JPH10329083A - Origin detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the mechanism origin of a pan tilt mechanism accurately. SOLUTION: Projection light 4 is radiated from a parallel direction to a shaft which is orthogonal to a pan shaft 6 of a pan tilt mechanism 2 by a projector 3. The projection light 4 is interrupted by the pan tilt mechanism 2, and an interruption detector 8 transmits interruption trigger by an output signal from a light receiving element 5 at that time. When the light is transmitted again after it is interrupted and received by the light receiving element 5, a transmission detector 9 transmits transmission trigger by the output signal of the light receiving element 5 at that time. By detecting a rotational angle around the pan shaft 6 and a rotational angle around a tilt shaft 7 at the time of triggering the interruption trigger and the transmission trigger respectively by a rotational angle detector 10, and obtaining the mean value of the respective rotational angles by a midpoint computer 12, it is possible to determine a mechanism origin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot, and more particularly to an apparatus for detecting the origin of a two-degree-of-freedom joint mechanism having a pan-tilt mechanism.

[0002]

2. Description of the Related Art A conventional industrial joint robot is disclosed in Japanese Unexamined Patent Publication No. 4-310393 (hereinafter referred to as "industrial robot").
As described in Prior Art 1), a method of specifying a mechanism origin using an origin detection sensor attached to each joint shaft, and a method of detecting a position of a laser slit light disclosed in Japanese Patent Application Laid-Open No. 5-280927 (Japanese Unexamined Patent Application Publication No. 5-280927). Hereinafter, as described in Prior Invention 2), there is known a method in which an image processing means such as a camera is attached to the end of a multi-degree-of-freedom robot, and a deviation from a reference position is mathematically obtained.

[0003]

However, in the above prior art 1, the origin detected by the origin sensor and the mechanism origin of the mechanism itself do not exactly match due to a sensor mounting error, a mechanism assembly error, or the like. There was a problem. On the other hand, the prior art 2 has a problem that complicated procedures and expensive measuring devices such as a camera and an image processing device are required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems.
It is an object of the present invention to provide an origin detecting device capable of simply and accurately detecting the origin of a tilt mechanism.

[0005]

According to the present invention, there is provided an apparatus for detecting the origin of a two-degree-of-freedom joint mechanism having a pan-tilt mechanism. A projector that emits projection light from a direction parallel to the axis to be cut, and a shutdown detector that outputs a trigger when the projection light is interrupted by the pan-tilt mechanism,
A transmission detector that outputs a trigger when the blocked projection light is transmitted again by the movement of the pan-tilt mechanism; and two types of rotation angles around the pan axis at the time of triggering according to the two types of triggers. A rotation angle detector for detecting two types of rotation angles around the tilt axis; an angle memory for storing the two types of rotation angles around the pan axis and the tilt axis; and two types of rotation memories each for the pan axis and the tilt axis. And a calculating means for calculating an average of the rotation angles. In the present invention, when the projection light is blocked by the pan-tilt mechanism and when the projection light is re-transmitted, the cut-off trigger and the transmission trigger are output, and the rotation angles around the pan axis and the tilt axis at the time of the trigger in response to these triggers Is detected, installation error,
It is not necessary to use a sensor including an adjustment error, and the mechanism origin of the joint mechanism can be accurately measured. Further, a camera, an image processing device and the like are not required.

Further, the present invention is characterized in that, in the above invention, a projection light detector which outputs a trigger every time the projection light is cut off and transmitted by the pan-tilt mechanism. In the present invention, since the cutoff and transmission of the projection light are detected by one projection light detector, the number of circuit adjustment steps can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of an origin detection device according to the present invention. 1 is a fixed base, 2 is a pan-tilt mechanism installed on the fixed base 1, and this pan-tilt mechanism 2 is a pan 2A provided on the fixed base 1 so as to be rotatable around a vertical tilt axis 6.
And a tilt 2B provided at the upper end of the pan 2 so as to be swingable around a horizontal tilt axis 7 orthogonal to the tilt axis 6. Reference numerals 3 and 5 denote a light projector and a light receiving element which are arranged to face the spaces on both sides of the tilt 3B. The floodlight 3
The projection light 4 is emitted toward the light receiving element 5 from a direction parallel to an axis orthogonal to the pan axis 6 of the pan-tilt mechanism 2. The projection light 4 is cut off when the tilt 2B is located on the optical path, and is received by the light receiving element 5 when the tilt 2B is not located, whereby the projection light 4 by the pan-tilt mechanism 2 is received.
Block and transmission are detected. The cutoff detector 8 and the transmission detector 9 are detection circuits that receive a signal from the light receiving element 5 and generate a cutoff trigger and a transmission trigger, respectively. The pan-tilt controller 13 is a controller that rotates the pan-tilt mechanism 2 around the pan axis 6 and swings the tilt 2B around the tilt axis 7. The rotation angle detector 10 detects the rotation angles of the pan axis 6 and the tilt axis 7 and outputs the rotation angle to the operation angle memory 11. The operating angle memory 11 is a memory that stores a rotation angle in a memory in conjunction with a blocking trigger and a transmission trigger output from the blocking detector 8 and the transmission detector 9.
The midpoint calculator 12 is a calculator for calculating the average of the rotation angles stored in the operation angle memory 11, and the calculated average value is panned.
Output to the tilt controller 13. Pan axis sensor 1
4. The tilt axis sensor 15 is panned with the fixed base 1 during initialization.
These are sensors for determining the reference point of the tilt mechanism 2, and these constitute an origin detection device 16.

Next, the operation of the origin detecting device 16 will be described. First, as an initializing operation, the pan / tilt mechanism 2 is rotated around the pan axis 6 by the pan / tilt controller 13 to obtain a reference point between the fixed base 1 and the pan / tilt mechanism 2, and the tilt 2 B is moved to the tilt axis 7. The pan / tilt mechanism 2 is moved around to a reference point detected by the pan axis sensor 14 and the tilt axis sensor 15. At this time,
The encoder counter of the rotation angle detector 10 is reset using the detection signals output from the pan axis sensor 14 and the tilt axis sensor 15 as a trigger.

FIG. 2 is a diagram showing the locus of the pan-tilt mechanism 2 during the first origin detection operation. In the first origin detection, the pan-tilt controller 13 rotates the pan-tilt mechanism 2 about the pan axis 6 and swings the tilt 2B about the tilt axis 7, so that the tilt 2B can sufficiently block the projection light 4 To the position. Here, when the tilt shaft 7 is fixed and rotated around the pan shaft 6, the pan-tilt mechanism 2
, The tip of the tilt 2B draws an arc-shaped locus, blocks the projection light 4 at the point a, and transmits again at the point b. The light receiving element 5 can be realized by an element that generates a voltage in accordance with the amount of the projection light 4, for example, a solar cell or the like. The cutoff detector 8 and the transmission detector 9 amplify the output of the light receiving element 5 and compare them with the reference voltages of the cutoff detector 8 and the transmission detector 9 to generate a cutoff trigger and a transmission trigger, respectively. Cutoff trigger and transmission trigger are rotation angle detector 1
The rotation angles of the points a and b with respect to the reference point of the pan axis 6 detected at 0 are stored in the angle memory 11. An average value of the stored operation angles is calculated by the midpoint calculator 12, and a midpoint c which is a first origin is determined.

FIG. 3 is a diagram showing the trajectory of the pan-tilt mechanism 2 during the second origin detection operation. In the second origin detection, the pan-tilt controller 2 rotates the pan-tilt mechanism 2 around the pan axis 6 to transfer the work to the middle point c. Here, when the pan shaft 6 is fixed and the tilt 2B is swung, the tilt 2
The tip of B draws an arc-shaped trajectory when the tilt 2B is viewed from the side, but draws a reciprocating linear trajectory in the vertical direction on the projection plane when viewed from the front. , At point d ′. The light receiving element 5 generates a voltage according to the amount of the projection light 4. The cutoff detector 8 and the transmission detector 9 amplify the output of the light receiving element 5 and generate cutoff triggers and transmission triggers, respectively, by comparing with the reference voltages of the cutoff detectors 8 and the transmission detector 9, respectively. The cutoff trigger and the transmission trigger store the rotation angles at points d and d ′ with respect to the reference point of the tilt axis 7 detected by the rotation angle detector 10 in the angle memory 11. An average value of the stored operating angles is calculated by the midpoint calculator 12, and a midpoint e, which is the second origin, is determined. The mechanism origin of the pan-tilt mechanism 2 is determined by the middle point c which is the first origin and the middle point e which is the second origin.

FIG. 4 is a block diagram showing the operation of the rotation angle detector 10. The rotation angle detector 10 includes incremental encoders 101 and 102 and an encoder counter 10.
3,104. The incremental encoders 101 and 102 output a rotation detection signal according to the rotation of the pan shaft 6 and the tilt shaft 7. Encoder counter 1
Numerals 03 and 104 count and calculate rotation detection signals of the rotation angle from the fixed point l and the reference point of the pan-tilt mechanism 2 detected by the pan axis sensor 14 and the tilt axis sensor 15 at the time of initialization.

FIG. 5 is a block diagram showing the operation of the interruption detector 8. The interruption detector 8 includes an amplifier 801, a comparator 80
2. It is composed of a reference voltage 804. The amplifier 801 amplifies the detection voltage including the cutoff information from the light receiving element 5.
The comparator 802 compares the amplified detection voltage with the reference voltage 804, and generates a cutoff trigger 803.

FIG. 6 is a block diagram showing the operation of the transmission detector 9. The transmission detector 9 includes an amplifier 901, a comparator 90
2, the reference voltage 904. The amplifier 901 amplifies a detection voltage including transmission information from the light receiving element 5.
The comparator 902 compares the amplified detection voltage with the reference voltage 904, and generates a cutoff trigger 903.

FIG. 7 is a block diagram showing the operation of the operation angle memory 11. The operating angle memory 11 has four memories 11
1, 112, 113 and 114. Memory 1
Reference numerals 11, 112, 113, and 114 denote a shutdown trigger 803 and a transmission trigger 903 when the first origin is detected and when the second origin is detected.
, And the operating angles of the counters 103 and 104 are stored.

As described above, in the origin detecting apparatus 1 according to the present invention, when the projection light 4 is blocked by the pan-tilt mechanism 2 and when it is re-transmitted, the light receiving element 5 detects the light 4 and based on the detection signal. The cutoff detector 8 and the transmission detector 9 output a cutoff trigger and a transmission trigger, respectively, and in response to these triggers, the pan axis 6 and the tilt axis 7 at the time of the trigger.
Since the mechanism origin of the pan-tilt mechanism 2 is determined by detecting the rotation angle of the surroundings, the mechanism origin of the joint mechanism can be accurately measured without the need for the origin sensor in the above-described prior art 1. Further, since a light projector and a light receiving element are used, a camera, an image processing device, and the like are not required, and the manufacturing cost of the device can be reduced.

FIG. 8 is a schematic configuration diagram showing a second embodiment of the present invention. In the present embodiment, one projection light detector 20 is provided as an output destination of the light receiving element 5 and this detector 20
Thus, a trigger is output each time the projection light is blocked or transmitted.

FIG. 9 is a block diagram showing the operation of the projection light detector 20. The projection light detector 20 includes an amplifier 201, a comparator 202, a delay circuit 203, a reference voltage 204, and an exclusive OR circuit 205. The output voltage of the light receiving element 5 is amplified by the amplifier 201 of the projection light detector 20. The signal amplified by the amplifier 201 is output from the comparator 202 to the reference voltage 20.
4 is converted to a rectangular wave signal having the cutoff and transmission information at the edge. The rectangular wave signal is sent to the exclusive OR circuit 205 and the delay circuit 203. The delay circuit 203 delays the rectangular wave by Δt and outputs it to the exclusive OR circuit 205. An exclusive OR circuit 205 generates a projection light trigger 206 having cut-off and transmission information from the two rectangular waves, and generates an operation angle memory l.
By storing the rotation angle of the feed pan-tilt axis in l, the mechanism origin e can be determined similarly to the above-described embodiment. Since other configurations are the same as those of the above-described embodiment, the same components are denoted by the same reference numerals, and description thereof will be omitted.

In such a configuration, since the trigger is generated by one transmitted light detector 20, the man-hours for the detector and circuit adjustment can be reduced.

FIG. 10 is a schematic configuration diagram showing a third embodiment of the present invention. In the present embodiment, two joint actuators have two degrees of freedom, but two drive actuators are not independent, and drive two-degree-of-freedom operations of joints while interfering with each other. Such two-degree-of-freedom operation can be realized by, for example, combining a swash plate drive mechanism and a universal joint.

In the example shown in FIG. 10, the joint mechanism 30
The joint has two drive axes, an X axis 31 and a Y axis 32. First, as an initial operation, the joint controller 40 rotates the X-axis actuator 33 and the Y-axis actuator mechanism 34 in order to obtain a reference point of the joint mechanism 30, and a reference detected by the X-axis sensor 35 and the Y-axis sensor 36. The joint mechanism 30 is moved to a point. At this time, the encoder counter in the rotation angle detector 10 is reset by using the detection signals output from the X-axis sensor 35 and the Y-axis sensor 36 as a trigger.

FIG. 11 is a diagram showing the trajectory of the joint mechanism 30 during the first origin detection operation. In the first origin detection, the joint controller 40 rotates and swings the joint mechanism 30 to move the joint light 30 to an arbitrary position where the projection light 4 can be sufficiently blocked. here,
When the X-axis actuator 33 and the Y-axis actuator 34 are rotated at the same speed and in the same direction, the joint mechanism 30 draws an arc-shaped trajectory, blocks the projection light 4 at the point a, and transmits again at the point b.
The light receiving element 5 generates a voltage according to the amount of the projection light 4.
The cutoff detector 8 and the transmission detector 9 amplify the output of the light receiving element 5 and generate a cutoff trigger and a transmission trigger, respectively, by comparing them with the reference voltages inside the cutoff detector 8 and the transmission detector 9, respectively. The cutoff trigger and the transmission trigger store the rotation angles at points a and b with respect to the reference points of the X-axis actuator 33 and the Y-axis actuator 34 detected by the rotation angle detector 10 in the angle memory 11. An average value of the stored operation angles is calculated by the midpoint calculator 12, and a midpoint c which is a first origin is determined.

FIG. 12 is a diagram showing the trajectory of the joint mechanism 30 during the second origin detection operation. In the second origin detection, the X-axis actuator 33 and the Y-axis actuator 34 are rotated by the joint controller 40 and moved to the middle point c. here,
When the X-axis actuator 33 and the Y-axis actuator 34 are rotated in the opposite directions at a constant speed, the joint mechanism 30 draws a reciprocating linear trajectory, blocks the projection light 4 at the point d, and transmits again at the point d '. The light receiving element 5 is composed of a solar cell or the like, and generates a voltage according to the amount of the projection light 4. Cutoff detector 8, Transmission detector 9
Amplifies the output of the light receiving element 5 and outputs the cutoff detector 8,
The cutoff trigger and the transmission trigger are generated by comparing with a reference voltage inside the transmission detector 9. The cutoff trigger and the transmission trigger store the rotation angles at points d and d ′ with respect to the reference points of the X-axis actuator 33 and the Y-axis actuator 34 detected by the rotation angle detector 10 in the angle memory 11. An average value of the stored operating angles is calculated by the midpoint calculator 12, and a midpoint e, which is the second origin, is determined. Next, the mechanism origin of the joint mechanism 30 is determined by the middle point c which is the first origin and the middle point e which is the second origin. It should be noted that the mechanism origin can be similarly obtained by changing the cutoff detector 8 and the transmission detector 9 to the projection light detector 20 shown in the second embodiment.

