Frequency Response Identification With Static Friction Compensation
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Solution Overview
Problem
Existing frequency response function identification systems fail to account for the influence of friction, particularly static friction, leading to increased identification errors.
Innovation Solution
A frequency response function identification system that estimates and subtracts static frictional force from the driving force, using a static friction model to facilitate accurate identification through local frequency modeling, thereby reducing processing load and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If friction influence is not considered in frequency response function identification, then the system construction is simple, but the identification accuracy deteriorates
Solution Approach 1:
The patent segments the friction force into two distinct components: static friction and dynamic friction. This segmentation allows the system to handle each friction type separately through dedicated estimation units, improving identification accuracy while maintaining manageable system complexity through modular architecture
Solution Approach 2:
The patent introduces an intermediary friction estimation and compensation mechanism between the driving force input and the frequency response identification process. The estimation units act as intermediaries that calculate friction forces based on state values, and the compensation unit subtracts these estimates from the driving force to obtain corrected effective driving force for accurate identification
2Measurement precision
If both static friction and dynamic friction are considered, then the identification accuracy improves, but the processing load increases
Solution Approach 1:
The patent divides the friction compensation task into separate processing units for static friction and dynamic friction. This segmentation allows independent optimization of each estimation process and enables parallel processing, reducing overall computational burden while maintaining high identification accuracy through comprehensive friction consideration
3Measurement precision
If a comprehensive friction model is used, then the identification accuracy improves, but the model construction complexity increases
Solution Approach 1:
The patent constructs friction models by segmenting them into static friction model and dynamic friction model components. Each model uses specific state variables appropriate to its friction type, simplifying the construction process for each individual model while achieving comprehensive friction compensation through their combination
Solution Approach 2:
The patent introduces intermediary estimation units that serve as mediators between the complex friction physics and the frequency response identification process. These units implement simplified friction models that capture essential friction behavior without requiring complex construction, making the overall system more manageable while maintaining accuracy
Data Source
AI summary
A frequency response function identification system 1 includes: an observer 14 that generates an estimated effective torque u{circumflex over ( )}e based on a torque command value ur and a motor angular displacement θM; and an identification unit 15 that identifies a frequency response function based on the estimated effective torque u{circumflex over ( )}e and the motor angular displacement θM. The observer 14 includes: an estimation unit 41 that estimates an estimated motor torque u{circumflex over ( )} from the torque command value ur; a static friction model 42 that outputs an estimated static frictional force τ{circumflex over ( )}f based on the motor angular displacement θM; and a calculation unit 43 that calculates the estimated effective torque u{circumflex over ( )}e based on the estimated motor torque u{circumflex over ( )} and the estimated static frictional force τ{circumflex over ( )}f. The identification unit 15 identifies the frequency response function from the estimated effective torque u{circumflex over ( )}e and the motor angular displacement θM using a local frequency modeling method.