JPS61153516A - Fault detector for angle sensor - Google Patents

Abstract

PURPOSE:To detect a fault of an angle sensor securely by sending a signal when the relative angle between two members attains to a specific value and also outputting a fault signal when the output signal of the angle sensor at this time deviates a specific permissible value. CONSTITUTION:A switch 3 and a lever 4 are provided at specific positions of the 1st member 1A and the 2nd member 1B to be detected by the angle sensor and a fault warning device 6 is put in operation if the detected value of the angle sensor 2 when the switch 3 operates is not within a specific range. Thus, a fault of the angle sensor 2 is detected securely and easily to improve the control precision and safety of a machine and a device, and it is easily decided where the fault occurs.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an angle sensor that detects the angle of rotating parts of various machines. This invention relates to a detection device.

[Background of the invention]

Angle sensors are used to detect the angles of rotating parts of various machines, and the machines are controlled based on the detected values of the angle sensors. For example, a hydraulic excavator, which is a construction machine, has a boom, arm, The relative angle of each is detected by an angle sensor, and the control device performs the necessary calculations and controls based on this detected value to draw the desired excavation trajectory at the tip of the packet. will be carried out.

By the way, when it comes to control based on the detected value of such an angle sensor, it is clear that if a failure occurs in the angle sensor, the desired control cannot be performed. If this happens, the machine being controlled will move unexpectedly, which is extremely dangerous.
-g, the control device is equipped with a failure determination function, and if the machine moves in a manner different from the command, it is determined that there is a failure and the machine is automatically stopped.

However, such means only determine that a failure has occurred in the control system, and only determine whether the failure is a failure of the angle sensor, a failure of the controller, or something else. It was impossible to distinguish whether it was a malfunction or not.

Moreover, in an I control system including a plurality of angle sensors, as in the example of controlling a hydraulic excavator, it is completely impossible to determine which angle sensor has failed. Furthermore, even if a certain angle sensor fails, if the degree of influence on the final control result of that angle sensor is small, the difference between the machine movement and the command may not be determined as a failure. There was a fear that inaccurate or incomplete operations would continue.

[Purpose of the invention]

The purpose is to solve the above-mentioned conventional problems and provide a failure detection device for an angle sensor that can reliably and easily detect the occurrence of a failure.

[Summary of the invention]

In order to achieve the above object, the present invention provides a signal generator that generates a signal when a relative angle between a first member and a second member that are targets for angle detection reaches a predetermined angle. When this signal is output, the detection value of the relative angle at that time is taken out from the angle sensor, and the comparison section compares this detection value with a tolerance value determined based on the predetermined angle. The present invention is characterized in that, as a result of the comparison, when it is determined that the detected value deviates from the allowable value, a failure signal is output from the output section.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of a failure detection device for an angle sensor according to an embodiment of the present invention, and FIG. 2 is a side view of the angle sensor mounting portion taken along line 1--2 in FIG.

In the figure, IA is the first member that constitutes the rotation mechanism, IB is the second member that constitutes the rotation mechanism, and the first member IA and the second member IB are rotatable by a shaft. connected.

In the example of a hydraulic excavator, the first member IA corresponds to, for example, a boom, and the second member IB corresponds to an arm.

Reference numeral 2 denotes an angle sensor that is provided at the connecting portion between the first member IA and the second member IB and detects the relative angle between them. The angle sensor 2 outputs a signal E according to the detected angle α. As clearly shown in FIG. 2, 3 is a switch attached to the first member IA, and 4 is a lever attached to the second member IB, which engages with the switch 3 to close it. . The switch 3 is set at a predetermined angle α from a first reference line Nt passing through the center of the angle sensor 2 and extending along the member IA.
. while the lever 4 is attached to the angle sensor 2.
A second reference line Nt extending along the member IB through the center of
Mounted in place on top. Therefore, the relative angle between the first member IA and the second member IB (first reference 'I
The angle between A N I and the second reference 111Ng) α is
α−α. When this occurs, the switch 3 and the lever 4 will be engaged. Due to this engagement, the movable body of the switch 3 is pushed in against the spring, and the switch 3 is turned on. Angle α is angle α. When released, the engagement is released and the switch 3 is turned off. When the switch 3 is turned on, the switch 3 outputs an on signal E. Reference numeral 5 denotes an arithmetic device which inputs the signals ESW and E1 and performs necessary calculations and control based on these signals, and is composed of, for example, a microcomputer. When the calculation device 5 performs predetermined calculations and controls and determines that the angle sensor 2 is malfunctioning, the calculation device 5 outputs a failure signal E-. 6
is a failure alarm device which is activated manually by a failure signal Ew to warn of a failure of the angle sensor 2.

Next, the principle of failure determination of the angle sensor 2 in the arithmetic unit 5 will be explained with reference to the graph shown in FIG.

In FIG. 3, the horizontal axis represents the angle α (the angle between the reference line N1 and the reference line N2), and the vertical axis represents the signal E output from the angle sensor 2. Here, it is assumed that the angle sensor 2 has a characteristic of outputting a signal E proportional to the angle α and is in a normal state. In this case, the minimum angle of the angle α is α1, the maximum angle is α, and each angle α
3. The output of angle sensor 2 at α mushroom is signal E.
ffIIE, t, the point Pr determined by them,
Since the angle sensor 2 has a proportional characteristic, Pt is directly
It's on AA. Also, the mounting angle α of the switch 3 above.

The output of the angle sensor 2 when E. Then, the point P0 determined by both is also directly on i%lA.

