JPH04110704A - Angle detecting device - Google Patents

Abstract

PURPOSE:To enable the re-detection with high reliability and high resolution without contact by providing a magnetic field generating member having a pair of magnets, of which N and S poles are opposite to each other, and providing a wave detecting device for generating the output signal corresponding to the relative rotation of a magnetic sensor. CONSTITUTION:A pair of magnet plates 24, 25 are provided in the inside surfaces of both side surfaces 22, 23 of a channel-form body 20 so that N and S pole are opposite to each other, and a supersaturation coil 27 as a magnetic sensor is provided in an internal space channel part 26. In parts near an origin O, since the magnetic flux is generated in the Z direction in parallel with each other, flux density of the magnetic flux crossing the XY flat surface becomes a constant value in outline, largeness of the magnetic field of a coordinate point on each X, Y, Z axis near the origin O becomes same with each other. Consequently, under the condition that the coil 27 is located in parallel with the Z axis direction, quantity of the magnetic flux passing through a core 28 forming the coil 27 becomes maximum, and the peak voltage on sine wave is generated in output terminals 33a, 33b of a wave detecting circuit 32. Namely, when a rotation angle of a magnetic field generating member 21 is set at theta, the signal output from the circuit 32 becomes sintheta.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an angle detection device suitable for application to, for example, a machine tool such as a robot having a rotating joint or an accelerator device of an automobile.

[Summary of the Invention 1] The present invention provides an angle detection device suitable for application to, for example, a machine tool such as a robot having a rotating joint portion or an accelerator device of an automobile, in which the north pole and the south pole are opposed to each other. A magnetic field generating member having a pair of arranged magnets, a magnetic sensor arranged to be relatively rotatable in the magnetic field formed by the pair of magnets, and a magnetic field generating member connected to the magnetic sensor. By being equipped with a detection circuit that generates an output signal according to relative rotation,
For example, the rotation angle of a rotating magnetic field generating member relative to a magnetic sensor is detected in a non-contact manner.

[Prior art 1] Conventionally, an angle detection device for measuring the rotation angle of the arm of a machine robot, the opening degree of a valve, etc. has, for example, a wire-wound resistor, and a voltage is supplied to both terminals of the resistor. In addition, a potentiometer, which is a variable resistor, is used to obtain an electrical signal corresponding to the angle of the object to be measured by means of a slider that is in mechanical contact with the resistor.

[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 vibrating environment. Furthermore, in oil plants, etc., there is a risk that sparks may be generated due to sliding due to the current flowing through the resistor, so it cannot be used as is. . Furthermore, since a wire winding is used for the resistor of the potentiometer, the resolution is relatively low.

The present invention has been made in view of these points, and an object of the present invention is to provide a non-contact angle detection device that is highly reliable and has high resolution.

Means for Solving the Problems J The angle detecting device of the present invention includes, for example, a pair of magnets (as shown in FIGS. 1 to 3) arranged so that their north and south poles face each other. 24) a magnetic field generating member (21) having (25); a magnetic sensor (27) disposed so as to be relatively rotatable in the magnetic field formed by the pair of magnets (24) and (25); The detection circuit (32) is connected to the magnetic sensor (27) and generates an output signal according to the relative rotation of the magnetic sensor (27).

[Function] According to the present invention configured as described above, when the magnetic sensor (27) disposed in the magnetic field generating member (21) rotates relatively in the magnetic field, the In other words, an electrical signal corresponding to the rotation angle is obtained, and by detecting this electrical signal with the detection circuit (32), an output signal corresponding to the rotation angle of the magnetic sensor (27) can be obtained. Therefore, a non-contact type angle detection device having high reliability and high resolution can be obtained.

[Embodiment] An embodiment of the angle detection device of the present invention will be described below with reference to the drawings.

In Fig. 1, (20) is an iron channel-shaped body made by bending etc. that also acts as a magnetic shielding member, and has side parts (22), (23) and a bottom part (24). There is. Both side parts (22
) and (23), a pair of magnet plates (24) and (25) are attached to the inner surfaces of the magnet plates (24) and (23), respectively, with their N and S poles facing each other. Here, a pair of magnetic plates (24) (
The channel-shaped body (20) to which 25) is attached functions as a magnetic field generating member (21). Note that the constituent material of the channel-like body (20) is not limited to a magnetic material, but may be a non-magnetic material.

Furthermore, the internal space groove (26) of the channel-like body (20)
A saturable coil (27) as a magnetic sensor is disposed at. As shown in FIG. 2, this saturable coil (27) has saturable coils (27a) and (27b),
A wire (29) is wound around a core (28) made of permalloy thin plate (thickness 0.1 mm) and having a rectangular cut portion in the center.
30) is arranged so that the plane part of the core (28) coincides with the Y-Z plane in Figure 1, and the striped line part of the core (28) in the figure coincides with the Z direction. It is arranged like this. In FIG. 1, the origin 0 is selected to be the center point of each of the depth yl, length Xl, and inner width zl. Further, the saturable coil (27) is actually fixed within a head holder (not shown). The head holder is attached to a frame (not shown), and the magnetic field generating member (21) is attached to a rotating member (not shown) as a member to be measured, so that the magnetic field generating member (21) rotates around the Y axis, for example. The coil is rotated in the direction of arrow A around the saturable coil (27).

