Servo Motor Control Device Sliding Mode Feedforward
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Solution Overview
Problem
Conventional servo motor control devices using model following control face issues with overshoot and hunting due to torque limitations, requiring users to be aware of the maximum torque output, which limits position and velocity followability.
Innovation Solution
A control device employing a feedforward controller that uses sliding mode control to manage model position, velocity, and torque, allowing the servo motor to operate within its maximum torque capabilities without user awareness, combined with a feedback controller for PID control to ensure accurate position and velocity tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a torque limiter is provided to limit the torque output from the model, then the torque output from the model is limited, but position followability and velocity followability are not ensured due to the torque limitation, so that a deviation increases
Solution Approach 1:
The feedforward controller generates the model orbit (model position and model velocity) in advance such that the model torque does not exceed the maximum torque that can be output from the servo motor. By pre-planning the trajectory to respect torque constraints, the system avoids the need for torque limitation during execution while maintaining position and velocity followability.
2Ease of operation
If PID control is used to control the model position and model velocity, then the position and velocity can be controlled, but when the model torque exceeds the maximum torque, the feedback controller cannot follow the orbit output from the model, so that overshoot and hunting occur
Solution Approach 1:
The feedforward controller pre-generates the model orbit ensuring that the required torque never exceeds the servo motor's maximum torque capability. This preliminary planning prevents the situation where PID feedback control would fail to track the orbit due to torque saturation, thereby eliminating overshoot and hunting while maintaining ease of operation.
3Force
If the user provides the position command value while being conscious of the maximum torque, then the torque can be managed, but the user operation becomes complex and position followability deteriorates
Solution Approach 1:
The feedforward controller automatically manages torque constraints by generating the model orbit within the servo motor's torque capabilities without requiring user intervention. The system self-regulates to ensure torque limits are respected while maintaining simple user operation through standard position command input.
Data Source
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AI summary
A user can cause a servo motor to perform desired operation without occurrence of overshoot and hunting while being unconscious of a maximum torque that can be output from the servo motor. A control device that implements model following control includes a feedforward controller that implements sliding mode control.