JPS5827075B2 - robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a robot axis control device, and more particularly to a constant velocity linear control device for a polar coordinate robot.

Conventionally, when driving a robot axis with an axis length R and a rotation angle θ as shown in FIG. 1, a microcomputer 1 is used as shown in FIG.

That is, the command pulses Pθ and PR whose output timing and number of pulses have been calculated by the microcomputer 1 are
It is input to the deviation counters 2 and 3 of the axis control system and R-axis control system.

The deviation counters 2 and 3 are given pulse signals from pulse generators 120 and 130 provided on the output shafts, respectively, and the deviation from the command pulses Pθ and PR is determined.

Thus, the digital deviation outputs of the deviation counters 2 and 3 are converted into analog signals by the DA converters 4 and 5, respectively, and the tacho generators 10 provided on the respective output shafts
The deviation from the outputs of 0 and 110 is amplified by amplifiers 6 and 7 to drive drive motors 8 and 9.

In this way, the θ-axis and the R-axis are operated in response to the command pulses Pθ and PR.

Here, the maximum value of the command speed of the command pulses Pθ and PR is determined by the cycle time and workload of the microcomputer, and is generally 500 pps to 1000 ps.
It is about ps.

Furthermore, as the number of axes of the robot increases, the maximum command pulse speed decreases in proportion.

Therefore, there is a drawback that the operating speed of the robot cannot be increased.

In other words, in the past, the interpolation function in a robot was performed by pulse distribution based on programming of a microcomputer, so the operating speed and accuracy of the robot reached a ceiling at the upper limit of its processing speed.

Therefore, an object of the present invention is to eliminate such drawbacks and improve performance.

This invention will be explained below.

In this invention, when the robot axis position is moved linearly from point A to point B as shown in Fig. 3, the robot axis can be reliably positioned at point B by determining dy and dr from the similar figures. It is.

That is, this method detects the movement of the θ-axis using a linear quantity called dy, replaces it with the feedback amount of the θ-axis, and instructs the R-axis to use the amount of dr derived according to the movement of dy as a deviation signal.

As a specific circuit example of such a method, a configuration as shown in FIG. 5 can be considered.

That is, in the figure, 10 is a pulse IP that commands the linear movement amount dy of the robot axis, and a multiplication/division circuit for obtaining a dy times signal (position change signal) from distance signals R and r counted by counters 11 and 12, which will be described later. , 13 is counter 1
14 is a multiplication/division circuit for obtaining a dR signal (both dr and dR are position changes) from the distance signals R and r counted by 1 and 12 and the dr signal; 14 is c obtained by the multiplication/division circuit 10;
a deviation counter 1 for calculating the deviation between the iy signal and the actual cty signal from the pulse generator 15 provided on the θ axis;
6 is a DA converter that converts the digital output of the deviation counter 14 into an analog signal, and 17 is a motor 18 for driving the θ-axis.
An amplifier 19 drives a speed signal from a tacho generator 20 for speed detection provided on the θ axis, and a counter 1.
21 is a multiplication/division circuit that obtains a transfer function correction signal from the dt distance signals R and r from 1 and 12; 21 is a deviation counter that calculates the deviation between the dy-fold signal position change signal from the multiplication/division circuit 13) and a zero value; 22 is a DA converter for converting the digital output from the deviation counter 21 into an analog signal, 23 is an amplifier for driving the R-axis drive motor 24, and 25 is a tacho generator 26 for speed detection provided on the R-axis. 27 and 28 are R
This is a pulse generator for obtaining position change signals dR and dr provided on the axis and the θ axis.

Furthermore, the formula consisting of the principle diagram in Fig. 3 is established, and the device is arranged so that it slides on the part 31 fixed with respect to the θ axis, as shown in 30 in Fig. 4. At the same time, dr detectors and earth inspection peaks and valleys are provided at, for example, 32 positions so as to be able to detect the dt expansion/contraction movement in the longitudinal direction of the R axis.

In this way, when the cty signal is input as an input command, dy is calculated from R and r at that point and the θ-axis is driven, and the R-axis is also driven from R and r at this time, thereby moving the robot axis in a straight line. It is possible to do so.

The multiplier/divider circuits 19 and 25 are provided in the speed loop because the θ axis and the tacho generator 20 are mechanically nonlinearly connected, and the analog signals from the DA converters 16 and 22 have a This is because since the element is included, it is necessary to include n in the feedback loop as well.

Also, in the speed loop, the pulling, that is, the suction, is constant dt.
dt, the robot axis performs uniform linear motion.

As described above, according to the control device of the present invention, it is possible to move on a secondary plane by giving only linear commands, so when the robot is to perform palletizing operations, etc., the number of teaching points is reduced and the ease of teaching is improved. The effect is large in this regard.

Note that the present invention can be similarly applied to the elevation axis of a robot, and the arrangement example of each detector shown in FIG. 4 may be as shown in FIG. 6.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a robot mechanism to which this invention can be applied;
FIG. 2 is a block diagram showing the conventional control system of such a robot, FIG. 3 is a diagram showing the operating principle of the present invention, and FIG.
6 and 6 are diagrams showing an example of the arrangement of detectors according to the present invention, and FIG. 5 is a diagram showing a control system according to the present invention. 1... Microcomputer, 2, 3... Deviation counter, 4, 5... DA converter, 6, 7... Amplifier,
10.13,19,25...Multiplication/division circuit, 14°21
...deviation counter.

Claims (1)

[Claims] 1 One end is rotatably fixed and has an arm mechanism that can control the length R1 angle θ, and the tip of the arm whose length changes as the arm freely rotates in a two-dimensional plane can be expressed in polar coordinates. A robot mechanism capable of moving to a position is provided with a mechanism that changes in a similar relationship with the movement of the tip of the arm, and this mechanism includes a linear position change detector and a speed detector corresponding to the length R. and a linear position change detector and a speed detector corresponding to the angle θ, and by configuring a feedback loop with the output signals from each of the detectors, the arm can be made to move linearly at a constant velocity with only a position command. A robot axis control device characterized by: