JPH04276502A - Angle detecting apparatus - Google Patents

Abstract

PURPOSE:To obtain a proportional output corresponding to the rotary angle even in the rotation exceeding 90 (+ or -45 deg.) of a rotary body to be measured. CONSTITUTION:The outputs of first and second saturable coils 3 and 4 which are relatively rotated in a magnetic-field generating member 12 which is rotated together with a rotary body to be measured as a unitary body are detected with first and second detecting circuits 32 and 52. Thus first and second sine- wave signals V1 and V2 are obtained. The first and second sine-wave signals V1 and V2 are processed with first and second limiter circuits 56 and 57, and a synthesized output V5 is obtained. The parts which are approximated with the straight lines of the first and second sine-wave signals V1 and V1 are synthesized, and the approximately trapezoidal-wave shaped signal is formed as the synthesized output V5. Thus, the proportional output corresponding to the rotary angle can be obtained even at the rotary angle exceeding 90 deg..

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle detection device suitable for use in machine tools such as cranes, power shovels and other construction machines, and robots, which have rotating joints.

0002

2. Description of the Related Art Conventionally, a potentiometer, which is a variable resistor, has been used as an angle detection device for measuring the rotation angle of an arm of a crane or the like. This potentiometer has a wire-wound resistor and a slider. Then, a slider is attached to the rotating shaft of the arm of the crane, etc., and a voltage is supplied to both terminals of the wire-wound resistor,
An electrical signal corresponding to the rotation angle of the arm is obtained by the output voltage of the slider that contacts this wire-wound resistor.

0003

[Problems to be Solved by the Invention] However, since this potentiometer has a structure in which the resistor and the contactor slide against each other, the life cycle is relatively short, and contact failure occurs in a vibration environment. There was a problem that such problems were likely to occur. Therefore, in order to solve this problem, the present applicant has proposed an angle detection device shown in Japanese Patent Application No. 2-231269. This angle detection device is
It consists of a magnetic field generating member in which the north and south poles are arranged so that they can rotate relative to each other, and is non-contact and highly reliable. , and has a simple structure.

The present invention has been made in connection with such technology, and is non-contact, highly reliable, has a simple structure, and can be rotated at rotation angles exceeding 90° (±45°). Another object of the present invention is to provide an angle detection device that can obtain a proportional output according to its rotation angle.

[0005]

[Means for solving the problems] The angle detection device of the present invention has the following features:
For example, as shown in FIG. 1, FIG. 2, and FIG. first and second magnetic sensors 3, 4 that output first and second sine wave signals V1, V2 based on the outputs of these first and second magnetic sensors 3, 4. detection circuits 32, 52, and first and second limiter circuits 56, which limit the first and second sine wave signals V1, V2 that are the outputs of the first and second detection circuits 32, 52, 57, and a combining circuit 64 which combines the outputs V3 and V4 of the first and second limiter circuits 56 and 57 to obtain a combined output V5. The rotation angle relative to the first and second magnetic sensors 3 and 4 is detected.

[0006]

[Operation] According to the angle detection device of the present invention, the magnetic field generating member 1
2, the outputs of the first and second magnetic sensors 3 and 4 that rotate relatively are detected by the first and second detection circuits 32 and 52.
The first and second sine wave signals V1 and V2 are detected by
The first and second sine wave signals V1 and V2 are subjected to limit processing by first and second limiter circuits 56 and 57, and a composite output V5 is obtained by a composite circuit 64. This composite output V5 is the first and second sine wave signals V1, V
Since the signal has a substantially trapezoidal waveform that is a composite of the range that can be approximated by the two straight lines, even at a rotation angle exceeding 90 degrees (±45 degrees), a proportional output can be obtained according to the rotation angle.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the angle detection device of the present invention will be described below with reference to the drawings. FIG. 2 is a partially sectional side view showing the relationship between the magnetic field generating member and the saturable coil of the angle detection device in this embodiment, and FIG. 3 is a schematic sectional view taken along the line A--A of the example in FIG.

In FIG. 2, reference numeral 1 denotes a main body portion, and a detection circuit, which will be explained in detail later, is arranged in this main body portion 1. Further, a cylindrical support 2 is fixed to the main body 1, and a first saturable coil 3 (first magnetic sensor) and a second saturable coil 4 (first As shown in FIG. 3, the magnetic sensors No. 2) are fixed at a distance of approximately θ1 (in this embodiment, θ1=60°). The material of the support body 2 is a non-magnetic material, for example, SUS-304 or brass.

