Servo Velocity Feedback Tuning for Response and Robustness
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Solution Overview
Problem
Existing servo control systems face challenges in independently adjusting the command response characteristic and robustness, making it difficult to maintain desired control characteristics while accommodating variations in motor load and disturbances.
Innovation Solution
A servo control device and method that incorporate a velocity feedback path with a first and second gain applied to pseudo-velocity, combined with a lowpass filter, allowing for independent adjustment of command response characteristic and robustness by modifying the transfer functions of the PI control and lowpass filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If P-PI control with model-based gain and filter element adjustment is used, then robustness to disturbance and load variation is improved, but the command response characteristic cannot be independently adjusted to the desired characteristic
Solution Approach 1:
The control system is segmented into two independent adjustment mechanisms: one for robustness (via inertia-based gain adjustment) and one for command response characteristic (via transfer function modification). This allows each aspect to be tuned separately without affecting the other.
Solution Approach 2:
The control system dynamically adapts gains and filter elements based on detected inertia, enabling the command response characteristic to be adjusted to match desired characteristics while maintaining robustness through automatic adaptation to load variations.
2Stability of the object's composition
If gain and filter element are varied according to load variation, then stable control is maintained, but the command response characteristic deviates from the desired model characteristic
Solution Approach 1:
The system uses feedback from inertia detection to automatically adjust gains and filter elements, ensuring that the command response characteristic accurately follows the desired model while maintaining stable control under varying load conditions.
3Ease of operation
If model parameters are adjusted to match desired transfer function, then command response characteristic is improved, but robustness to disturbance is varied and degraded
Solution Approach 1:
The adjustment mechanisms are segmented into independent components: one set of parameters (gains and filter elements) is adjusted based on inertia detection to maintain robustness, while another set is adjusted based on desired transfer function matching to achieve accurate command response characteristics.
Data Source
AI summary
A servo control device to execute an operation in a discrete time system may include a velocity feedback path having a difference means calculating a pseudo-velocity from a detected position and a lowpass filter, and a PI control means executing a proportional integration control operation on a deviation between the pseudo-velocity and the position deviation to create a drive command for the driver. The velocity feedback path includes a first gain means applying a first gain to the pseudo-velocity, a delay means delaying the pseudo-velocity, and a second gain means applying a second gain to the delayed pseudo-velocity. A sum of an output of the first gain means and the second gain means is inputted to the lowpass filter, and “Fa(z)=1/(1−z−1Fb(z))” is satisfied where a transfer function of the PI control means is Fa(z), and a transfer function of the lowpass filter is Fb(z).