JPH0791939A - Angle-of-rotation detector - Google Patents

Abstract

PURPOSE:To provide a small angle-of-rotation detector with a simple construction. CONSTITUTION:This angle-of-rotation detector is made up of a shank part 1, a ball part 2 and a holder part 3. The ball part 2 has a spherical part in contact with the holder part 3 as bearing and is made rotatable freely through the shank part 1. Light emitted from a light emitting element 4 provided at the ball part 2 is formed as light spot on a split photodetector 7 provide at the holder 3 and undergoes a photoelectric conversion to be processed by an arithmetic processing means 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a rotation angle.

[0002]

2. Description of the Related Art Conventionally, encoders and photoelectric autocollimators have been known as angle detecting devices utilizing the photoelectric method. The encoder is a detection device that includes a scale marked on the disk and a sensor that reads the scale, and detects the rotation amount of the disk by counting the pulses from the scale. However, there is a drawback that only the rotation amount of the disk can be measured, that is, only the angle around a certain rotation axis can be detected. On the other hand, the photoelectric autocollimator is
By detecting where the light reflected from the reflector (generally a mirror) returns, the tilt angle of the reflector can be measured. The angle resolution is very high, and it has a feature that two axes can be detected simultaneously, but on the other hand, it is impossible to measure a large angle, and there is a drawback that the system becomes large.

Generally, the degree of freedom for determining the position state of an object is
Generally three degrees of freedom for translation and three rotations around each axis
There are 6 degrees of freedom in total. 3 of which are parallel movements
The degree of freedom is constrained and only three degrees of freedom of rotation are allowed, and in order to detect the direction and angle, in the method using the conventional encoder, a gimbal structure is configured and three encoders are used. It was possible to detect the angles of three axes.

Further, as an example of an apparatus for detecting an angle by means other than an encoder, or an apparatus for detecting an angle by converting it into a displacement, a manual operation of an industrial robot using a differential transformer found in JP-B-47-30156 is used. Lever device ", a" joystick "for detecting the length of a telescopic link, which is disclosed in JP-A-60-225207, and a" joystick-type controller "using a linear actuation potentiometer, which is disclosed in JP-A 1-140976.

[0005]

The method using the gimbal and the encoder and the above-mentioned conventional embodiment have a problem that the number of constituent elements is large, so that a trouble such as a failure is likely to occur. There is also a limit to miniaturization as an angle detection device. An object of the present invention is to provide a rotation angle detecting device having a simple structure and a small size in order to solve the above problems.

[0006]

[Means for Solving the Problems] In order to solve the above problems,
The present invention relates to a ball portion for a spherical joint and a holder for forming the spherical joint by accommodating the ball portion.
Section, a light emitting member provided on one of the ball section and the holder section, a light receiving member provided on the other side, and means for detecting an output signal from the light receiving member and performing arithmetic processing. The holder and the ball that form the spherical joint.
It is characterized by detecting a relative angle with respect to the projection part. Further, the light receiving member is a four-division light receiving element.

[0007]

With the above construction, by using the divided light receiving members of three or more divisions as the light receiving member, the angle of the two axes can be detected by one sensor, and the processing can be performed at the same time. Further, until now, a mechanism such as a gimbal structure was required to install two sensors such as an encoder and to provide two axes of freedom, but in the present invention, only a spherical joint and one sensor are used. Since it can be used for installation, the entire device can be made compact.

[0008]

1 is a schematic sectional view of a rotation angle detecting device for a spherical joint. An embodiment of a rotation angle detection device for a spherical joint is shown. The spherical joint is composed of a shank portion 1, a ball portion 2, and a holder portion 3. The ball portion 2 has a spherical portion in contact with the holder portion 3 as a bearing, and can freely rotate through the shank portion 1. Has become. A light emitting element 4 (for example, an LED) is provided on the ball portion 2 or the holder portion 3 of the spherical joint, and a light spot is formed on the light receiving element 7 via the lens A5 and the lens B, photoelectrically converted, and processed by the arithmetic processing means 8. It The lens A is a lens that makes the light from the light source have a required spot size, and the lens B is a lens that makes the light coming from the lens A vertically incident on the light receiving portion. In this embodiment, the light emitting element is provided in the ball portion 2 and the light receiving element is provided in the holder portion 3. However, the light emitting element may be provided in the holder portion and the light receiving element may be provided in the ball portion. In this embodiment, the light emitting power source 9 is provided inside the ball portion 2, but it may be introduced from outside the ball by an optical fiber. As the shape of the light receiving portion, there are two types, that is, a light receiving portion in which a spherical light receiving portion and a flat surface having a small area are combined.
The sizes of the spot and the light receiving element are set according to the angle range to be detected.

