JPH0316013Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a device for detecting the rotational position of a rotating member, and particularly in a range of less than about 2 rotations of the rotating member. This invention relates to a device designed to detect.

For example, a limit switch is attached to either the rotating member or the member facing the rotating member,
The other member is provided with a protrusion that comes into contact with the plunger of this limit switch as the rotating member rotates, and when the rotating member rotates to that position, the limit switch is activated and the end of rotation is detected. There are various types. However, in the case of such a device, the range in which the rotational position can be detected is less than about one rotation, to be more precise, it is only the angular range remaining after subtracting the angle corresponding to the width of the protrusion from 360 degrees. Such devices are already widely used in various machines, and are also used in rotating parts such as the arms and wrists of industrial robots, but it is necessary to detect rotation within a range of approximately one revolution or more. The number of such cases is increasing. For example, in a welding robot, etc., the rotation of the arm or wrist is controlled within a range of about one rotation or less, and if you want to work to the limit of the rotation range and then rotate a little more, the reverse is possible. It is necessary to move the wrist or arm to the desired position by rotating the wrist or arm in the same direction or by changing the position of the other arm. What is required is something that goes beyond rotation. Conventionally, to meet this need, there is a device that uses two limit switches, for example, and takes measures to distinguish between when the limit switch operates at the end of rotation and when it operates at a position other than the end of rotation. Because it is necessary
Since the structure is complex and bulky, it is difficult to mount it compactly on the arm of an industrial robot.

This idea was developed by focusing on the problems of the conventional technology, and it has a simple, non-bulky structure that allows the rotation range of the rotating member to be less than about 2 turns, more precisely from 720 degrees to protrusions etc. An object of the present invention is to provide a rotational position detection device that detects the rotational position of a rotational member within the remaining angle range after subtracting the angle corresponding to the width of the detected piece.

This invention is based on the above-mentioned rotational position detection device, in which a piece to be detected, such as a contact piece for a limit switch, is provided via an elastic means, such as a leaf spring.
The detecting means is characterized in that the pressing means provided at the position of the limit switch, for example, presses the ammunition means, so that the piece to be detected will not be detected at any position other than the detection position, for example, at the end of rotation, even if it comes to the position of the detecting means. do.

The detection piece for detecting the end of rotation in the clockwise direction and the detection piece for detecting the end of rotation in the counterclockwise direction are respectively attached to the ammunition means mounted as follows. There is.

The bullet means is shaped along the rotating direction, and has one end fixed to the outer periphery of the rotating member or the inner periphery of a member opposing this, and gradually moves toward the other end on the outer circumferential surface of the rotating member or After being separated from the inner circumferential surface of the opposing member, it is separated at a substantially constant interval and is open at the other end, and is swingable in the radial direction when viewed from the center of rotation. There are also two types of ammunition means, each of which is provided apart from each other along the direction of rotation, and one of the ammunition means has a fixed end located in the counterclockwise direction of rotation with respect to the open end, and the other The fixed end of one of the ammunition means is located in the clockwise direction of rotation relative to the open end. The detection piece for detecting the end of rotation in the clockwise direction is attached to the middle of one of the ammunition means, and the detection piece for detecting the end of rotation in the counterclockwise direction is attached to the middle of the other ammunition means. It is attached in the middle of the means. Furthermore, each of these ammunition means is positioned and fixed such that the detection piece attached to each of them is located at a position including an appropriate angle around the center of rotation.

On the other hand, pressing means for pressing each of the above-mentioned ammunition means is provided at the position where the detection means is provided, but the distance between the ammunition means and its fixed surface is is shorter than the separation distance of
Therefore, when the rotating member rotates and the ammunition means approaches from the open end, the pressing means moves without pressing the ammunition means, so when the detection piece reaches the detection means position, the detection means detected by. However, when the ammunition means approaches from the fixed end, it is pressed by the pressing means, so that even if the detected piece comes to the detection means position, it will not be detected.
In this way, each end of rotation of the rotating member is detected while each ammunition means is pressed and released, and each detected piece relative to the center of rotation is detected. The range of rotation is determined by the angular positional relationship. In other words, if each detected piece is at the same position, the rotation end can be detected 360 degrees, but the detected piece for detecting the counterclockwise rotation end is
If it is placed further away in the clockwise direction from the device for detecting the end of clockwise rotation, the rotation axis can be detected for rotations exceeding 360 degrees, and in the opposite case, rotations up to 360 degrees can be detected. The end of rotation can be detected.
However, the end of rotation cannot be detected for rotations exceeding 720 degrees.

An example in which this invention is used to detect the rotational position of an arm of a multi-jointed robot will be described below with reference to the drawings, but the implementation of this invention is not limited to this example.

In FIGS. 1 and 2a to 2d, the most advanced arm 1 of the articulated robot R, which is not shown in its entirety, is at the axis 1.
It rotates around a, and arm 1 has bearings 1b ₁ and 1b ₂
It supports the most extreme rotation shaft 2 (rotation member) via the rotation shaft 2 and is opposed to the rotation shaft 2. A substantially cylindrical member 1c constituting the arm 1 is provided with an opening 1d, and a photo switch 3 (detection means) is screwed onto a mounting bracket 3a, fitted into the opening 1d, and then screwed into the member 1c with a screw 3b. It is installed.
The photo switch 3 has electrical wiring (not shown) from which an on/off signal can be taken out. As the rotation shaft 2 rotates, the light path position 3c of the photo switch 3 is adjusted by the light shielding piece 8.
The rotational position is detected by blocking the parts a and 8b. Pins 3d, 3e (pressing means)
is provided below the optical path 3c, and the leaf spring 7
Press down a and 7b respectively.

