JPH0229443Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a robot, particularly a so-called teaching playback type robot.

For example, an operator first moves the tip of a robot body that has an injection nozzle to perform a pseudo-painting operation on an object to be painted that is being conveyed by a conveyance device, and at the same time stores the contents of the operation in a storage device (generally After all the work contents are memorized, the memorized work contents are read out, and the painting work is automatically performed again according to the read-out work contents (this is generally called a playback operation).・Playback type painting robots are known.

Among these known robots, there is a painting robot in which a plurality of movable bodies including a moving amount detection means for detecting the amount of movement from a reference position of an object to be painted conveyed by a conveying device from a reference position and a spray nozzle are connected at each joint. The robot has a position detector that detects the relative position of the movable body at each joint. The position signals from the detector are sequentially stored in a storage device, and during a playback operation, an interpolation calculation circuit calculates interpolation positions between positions corresponding to two position signals read from the storage device using a constant number of interpolations, The calculation result signal from the interpolation calculation circuit is used as a target value so that each movable body reaches from one storage position to the next storage position every time the movement amount detected by the movement amount detection means increases by the predetermined amount. In a robot that uses a position signal from a position detector as a current value to sequentially position each movable body of the robot body using a servo circuit, if a teaching operation is performed when the transport speed of the transport device is relatively slow, it may cause problems during playback operation. There is a possibility that the painting trajectory may deviate from the original painting trajectory by a wide margin.

Examples of coating by the above-mentioned known robot are shown in FIGS. 1a and 1b. The movement amount detection means usually includes a pulse generator that emits one pulse every time the object to be coated moves a certain distance, and a counter that counts the number of pulses. In FIGS. 1a and 1b, the X and Y coordinates indicate coordinates fixed to the object to be painted, and the solid line L is the coating locus during teaching on the object to be painted. That is, during teaching, time t
= The painting point at point A0 (X0, Y0) at t0 is
At t=4T, point A1 (X1, Y
1), and at t=8T, point A2 (X2, Y
2) is reached.

That is, the teaching is performed every time the pulse generator generates four pulses, and in the case of Figure 1a, the conveyance speed is fast and the teaching time is 4T.
During this time, four pulses are generated from the pulse generator. However, in the case of FIG. 1b, it is assumed that the conveying speed is slow and the pulse generator generates two pulses during a time period of 4T. Therefore, during the teaching operation, in the case of Figure 1 a, the points A0 (X0, Y0),
The relative positions of the movable bodies corresponding to point A1 (X1, Y1) and point A2 (X2, Y2) are stored,
In the case of Fig. 1b, for example, point A0 (X0, Y0),
Only the relative positions of the movable bodies corresponding to point A2 (X2, Y2) are stored;
The relative positions of the movable bodies corresponding to 1) are not stored. Therefore, during playback, for example, the interpolation number is 4.
When the robot is set to perform interpolation calculations and playback is performed, the interpolation positions corresponding to painting points B1, B2, B3, B4, B5, and B6 are determined by interpolation in the case of Fig. 1a, and during playback. The painting trajectory is points A0, B1, B2, B3, A1,
The broken line L1 passes through B4, B5, B6, and A2, but in the case of Figure 1b, the painting points C1 and C are drawn by interpolation.
The interpolation positions corresponding to 2 and C3 are found, and the painting trajectory during playback is at points A0, C1, C2, and C.
3, it passes through A2 and becomes almost a broken line L2. If the coating trajectory L during teaching is an upwardly convex curve, the coating trajectory L2 during playback will deviate from the coating trajectory L by a large width compared to the trajectory L1, for example, the distance d between points A1 and C2 There will be a deviation of . In addition, it is obvious that the trajectory L2 from point A2 to the painting point during the next playback bends significantly at point A2 compared to the trajectory L1.

This invention was made in view of the above points,
The purpose is to provide an industrial robot in which each movable body can be smoothly played back with a coating trajectory close to the coating trajectory during teaching, regardless of the conveyance speed during teaching.

