Linear Motor Speed Controller with Integral Value Storage
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Solution Overview
Problem
The responsiveness of linear motors is compromised when correcting for external forces like gravity, as it reduces the thrust force and can lead to delayed responses due to the need to cancel out these forces with current adjustments.
Innovation Solution
A control device and method that includes a speed controller, current controller, and correction value storage unit, which calculates and stores integral values to improve responsiveness by setting initial values for integration operations when resuming control or changing directions, thereby enhancing the motor's ability to maintain position without relying on external force cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current value is corrected to generate a thrust force that cancels out external force, then the movable element can maintain position against gravity, but the thrust force for moving the movable element is reduced and response is delayed
Solution Approach 1:
The patent applies preliminary action by storing the integral value from the speed controller before resuming control or changing direction. This pre-stored value represents the accumulated correction needed to counteract external forces like gravity. When control resumes or direction changes, this pre-calculated integral value is immediately applied as the initial value, allowing the system to instantly compensate for external forces without waiting for the integration to build up gradually. This eliminates the delay that would otherwise occur while the integral term develops, thus improving response speed while maintaining position stability.
2Stability of the object's composition
If the current value is corrected to cancel out external force, then position stability is improved, but the thrust force available for movement is reduced
Solution Approach 1:
The patent resolves this contradiction by pre-calculating and storing the integral value that represents the exact correction needed to counteract external forces. This pre-computed value is then immediately applied when control resumes or direction changes, providing instant position stability without requiring a gradual build-up of the integral term. The stored integral value ensures that the full thrust force is available for movement while simultaneously providing the necessary correction for position stability.
Data Source
AI summary
A control device for a linear motor includes a speed controller that calculates a current command value by an integration operation using a first integral value of a difference between a moving speed of a movable element provided in the linear motor and a speed command value calculated on the basis of a position command value, a current controller that applies a voltage to the linear motor on the basis of the current command value, and a correction value storage unit that stores the first integral value of the speed controller when the movable element remains at a position indicated by the position command value. When resuming control of the linear motor, the speed controller sets the first integral value stored in the correction value storage unit as an initial value for the integration operation before the brake controller turns off the brake device.