[0023]

As described above, according to the origin detecting apparatus of the present invention, the origin of the two-degree-of-freedom joint mechanism can be accurately obtained. The reason is that the mechanism origin of the joint mechanism is measured using the projection light of the projector arranged in the space without using a sensor including an attachment error and an adjustment error. Further, according to the present invention, the origin can be detected at lower cost than other conventional methods for measuring the mechanical origin of the joint mechanism. The reason is that the conventional method uses a camera and an image processing device, whereas the light can be detected by a light projector and a light receiving element. Further, according to the present invention, the number of circuit adjustment steps can be reduced. The reason is that the projection light detector described in the second embodiment is used to detect the cutoff and transmission of the projection light with one detector.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a locus of a pan-tilt mechanism during a first origin detection operation.

FIG. 3 is a diagram showing a locus of a pan-tilt mechanism during a second origin detection operation.

FIG. 4 is a block diagram showing the operation of the rotation angle detector.

FIG. 5 is a block diagram showing the operation of the interruption detector.

FIG. 6 is a block diagram showing an operation of an operation angle memory.

FIG. 7 is a block diagram showing the operation of the transmission detector.

FIG. 8 is a schematic configuration diagram showing a second embodiment of the present invention.

FIG. 9 is a block diagram showing the operation of the projection light detector.

FIG. 10 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 11 is a diagram illustrating a trajectory of a joint mechanism during a first origin detection operation.

FIG. 12 is a diagram illustrating a trajectory of a joint mechanism during a second origin detection operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixed stand, 2 ... Pan-tilt mechanism, 3 ... Floodlight, 4 ...
Projection light, 5: light receiving element, 6: pan axis, 7: tilt axis, 8
... Interruption detector, 9 ... Transmission detector, 10 ... Rotation angle detector,
11: Operating angle memory, 12: Midpoint calculator, 13: Pan-
Tilt controller, 14: Pan axis sensor, 15: Tilt axis sensor, 20: Projection light detector, 30: Joint mechanism, 3
1: X axis, 32: Y axis, 33: X axis actuator, 3
4 Y-axis actuator, 35 X-axis sensor, 36 Y
Axis sensor, 40 ... joint controller, 101, 102 ...
Incremental encoder, 103, 104: encoder counter, 111, 112, 113, 114: memory, 201: amplifier, 202: comparator, 203: delay circuit, 204: reference voltage, 205: exclusive OR circuit, 2
06 Projection light trigger, 801 Amplifier, 802 Comparator, 803 Cutoff trigger, 804 Reference voltage, 901
Amplifier, 902: comparator, 903: transmission trigger, 904
... reference voltage.

Claims (2)

[Claims] 1. An apparatus for detecting an origin of a two-degree-of-freedom joint mechanism having a pan-tilt mechanism, comprising: a projector for emitting projection light from a direction parallel to an axis orthogonal to a pan axis of the pan-tilt mechanism; An interruption detector that outputs a trigger when the projection light is interrupted by the pan-tilt mechanism, and a transmission detector that outputs a trigger when the interrupted projection light is transmitted again by the movement of the pan-tilt mechanism. A rotation angle detector for detecting two types of rotation angles around the pan axis and two types of rotation angles around the tilt axis at the time of triggering according to the two types of triggers; An origin detecting device, comprising: an angle memory for storing a rotation angle around an axis; and a calculating means for calculating an average of each of two types of rotation angles around the pan axis and the tilt axis. 2. The origin detection device according to claim 1, further comprising a projection light detector that outputs a trigger each time the projection light is blocked or transmitted by a pan-tilt mechanism.