JPH0687201B2 - Robot controller - Google Patents

Description

The present invention relates to a control device for a robot.

In an industrial robot of a so-called teaching playback system, if points A and B shown in FIG. 1 are teaching points for the robot, the processing unit (CPU) constituting the controller of the robot will teach those teaching points A, Based on the position data of B, that is, the teaching data, the movement amount of the robot is calculated with one unit of one minute movement section Pi to Pi _{+ 1} (i = 1,2, ... n) shown in FIG. 2 (interpolation calculation) Then, a movement command for each axis in the minute movement section is issued.

The robot moves in the section Pi to Pi _{+ 1} by the movement command, but due to various factors, the deviation ΔE between the actual movement trajectory A of the robot and the calculated movement trajectory B as shown in FIG. May occur. Therefore, conventionally, the deviation ΔE is detected by the positional deviation detection sensor 1 shown in FIG. 3, and the deviation ΔE latched by the latch circuit 2 is input to the processing device 3 to issue a movement command in a direction to eliminate the deviation ΔE. A method of correcting is implemented. In the figure, the memory 4 stores the teaching data and the like.

By the way, when the movement command is corrected by software by the processing device 3, as shown in FIG. 4, Pi-Pi _{+ 1}
The deviation detected in the section is actually corrected by Pi ₊₃ to Pi
₊₄ sections. Therefore the conventional robot in Pi ₊₁ ~Pi ₊₂ interval and Pi ₊₂ ~Pi ₊₃ section shown in FIG misalignment Δ
There is an inconvenience that the displacement is accompanied by E, that is, the displacement is not immediately corrected after the displacement is detected.

It is an object of the present invention to provide a robot control device capable of performing more accurate robot positioning by minimizing a delay in correction with respect to the movement command.

Therefore, in the present invention, the movement amount of the minute movement section between the teaching points is interpolated to generate the movement command signal composed of the pulse train corresponding to the movement amount, and the movement of the robot based on the movement command signal is performed. In a robot controller configured to detect a deviation of a trajectory and correct the movement command so as to eliminate the deviation, a synchronization circuit that synchronizes the movement command signal with a first clock signal; 1 for inverting the clock signal, correction pulse generating means for passing the clock signal output from the inverting means by the number corresponding to the deviation, the movement command signal synchronized by the synchronizing circuit, and the correction The OR circuit that takes the logical sum of the output signal of the pulse creating means and the output signal of the OR circuit is twice the first clock signal. And sampled at a second clock signal having a frequency, it is provided a sampling circuit for outputting the corrected move command signal.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 5 shows an embodiment of the control device according to the present invention.

In this device, the latch circuit 4 outputs the movement command data D _T (parallel signal) for the Pi to Pi ₊₁ section shown in FIG. 1 output from a central processing unit (hereinafter referred to as CPU) of a computer (not shown). Data to be latched at a predetermined timing and data latched by this circuit 4
_DT is input to a binary rate multiplier 5 (binary rate multiplier, hereinafter abbreviated as BRM).

The BRM5 is based on the data D _T and is Pi ₊₁ from the Pi point.
The pulse train signal for moving the robot at a predetermined speed to the point is output. This pulse train signal shown in FIG.
S ₂ is created by dividing the clock signal S ₁ shown in the figure by the data D _T.

The synchronizing circuit 6 inputs the pulse train signal S ₂ and the clock signal S ₃ shown in the same figure to synchronize the signal S ₂ with the signal S _{3. From} this circuit 6, the synchronizing circuit 6 synchronizes with the signal S ₃ . Signal S
₄ (see Fig. 6) is output.

The gate circuit 7 is the sign data D output from the CPU.
_{When S1} (“1” when moving the robot in the forward direction, “0” when moving the robot in the reverse direction) is “1”, the above signal S ₄ is output to the OR circuit 8, and when it is “0”, the above signal S ₄ is output. This serves to output the signal S ₄ to the other OR circuit 9.

The counter 10 inputs the correction data D _C (parallel signal) indicating the deviation ΔE shown in FIG. 2 from the latch circuit 2 shown in FIG. 3, presets the same, and outputs the clock from the inverter 11. It serves to count down the inverted signal S ₅ (see FIG. 6) of the signal S ₃ .

The gate circuit 12 starts counting from the counter 10, for example, when data D _C is preset in the counter,
The inverted signal S ₅ is output until the count content of the counter reaches zero, and the number of pulses of the output signal S ₆ shown in FIG. ₆ is the data D _C, that is, the deviation ΔE. It corresponds to.

The gate circuit 13 outputs the sign data D output from the CPU.
_S2 is output to the signal S ₆ to the OR circuit 8 when the "1",
The signal S ₆ is output to the OR circuit 9 when it is “0”.

The sampling circuit 14 samples the signals S ₇ , S ₈ output from the OR circuits 8, 9 with a clock signal S ₉ (see FIG. 6) having a frequency twice that of the clock signal S ₃ . , Thus, for example with respect to signal S ₇ and outputs a signal S ₇ 'shown in Figure 6. The clock signal S ₃ is obtained by dividing the signal S ₉ by a frequency divider (not shown).

The deviation counter 15 is the output signal of the sampling circuit 14.
The signals S ₇ ′ and S ₈ ′ and the output pulse of the encoder 17 fed back through the direction discriminating circuit 16 are input and a signal S ₁₀ corresponding to the count content is output. Then, this signal S ₁₀ is sent to the servo amplifier 19 via the D / A converter 18.
To drive an actuator 20 (for example, a servomotor) for operating the robot.