The first and second saturable coils 3 and 4 are
As shown in FIG. 4, each has a core 5 made of a thin permalloy plate, and includes two saturable coils 3A (4B) and 3B (4B) in which windings 6 and 7 are applied to the core 5. . The outputs of the first and second saturable coils 3 and 4 are supplied to a detection circuit (described later).

As shown in FIG. 2, the main body 1 is fixed to a frame 8 with screws. Further, a cylindrical case 9 with a bottom is coaxially arranged so as to cover the support body 2 . Magnets 10 and 11 are fixed to the inner peripheral surface of the case 9 so that their north and south poles face each other. Therefore, the magnets 10 and 11 cause the first and second saturable coils 3,
A direct current magnetic field is generated which acts on 4. Case 9 and magnet 10
, 11 constitute a magnetic field generating member 12. Note that the material of the case 9 is preferably a magnetic material. It does not have to be a magnetic material.

A hole 9A is formed in the bottom of the case 9, and a rotating shaft of a rotating body 13 to be measured, such as a robot arm, is fixed to the hole 9A. By being fixed, the magnetic field generating member 12 and the rotating body 13 to be measured are integrally configured. Therefore, the magnetic field generating member 12 and the rotating body to be measured 13
means that the first and second
It rotates relative to the saturable coils 3 and 4 of.

As shown in FIG. 5, the output terminals of the first and second saturable coils 3 and 4 are connected to first and second detection circuits 32 and 52 housed in the main body 1. . Note that since the first and second detection circuits 32 and 52 have the same configuration, only the first detection circuit 32 will be described as necessary to avoid complexity.

The first detection circuit 32 has a period of approximately 40 μs.
, has a pulsed voltage oscillator 34 with a pulse width of about 1 μs and a voltage amplitude of 30 V, and the output of this oscillator 34 is used for the first and second
is supplied to the saturable coils 3 and 4 through a transformer 35. Further, 36 and 36 are series resistors, 37 and 37 are diodes, 38 and 38 are output resistors, and 39, 39, and 40 are capacitors, and the first detection circuit 3 configured in this way is
2 is analog voltage output V1 between output terminals 33A and 33B
is generated.

To explain in detail the process of generating the analog voltage output V1, the saturable coils 3A and 3B are brought into a substantially magnetically saturated state in opposite directions by a pulsed current supplied from the oscillator 34 through the transformer 35. There is. In this state, when a DC magnetic field is applied to the core 5, the inductance of one saturable coil (for example, the saturable coil 3A) increases, and the inductance of the other saturable coil (therefore, the saturable coil 3B) decreases. It changes like this. According to this change in inductance, the pulsed voltage supplied to the anode side of the diodes 37, 37 changes, and the rectified voltage generated at the output resistors 38, 38 also changes accordingly. Since changes in the rectified voltages occur in opposite directions, the difference between these two rectified voltages becomes the output V1 of the first detection circuit 32. This output V1 becomes a sinusoidal voltage corresponding to the relative rotation of the first saturable coil 3.

In the second detection circuit 52 as well, a sinusoidal voltage output V2 corresponding to the relative rotation of the second saturable coil 4 is obtained from the rectifier circuit 53. In addition, the output V2
Since the first and second saturable coils 3 and 4 are installed apart by an angle θ1=60° as shown in FIG. 3, the phase of V1 is delayed by 60° compared to the phase of the output V1. become.

The voltage outputs V1 and V2 of the first and second detection circuits 32 and 52 are passed through the multi-core shielded wire 55 (see FIG. 2) to the first and second limiter circuits 56 and 5 shown in FIG.
7. First and second limiter circuits 56, 5
7 has a series resistor 58 (59) and Zener diodes 60 (62) and 61 (63) connected with opposite polarities. The input/output characteristics of the first and second limiter circuits 56 and 57 in this embodiment are as shown in FIG.
The output voltage changes linearly until the input voltage reaches the limiter voltage of ±3 (V), and the characteristics are selected such that it is limited at higher voltages. This characteristic is determined by the Zener voltage of the Zener diodes 60 to 63 and the Zener diode forward voltage.

Outputs V3 and V4 of the first and second limiter circuits 56 and 58 are passed through a combining circuit 64 to a combined output V5. FIG. 1 is a block diagram showing the overall configuration of the angle detection device according to the present embodiment described above. Each component is as described above.

