Motor Drive Dynamic Offset Interpolation for Following Error Reduction
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Solution Overview
Problem
Motor control systems face challenges in achieving precise control and reducing following error due to the complexity of dynamic systems and the need for experienced technicians to tune gain values, which limits performance and increases the computational burden.
Innovation Solution
A motor drive system that interpolates and filters dynamic offset values at a faster update rate than the reference signal, using these values in combination with control loops to generate voltage or current references for improved motor control, reducing following error and simplifying the tuning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If dynamic offset values are provided at a slow update rate to reduce computational burden, then the external processing device and communication network are less burdened, but the motor control precision and following error reduction are compromised
Solution Approach 1:
The dynamic offset values are pre-calculated at a slower update rate by the external processing device, then interpolated at the faster servo update rate within the motor drive. This preliminary calculation approach reduces the computational burden on external devices while maintaining control precision through subsequent interpolation.
Solution Approach 2:
An interpolation mechanism acts as an intermediary between the slowly updated offset values and the fast control loops. The interpolator generates intermediate offset values at the servo update rate, bridging the gap between slow computation and fast control requirements.
2Measurement precision
If complex tuning of gain values is performed to improve motor control performance, then control precision is improved, but the complexity of the system and the need for experienced technicians increases
Solution Approach 1:
The system uses pre-calculated dynamic offset values that automatically compensate for system dynamics without requiring manual tuning of gain values. This self-adjusting approach improves control precision while reducing system complexity and eliminating the need for experienced technicians to perform complex tuning.
Solution Approach 2:
Instead of tuning multiple gain parameters in complex control loops, the system changes the approach by introducing dynamic offset values that directly compensate for system behavior. This parameter change simplifies the control structure while maintaining or improving precision.
3Loss of energy
If the offset signal is updated at the same slow rate as the reference signal, then communication bandwidth is reduced, but the following error increases due to insufficient update frequency
Solution Approach 1:
Offset values are pre-calculated at a slower rate and stored, then interpolated to generate the full sequence of offset values needed for high-frequency control. This preliminary calculation reduces communication bandwidth while maintaining reliability through interpolation.
Solution Approach 2:
The interpolation process ensures continuous availability of offset values at the required servo update rate, maintaining the continuity of useful action in the control loop without requiring continuous high-bandwidth communication of offset signals.
Data Source
AI summary
A system and method for motor control includes at least one dynamic offset value provided to a motor drive. Each dynamic offset value is determined by an external processing device and transmitted to the motor drive. The external processing device includes a rigid-body model of the motor and of the load controlled by the motor to generate each dynamic offset value. The dynamic offset value may be a position, velocity, or torque offset signal or a combination thereof. Each dynamic offset value and the desired motion profile are provided at a first update rate. The system control loops execute at a second update rate faster than the first update rate. Each dynamic offset value and the reference command are interpolated to generate values for each period of the second update rate. The interpolated values are provided to the system control loops to achieve desired performance of the motor.