JP3457019B2 - Tracing control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a robot that performs a copying operation such as welding, fusing, painting, and applying an adhesive, and a control method for a copying machine tool. 2. Description of the Related Art A conventional copying control method, and stores target command obtained by teaching or math, and methods used during copying operation (first method), to some extent modify the target command by the sensor information Method (second method )
And a method using only a sensor signal (third method ). [0003] However, in the first method of the prior art which does not use a sensor, it takes time and effort to create a target command, cannot adapt to installation errors, and requires a large amount of memory. There were problems such as doing. In the second and third methods using sensors, the target command of the current follow-up operating point is used, but the target command of the future time is used positively. Since no attempt has been made to eliminate the delay, it has been necessary to delay the copying operation to such an extent that the delay of the copying operation drive axis can be ignored. On the other hand, the copying control robot disclosed in Japanese Patent Application Laid-Open No. 2-15956 uses a future position / future posture, but a future target position command is not detected by a sensor, but is stored in advance. Alternatively, since it is calculated from the current position, it does not predict future follow-up deviation and does not perform correction so as to minimize the predicted value, there will be a delay between the target value and the hand Is similar. Accordingly, it is an object of the present invention to provide a tracking control method that eliminates a delay of a servo system of a tracking operation drive shaft. [0004] In order to solve the above problems, the present invention outputs a correction command so as to level the position of a control target in accordance with a target position command obtained by a sensor. In the copying control system, a target position command up to several steps in the future is obtained by a sensor during a copying operation, and a correction command is output by preview / prediction control to operate the control target. [0005] According to the above-mentioned means, since the delay of the servo system of the drive shaft for tracing operation is eliminated, the tracing operation with higher speed and higher accuracy can be performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is a block diagram in the case where the copying operation is performed by one motor. Here, 1 is a preview controller, which is a target command r up to the M-step future.
(i), r (i + 1),..., r (i + M)
The position signal y (i) from the position detector 4 is input, and a correction command u (i) determined to minimize the predicted follow-up deviation at the future time is output. The correction command u (i) is located
Directive . For example, according to the method invented by the present applicant, the correction instruction is given by the following equation. [0007] Here, qm, Q, and gn are constants determined from the step response of the controlled object. Also, the target command to be input is only r (i + M) of the M step future time,
r (i), r (i + 1),..., r (i + M-1) may be stored in the preview controller. Reference numeral 2 denotes a controller for the follow-up drive shaft motor 3, reference numeral 5 denotes a sensor for obtaining a future target value, and reference numeral 6 denotes a signal processing circuit. Copying drive shaft motor controller 2
Is a correction command u which is a position command as described above.
(i) is driven to drive the operation axis motor 3. Next, when the present invention is applied to a copying machine tool,
FIG. 2 shows an example of such a case . Reference numeral 11 denotes a sensor that detects a distance from the model 14 and is fixed to the disk 12. Disk 12
Is rotated by the T-axis motor so that the sensor 11 is always on the operating point following the M-step future time. In addition,
The Z-axis motor of the machine tool according to the present invention is shown in FIG.
1 corresponds to the motor 3. A spindle 13 for rotating the ball end mill 16 is connected to a T-axis motor.
The Z-axis motor of the tracing drive shaft moves in the vertical direction. An XY table 17 moves the model 14 and the work 15 in the horizontal direction. Sensor 11 at time i
Let a (i + M) be the output signal of A, A be the ideal distance between the sensor and the model, and z (i) be the output signal of the position detector of the z-axis motor. r (i +
M) can be obtained by r (i + M) = z (i) + a (i + M) -A, so that the tracing operation is performed by moving the Z axis of the tracing drive shaft in the configuration shown in FIG. Is performed. Note that the output signal z (i) of the position detector of the z-axis motor
Is equivalent to the position signal y (i) in FIG.
it is obvious. When the speed of the XY table changes, change the value of M or attach a plurality of sensors,
The response may be obtained by moving the sensor in the radial direction. FIG. 3 shows an embodiment in which the present invention is applied to a robot that performs a following operation. Using the future target command 10 obtained from the visual sensor 31, the target command of the arm 33 is corrected by the preview control so that the tip of the end effector 32 moves along the object 34. As described above, according to the present invention, by utilizing the target command of the future time obtained by the sensor,
The preview control eliminates the delay of the servo system of the tracing operation drive axis, so that there is an effect that a tracing control system that performs a higher-speed and higher-precision tracing operation is realized.

[Brief description of the drawings] FIG. 1 shows a specific embodiment of the present invention. FIG. 2 is a diagram showing a specific embodiment of the present invention. FIG. 3 is a diagram showing a specific embodiment of the present invention. [Explanation of symbols] 1 preview controller 2 Copying axis motor controller 3 Copying axis motor 4 Position detector 5 Sensor 6. Sensor signal processing circuit

Claims (1)

(57) [Claim 1] A correction command is output according to a target position command obtained by a sensor so as to level the position of a controlled object .
In that copying control system, when the copying operation, the sensor detects a target position command to several steps future control operation period, as the target command the target position command, tracking error future time predicted, i.e., the target Command and the position of the controlled object
A control method characterized by operating a controlled object by a preview / prediction control that outputs a correction command determined to minimize a deviation from the position .