JP2778285B2 - Copying sensor robot system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying type sensor robot system used for welding, cutting, polishing and the like.

[0002]

2. Description of the Related Art In a copying sensor robot system, a displacement of a work target with respect to a working point of a robot is detected by a copying sensor, and this is fed back to a robot trajectory calculation to correct a position in real time, thereby improving work quality. It is intended to improve.

[0003] The displacement of the work object from the work point of the robot is usually obtained in a coordinate system determined by a tool at the tip of the robot. This shift is converted to the Cartesian coordinates of the robot,
In the interpolation calculation for calculating the position of the robot at regular intervals, the target position calculated next is corrected. The corrected target position is converted into the position of each axis of the robot to realize the copying.

The flow of trajectory calculation control of a robot controller in a conventional scanning sensor robot system will be described with reference to the block diagram of FIG.

In FIG. 3, a trajectory calculation unit 3 calculates the position of the robot 11 at regular intervals with reference to a program stored in a storage unit (not shown) which is taught. The coordinate conversion unit A4 converts the output of the trajectory calculation unit 3 into the position of each operation axis of the robot 11. The servo controller 9 controls the position of each operation axis of the robot 11 via the servo amplifier 10 according to the output of the coordinate converter A4. Also, the locus correction unit 8
Indicates that the output of the copying sensor 1 obtained from the coordinate conversion unit B6 is fed back to the trajectory calculation unit 3 to realize the copying.
Reference numeral 5 denotes a sensor control unit that outputs a position correction amount in the wrist coordinate system of the robot 11 from the output of the scanning sensor 1, and 6
Denotes a coordinate conversion unit B for converting the output of the sensor control unit 5 into the reference coordinate system of the robot, and 15 denotes a robot control device.

[0006]

For example, in the case of a 6-axis vertical multi-indirect robot, the interpolation calculation is usually about several tens of msec with the current microcomputer, so that the trajectory calculation is corrected to be much larger than the deviation from the scanning sensor. It takes a maximum of several tens of msec to complete. In addition, slow acceleration / deceleration,
Including the response delay such as the servo control and the communication overhead, the response time until the position of the robot is actually corrected takes about 100 msec. That is,
The dead time during which the robot does not respond to the output of the copying sensor is about 100 msec.

If the response of the robot to the output of the copying sensor is delayed, the deviation between the working point and the recognized position increases. For this reason, as the work speed increases, the work quality deteriorates, such as a decrease in the scanning accuracy and a meandering locus. Therefore, the response time of the robot is one of the factors that greatly affect the speeding up of work in the copying sensor robot system. For the scanning sensor robot,
In a situation where high speed is required, speeding up the response of the scanning sensor is a major issue.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scanning sensor robot system in which the response time of the robot scanning control is greatly reduced, and the scanning accuracy is not reduced and the locus does not meander even during high-speed operation.

[0009]

According to the present invention, in order to achieve the above object, the output of a conventional copying sensor is converted into a reference coordinate system of a robot by a coordinate conversion unit B, and the coordinate conversion unit B
The output of the trajectory correction unit is input to the trajectory correction unit, the trajectory correction unit corrects the motion trajectory, and the output data of the trajectory correction unit is fed back to the trajectory calculation unit. A, the position of each motion axis of the robot is converted, and the output of the coordinate conversion unit A is input to the servo control unit, and at the same time, the output data of the trajectory correction unit is output to the trajectory calculation unit.
The robot controller is configured to directly feed back to the servo controller independently of the output .

[0010]

As is apparent from FIG. 3, conventionally, since the position is corrected in synchronization with the cycle of the trajectory calculation unit, the processing of the trajectory calculation unit must be performed at high speed in order to shorten the response time. Was. However, since this is determined by the performance of the microcomputer, there is a limit to speeding up.

On the other hand, in the present invention, as is apparent from FIG. 1, the position correction is executed independently of the trajectory calculation and asynchronously. Therefore, it is possible to shorten the response time by increasing the speed of the position correction processing (e.g., increasing the priority of the processing, shortening the processing time by using an approximation algorithm).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of a scanning sensor robot system according to the present invention, application of a six-axis articulated arc welding robot to an arc sensor system will be described.

The arc sensor obtains positional information of a groove of a weld joint in a welding operation based on a welding signal (welding current, arc voltage, etc.) of an arc welding machine.
In arc welding robot systems, it is the most practical welding line tracking sensor at present. FIG. 2 shows the configuration of the present system.

The arc welding robot 14 is controlled by the robot controller 2. In the robot control device 2, the trajectory calculation unit 3 calculates the position of the arc welding robot 14 at regular intervals in the orthogonal coordinate system with reference to an operation program stored in a storage unit (not shown). The coordinate conversion unit A4 converts the output of the orthogonal coordinate system of the trajectory calculation unit 3 into the position of each operation axis of the arc welding robot 14. The servo controller 9 controls the position of each operation axis of the arc welding robot 14 according to the output of the coordinate converter A4. The output of the servo control unit 9 is transmitted to the arc welding robot 1 via the servo amplifier 10.
Sent to 4.

Regarding the scanning control, the arc sensor 13
Detects the welding signal of the arc welding machine 12, and recognizes the position of the welding line in the wrist coordinate system by the sensor control unit 5. The coordinate conversion unit B6 converts the wrist coordinate system output of the sensor control unit 5 into a rectangular coordinate system, and the coordinate conversion unit C7 converts the rectangular coordinate system output of the coordinate conversion unit B6 into a joint coordinate system. The trajectory correction unit 8 sends the output of the coordinate conversion unit C7 to the servo control unit 9.
With the configuration described above, welding line scanning is realized by a scanning sensor robot system using an arc sensor.

FIG. 1 shows the scanning sensor 1 as an arc sensor 13.
FIG. 2 is a block diagram showing a configuration of a general copying sensor robot system in which the robot 11 is not limited to the arc welding robot 14, respectively. 1 is the same as the configuration in FIG. 2 except for the sensor 1 and the robot 11, and has the same function.

[0017]

As is apparent from the above description, according to the present invention, since the position is corrected by the scanning sensor independently of the normal trajectory control, the response time of the scanning control can be shortened. As a result, the copying accuracy at the time of high-speed operation of the robot is improved, and workability is improved, and at the same time, work quality can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a general embodiment of a scanning sensor robot system according to the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment using an arc sensor in the scanning sensor robot system of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional scanning sensor robot system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 scanning sensor 2 robot control device 3 trajectory calculation unit 4 coordinate conversion unit A 5 sensor control unit 6 coordinate conversion unit B 7 coordinate conversion unit C 8 trajectory correction unit 9 servo control unit 10 servo amplifier 11 robot

Claims (1)

(57) [Claims] A robot having a plurality of motion axes, a scanning sensor for outputting position information of a work target with respect to a work point of the robot, and a robot control device;
A trajectory calculation unit for calculating a motion trajectory of the robot in the basic coordinate system of the robot, a coordinate conversion unit A for converting an output of the trajectory calculation unit into a position of each motion axis of the robot,
A servo control unit that controls each operation axis of the robot based on the output of the coordinate conversion unit A; a servo amplifier that controls a servo motor that drives each operation axis of the robot based on the output of the servo control unit; A sensor control unit that outputs a position correction amount in the robot's wrist coordinate system from an output of the scanning sensor, a coordinate conversion unit B that converts the output of the sensor control unit into a reference coordinate system of the robot, and an output of the coordinate conversion unit B And a trajectory correction unit for correcting a motion trajectory based on the output of the coordinate conversion unit C. The output of the trajectory correction unit is calculated by the trajectory calculation. Part of
A scanning sensor robot system that performs position correction by feeding back to the servo control unit independently of output .