An end effector 4 is attached to the rotation shaft 2, and the rotary shaft 2 is connected to a motor 6 via a reduction gear 5. The rotation shaft 2 is rotated around the axis 2a by the motor 6, and the attitude of the end effector 4 can be changed. On the outer periphery 2b of the cylindrical portion of the rotation shaft 2, rectangular plate springs 7a and 7b (elastic means) provided with light shielding pieces 8a and 8b (detected pieces) are bent into an arc shape, and further light shielding pieces 8a and 7b (elastic means) are bent into an arc shape. , 8b can be positioned in the optical path 3c.
Further, the leaf springs 7a and 7b each have a light shielding piece 8.
The positional relationship is such that the angle formed by each extension of the front edge 8a ₁ of the front edge 8a 1 of the light shielding piece 8b and the front edge 8b ₁ of the light shielding piece 8b forms 60 degrees including the axis 2a, and the pin 3
It is attached with one side open so that it can be pressed or not pressed by d and 3e. In addition, the unsupported side 7 of the leaf springs 7a, 7b
a ₁ and 7b ₁ have sufficient length to maintain the pressed state by the pins 3d and 3e over a necessary range.

In FIG. 2a, the shaft 2 is at the end of rotation in the clockwise direction, and the front edge _8a1 of the light shielding piece 8a is blocking the optical path 3c, so the photo switch 3 is turned off by outputting an OFF signal. It is detected that the rotation shaft 2 is at the clockwise rotation end position. In addition, leaf spring 7
b is pressed by pin 3e. When the rotating shaft 2 is rotated counterclockwise from this state and the light shielding piece 8b comes close to the photo switch 3 as shown in FIG. 2b, the leaf spring 7b is still pressed by the pin 3e, so that The light shielding piece 8b allows ventilation to pass through the photo switch 3 without blocking the optical path 3c.

As it rotates further counterclockwise, the leaf spring 7
While a is being pressed by the pin 3d, the light shielding piece 8a comes close to the photo switch 3 as shown in FIG. 2c. Since the leaf spring 7a is pressed,
The light shielding piece 8a passes through the position of one rotation without blocking the optical path 3c. The leaf spring 7b is connected to pin 3.
Follow e without being pushed. When the photo switch 3 further rotates counterclockwise, the front edge _8b1 of the light shielding piece 8b blocks the optical path 3c as shown in FIG. 2d, so the photo switch 3 outputs an OFF signal. Thereby, it is detected that the rotation shaft 2 has reached the rotation end position in the counterclockwise direction. Since the front edge 8a ₁ of the light shielding piece 8a and the front edge _8b1 of the light shielding piece 8b are separated by 60 degrees, the rotation end position can be detected over a range of 420 degrees as described above. That is, it has a simple and compact structure that can be easily incorporated into the arm of a multi-jointed robot, and the end position of rotation can be detected even when the rotation is one rotation or more. It goes without saying that the signal from the photo switch 3 detected and output in this manner can be input to a control circuit (not shown) of the rotation shaft 2 and used to stop the rotation of the rotation shaft 2.

As another example, the light detector such as the photo switch in the above embodiment may be used as a limit switch, the light shielding piece may be used as a mechanical contact piece such as a dog, or a magnetic detection switch such as a proximity switch and an iron piece may be used. be able to. Further, instead of the leaf spring, a link mechanism supported via a coil spring may be used. The range in which the rotation is detected can be 360 degrees or less, broadly less than about 2 rotations or more precisely, the remaining angle range obtained by subtracting an angle corresponding to the width of the light-shielding piece from 720 degrees. The functions and effects of these other embodiments are also the same as those of the previous embodiments.

As described above, this invention has the remarkable effect of being able to detect the rotational position of the rotational member within a rotational range of less than about two rotations with a simple and compact structure.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a cutaway side view, and FIGS. 2a to 2d are cross-sectional views taken in the direction of arrows. In FIGS. 1 and 2a to 2d, 1...
Arm (member facing the rotating member), 2... Rotating shaft (rotating member), 3... Photo switch (detecting means),
3d, 3e...pin (pressing means), 7a, 7b...
...Plate spring (magnetic means), 8a, 8b... Light shielding piece (detection target piece).

Claims (1)

[Claims for Utility Model Registration] (1) Either a rotating member or a member facing the rotating member is provided with a detection means facing the other member; The member includes a detection piece for detecting a clockwise rotation end detected by the detection means and a detection piece for detecting a counterclockwise rotation end detected by the detection means. In the rotational position detection devices provided facing each other, along the rotational direction on the outer periphery of the rotational member or the inner periphery of a member facing the rotational member, and one end fixed to one of the members. From this point, as it moves toward the other end, it gradually separates from the fixed member, and then separates at approximately constant intervals, and is opened at the other end, and is capable of swinging in the radial direction when viewed from the center of rotation. ammunition means are provided apart from each other along the rotational direction, and one of the ammunition means positions the fixed end counterclockwise with respect to the open end and rotates in the clockwise direction in the middle thereof. A detection piece for detecting the moving end is provided, and the other mobile means positions the fixed end clockwise with respect to the open end, and detects the counterclockwise rotation in the middle thereof. detection pieces are provided, and these detection pieces are mounted so as to be at positions including an appropriate angle around the center of rotation, and each of the bullets is mounted at the position where the detection means is provided. A rotating position detection device provided with a pressing means capable of pressing each of the mobile means when the mobile means enters from the fixed end. (2) The rotating position detecting device according to claim 1, wherein the detecting means is a photo switch, and the detected piece is a light shielding piece. (3) The rotating position detecting device according to claim 1, wherein the detecting means is a limit switch, and the detected piece is an abutting piece. (4) The rotating position detecting device according to claim 1, wherein the detecting means is a magnetic detection switch, and the detected piece is a magnetic material piece.