JPH0368813A - Rotation angle sensor - Google Patents

Abstract

PURPOSE:To detect an angle without using mechanical contact points and without the effect of noises by movably containing a weight part in a hollow spherical body having one light projector and a plurality of photodetectors on the outer surface, and moving the weight part in the spherical body. CONSTITUTION:A weight part 8 is movably contained in a rotary part 6. In the rotary part 6, a light projector 2 for inputting light into a spherical body 1 is attached at the outer surface of the hollow spherical body 1 formed of a transparent material, and a plurality of photodetectors 3 for detecting the light from the light projector 2 are attached to the other outer surface. The outside of the spherical body 1 is covered with an opaque material 4. In the weight part 8, a weight 5 made of an opaque material is attached in a hollow spherical body 7 comprising a transparent material having the size so that the body can be turned in the rotary part 6. Even if the rotary part 6 is rotated in any direction, the weight 5 of the weight part 8 is located at the lowest position in the rotary part 6. The input light for the photodetector 3 from the light projector 2 is interrupted with the weight 5. The fact that light for which photodetector 3 is interrupted is judged. In this way, the rotation angle can be detected without erroneous operation due to poor contact or the like.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a rotation angle sensor, and is particularly used for robots such as robots 1 to 3 that have a plurality of joints on a base and make rotational movements. Regarding rotation angle sensor.

[Prior Art] Conventionally, as this type of rotation angle sensor, for example, the first
As shown in FIG.
There is a potentiometer that extracts the voltage corresponding to the position of and determines the rotation angle. Reference numeral 14 in FIG. 10 is a wiper 12
and a group of output terminals of the resistor 13.

[Problems to be Solved by the Invention] However, in the conventional rotation angle sensor described above, since the wiper 12 and the resistor 13 are in contact with each other,
There is a drawback that malfunctions may occur due to poor contact, and there is also a drawback that rotation angles can only be detected in a certain direction. Further, it has the disadvantage that it is susceptible to the effects of electric and magnetic field noise generated by switching by high-power equipment.

[Means for Solving the Problems] The means of the present invention for solving these problems is to attach one projector to the outer surface of a hollow sphere made of a transparent material to input light into the sphere, A plurality of light receivers are attached to the other outer surface to detect the output light from the inside of the sphere due to the above input, and the sphere is covered with an opaque material so that no light other than the light source enters the inside of the sphere. contains a movable weight such that the weight is always at the bottom no matter which direction the sphere is facing, and determines which receiver the input light is blocked by this weight. The rotation angle sensor is capable of detecting the rotation angle.

[Example] Hereinafter, a rotation angle sensor according to an example of the present invention will be described based on the accompanying drawings.

As shown in FIGS. 1 to 3, the rotation angle sensor according to the embodiment includes a hollow sphere 1 made of a transparent material, and 14 projectors 2 for inputting light into the sphere 1 attached to the outer surface of the sphere. A plurality of light receivers 3 for detecting the light from inside the sphere 1 due to the above-mentioned input are installed on the other outer surface, and a light receiver 2 and a light receiver 3 are installed to prevent light other than the emitted light a2 from entering the inside of the sphere 1. The sphere 1 is covered from the outside with an opaque material 4, and the rotary part 6 shown in FIG. 1 is made up of these elements. Further, inside the sphere 1 of the rotating part 6, there is a weight part 8 in which a weight 5 made of an opaque material is attached to the inside of a hollow inner sphere 7 made of a transparent material large enough to be easily rotated inside the sphere 1. It is a container. Then, no matter which direction the rotating part 6 rotates, that is, which direction it faces, the weight 5 is always at the bottom, and it is determined which light receiver 3 the light is blocked by the weight 5. This allows the rotation angle to be detected.

Next, in this rotation angle sensor, the rotating part 6 and the weight 5
The basic aspect of the positional relationship between the two will be explained.