Next, the operation of the detecting device having the above basic structure and using the four-divided light receiving element as the divided light receiving member will be described. FIG. 2 shows four divided areas A of the four-divided light receiving element,
It is a figure explaining the initial position of B, C, D and the spot on a light-receiving surface, and the position where the ball moved angularly. The light emitted from the light source is divided into four light receiving parts A through the lens,
The spots are irradiated on B, C, and D. The state at this time is the initial position. When the ball part moves by a certain angle, the light spot formed on the light receiving part also moves corresponding to the ball part. At that time, the angle change from the initial position is obtained as a voltage output change of each of the divided light receiving portions, and the position and the angle from the initial position are in a proportional relationship, so that the rotation angle can be obtained by this calculation.

FIG. 3 is a block diagram of output signal processing of each light receiving area of the arithmetic processing means 8. The photocurrent generated in each light receiving region is converted into a voltage signal by the preamplifiers 10a to 10d and processed by the signal processing circuit 11 and the arithmetic processing circuit 12. Here, a calculation method for receiving the light emitted from the light emitting member on the divided light receiving member surface and obtaining the angle from each of the obtained voltage outputs will be described.

The light applied to each light receiving region is converted into a voltage by photoelectric conversion. Let S (N) be the illuminated area of the light receiving portion N, V (N) be the photoelectrically converted voltage of the light receiving portion N, and k be the conversion coefficient by photoelectric conversion.
It is expressed as (N) = k · S (N). Assuming that the area of the light receiving portion N at the initial position is Si (N), the light spot is irradiated near the center of the divided light receiving portion, and the area irradiated to each light receiving portion is Si (A) = Si (B) = Si (C) = Si
(D). Here, if the photoelectrically converted voltage of the light receiving portion N is Vi (N), the voltage obtained from each light receiving portion is Vi (A) = Vi (B) = Vi (C) = Vi (D).
Becomes

The angle detection when a certain angle moves is as follows. Let Sm be the area of the light-receiving portion N that has moved a certain angle.
(N), the photoelectrically converted voltage of the light receiving portion N is Vm (N). Position P (n) of the light spot moved from the initial position
Is expressed as a function of the output voltage of each region of the divided light receiving element, P (x) = Vm · (((A + B) − (C + D)) / (A
+ B + C + D)) P (y) = Vm · (((B + C) − (A + D)) / (A
+ B + C + D)), and the moving direction and moving amount can be calculated.

The position P (n) which is moved by a certain angle and the angle θ (n) have the following relationship. θ (n) = h · P (n) h: constant Therefore, the angle around each axis can also be obtained.

The angle around the X axis is θ (X) = h · P
(X) and the angle around the Y axis is θ (Y) = h.
P (y). In this way, the rotation angle can be calculated by a simple calculation.

[0015]

According to the present invention, there is an effect that a method for detecting an angle of two axes, which has conventionally required an installation space, can be made compact. Specifically, the structure of the operation joystick of a game machine or the operation unit of a moving body can be made compact.

[Brief description of drawings]

FIG. 1 is a sectional view of a spherical joint type rotation angle detection device.

FIG. 2 is a diagram showing a position of a light spot on a four-division light receiving element, an initial position (a) and a position (b) when moved by a certain angle.

FIG. 3 is a block diagram of the steps from detection by a light receiving element to calculation processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 shank part 2 ball part 3 holder part 4 light emitting member 5 lens A 6 lens B 7 light receiving member 8 arithmetic processing means 9 power source of light emitting member 10a-10d preamplifier 11 signal processing circuit 12 arithmetic processing circuit

Claims (2)

[Claims] 1. A ball part for a spherical joint, a holder part for forming a spherical joint by housing the ball part, a light emitting member provided on either the ball part or the holder part, and the other part. A light receiving member provided in
A rotation angle detecting device having means for detecting an output signal from the light receiving member and performing arithmetic processing, and detecting a relative angle between a holder portion and a ball portion forming a spherical joint. . 2. The rotation angle detecting device according to claim 1, wherein the light receiving member is a four-division light receiving element.