Robot Servo Control for Reduction Gear Bending Compensation
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Solution Overview
Problem
In articulated robots, the bending of reduction gears due to gravitational and interference torques leads to position errors that are not accurately corrected by existing methods, which sum these torques, causing inaccuracies in robot arm positioning.
Innovation Solution
A robot control device that separates the gravitational and interference torques applied to the reduction gears, calculating distinct correction values for each to accurately correct the position command, thereby reducing the influence of bending on the robot arm's position accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the correction is based directly on the external torque (sum of gravitational and interference torques), then the correction process is simple, but the bending correction is not performed properly due to different bending behaviors between gravitational and interference torque components
Solution Approach 1:
The patent segments the external torque into two distinct components: gravitational torque and interference torque. Each component is calculated and corrected separately through dedicated correction means (gravitational torque correction means and interference torque correction means), allowing for precise correction of each torque's specific bending effect rather than treating them as a single combined torque.
2Manufacturing precision
If separate correction values are calculated for gravitational and interference torques, then the position error correction accuracy is improved, but the device complexity increases
Solution Approach 1:
The correction system is segmented into specialized sub-systems: gravitational torque correction means and interference torque correction means. Each sub-system is optimized for its specific torque type, improving correction accuracy while maintaining manageable complexity through functional specialization rather than a single complex correction mechanism.
Solution Approach 2:
The robot control device integrates multiple correction functions within a unified control architecture. The gravitational torque correction means and interference torque correction means operate within the same control device, sharing common resources such as the robot parameter storage and control processing capabilities, thereby achieving high correction accuracy without proportionally increasing overall device complexity.
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
A robot control device includes the following: a main control unit; a servo control unit, which receives a position command θc from the main control unit; and a bending correction block (24), which corrects the bending of the reduction gear connected to the servo motor. The bending correction block (24) includes the following: a first position-correction-value calculation means (63), which finds a first position-command correction value θsgc based on the position command θc; and a second position-command-correction-value calculation means (64), which finds a second position-command correction value θskc based on the interference torque τa. The servo control unit drives the servo motor based on a new position command obtained by adding the first position-command correction value θsgc and the second position-command correction value θskc to the position command θc.