By the way, if a failure occurs in the angle sensor 2 or if the angle sensor 2 is incorrectly installed, the angle α at which the switch 3 is activated. The output of the angle sensor 2 at is the signal E,. Therefore, by comparing the output signal of the angle sensor 2 when the switch 3 is turned on with the value E9°, it is possible to detect whether there is a failure in the angle sensor 2. will be possible.

However, -m, switch 3 is placed at exactly the angle α. Considering the structure of the switch 3 itself, the mounting means for the switch 3 and the lever 4, etc., it is very difficult to configure the switch 3 to operate in such a way as shown by the broken line in FIG. The existence of angular widths cannot be avoided.

Therefore, the angle α. An angular range α1 determined by a value D (centered on the angle α, ±D) that is slightly larger than the operating width shown by the broken line is set. That is, the angle range α3 is (α.-D)<α3×(α.+D), and the angle (α@-D), (α.+D)
The output signals of the angle sensor 2 when
. -,,E,. If all, then when the output signal E3 of the angle sensor 2 when the switch 3 is activated is within the range of the above signal E3°-1+g,, os, that is, Eα・-ka≦Eα≦E,・◆■ At this time, if it is determined that the angle sensor 2 is normal, it is possible to determine whether there is a failure.

In this embodiment, failure of the angle sensor 2 is determined using the above principle, and its operation will be explained with reference to the flowchart shown in FIG. 4.

During the relative movement of members IA and IB, the microcomputer always receives the output signal E of the angle sensor 2 (step S), and the switch 3 is turned on (ESM"1).
(Step S) The above steps S+ and Sg are repeated until the switch 3 is turned on.

When the switch 3 is turned on, the output signal E of the angle sensor 2 at that time is taken in (step S3), and this signal E3
First, the value E,. 4Il (step S4), the signal E, has the value E,. If it is less than or equal to 1, then the value is E. −0 (procedure S,), the signal E, has the value E,. If the value is -0 or more, the angle sensor 2 is assumed to be normal, and the procedure S is repeated again.
, -SS are repeated.

In step S4, the signal E9 has the value E,. If it is determined that the value exceeds 1, or in step S, the signal E.

is the value E,. If it is determined that the value is less than -0, the microcomputer outputs a failure signal E8 (step sh).
, This activates the failure alarm device 6 to notify the staff of the failure of the angle sensor 2.

In this way, in this example, a switch and a lever are provided at predetermined positions on the first and second members to be detected by the angle sensor, so that when the switch is activated, the detected value of the angle sensor falls within a predetermined range. Since the failure alarm device is activated when the angle sensor is outside, failures in the angle sensor can be detected reliably and easily, which further improves the control accuracy and safety of the machinery and equipment to which the angle sensor is installed. It can be raised. Furthermore, when multiple angle sensors are provided, if each angle sensor is equipped with such a device, it is possible to determine the failure of each angle sensor, and the location of the failure can be easily determined. can. Furthermore, since failure monitoring is always performed, safety can be improved from this aspect as well.

In addition, in the above description, the hydraulic excavator which is a construction machine was illustrated, but the present invention is not limited to this, and can be applied to any machine or device that uses an angle sensor. or,
In the explanation of the above embodiment, the case where the angle sensor has a proportional characteristic was explained, but it is not necessarily limited to an angle sensor having a proportional characteristic, and an angle sensor having characteristics as shown in FIG. 5 may be used. The structure and operation of the failure detection device for an angle sensor having such characteristics are also the same as those shown in the above embodiment, and the symbols used in FIG. 5 are used in FIG. 4. We believe that it can be easily understood by using the same reference numerals.

Furthermore, it is a matter of course that the microcomputer used in the arithmetic unit can be the microcomputer used in the other 11m. Furthermore, the arithmetic unit can be configured without using a microcomputer. Further, the failure alarm device can be replaced with a display device or a stop device for stopping the machine or device, or these can be provided together as appropriate.

〔Effect of the invention〕

As described above, in the present invention, a signal is output when the relative angle between two members reaches a predetermined angle, and a failure signal is output when the output signal of the angle sensor at that time deviates from a predetermined tolerance. This makes it possible to reliably and easily detect failures in the angle sensor, improve control accuracy and safety of machines and equipment, and easily determine the location of the failure. .

[Brief Description of the Drawings] Fig. 1 is a block diagram of a failure detection device for an angle sensor according to an embodiment of the present invention, Fig. 2 is a side view taken from line ■-■ in Fig. 1, and Fig. 3 is an angle Sensor output characteristic diagram, Figure 4 is the first
A flowchart explaining the operation of the apparatus shown in FIG. 2 and FIG. 2, and FIG. 5 is an output characteristic diagram of another angle sensor. IA...first member, IB...second member, 2
...Angle sensor, 3...Switch, 4...
Lever, 5...Arithmetic device, 6...Failure alarm device.

Claims (1)

[Claims] 1. An angle sensor that detects a relative angle between a first member and a second member, comprising: a signal generating unit that outputs a signal when the relative angle reaches a predetermined angle; , a comparison section that compares the angle, the detection value of the sensor, and a tolerance value determined based on the predetermined angle when the signal is output from the signal generation section; A failure detection device for an angle sensor, comprising: an output section that outputs a failure signal when the value deviates from the permissible value. 2. In claim 1, the signal generating section includes a switch device attached to a predetermined position of the first member and a switch device attached to a predetermined position of the second member to actuate the switch. 1. A failure detection device for an angle sensor, comprising: an operating section;