Robot Speed Reducer Error Identification Under Gravitational Torque
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Solution Overview
Problem
Robot control devices often fail to generate effective correction signals for canceling out error vibrations in speed reducers due to changes in gravitational torque, causing deviations in phase difference and amplitude values.
Innovation Solution
An angular transmission error identification system that uses periodic functions with phase and amplitude parameters corresponding to gravitational torque, allowing for accurate identification of angular transmission errors even when gravitational torque changes, and adjusts parameters based on whether the torque is positive or negative.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the phase difference and amplitude are set using fixed values or simple measurement methods, then the device complexity is reduced, but the manufacturing precision of the correction signal deteriorates when gravitational torque changes
Solution Approach 1:
The patent applies dynamics by making the phase difference and amplitude parameters variable rather than fixed. The system dynamically adjusts these parameters based on the gravitational torque acting on the joint, using different functions (first and second functions) to calculate appropriate values according to the current torque conditions, thereby maintaining correction precision across varying operational states
Solution Approach 2:
The patent implements parameter changes by modifying the phase difference and amplitude values based on gravitational torque variations. The correction signal generation unit changes these parameters according to calculated functions that account for torque magnitude and direction, ensuring accurate error vibration cancellation under different gravitational conditions
2Manufacturing precision
If the phase difference and amplitude are adjusted to accommodate gravitational torque changes, then the manufacturing precision of the correction signal is improved, but the device complexity increases
Solution Approach 1:
The patent manages parameter changes by implementing structured functions that calculate phase difference and amplitude based on gravitational torque. The system uses first and second functions selected according to torque conditions, providing a systematic approach to parameter adjustment that balances precision with manageable complexity
Solution Approach 2:
The patent handles dynamics by implementing real-time calculation of correction parameters based on current gravitational torque conditions. The correction signal generation unit dynamically selects and applies appropriate functions to maintain accurate angular transmission error identification across varying operational states
3Device complexity
If a single correction function is used for all gravitational torque conditions, then the device complexity is reduced, but the reliability of error vibration cancellation deteriorates when torque characteristics vary
Solution Approach 1:
The patent applies local quality by using different correction functions (first and second functions) for different gravitational torque conditions. Each function is optimized for specific torque ranges and characteristics, ensuring reliable error vibration cancellation tailored to local operational conditions rather than using a single generic function
Solution Approach 2:
The patent ensures reliability through parameter changes by selecting appropriate correction functions based on gravitational torque conditions. The system changes the correction parameters (phase difference and amplitude calculation methods) according to the specific torque state, maintaining effective error vibration cancellation across diverse operational scenarios
Data Source
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AI summary
Provided is an angular transmission error identification system that identifies an angular transmission error of a speed reducer (13) of a robot arm (4) including a joint (7) that is rotationally driven by a motor (11) via the speed reducer (13), the angular transmission error identification system including an identification unit (46) that calculates an amplitude parameter and a phase parameter of an angular transmission error identification function, which is a periodic function that models an angular transmission error of the speed reducer (13) and has the amplitude parameter and the phase parameter, and identifies the angular transmission error using the angular transmission error identification function, in which the identification unit (46) calculates an amplitude parameter corresponding to a gravitational torque current value which is a gravitational torque value acting on a joint when the angular transmission error is identified using a first amplitude function or a 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 phase function or a second phase function according to a value of the gravitational torque current value.