The encoder 17 outputs a pulse signal in conjunction with the actuator 20. Further, the direction discriminating circuit 16 supplies the pulse signal output from the encoder 17 to the down count input terminal of the deviation counter 15 when the pulse train signal S ₇ ′ for moving the robot in the positive direction is output from the sampling circuit 14. When the pulse train signal S ₈ ′ for moving the robot in the reverse direction is output from the sampling circuit 14, the output pulse of the encoder 16 is applied to the up-count input terminal of the counter 15. Therefore, the count content of the counter 15 becomes smaller with the operation of the actuator 20, and when the count content becomes zero, the signal S ₁₀ disappears and the movement of the robot stops.

In the apparatus shown in FIG. 5, the command data D _T for the minute sections Pi to Pi ₊₁ based on the teaching data collectively refer to the command data in the X, Y, and Z directions in the case of a three-axis robot, for example. And the command data D _T for each of those axes
(X), D _T (Y), D _T (Z) are output in a time division manner in the section Pi to Pi ₊₁ . Further, the D / A converter 18, the amplifier 19, the actuator 20, and the direction discriminating circuit 16 are also collectively referred to for each of the above axes.

Since the control device according to this embodiment is configured as described above, the correction command D _C (in this case, the movement command data D _T in the Pi to Pi ₊₁ section based on the teaching data and the deviation ΔE (in this case, (Representing the shift between the Pi _{-1 to} Pi intervals in FIG. 1) is input, the synchronizing circuit 6 outputs the signal S ₄
However, the signal S ₆ is output from the gate circuit 12, respectively.

Now, assuming that the signal S ₄ is a pulse train command signal for moving the robot in the X axis direction, the signal S ₆ is a correction pulse train signal for the X axis. When the robot is moved in the forward direction by the signal S ₄ , the data D _T is input and at the same time, “1” is input as the signature data D _S1 to the gate circuit 7, and the position of the robot is moved in the forward direction. In the case of correction, "1" is input to the gate circuit 13 as the sign data D _S2 at the same time when the data D _C is input. Therefore, in this case, the OR circuit 8 outputs the signal S _{7 which} is the logical sum of the signals S ₄ and S _6, and the sampling circuit 14 outputs the signal S ₇ ′ accordingly. The signal S ₇ ′ is obtained by correcting the pulse train command signal S ₄ in the X-axis direction on the basis of the deviation data D _C.
In the section Pi-Pi _{+ 1} , the robot is X in the section Pi- _1- Pi.
It is moved and positioned so as to eliminate the axial deviation ΔE.

When the robot position is corrected in the opposite direction, "0" is input to the gate circuit 13 as the sine data D _S2 , so the above signal S ₆ is applied to the OR circuit S ₈ and the sampling circuit.
It is inputted to the down count input terminal of the deviation counter 15 via 14. Therefore, in this case as well, the robot is moved so as to eliminate the above-mentioned deviation as in the above.

Although the case where the robot is moved in the X axis direction has been described above, the pulse train movement command signal S ₂ is corrected in the same manner when the robot is moved in the Y and Z axis directions.

Further, in the above embodiment, the sampling circuit 14
Although the overlapping portion a of the pulse in the signal S ₇ shown in the figure is separated into three pulses, the sampling circuit 14 can be omitted if a slight deviation correction error is allowed.

As is apparent from the above embodiment, the present invention corrects the pulse train movement command signal for the minute movement section based on the teaching data on the basis of the deviation data by pure hardware. The signal correction is performed very quickly. Therefore, the positional deviation of the robot can be corrected quickly and the positioning accuracy of the robot can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a minute movement section in which the teaching points are subdivided, FIG. 2 is a diagram exemplifying a mode of positional deviation when a robot moves in the minute movement section, and FIG. FIG. 4 is a block diagram conceptually and partially showing an example of the control device of FIG. 4, FIG. 4 is a view showing a mode of positional deviation correction in the device shown in FIG. 3, and FIG. 5 is control of a robot according to the present invention. FIG. 6 is a block diagram showing an embodiment of the device, and FIG. 6 is a timing chart for explaining the operation of the device shown in FIG. 1 ... Positional deviation detection sensor, 4 ... Latch circuit, 5 ...
Binary rate multiplier, 6 ... Synchronizing circuit, 7,12,13 ... Gate circuit, 8,9 ... OR circuit, 10 ... Counter, 14 ... Sampling circuit, 15 ... Deviation counter.

Claims (1)

[Claims] 1. A movement command signal consisting of a pulse train corresponding to this movement amount is interpolated to interpolate a movement amount of a minute movement section between teaching points, and a movement locus of a robot based on the movement command signal is deviated. A robot controller configured to correct the movement command so as to eliminate the shift, and a synchronization circuit for synchronizing the movement command signal with a first clock signal; Inverting means for inverting the signal, correction pulse creating means for passing the clock signal output from the inverting means by the number corresponding to the shift, the movement command signal and the correction pulse creating synchronized by the synchronizing circuit. An OR circuit that takes the logical OR of the output signal of the means, and an output signal of the OR circuit, which has a frequency twice that of the first clock signal. To be sampled at the second clock signal, the corrected sampling circuit which outputs a moving command signal, the control apparatus for a robot, characterized in that it comprises a.