Servo Gain Ratio Adjustment for Inertia Uncertainty
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Solution Overview
Problem
The existing control systems for servomotors face instability and overshoot issues when the set inertia value deviates from the actual inertia value, leading to oscillations and sudden changes in operation during adjustments of control parameters.
Innovation Solution
An adjustment apparatus that adjusts the position proportional gain and velocity proportional gain in parallel, setting their ratio to a value smaller than when the actual inertia value is determined, and gradually increasing these gains to prevent overshoot and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the servo driver sets the inertia value independently of the position gain and velocity gain, then the adjustment process is simplified and more autonomous, but the control stability deteriorates when the set inertia value deviates from the actual inertia value
Solution Approach 1:
The patent merges the adjustment of position gain and velocity gain into a unified process controlled by a single ratio parameter. When the inertia value is yet to be determined, the gain adjustment unit sets the ratio of position proportional gain to velocity proportional gain to a value smaller than the ratio set when the inertia value is determined, thereby coordinating both gain adjustments together to maintain control stability.
Solution Approach 2:
The patent changes the ratio parameter of position gain to velocity gain based on the determination status of the inertia value. By adjusting this ratio parameter to be smaller when inertia is undetermined, the system adapts the control characteristics to match the current state of knowledge, preventing instability caused by parameter mismatches.
2Manufacturing precision
If the position proportional gain and velocity proportional gain are adjusted independently, then each gain can be optimized separately, but the control system becomes more complex and adjustment becomes difficult
Solution Approach 1:
The patent combines the adjustment of position proportional gain and velocity proportional gain into a single coordinated process by controlling their ratio. This merging approach maintains the ability to optimize both gains while simplifying the adjustment procedure to a single parameter control, reducing the complexity of the adjustment process.
3Speed
If the ratio of position proportional gain to velocity proportional gain is set to the standard value when inertia is undetermined, then the control response is faster, but overshoot and oscillation occur
Solution Approach 1:
The patent changes the ratio parameter of position gain to velocity gain based on the inertia determination status. When inertia is yet to be determined, the ratio is set to a smaller value than the standard ratio used when inertia is determined. This parameter adjustment slows down the control response slightly but prevents overshoot and oscillation, thereby improving reliability during the adjustment phase.
Data Source
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AI summary
Control that is less likely to cause an overshoot is performed when an actual inertia value is yet to be determined. A development support apparatus (10) sets a ratio of a position proportional gain to a velocity proportional gain to a value smaller than a ratio set when a servo driver (20) has determined an actual inertia value of a load machine (40).