Motor Controller Dynamic Time Constant Adjustment
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Solution Overview
Problem
Conventional motor controllers face challenges in determining an appropriate acceleration/deceleration time constant, leading to instability and reduced machining efficiency, as they either require additional sensors or simply adjust control parameters without ensuring physical operational feasibility.
Innovation Solution
A motor controller that includes an acceleration/deceleration time constant storing unit, a position command creating unit, a position detection unit, a speed command creating unit, an ideal response computing unit, and a response comparing unit, which uses a low-pass filter to compute and compare ideal and actual responses, adjusting the time constant based on inertia estimation to ensure stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the acceleration time is made short to improve machining efficiency, then productivity increases, but position control stability deteriorates causing vibration
Solution Approach 1:
The system dynamically adjusts the acceleration/deceleration time constant based on the detected load inertia. When heavy load is detected, a longer time constant is applied to maintain stability; when light load is detected, a shorter time constant enables faster acceleration. This dynamic adaptation resolves the contradiction by making the time constant variable rather than fixed.
Solution Approach 2:
The invention changes the control parameter (acceleration/deceleration time constant) based on the detected load conditions. By estimating load inertia from motor current and speed feedback, the system selects appropriate time constant values to optimize both productivity and stability for different operating conditions.
2Stability of the object's composition
If the acceleration/deceleration time constant is set to ensure control stability, then position control stability is maintained, but machining efficiency decreases due to longer acceleration time
Solution Approach 1:
The system uses dynamic parameter adjustment based on real-time load detection. Instead of using a conservative fixed time constant that limits acceleration for all conditions, the system adapts the time constant to match actual load requirements, enabling faster acceleration when possible while maintaining stability when needed.
Solution Approach 2:
The system automatically detects load inertia and self-adjusts the acceleration/deceleration time constant without external intervention. This self-service capability allows the system to optimize its own performance parameters based on actual operating conditions, eliminating the need for manual tuning or conservative default settings.
3Reliability
If conventional parameter adjustment methods are used to improve tracking ability, then control performance improves, but the command trajectory is altered and physical operational feasibility is lost
Solution Approach 1:
The invention separates the command trajectory generation from the control parameter adjustment. The position command creating unit generates physically accurate command trajectories based on actual machine characteristics, while the response comparing unit and time constant adjusting unit independently optimize control performance by adjusting the time constant. This segmentation preserves physical feasibility while improving control reliability.
Solution Approach 2:
The system uses feedback from the response comparing unit to detect deviations between ideal and actual responses. This feedback drives automatic adjustment of the acceleration/deceleration time constant without modifying the original command trajectory, thereby maintaining physical operational feasibility while improving tracking ability.
4Measurement precision
If additional sensors such as acceleration detectors are added to detect acceleration for gain correction, then measurement precision improves, but device complexity increases
Solution Approach 1:
The invention uses motor current as an intermediary to indirectly measure load inertia and acceleration characteristics. Instead of directly measuring acceleration with additional sensors, the system infers mechanical state from electrical measurements (current and speed), which are already available in the motor control system. This intermediary approach provides the needed information without adding hardware complexity.
Solution Approach 2:
The system replaces mechanical measurement devices (acceleration sensors, position sensors on load) with electrical measurement-based estimation. By using motor current and speed feedback to calculate load inertia and detect acceleration, the invention substitutes complex mechanical sensing systems with simpler electrical measurements and computational estimation.
Data Source
AI summary
A controller of a motor includes: an acceleration/deceleration time constant storing unit that stores an acceleration/deceleration time constant; a position command creating unit that creates a position command value based on the acceleration/deceleration time constant; a position detection unit that detects a rotation position of the motor; a speed command creating unit that creates a speed command for the motor on the basis of the position command value and a position detection value detected by the position detection unit; an ideal response computing unit that computes an ideal response from the position command value; and a response comparing unit that compares the ideal response with an actual response detected by the position detection unit. The response comparing unit changes the acceleration/deceleration time constant stored in the acceleration/deceleration time constant storing unit when it is determined that the ideal response does not match the actual response.