Robot Joint Transmission Control With Adaptive Friction Estimation
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Solution Overview
Problem
Existing robot arm control systems face challenges in accurately compensating for varying friction in robot joint transmissions due to temperature changes and wear, which affects the precision and safety of robotic movements.
Innovation Solution
The implementation of an adaptive friction compensation method that estimates friction torque online using angular position measurements and mathematical models of the robot joint transmission, allowing for dynamic adaptation of motor control signals to account for changing friction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional static friction compensation is used in robot controller, then device complexity is reduced, but manufacturing precision and control accuracy deteriorate due to inability to account for friction variations caused by temperature and wear
Solution Approach 1:
The patent applies dynamics by transitioning from static friction compensation to dynamic adaptive friction compensation. The friction compensation values are continuously updated based on real-time motor torque and angular velocity measurements, allowing the control system to adapt to changing friction conditions caused by temperature variations and wear, thereby maintaining high control accuracy without requiring complex additional hardware
Solution Approach 2:
The patent implements feedback by using actual motor torque and angular velocity measurements to continuously update the friction compensation values. The controller compares the measured values with the dynamic model predictions and adjusts the friction compensation accordingly, creating a closed-loop system that maintains accuracy despite friction variations over time and operating conditions
2Measurement precision
If adaptive friction compensation is implemented to improve control precision, then measurement precision improves, but device complexity increases due to online estimation requirements
Solution Approach 1:
The patent applies self-service by using the robot arm's own operational data (motor torque and angular velocity measurements during normal operation) to estimate and compensate for friction. No separate calibration procedures, additional sensors, or external measurement equipment are required - the system uses its existing operational information to maintain high measurement precision for friction torque
Solution Approach 2:
The patent changes parameters by using dynamic friction compensation values that are continuously updated based on operating conditions rather than fixed static values. The friction compensation parameters are adjusted in real-time based on motor torque and angular velocity, allowing the system to adapt to temperature and wear variations without adding complex measurement equipment
3Reliability
If friction compensation is updated frequently to account for wear and temperature changes, then reliability improves, but use of energy increases due to continuous online estimation
Solution Approach 1:
The patent applies continuity of useful action by continuously updating friction compensation during normal robot operation without requiring separate calibration phases or interrupting the workflow. The adaptive friction compensation operates continuously in the background, maintaining reliability by constantly adapting to wear and temperature changes while using computational resources efficiently during regular operation
Data Source
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AI summary
A method of controlling a robot arm with robot joints, where the joint motors of the joints are controlled based on a signal generated based on the friction torque (formula I) of at least one of the input/outside of the robot joint transmission and the robot joint transmission torque (formula II) between the input side and the output side of the transmission. The friction torque is determined based on: at least two of the angular position of the motor axle; the angular position of the output axle and/or the motor torque provided to the motor axle by the joint motor. The robot joint transmission torque is determined based on : at least one of the angular position of the output axle; the angular position of the output axle and/or the angular position of the motor axle; the angular position of the motor axle and the motor torque provided to the motor axle by the joint motor.