTION:In a servo amplifier 12, an input terminal 2-a for introducing a monitoring signal and constant voltage diodes 2-b and 2-c, which are connected in parallel with a forcer 1-c of a fed-back element in an oscillating part 11, are provided. Therefore, when a feedback loop is cut by the occurrence of a fault in the oscillating part 11, a monitoring signal is outputted through an oscillator 3 and the terminal 2-a, based on the difference in gain between the time of normal operation and the time of fault, at an output terminal Z as a large level signal. Thus the fault is monitored. In this way, a monitoring forcer is omitted, the output and the fault signal are not required to be separated, and the constitution of the fault monitoring device can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a constant fault monitoring circuit for a null method measuring instrument, a so-called servo-type measuring instrument (hereinafter referred to as a servo measuring instrument), using feedback control.

(Prior Art) FIG. 1 is a block diagram of a fault monitoring circuit for explaining an example of a conventional constant monitoring method applied to a vibration accelerometer that is a part of a servo-type measuring instrument.

In the figure, 1-a is a pendulum, 1-b is a detector that detects the motion of pendulum 1-a as an electrical signal, and 1-c receives the output of servo amplifier 2 and returns acceleration to pendulum 1-a. A feedback element 1-d called a fumesa or torquer (hereinafter referred to as a forcer) is a monitoring forcer that receives a constant monitoring signal from the oscillator 3 and continues to apply acceleration to the pendulum 1-a. The constant monitoring signal from the oscillator 3 usually uses a frequency, for example, a high frequency, that does not overlap with the frequency range to be measured in the system. □Furthermore, the pendulum 1-a, the detector 1-b, and the forcer for monitoring the feedback element 1-C1 are mechanically integrated into one unit and are configured as an excitation unit 1.

As shown in the figure, the output resistance RL section of the servo amplifier 2 has the vibration acceleration 2 and the vibration command speed α by the monitoring forcer 1-d.
' is obtained, and this output is separated by a low-pass filter 4 or a high-pass filter 5, and an output and a monitoring signal are output. For this reason, if a fault occurs inside the converter 1, the fault signal will generally not be detected.

In such a conventional constant monitoring method of a servo measuring instrument, the forcer 1-d for monitoring is required, which complicates the structure of the vibrating section 1, which itself becomes a cause of failure.

Further, as mentioned above, there is a drawback that it is necessary to separate the output and the fault monitoring signal.

(Object of the Invention) In order to solve these drawbacks, the present invention provides a feedback control amplifier, a so-called servo amplifier, with a monitoring signal input terminal connected in parallel to a returned element in a servo-type measuring instrument using feedback control. The circuit is configured so that when the feedback loop is disconnected due to a failure, the gain difference in the system from that during normal operation can be detected, and the occurrence of a failure can be detected. It is an object of the present invention to provide a fault monitoring circuit for a servo-type measuring instrument that does not include a forcer.

Embodiments of the present invention will be described in detail below with reference to the drawings.

(Configuration of the Invention) The configuration of the present invention includes a pendulum, a detector that detects the movement of the pendulum as an electrical signal, and a feedback element (forcer) that receives the output of a servo amplifier and returns acceleration to the pendulum. In a servo-type measuring device using feedback control, which is composed of a transducer section and a servo amplifier for feedback control, an input terminal for introducing an output of a monitoring signal into the servo amplifier for feedback control, and an input terminal for introducing an output of a monitoring signal to the servo amplifier for feedback control, and Fault monitoring of a servo system measuring instrument, characterized by having a circuit configuration that includes a pair of constant voltage diodes connected in parallel and detects the gain difference of the system when the feedback loop is broken due to the occurrence of a fault and when the system is operating normally. It is a circuit.

(Example) Figure 2 is a detailed explanation of the present invention. FIG. 2 is a block diagram of a fault monitoring circuit applied to a vibration accelerometer of a shape measuring instrument.

In the same figure, A11 is a resonating section composed of a pendulum 1-a1, a detector 1-b, and a feedback element 1-C, which are the same components as in FIG.

2-a is a monitoring signal input terminal, 2-b and 2-c are a constant voltage diode pair connected in parallel to the feedback element (forcer) 1-c, and the servo amplifier 12 is connected from these and the output resistor round part. It consists of

The circuit of the present invention differs from the measurement system of the conventional circuit (FIG. 1) in that the feedback element (forcer) 1-C is part of the negative feedback system of the servo amplifier 12 as shown in the figure, and the negative feedback resistor R8 connected in series with. When the output of a monitoring signal from the oscillator 3 is inputted to such a circuit through the input terminal 2-a, if there is no fault in the converter 1, the signal e shown by is output from the output terminal 2-a. can be obtained.