According to the present invention, the present invention includes a speed/movement amount detection means for detecting the conveyance speed of the workpiece being conveyed by the conveyance device and the movement amount of the workpiece from a reference position; A robot main body in which movable bodies are connected at each joint, a position detector that detects the relative position of the movable bodies at each joint, and a position signal from the position detector at a first predetermined time interval during a teaching operation. and a movement amount signal from the speed/movement amount detection means, and sequentially reads out the stored movement amount signal and position signal at a second predetermined time interval during a playback operation; During the playback operation, a speed difference is detected by comparing the conveyance speed of the workpiece during teaching obtained from the movement amount signal read from the storage means and the conveyance speed of the workpiece from the speed/movement amount detection means. a correction circuit that corrects the position signal read from the storage means based on the speed difference detected by the speed difference detection means during a playback operation; an interpolation calculation circuit that calculates an interpolated position between positions corresponding to two position signals corrected by a predetermined number of interpolations; This is achieved by an industrial robot comprising a servo circuit that sequentially positions each movable body of the robot body using signals as current values.

Next, a preferred specific example of the present invention will be explained based on the drawings.

In the figure, 1 is a conveyor that conveys objects 2 and 3 to be coated in the direction A;
A conveyor pulse generator 4 is provided which generates one pulse every time a certain amount of 3 is conveyed.
A switch 6 is provided on the fixed wall surface 5 and is activated when the objects 2 and 3 reach a predetermined reference position. It is fixed to the floor 7 with a base 8, and also has an injection nozzle 9 and arms 10, 1 as movable bodies.
1. A robot main body 17 is provided in which the support plate 12 is connected by joints 13, 14, 15, and 16. The robot body 17 further includes each joint 13, 14, 1.
Position detectors 18, 19, 20, and 21 are provided to detect the mutual positions of the movable bodies at 5, 16, and 16.

Note that the number of arms, the number of joints, and the direction of movement may be determined as desired.

The conveyor pulses 22 generated by the pulse generator 4 are input to counters 23 and 24, and the number of pulses is counted. Counter 24 is reset by actuation of switch 6. 25 is a time monitoring circuit, which outputs a pulse 26 to the counter 24 and detectors 18, 19, 20, 21 at fixed time intervals T1 during the teaching operation to generate the movement amount signal 2.
7 and the position signal 28 are sequentially stored in the storage device 29. The circuit 25 controls the time during the playback operation.
A pulse 26 is applied to the readout control circuit 30 every T1 to sequentially read out the movement amount data 27 and the position data 28 stored in the storage device 29 by a teaching operation. The circuit 25 also sends pulses 31 to the counter 23 at regular time intervals T2 during the playback operation.
give to Note that the times T1 and T2 may be equal,
In the following explanation, T2=T1. counter 23
Each time it receives a pulse 31, it outputs the contents of the counter 23 as a transport speed signal 32 of the conveyor 1 and is reset to zero.

The speed/movement detection means is composed of a pulse generator 4, a switch 6, counters 23 and 24, and a time monitoring circuit 25.

Further, the storage means includes a storage device 29, a time monitoring circuit 25, and a read control circuit 30.

The speed difference detection circuit 33 as a speed difference detection means is reset to 0 by the switch 6 and receives from the readout control device 30 the initial movement amount data at the time of teaching, in other words, the number of conveyor pulses which is the conveyor speed data at the time of teaching. This number of conveyor pulses is compared with the conveyor speed data at the time of playback output from the counter 23, that is, the number of conveyor pulses. In other words, circuit 33
compares the number of conveyor pulses during teaching and during playback in a predetermined unit time T by the time monitoring circuit 25. The circuit 33 detects the difference in the number of conveyor pulses, which is the difference between the conveyor speed during playback and the conveyor speed during teaching, and converts this difference into a coordinate conversion circuit 3 as a correction circuit.
Give to 4. The circuit 34 is further given position data of the movable bodies 9, 10, 11, and 12 during teaching from the device 30, and the circuit 34 receives the difference between the conveyor speed during teaching and the conveyor speed during playback, that is, the number of conveyor pulses. The difference between the position of the workpiece during teaching and playback at each time in each unit time T, which occurs according to the difference in the number of conveyor pulses per unit time T, is calculated. The conveyor movement amount per pulse is reset according to the degree of difference between the movable bodies 9, 10, 11,
The target position of No. 2 is calculated and set as target positioning position data 28a.

