Robot Speed Reducer Error Identification Under Changing Gravity Torque
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Solution Overview
Problem
Conventional robot control devices fail to accurately generate correction signals for canceling out error vibrations in speed reducers due to changes in gravitational torque, which affect the phase difference and amplitude of error vibrations.
Innovation Solution
An angular transmission error identification system that calculates amplitude and phase parameters using specific functions based on gravitational torque values, distinguishing between positive and negative torque ranges to model and identify angular transmission errors accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single amplitude function and phase function are used for all gravitational torque values, then the device complexity is reduced, but the identification accuracy deteriorates when gravitational torque changes
Solution Approach 1:
The gravitational torque range is segmented into multiple ranges (first range and second range), with each range having its own amplitude function and phase function. This segmentation allows the system to maintain high identification accuracy across different gravitational torque conditions while managing complexity through organized functional divisions.
Solution Approach 2:
The system dynamically selects appropriate amplitude and phase functions based on the current gravitational torque value. When gravitational torque changes, the system transitions between different function sets, enabling adaptive identification accuracy without requiring a single complex function to cover all conditions.
2Reliability
If the amplitude parameter and phase parameter are kept fixed, then the ease of operation is improved, but the reliability deteriorates when gravitational torque changes
Solution Approach 1:
The system incorporates gravitational torque value as feedback to dynamically determine the appropriate amplitude and phase parameters. The control device continuously monitors gravitational torque and selects corresponding functions from predefined sets, ensuring reliable error vibration cancellation without manual parameter adjustment.
Solution Approach 2:
The system changes parameters (amplitude and phase) based on gravitational torque conditions by selecting from multiple predefined function sets. This parameter adaptation maintains reliability across different operating conditions while keeping the implementation straightforward through predefined functional relationships.
3Measurement precision
If different amplitude functions and phase functions are used for different gravitational torque ranges, then the identification accuracy is improved, but the device complexity increases
Solution Approach 1:
The control system segments the gravitational torque operating range into distinct ranges, each with dedicated amplitude and phase functions. This segmentation improves identification accuracy within each range while managing overall system complexity through structured organization of multiple simple functions rather than one complex function.
Solution Approach 2:
The control device is designed with multi-functionality to handle different gravitational torque conditions using a unified architecture that selects from multiple amplitude and phase function sets. This universal design approach maintains identification accuracy across varying conditions without requiring separate control systems for each scenario.
Data Source
AI summary
An angular transmission error identification system that identifies an angular transmission error of a speed reducer of a robot arm including a joint that is rotationally driven by a motor via the speed reducer, including an identification unit that calculates amplitude and phase parameters of an angular transmission error identification function, which is a periodic function that models an angular transmission error of the speed reducer and has the parameters, and identifies the error using the function, wherein the unit calculates an amplitude parameter corresponding to a gravitational torque current value which is a value acting on a joint when the error is identified using a first or second amplitude function according to a value of the gravitational torque current value, and calculates a phase parameter corresponding to the gravitational torque current value using a first or second phase function according to a value of the gravitational torque current value.