However, e is the oscillator output voltage (monitoring signal), AI is the amplifier gain for the monitoring signal, P is the transfer function for the pendulum acceleration, S is the detector sensitivity, and A.

is the servo amplifier gain for the detector signal, RL is the feedback signal detection resistor, Ro is the servo amplifier negative feedback resistor, Ff
is the electric acceleration conversion constant of the feedback element (forcer).

On the other hand, the output eα with respect to the input acceleration α is.

If A1=Ao, the ratio r between equations (1) and (2) is r
=e/eα=e/αps...mark (3).

The constant monitoring signal voltage e is input so that γ is about 1/10 of the minimum acceleration value αmin to be observed.

If a failure occurs in the converter 1 and the feedback loop is no longer configured, the output e' due to the monitoring signal e will be e' =
eAl = eAo ++ (4).

At this time, the ratio r' of e' and e is becomes.

Generally, in a servo open-side system, since the feedback effect is utilized, γ' takes an extremely large value. That is, the level of chv that can clearly distinguish between a normal state and a fault state changes from a signal level that is not detected during normal observation to a level that greatly exceeds the detection limit. Feedback element (forcer) 1-C
If a disconnection occurs in the voltage regulator diodes 2-b, 2-
Although current begins to flow through c, the feedback element (forcer) 1-C has no effect, and a similar fault signal is obtained at the output.

The waveforms at point y and two points at this time are as shown in FIG. 3, assuming that e is a sine wave. The zener voltage ad of the diode is the oscillator output voltage (monitoring signal) and the amplifier maximum output e.
An appropriate selection can be made taking m into consideration. As an incidental effect, in this circuit configuration, the unit input special current flowing through the feedback element (forcer) 1-C during steady operation is
It is always kept constant regardless of internal resistance changes, etc.

(Effects of the Invention) As described above, according to the present invention, the input terminal for introducing the output of the monitoring signal into the servo amplifier for feedback control, and the constant voltage diode pair connected in parallel to the feedback element (forcer). By providing this, it is possible to remove the conventionally used monitoring forcer, and there is no need to separate the output and fault signals, which has the advantage of simplifying the configuration of the monitoring system.

That is, in the conventional method, the fault detection signal is large during normal operation, whereas in the present method, the fault detection signal is large during a fault, and the fault detection is logically reversed.

Therefore, the present invention can be widely used not only for accelerometers such as those described in the example, but also for measuring instruments constituting servo systems, and is highly effective in detecting equipment failures at an early stage.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a fault monitoring circuit of a conventional servo type measuring instrument, Fig. 2 is a block diagram of a fault monitoring circuit of a servo type measuring instrument of the present invention, and Fig. 3 is a block diagram of a fault monitoring circuit of a servo type measuring instrument of the present invention. FIG. 1-a... Pendulum, 1-b... Detector, 1-c... Feedback element, 2-a... Input terminal; l-b, 2-c...
... Constant voltage diode pair, Ro... Negative feedback resistor, RL
・Output resistance, F...acceleration conversion constant, 2...output terminal, α...input acceleration, 10...transducer, 12...
servo amplifier. Patent applicant Oki Electric Industry Co., Ltd. Figure 3 Y point 2 point procedural amendment (pass) Commissioner of the Patent Office 1 Indication of the case 1982 Patent application No. 148747 4 Address of agent (105) Tokyo 1-7i12 Toranomon, Minato-ku
No. 5, Subject of amendment Column 6 of "Detailed Description of the Invention" in the specification, Contents of amendment: "Vibration acceleration 2" in line 20 of page 2 of the specification is corrected to "vibration acceleration α" .

Claims (1)

[Claims] A pendulum, a detector that detects the movement of the pendulum as an electrical signal, and a feedback element (forcer) that receives the output of an amplifier and returns acceleration to the pendulum. and a servo amplifier for feedback control, an input terminal for introducing the output of a monitoring signal into the servo amplifier for feedback control is connected in parallel to the feedback element. 1. A fault monitoring circuit for a servo type measuring instrument, characterized in that the circuit is configured to include a pair of constant voltage diodes, and to detect a difference in gain of the system when the feedback loop is broken due to a fault, and when the system is in normal operation.