That is, the circuit 33 calculates the transport speed of the workpiece during teaching from the difference between the movement amount stored at time tn during the teaching operation from the readout control circuit 30 and the movement amount stored at time tn+1, and calculates the transport speed of the workpiece during teaching. The difference between the determined conveyance speed of the workpiece at the time of teaching and the conveyance speed of the workpiece at the time of playback from the counter 23 is detected, and the circuit 34 as a correction circuit determines that the workpiece was taught at time tn+1 during the teaching. In order to determine the position at the time of position playback operation, the circuit 3 calculates the position from the difference between the conveyance speed of the workpiece during teaching and the conveyance speed of the workpiece during playback detected by the circuit 33.
The position data at time tn+1 from 0 is corrected to determine the target position at the time of playback, and position data 28a is generated.

Incidentally, similar corrections are also successively applied to time tn and the like. Of the position data 28a, time tn
The converted position data Pn, Pn+1 corresponding to the stored position data at
to the interpolation calculation circuit 35, and the position Pn and
The interpolated position between Pn+1 is determined by linear interpolation. Note that the interpolation number N in the circuit 35 may be selectively set in advance, but is set to be proportional to the conveyor speed during playback, for example. That is, the circuit 35 includes registers 35a and 35b that receive the n-th and n+1-th position data Pn and Pn+1, respectively, a switching circuit 35d that sequentially supplies the contents of the registers 35a and 35b to the division circuit 35c,
A multiplication circuit 35e multiplies the conveyor speed data from the counter 23 by a constant value and supplies it to the division circuit 35c as an interpolation number N, and the outputs Pn/N and Pn+1/N of the division circuit 35c are applied to an integer value i (corresponding to the interpolation point) 1≦i≦N) and outputs the values Pn/N・i and Pn+1/N・i, and a multiplication circuit 35f that outputs the values Pn/N・i and Pn+1/N・i to the registers 35g and 35h, respectively. Working selector switch 35j, registers 35h and 35
Find the difference with g and give it to the adder circuit 35k as the value Pn+1-Pn/N・i.The subtracter circuit 35m then calculates the sum of the output of the register 35a and the output of the subtracter circuit 35m, and calculates the interpolation position Qi=Pn+1-Pn/N. - It consists of an adder circuit 35k that outputs as i.

The output of the interpolation circuit 35 is the movable body 9, 10, 11,
It is applied to the drive and drive control device 36 as a servo circuit of 12 to operate a hydraulic system connected to a hydraulic source 36a, and is used to sequentially set the movable bodies 9, 10, 11, and 12 at target positions.

The control circuit 37 is configured as described above.

In the industrial robot 38 of the present invention configured as described above, during teaching, the time monitoring circuit 25 emits one pulse every 4T for the trajectory L, and the movable bodies 9, 10, 11 emit one pulse every 4T. , 12 positions are taught, and during playback,
The conveyor pulse generator 4 emits one pulse every time T, and the interpolation number N is 4 (in other words, the multiplier 3
5e multiplied by the value 1), the dashed line L1 shown in FIG. 1a is obtained as the playback locus. Moreover, this locus L1 during teaching does not depend on the conveyor speed. Therefore, it is possible to teach at a relatively slow conveyor speed during teaching, and the playback trajectory has a small difference from the trajectory L and is a polygonal trajectory with a relatively small angle. In addition, the speed of the painting spots on the objects 2, 3 to be painted does not depend on the conveyor speed, so that in practice a constant amount of paint is always applied onto the objects 2, 3 to be painted. Furthermore, during playback under the above teaching conditions, if the conveyor speed is relatively slow and the pulse generator 4 is set to emit one pulse every 2T and the multiplier 35e is set to multiply by the value 1, the interpolation number N becomes 2, and when viewed in the same coordinate system as in FIG. 1a, the painting point during playback becomes approximately the locus L3 in FIG. 1c. Note that D1 and D2 indicate interpolation positions.

