Robot Drift Compensation via Gearbox Temperature Estimation
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Solution Overview
Problem
Robot movement deviations caused by gearbox temperature variations lead to reduced precision in industrial robots, affecting product quality, despite existing solutions that do not effectively compensate for these temperature-induced drifts.
Innovation Solution
A device and method within the robot controller that includes a drift compensating unit, utilizing a grey-box dynamic model to estimate gearbox temperature effects, allowing for real-time adjustment of motor control values to counteract thermal drift, thereby improving positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gear box is used between the motor and robot section, then the robot can achieve controlled movement, but temperature variations in the gear box cause movement deviations and reduce precision
Solution Approach 1:
The patent applies parameter changes by using a grey-box dynamic model that calculates temperature-based compensation values. The model takes motor temperature as input and computes drift compensation parameters that are applied to adjust the robot's target positions, thereby compensating for thermal expansion effects in the gear box without changing the physical structure
Solution Approach 2:
The patent replaces mechanical temperature compensation mechanisms with a computational approach. Instead of using mechanical devices to physically compensate for thermal drift, the system uses software-based drift compensation calculations that process motor data and generate corrected position commands, substituting mechanical complexity with information processing
2Manufacturing precision
If temperature compensation is implemented using traditional methods, then some drift correction is achieved, but the solutions are complex and require additional hardware
Solution Approach 1:
The patent implements self-service by using the motor's own temperature data (which is already measured for control purposes) to compensate for gear box drift. The system serves itself by utilizing existing sensor data and internal processing capabilities, eliminating the need for separate temperature sensors or additional measurement hardware
Solution Approach 2:
The patent applies universality by making the motor serve multiple functions: it not only drives the robot section but also provides temperature information for drift compensation. The existing motor control system is extended to also perform temperature monitoring and drift calculation, making the motor a multi-functional component that reduces overall system complexity
3Manufacturing precision
If drift compensation is added to the robot controller, then positional accuracy improves, but implementation costs increase
Solution Approach 1:
The patent applies dynamics by implementing a dynamic drift compensation model that continuously adapts to changing operating conditions. The grey-box dynamic model updates compensation values in real-time based on motor temperature variations and operational parameters, allowing the system to maintain accuracy across different working conditions without requiring multiple fixed compensation mechanisms
Data Source
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AI summary
The invention concerns a method, device, and computer program product for compensating robot movement deviations caused by a gear box (20) as well as to a robot arrangement comprising such a device. The device (36) comprises a drift estimating block (42) configured to obtain motor data ( q r ) and motor torque data (τ) related to the motor (22), determine a measure of the temperature of the gear box (20) based on the motor data ( q r ) and motor torque data (τ) and estimate the drift ( Δq ) based on a drift value of the robot section, the drift value in turn being obtained based on the gearbox temperature measure and a gravitational torque (τ grav) of the motor, and a drift adjusting block (44) configured to adjust a control value ( q r ) used to control the positioning of the robot based on the estimated drift ( Δq ).