Next, the operation of the above embodiment will be explained. In FIG. 2, when the magnetic field generating member 12 rotates integrally in the direction of arrow B with the shaft 14 as the rotation axis due to the rotation of the rotating body 13 to be measured, the first and second saturable coils 3 and 4 12. Due to this rotation, the angle of intersection between the lines of magnetic force generated by the magnets 10 and 11 and the first and second saturable coils 3 and 4 changes in accordance with the rotation angle. Then, the inductance of the saturable coils 3A (4A) and 3B (4B) changes as described above. This change in inductance is supplied to the first and second detection circuits 32 and 52. The outputs V1 and V2 of the first and second detection circuits 32 and 52 are obtained as ±6 volt p-p sine wave signals with a 60° phase difference, as shown in FIG. 8A.

The outputs V1 and V2 are shaped into outputs V3 and V4 as trapezoidal waveform signals limited to ±3 volts by the first and second limiter circuits 56 and 57, respectively (see FIGS. 8B and 8C). ). These outputs V3 and V4 are added by a combining circuit 64 to obtain a trapezoidal waveform combined output V5. This composite output V5 is generated at an angle of 0°±30 which can be approximated to a straight line among the first and second sine wave signals V1 and V2.
Since it is synthesized in the range of -30° to +90° (120° range), it is proportional to the rotation of the rotating body 13 to be measured in the range of ±60° in center distribution. Output (linear approximation area) can be obtained. Note that this example is an example in which outputs V1 and V2 are combined within a range of ±30°, but by changing the circuit so that they are combined within a range of ±45°, the linear approximation range can be changed to ±90°. (1
80°). Generally, the angular range that produces an output proportional to the angle of the sine wave is ±45° (9
According to the present invention, a linear range can be obtained in a range exceeding 90°, which is a remarkable effect.

Note that the synthesis circuit 64 in the above embodiment
As shown in FIG. 6, the circuit has a configuration in which first and second limiter circuits 56 and 57, which provide an output V3 and an output V4, are simply connected in series. The transformer 35 allows the first limiter circuit 5 to be simply connected in series in this way.
This is because 6 and the second limiter circuit 57 are insulated. If not insulated, as a composite circuit 64,
For example, an adder using an operational amplifier may be used.

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various configurations without departing from the gist of the present invention.

[0022]

As explained above, according to the angle detecting device of the present invention, the detection circuit detects the outputs of the first and second magnetic sensors rotating relative to each other in the magnetic field generating member. First and second sine wave signals are obtained, and these first and second sine wave signals are subjected to limiter processing to obtain a combined output. This composite output is a substantially trapezoidal waveform signal that is a composite of the portions of the first and second sine wave signals that are approximated by a straight line, so even at rotation angles exceeding 90 degrees, the output is proportional to the rotation angle. This has the effect that output can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the angle detection device of the present invention.

FIG. 2 is a partial cross-sectional view showing the mechanical relationship between the magnetic field generating member and the saturable coil in the example of FIG. 1;

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a front view showing a detailed configuration of the saturable coil shown in the example of FIG. 1;

FIG. 5 is a circuit diagram showing a detailed configuration of the detection circuit shown in the example of FIG. 1;

FIG. 6 is a circuit diagram showing detailed configurations of the limiter circuit and synthesis circuit shown in the example of FIG. 1;

FIG. 7 is a characteristic diagram of the limiter circuit shown in the example of FIG. 6;

FIG. 8 is a waveform diagram used to explain the operation of the example in FIG. 1;

[Explanation of symbols]

3, 4 First and second saturable coils 12 Magnetic field generating members 32, 52 First and second detection circuits 56, 57
First and second limiter circuit 64 Synthesis circuit

Claims (1)

[Claims] 1. A magnetic field generating member, first and second magnetic sensors rotatably arranged relative to the magnetic field generating member in a magnetic field formed by the magnetic field generating member, and first and second detection circuits that output first and second sine wave signals based on the outputs of the first and second magnetic sensors; It includes first and second limiter circuits that limit the two sine wave signals, and a synthesis circuit that synthesizes the outputs of these first and second limiter circuits to obtain a synthesized output. An angle detecting device characterized in that the relative rotation angle of the magnetic field generating member with respect to the first and second magnetic sensors is detected.