The output terminals of the saturable coils (27a) and (27b) are the third
It is connected to the detection circuit (32) shown in the figure. This detection circuit (32) has a period of about 40 μs, a pulse width of about 1 μs,
It has a pulsed voltage oscillator (34) with a voltage amplitude of 30V,
The configuration is such that the output voltage of the saturable coil (27) is supplied. In Figure 3, (35) is a transformer, (3
6) (36) is series resistance, (37) (37) is diode, (38) (38) is output resistance, (39) (
39) (40) is a capacitor, and the output terminal (33
a) An analog voltage output is generated at (33b). To explain in detail the process of generating analog voltage output, the saturable coils (27a) and (27b) are
Transformer (35) based on pulsed voltage oscillator (34)
The pulsed currents supplied from the cores (28) bring them into a substantially magnetically saturated state in opposite directions, and when a DC magnetic field is applied to the core (28), one of the saturable coils (for example, the saturable coil (27a)) The inductance increases and the other saturable coil (thus the saturable coil (27b)
) changes so that the inductance decreases. Depending on this change in inductance, the diodes (37) and (3
7) The pulsed voltage supplied to the anode side changes,
Correspondingly, the rectified voltage generated at the output resistors (38) and (38) also changes. Changes in these rectified voltages occur in opposite directions, so the difference between these two rectified voltages is determined by the detection circuit (
32) is the output. The detection circuit (32) is configured to generate a voltage of ±6 volts when a magnetic field of ±50 Gauss acts on the saturable coil (27) in the X direction. In other words, the saturable coil (27) is extremely sensitive to the magnetic field in the X direction.

Further, since the saturable coil (27) is saturated when a magnetic field of ±5000 Gauss is applied in the X direction or in the X direction, it does not operate as a saturable coil in the X direction or in the X direction (its sensitivity is low). FIG. 4 shows the output characteristics of the detection circuit (32) corresponding to the X-direction magnetic field of the saturable coil (27). As can be seen from Figure 4, this output characteristic is such that the output voltage increases almost linearly up to a magnetic field of ±50 Gauss, where the output voltage becomes ±6 V, and at higher magnetic fields it gradually saturates to ± 1
It has a characteristic of outputting a voltage of approximately ±9V in a magnetic field of 0.00 Gauss.

As will be explained in detail later, by connecting an interpolation circuit and a counter in series to the output of the detection circuit (32),
In addition to analog output, digital output can also be obtained.

Next, the operation of the above embodiment will be explained.

In Figure 1, near the origin 0, magnetic flux is generated parallel to the X direction, so the magnetic flux density of the magnetic flux interlinking with the
The magnetic fields at the coordinate points on the Y-axis are of the same magnitude (the magnetic fields at the coordinate points on the X-axis and the magnetic fields at the coordinate points on the Y-axis are equal in magnitude, The magnetic field at the coordinate point on the Z axis is different). therefore,
As shown in FIG. 1, in a state where the saturable coil (27) is arranged parallel to the Z-axis direction, the saturable coil (27)
) Since the amount of magnetic flux passing through the core (28) constituting the detector circuit (32) is maximized, the output terminal (33a) of the detection circuit (32) (3
3b), a sinusoidal peak voltage occurs. When the magnetic field generating member (21) rotates around the Y axis, a sinusoidal voltage signal is generated at the output terminals (33a) (33b). That is, the magnetic field generating member (21
) is the rotation angle of θ, the signal output from the detection circuit (32) becomes sin θ.

In this case, according to this embodiment, the detection circuit (32 ), it is possible to obtain output signals corresponding to the rotation angle of the machine robot's arm, the opening degree of the accelerator valve, etc. in a non-contact state. Therefore, it is possible to construct an angle detection device with higher reliability and higher resolution than a potentiometer, which is a conventional variable resistor.

Further, even if the magnetic field generating member (21) moves in the X, Y, and Z axis directions, the magnitude of the magnetic field does not change, so the detection output value does not change, and there is an advantage that the device operates stably even in a vibration environment.

FIG. 5 shows the configuration of another embodiment of the angle detection device of the present invention. In Fig. 5, (60) is a magnetic field generating member, and the case (61) is made of iron or a material with high magnetic permeability because it also acts as a magnetic shielding member, and has an outer diameter of approximately 20 mm and a length of approximately It has a 25mm cylindrical shape. This magnetic field generating section (40) has a hole (41) with a diameter of φ9, and a detection head (43) integrally fixed to the head holder (42) is inserted into this hole (41). Further, the head holder (42) is provided with holes (44) (44) for fixing the head holder, as shown in FIG.
The screw (45) is passed through and fixed to the frame (46).

