Pseudo-Velocity Servo Feedback for Independent 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
1Ease of operation
If a model is constructed for controlling a motor or robot and P-PI control is performed based on the model, then the control system can operate with basic stability, but it is still difficult to adjust the command response characteristic to the desired characteristic and the robustness cannot be independently adjusted from the command response characteristic
Solution Approach 1:
The control system is segmented into distinct functional blocks: a command response characteristic setting unit that independently sets command response parameters, a robustness setting unit that independently sets robustness parameters, and a control parameter generation unit that combines these parameters. This segmentation allows independent adjustment of command response characteristics and robustness without affecting each other, resolving the technical contradiction.
Solution Approach 2:
The control system dynamically generates control parameters by combining independently set command response parameters and robustness parameters. The control parameter generation unit creates time-varying control parameters that adapt to the desired command response characteristics while maintaining robustness, enabling flexible adjustment without system redesign.
2Reliability
If the robustness (disturbance characteristic) is adjusted, then the system can handle disturbances better, but the command response characteristic is varied and cannot be maintained
Solution Approach 1:
The control system separates robustness parameters from command response parameters into independent setting units. The robustness setting unit adjusts disturbance handling characteristics without affecting the command response setting unit, allowing robustness to be enhanced while maintaining desired command response characteristics through independent parameter adjustment.
Solution Approach 2:
The control system uses feedback mechanisms where the control parameter generation unit continuously combines command response parameters and robustness parameters to generate optimal control parameters. This feedback loop ensures that adjustments in robustness parameters do not degrade command response characteristics, as the system adapts parameters based on their interrelationships.
3Speed
If the command response characteristic is adjusted, then the system responds faster to commands, but the robustness is varied and cannot be maintained
Solution Approach 1:
The control system divides parameter adjustment into independent segments: command response characteristic setting for speed optimization and robustness setting for disturbance handling. This segmentation enables the command response speed to be increased through parameter adjustment without compromising robustness, as each aspect can be optimized independently and combined in the control parameter generation unit.
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).