Motor Servo Rigidity Tuning Using Frequency Response Measurement
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Solution Overview
Problem
Existing servo adjustment methods for motor driving devices require a long time due to the sequential increase of rigidity indices, which can lead to prolonged adjustment times and potential oscillation-induced damage.
Innovation Solution
A method and device that measure frequency characteristics, determine the highest rigidity based on these characteristics, and combine rigidity and command response indices to measure an evaluation index, allowing for direct determination of the highest rigidity without sequential index increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rigidity index is increased sequentially to search for the highest rigidity, then the rigidity determination is performed, but the time required for servo adjustment becomes long
Solution Approach 1:
The patent applies preliminary action by measuring the frequency characteristic of the motor operation amount with respect to the control command before determining the rigidity index. This frequency characteristic measurement provides advance information about the system's dynamic behavior, allowing the rigidity determination to be made directly based on this pre-acquired data rather than through sequential trial-and-error increases of the rigidity index. This preliminary measurement enables the system to jump directly to the optimal rigidity value, significantly reducing the adjustment time while maintaining determination accuracy.
2Measurement precision
If the sequential increase of rigidity indices is performed, then the rigidity determination is achieved, but oscillation-induced damage may occur
Solution Approach 1:
The patent applies feedback by utilizing the frequency characteristic measurement results to determine the appropriate rigidity index. The frequency characteristic provides information about the system's resonant frequencies and dynamic response, allowing the rigidity determination to account for these characteristics and avoid setting the rigidity index at values that would excite harmful oscillations. This feedback-based approach ensures that the rigidity is determined accurately while preventing oscillation-induced damage by selecting rigidity values that are consistent with the system's natural frequency characteristics.
3Productivity
If the frequency characteristic measurement is performed before rigidity determination, then the servo adjustment time is reduced, but the measurement process becomes more complex
Solution Approach 1:
The patent applies merging by combining the frequency characteristic measurement with the existing servo adjustment process. Instead of treating them as separate, independent measurement steps, the frequency characteristic measurement is integrated into the servo adjustment workflow, where the same control commands and operation amounts used for servo tuning are also used to acquire frequency characteristic data. This merging of measurement purposes reduces the overall complexity of the measurement process while maintaining high servo adjustment efficiency, as the system performs multiple functions using the same experimental setup and data collection procedure.
Data Source
AI summary
A servo adjustment method of a motor driving device includes a frequency characteristic measurement step, a rigidity determination step and an index measurement step. In frequency characteristic measurement step, the frequency characteristic of the motor operation amount with respect to the control command is measured. In rigidity determination step, the highest rigidity, which is the maximum candidate value satisfying the predetermined margin among the plurality of candidate values of the rigidity index, is determined based on the frequency characteristic. In index measurement step, the rigidity index and the command response index are combined to measure the evaluation index during the operation by the internal position command based on the command pattern or the external position command from the host device. In the servo adjustment method of the motor driving device, rigidity determination step is executed after frequency characteristic measurement step, and index measurement step is executed after rigidity determination step.