This case also has the same advantages as described above.
Note that if the movable bodies 9, 10, 11, and 12 are simultaneously multi-axis controlled, the trajectory L3 can match the trajectory L1.

Note that instead of inputting the output of the counter 23 directly to the multiplier 35e, the output of the counter 23 is input to the reciprocal calculator 35n to obtain the reciprocal of the conveyor speed during playback, and a number inversely proportional to this conveyor speed is input to the multiplier 35e. It is also possible to input the . In this case, the interpolation number N is inversely proportional to the conveyor speed. Therefore, the conveyor speed is high and the movable bodies 9,1
When 0, 11, and 12 are moved at a high speed relative to the floor (stationary system), the number of interpolations is smaller compared to when the conveyor speed is relatively slow and the time required for the interpolation calculation process is reduced. The movable body can easily follow the movement of a conveyor moving at high speed.

It is also possible to set the interpolation number N in proportion to the conveyor speed during teaching instead of the conveyor speed during playback. This is done by inputting.

For example, during playback, assume that the conveyor speed is kept constant and the pulse generator 4 emits one pulse every time T. If the pulse generator 4 emits one pulse every time T during teaching (assuming the teaching time interval by the circuit 25 is 4T), the same playback trajectory L as in FIG. However, if the pulse generator 4 emits one pulse every 2T during teaching (assuming the teaching time interval by the circuit 25 is 4T), the playback trajectory L3 will be as shown in FIG. 1c.

On the other hand, if the plurality of movable bodies 9, 10, 11, 12 are substantially simultaneously multi-axis controlled, the circuit 35 of the control circuit 37 shown in FIGS. 3 and 4 may not necessarily be provided.

As described above, according to the present invention, since the painting robot teaches the painting point at regular intervals, it can playback with a relatively smooth painting path with few errors, regardless of the shape of the actual painting path to be taught. can be done.

[Brief explanation of the drawing]

Figures 1a, b, and c are explanatory diagrams of coating trajectories, Figure 2 is an explanatory diagram of a painting robot according to a preferred embodiment of the present invention, and Figure 3 is a block diagram of a control circuit according to a preferred embodiment of the present invention. 4 are block diagrams of a specific interpolation circuit of the present invention. 2, 3... Worked object, 4... Pulse generator, 9, 10, 11, 12... Movable body, 17...
Robot body, 18...Position detector, 23, 24
...Counter, 29...Storage device, 36...Drive and drive control device, 38...Robot main body.

Claims (1)

[Scope of utility model registration request] A robot comprising a speed/movement detection means for detecting the transport speed of a workpiece being transported by a transport device and the amount of movement of the workpiece from a reference position, and a plurality of movable bodies connected at each joint. a position detector that detects the relative position of the movable body at each joint; and a position signal from the position detector and the speed/travel amount detection means at a first predetermined time interval during a teaching operation. storage means for sequentially storing the stored movement amount signal and the position signal, and sequentially reading out the stored movement amount signal and position signal at second predetermined time intervals during a playback operation; a speed difference detection means for detecting a speed difference by comparing the conveyance speed of the workpiece during teaching obtained from the read movement amount signal and the conveyance speed of the workpiece from the speed/movement amount detection means; and a playback operation. At this time, a correction circuit that corrects the position signal read from the storage means based on the speed difference detected by the speed difference detection means, and a correction circuit that corrects the two position signals output from the correction circuit. an interpolation calculation circuit that interpolates and calculates interpolation positions between corresponding positions using a predetermined interpolation number;
An industrial robot comprising a servo circuit that sequentially positions each movable body of the robot body using a calculation result signal from an interpolation calculation circuit as a target value and a position signal from a position detector as a current value.