Resolver Shaft Angle Error Compensation via Velocity Correction
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Solution Overview
Problem
Existing rotational angle sensing systems for rotating shafts, such as resolver assemblies, are prone to measurement errors due to manufacturing variations and mechanical alignment issues, affecting the accuracy of rotational angle and speed measurements in control systems.
Innovation Solution
A measurement system comprising a resolver assembly connected to an integrated circuit that calculates rotational angle errors by determining true angular velocity and applying velocity corrections, using equations to refine measurements and generate encoder emulation signals for precise position feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional rotational angle sensing systems (resolver assemblies) are used, then rotational angle measurement is provided, but measurement errors occur due to manufacturing variations and mechanical alignment issues
Solution Approach 1:
The system measures actual rotational angles at multiple discrete positions, calculates velocity between positions, determines velocity corrections, and generates rotational angle error terms that are fed back to correct future measurements. This closed-loop feedback mechanism continuously compensates for manufacturing variations and alignment errors, resolving the contradiction between providing measurement capability and eliminating measurement errors.
Solution Approach 2:
The invention changes the approach from direct single-point angle measurement to multi-point angular position measurement with velocity-based correction. By measuring at multiple discrete positions around the rotation and using velocity calculations between these positions, the system transforms the measurement process to identify and correct systematic errors, thereby improving measurement precision while accounting for manufacturing variations.
2Measurement precision
If multiple position sensing devices and tight machine tolerances are used, then measurement accuracy improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The system segments the rotational measurement into multiple discrete angular positions around the shaft rotation. By measuring at several specific positions rather than continuously, the system can calculate velocities between discrete points and determine corrections for each position. This segmentation approach achieves high accuracy without requiring multiple simultaneous sensing devices, reducing device complexity.
Solution Approach 2:
The system uses the resolver assembly's own output signals to generate correction terms. By processing the resolver's measured angular positions and calculating velocity-based corrections, the system self-corrects its measurement errors without requiring external calibration equipment or additional complex sensing mechanisms, thereby improving precision without proportionally increasing complexity.
3Measurement precision
If manual adjustments and post-assembly calibrations are performed, then measurement errors are corrected, but installation time and operational complexity increase
Solution Approach 1:
The system performs preliminary error characterization by measuring rotational angles at multiple discrete positions during a test run. These preliminary measurements are used to calculate velocity corrections and generate rotational angle error terms that are stored for future use. This preliminary action during installation eliminates the need for time-consuming manual adjustments and post-assembly calibrations, as the system automatically compensates for errors using the pre-calculated correction terms.
Solution Approach 2:
The system automatically performs what would traditionally require manual adjustment and calibration by using its own measurement data to generate correction terms. The controller automatically calculates velocity corrections between discrete positions and generates error compensation terms without requiring technician intervention, thereby maintaining measurement precision while eliminating time loss associated with manual calibration procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides accurate rotational angle and speed measurements by correcting for errors, ensuring reliable operation across a wide range of temperatures and improving control system performance.
Implementation Method 1
Resolver assemblies and other rotational sensing systems can provide precise measurement of the rotational angle
Data Source
AI summary
A rotatable shaft is equipped with a measurement device that generates output signals corresponding to discrete angular positions of the shaft. Rotational angles of the shaft are measured for a complete rotational period. A true angular velocity of the shaft is determined. Angular velocity is calculated between contiguous pairs of the discrete angular positions. A velocity correction is determined, and a rotational angle error term is determined based upon the velocity correction.