FIG. 4 shows a case where the diameter of the projector 2 is set to be at the lowest position when the projector is stationary, and in this case, none of the light receivers 3 detect light. FIG. 5 shows a case where the weight 5 is located on the light receiver 3 at an angle θ from the light emitter 2, and in this case, the output of the light input from the light emitter 2 to the light receiver 3 is blocked. FIG. 6 shows a case where the hanging 5 is located at a position 2 apart from the emitter 2 by an angle part 2, and is located astride two light receivers 3. In this case, the light received from the emitter 2 is received. The input to the receiver 3 is attenuated, and at this time, the cutoff of the light receiver 3 is determined based on the amount of attenuation.

Next, a case where the rotation angle sensor according to this embodiment is used in an articulated robot 10 as shown in FIG. 9, for example, will be described. First, as shown in Figure 7, for example,
A rotating part 6 is fixed to one arm 10a with the position where the weight 5 is located on the projector 2 as a reference position. In this state, when the arm 10a rotates, the rotating portion 66 of the rotation angle sensor rotates following this rotation.

In this case, the weight part 8 is always in a stationary state, and the weight is always located at the lowest position. That is, the rotating part 6 rotates relative to the weight 5. Therefore, as shown in FIG. 8, when the arm 10a rotates by an angle θ, the sag 5 reaches the receiver 3 which is away from the emitter 2 by an angle θ, and the input to the receiver 3 is cut off. By determining the interruption, the rotation angle θ is detected. That is, the emitter 2 and the receiver 3
The angle θ between the two ends becomes the rotation angle of the arm 10a, and this rotation angle can be detected.

[Effects of the Invention] As explained above, according to the rotation angle sensor of the present invention,
Since the angle is detected by moving the weight within the sphere, no mechanical contacts are used, so there is no malfunction due to poor contact, etc. Also, since it is made of non-magnetic material, switching with high-power equipment is not possible. This has the effect of being less susceptible to the effects of electric and magnetic field noise generated by, etc. Also, instead of detecting the rotation angle in a fixed direction like a potentiometer, it is possible to detect the rotation angle in all directions using a light receiver attached to the outside of the transparent sphere, which has the effect of increasing versatility.

[Brief explanation of drawings]

FIG. 1 is a front view showing main parts of a rotation angle sensor according to an embodiment of the present invention, FIG. 2 is a front view showing other main parts of a rotation angle sensor according to an embodiment, and FIG. 3 is a front view showing main parts of a rotation angle sensor according to an embodiment. FIG. 4 is a front view showing an assembled state of the rotation angle sensor, FIG. 4 is a partial front view showing an example of the position of the weight of the rotation angle sensor, and FIG. Fig. 6 is a partial front view showing an example of the position of the weight of the rotation angle sensor and showing an example where one light receiver is at the bottom. Fig. 7 is a partial front view showing an example of the case where the rotation angle sensor is installed at the bottom, Fig. 7 is a view showing an example of the mounting state of the rotation angle sensor when the mounting part is in a stationary state, and Fig. 8 is a diagram showing an example of a case where the rotation angle sensor is in a stationary state. Fig. 9 is a perspective view showing a robot with a large number of rotary joints in which a rotation angle sensor is used, and Fig. 10 shows a conventional rotation angle detection state. FIG. 2 is a principle diagram of a potentiometer that is an example of a sensor. 1: Sphere 2: Emitter 3: Receiver 4: Opaque material 5: Weight 6: Rotating part 7: Internal sphere 8: Weight part

Claims (1)

[Claims] One light emitter that inputs light into the sphere is attached to the outer surface of a hollow sphere made of transparent material, and a plurality of light receivers are attached to the other outer surface to detect the output light from the inside of the sphere due to the above input, The sphere is covered with an opaque material to prevent light from sources other than the projector from entering the sphere, and a weight that can be moved inside the sphere is housed so that the weight remains constant no matter which direction the sphere faces. A rotation angle sensor characterized in that the rotation angle can be detected by placing the weight at the bottom and determining which of the light receivers input light is blocked by the weight.