Fig. 6 and Fig. 7 showing a cross section taken along line E-E of Fig. 6.
As understood from the above, the hole (41) is connected to the flange (4).
7a) is formed by the inner circumferential surface of the cylindrical member (47). This cylindrical member (47) is a molded body of non-magnetic material, for example plastic. A pair of rectangular parallelepiped ferrite magnets (48) and (49) are attached and fixed to the outer circumferential surface of this cylindrical member (47) so that their N and S poles face each other. The width of magnets (48) (49) is 2III
I, the thickness is ll1lI+, and the length is 14 mm. The cylindrical member (47) is fixed to the inner wall of the magnetic field generating member (60) with adhesive or the like. In addition, a hole (50) of φ5 and a thread groove (51) are formed in the magnetic field generating member (60), and the rotation axis (52a) of the rotating body to be measured (52) is inserted into this hole (50). By inserting it through and fixing it with the screw (53), the rotating body to be measured (52) and the magnetic field generating member (6
0) will rotate integrally in the direction of arrow B. The saturable coil used as the magnetic sensor is the same as the saturable coil (27) shown in Fig. 2, and the output terminal of the saturable coil (27) is connected to the detection circuit via the multi-core shielded wire (54). (32) (Fig. 3).

Also in this example, when the magnetic field generating member (60) rotates in the direction of arrow B (around the Y axis), a sinusoidal output signal is obtained from the detection circuit (32). The output characteristics of the detection circuit (32) with respect to the rotation angle θ are expressed as shown in FIG.
If the magnetic field in the Z direction does not exceed 50 Gauss, the output voltage will be generated linearly if the rotation angle θ is within ±30". Therefore, an output corresponding to an accurate sine wave will be obtained within ±30". Become.

In the angle detection device shown in FIGS. 5 to 7, the rotating body to be measured (52), and thus the magnetic field generating member (60)
Even if there was a deviation of ±1 mm in the direction or the Z direction, no change in the output voltage was observed. The magnet (
4B) Since the length of (49) was 14 mm, no change in output voltage was observed. That is, the angle detection device according to this embodiment operates with high stability even under a vibration environment.

FIG. 9 shows the configuration of still another embodiment, and shows an angle detection device (55) in which a detection head, a head holder, and a detection circuit are integrally manufactured. As shown in FIG. 10, this angle detection device (55)
Two saturable coils (27
) (27) and this saturable coil (27) (27)
Two detection circuits (32) (32) each connected to
) (Fig. 11) Detection circuit housing member (56)
It has In this example, the detection circuit (32) (32)
Therefore, as shown in Fig. 11, sine wave and cosine wave signals are generated, so an analog output signal that covers the entire 360° rotation angle in the direction of arrow C (Fig. 9) of the magnetic field generating member (not shown) is generated. will be obtained. And the 11th
As shown in the figure, an interpolation circuit (57) and a counter (58) are connected to the detection circuit (32) (32).
The number of interpolated pulses output from the counter (58)
By counting with , it is possible to obtain a digital output corresponding to the rotation angle.

According to the embodiment described above, the magnetic field generating member and the saturable coil serving as the magnetic sensor can be configured separately, so that the magnetic field generating member can be easily attached to the rotating shaft of the member to be measured, for example. It has the effect of being able to

Further, when the pair of magnets is substantially surrounded by a magnetic material, the magnetic material acts as a magnetic shielding member, so that leakage magnetic flux is relatively reduced.

In addition, when a saturable coil is used as a magnetic sensor, the magnetic detection sensitivity is relatively high, making it possible to use a magnet with a small magnetic field, thereby reducing the -layer leakage magnetic flux.

Furthermore, the angle detection device incorporating two magnetic sensors can also be used as a resolver.

Furthermore, for example, the rotating body to be measured (5
If the amount of eccentricity or axis misalignment in 2) is large, the components of the magnetic field generating member (60) can be similarly enlarged to improve the outer periphery of the detection head (43) without changing the output characteristics of the detection circuit (32). The clearance between the two surfaces can be increased.

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

[Effects of the Invention] According to the angle detection device of the present invention, when the magnetic sensor placed in the magnetic field generating member rotates relatively in the magnetic field, an electrical signal corresponding to the rotation angle is obtained, and this electrical signal is By detecting the target signal with a detection circuit, it is possible to obtain an output signal according to the rotation angle of the magnetic sensor, so it is possible to obtain the effects of being non-contact, highly reliable, and having high resolution.

FIG. 2 is a circuit block diagram applied to the angle detection device shown in the figure.

(21) is a magnetic field generating member, (24) and (25) are magnets,
(27) is a saturable coil, and (32) is a detection circuit.

[Brief explanation of the drawing]

Claims (1)

[Claims] a magnetic field generating member having a pair of magnets arranged such that their north and south poles face each other; a magnetic sensor arranged so as to be relatively rotatable in a magnetic field formed by the pair of magnets; An angle detection device comprising: a detection circuit connected to the magnetic sensor and generating an output signal according to relative rotation of the magnetic sensor.