JPH083420B2 - Tilt angle sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inclination angle detection sensor that electrically detects a changing inclination angle of an object to be measured, particularly an oscillating body, with respect to a horizontal or gravitational direction.

(Prior Art) Conventionally, an inclination angle detection sensor for detecting the inclination of the support portion of the pendulum has been put into practical use by utilizing that the pendulum is always oriented in the vertical direction by the action of gravity. This is because the position of the pendulum relatively changes according to the inclination of the supporting portion, and therefore the inclination angle is detected by directly or indirectly electrically detecting the change in the position of the pendulum when it is inclined with respect to the reference position. Is to seek. No. 57-94813, No. 58
This is the prior art described in -177811. Such a conventional sensor having a pendulum structure requires a very delicate skill in processing and assembling the suspension wire portion of the pendulum and requires a high precision technique. As a result, it is expensive. In addition, the fluctuation of the position at the time of reference due to the deformation of the suspension wire portion due to the temperature change, the impact, etc. is large, and it is unavoidable that there is an error in the inclination angle detection.

(Problems to be Solved by the Invention) The present invention eliminates the inclination angle detection error due to temperature change, impact, etc., without requiring the advanced processing and assembly techniques found in the conventional inclination angle detection sensors as described above. The purpose of the present invention is to provide an inexpensive and highly accurate inclination angle detection sensor having a completely different structure from the inclination angle detection sensor of the conventional suspension wire structure.

(Means for Solving Problems) In the inclination angle detection sensor of the present invention, in FIG. 1 showing an embodiment, a magnet 2 having a magnetic fluid 3 attracted and held by both poles is shown.
Is contained in the container 1 attached to the sensor main body, the magnet 2 is kept in a constant state of being floated by the magnetic fluid 3, and the inside of the container 1 can be freely moved by the action of gravity due to the inclination of the container 1 (and hence the sensor main body) It is configured so that it can be moved.
Next, the detection coil 4 for detecting the position of the magnet 2 that moves by tilting around the container 1 and the drive coil 5 for generating an electromagnetic force that moves the magnet 2 to its original position against gravity are wound, In addition, the drive circuit 6 that operates as follows is provided. That is, the drive circuit 6 inputs the output from the detection coil 4 generated according to the movement of the magnet 2 that occurs at the time of tilting, and thereby supplies the control current 7 for energizing the drive coil 5 to cause the magnet 2 to move in the opposite direction. The signal processing is performed so that the drive coil 5 generates an electromagnetic force that moves in the direction and is always at the original reference position and resists gravity.

(Operation) When the inclination angle detection sensor of the present invention is configured in this way, when the container 1 inclines from the horizontal direction by θ in FIG.
Gravity component mgsin θ (m: mass of magnet, g: gravitational acceleration) in the direction of the magnet 2 acts to cause the magnet 2 and the magnetic fluid 3 to slide down in the lower direction and displace from the reference position 10, and the output corresponding to this displacement 11 Obtained from the detection coil 4. By this output, the control current 7 of i is supplied from the drive circuit 6 to the drive coil 5, and the magnet 2 is pulled back to the reference position 10. The returning force is ki (k: constant)
Since it is proportional to the control current 7 and has the same magnitude and the opposite sign as mg sin θ, the inclination angle θ of the container 1 can be detected by measuring the magnitude and sign of the control current 7.

(Embodiment) FIG. 1 shows the structure of an inclination angle detection sensor according to an embodiment of the present invention. The inclination angle detection sensor is, for example, a bar-shaped magnet 2 and is held around a magnetic pole of the magnet 2 by suction. A magnetic fluid 3 for floating the magnet 2 so that it can move freely, and a high-resistance or insulator containing the magnet 2 and the magnetic fluid 3, which is made of a non-magnetic material, for example, a cylindrical container 1 And the magnets 2 arranged around the container 1 are spaced apart from each other by the same number of turns and size for detecting the displacement 11 (Fig. 2) from the reference position 10 (Fig. 2). Two detection coils 4 and a drive circuit 6 for supplying a control current 7 to the drive coil 5 for generating a force for returning the magnet 2 to the reference position 10 based on the output from the detection coil 4,
Two drive coils 5 arranged to generate an electromagnetic force that pulls the magnet 2 back to the reference position 10 by the control current 7.
(The number is not necessarily two). Then, in the embodiment of FIG. 11, two detection coils 4
Are connected in series to an AC constant voltage source S, and the terminals of each detection coil 4 are connected to a drive circuit 6 as shown in the figure.

With this arrangement, since the magnetic fluid 3 gathers around the magnetic poles of the magnet 2, the magnet 2 floats above the wall surface of the container 1, and when the container 1 tilts, it can move freely in the lower direction due to gravity. When the magnet 2 is located at the center of the two detection coils, the reference position 10 (FIG. 2) is set, and when the container 1 is tilted by an angle θ from the horizontal direction as shown in FIG. The magnetic fluid 3 slides down in the lower direction and moves from the reference position 10 by a displacement 11. Therefore, the inductance of each detection coil 4 changes, and the voltage change corresponding to this displacement is output from the detection coil 4.

The drive circuit 6 amplifies and shapes the output voltage from the detection coil 4 to move the magnet 2 to the reference position 10 as shown in FIG. 2 (b).
The control current 7 necessary for pulling back to the drive coil 5 is supplied to the drive coil 5. That is, the drive circuit 6 inputs the output of the detection coil 4 generated in accordance with the movement of the magnet 2 that occurs when the container 1 is tilted, and supplies the control current 7 for energizing the drive coil 5, whereby the magnet 2 is moved forward. It is constituted by appropriate well-known means so that signal processing is performed so as to generate an electromagnetic force in the direction opposite to gravity and to move in the direction opposite to that of the original reference position 10 and in the direction against gravity. An appropriate servo mechanism for detecting the displacement 11 of the magnet 2 and controlling the displacement 11 to zero at the same time is formed. For example, the drive circuit 6 amplifies the difference between the terminals voltage generated in the detection coils 4 and inputs the amplified voltage to the servo motor, and the slider of the sliding type variable voltage divider rotates the servo motor. The control current 7 may be supplied by moving the voltage obtained from the slider into a current by moving the voltage in both positive and negative directions around zero volt. Also, this voltage difference is monitored by a microcomputer, and the control current 7 is increased as long as there is a voltage difference, and when the voltage difference becomes zero, that is, when the magnet is pulled back to the reference position by the drive coil 5, control is performed. It is also possible to stop the increase of the current 7 and maintain the current value at that time. Thus, it will be apparent that the drive circuit 6 can be composed of many well-known circuits.

Now, in the inclination angle detection sensor of FIG. 1, when the container 1 is inclined by an inclination angle θ with respect to the horizontal, the magnet 2 will slide down to the lower side under the gravity of the component of mgsin θ in the magnet direction in the container 1. And Here, m is the mass of the magnet (strictly including the mass of the magnetic fluid attracted and held by the magnet), g
Is the gravitational acceleration. The electromagnetic force exerted by the drive coil 5 to keep the magnet 2 at the reference position 10 is ki (k: constant, i: control current 7 flowing in the drive coil 5), and this force will cause the magnet 2 to slip down. When the force is opposite in sign and the magnitude is equal and equilibrium is reached, mgsin θ = −ki holds. Therefore, the tilt angle θ can be obtained by measuring the magnitude and sign of the control current i in such a balanced state.

FIG. 3 is a circuit diagram of another embodiment of the present invention. In this embodiment, the configurations of the container 1, the magnet 2 and the magnetic fluid 3 are the same as those in FIG. In this case, the drive coil 5 is composed of one. In this case, each detection coil 4 is connected in parallel to the AC constant voltage source S, and the current flowing through each detection coil 4 can be detected by the drive circuit 6. When the container 1 tilts, a magnet 2 is attached to each detection coil 4.
Of the control current 7 output from the drive circuit 6 by detecting the current change in the drive circuit 6
Is supplied to the drive coil 5, and the magnet 2 is pulled back to the reference position 10. Therefore, the tilt angle θ can be obtained by measuring the control current 7 as in the case of FIG.

FIG. 4 is a block diagram showing another embodiment of the present invention. In this case, the detection coils 4a and 4b are wound around the container 1 so as to form a differential transformer. Of these, the coil 4a is a primary coil and is excited by an AC constant current source S. The coil 4b is a secondary coil, which is connected to the drive circuit 6 and outputs a voltage corresponding to the displacement of the magnet 2 when the container 1 tilts. The output of the secondary coil 4b causes the drive circuit 6 to supply a control current 7 to the drive coil 5 so as to pull the magnet 2 back to the reference position 10. Therefore, the tilt angle can be obtained by measuring the control current 7 as in the case of FIG.

While some embodiments have been shown above, it will be apparent that many other variations are possible.

(Effects of the Invention) As described above, the inclination angle detection sensor according to the present invention has a simple structure in which the detection coil and the drive coil are arranged around the container containing the magnet and the magnetic fluid. Does not require advanced processing or assembly technology. Further, this sensor is of a servo system which detects the displacement of the magnet and controls so as to make the displacement zero. For these reasons, the present invention can provide an inexpensive and highly accurate inclination angle detection sensor. This tilt angle detection sensor can detect the tilt of the object to be measured with high accuracy, and feedback control can be applied to the tilt angle adjustment drive unit of the object or other objects related to the detected electric signal. The sensor can be used as an inexpensive element for automatic control or remote control. The inclination angle detection sensor has an extremely small inclination angle detection error with respect to temperature change, impact, etc., as compared with the conventional sensor.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a tilt angle detection sensor according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are explanatory views showing a state in which a magnet is displaced and a state in which a magnet is pulled back during tilting, respectively.
FIG. 3 is a circuit diagram of another embodiment, and FIG. 4 is a configuration diagram of an embodiment of the differential transformer system. 1: container, 2: magnet, 3: magnetic fluid, 4: detection coil, 4a: primary coil of differential transformer, 4b: secondary coil of differential transformer, 5: drive coil, 6: drive circuit, 7: control Current, 10: Reference position, 11: Displacement, S: Power supply

Claims (6)

[Claims] 1. A magnet, which holds a magnetic fluid by suction, is built in a flat-bottomed container so as to be movable by tilting, and a detection coil and a magnet for detecting the displacement of the magnet from the reference position are provided in the container to the reference position. In addition to winding the drive coil for pulling back, a drive circuit is provided, and this drive circuit inputs the output from the detection coil accompanying the movement of the magnet due to the inclination of the container to always make the displacement of the magnet zero. A tilt angle detection sensor, which is configured to output a control current for energizing the drive coil, and is configured to detect the tilt angle of the flat-bottomed container by measuring the magnitude and sign of this control current. 2. The inclination according to claim 1, wherein the drive circuit is configured to input a voltage appearing in the detection coil when a constant current is supplied to the detection coil and output a control current. Corner detection sensor 3. The tilt angle detection sensor according to claim 2, wherein the detection coil is composed of two coils connected in series and having the same number of turns and the same size. 4. The tilt angle detection sensor according to claim 1, wherein the drive circuit is configured to input a current generated when a constant voltage is applied to the detection coil and output a control current. 5. The tilt angle detection sensor according to claim 4, wherein the detection coil is composed of two coils connected in parallel and having the same number of turns and size. 6. The tilt angle detection sensor according to claim 1, wherein the detection coil is composed of a differential transformer.