Distributed Multi-Axis Motion Control for Coupling Force Compensation
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Solution Overview
Problem
Existing multi-axis motion control systems require complex and costly dedicated computation devices to manage dynamic models, leading to reduced performance due to open-loop torque commands and limited position loop update rates, which are sensitive to errors and drift in operating parameters.
Innovation Solution
A distributed multi-axis motion control system where each motor drive determines its motion state based on axis commands and shares this information with adjacent drives, using velocity, acceleration, and wrench matrices to dynamically adjust torque and compensate for coupling forces, thereby reducing the need for centralized computation and enhancing control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated computation device is used to manage dynamic models for multi-axis motion control, then control coverage is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the centralized dynamic model management into distributed components, with each motor drive controlling its own axis while exchanging motion state information with adjacent drives. This segmentation eliminates the need for a dedicated computation device while maintaining control coverage through decentralized decision-making.
Solution Approach 2:
Each motor drive independently determines its own motion state and compensates for coupling forces using information from adjacent axes. The system serves itself by having each component manage its own control functions rather than relying on external centralized computation.
2Ease of manufacture
If open-loop torque commands are used in centralized control, then implementation is simplified, but control precision deteriorates due to sensitivity to errors and drift
Solution Approach 1:
The patent implements closed-loop control where each motor drive continuously determines its motion state based on axis commands and feedback from adjacent drives. This feedback mechanism compensates for errors and drift in real-time, maintaining control precision without sacrificing implementation simplicity.
3Stability of the object's composition
If position loop update rates are limited in centralized control, then system stability is maintained, but productivity decreases
Solution Approach 1:
The patent segments the control system into independent motor drives that operate in parallel, allowing each to execute control loops at high update rates without compromising overall system stability. This distributed architecture enables faster productivity while maintaining stability through decentralized control.
4Reliability
If a centralized dynamic model is used, then comprehensive control is achieved, but loss of time occurs due to centralized computation bottlenecks
Solution Approach 1:
The patent distributes the dynamic model computation across multiple independent motor drives, eliminating centralized computation bottlenecks. Each drive simultaneously processes its own control calculations while exchanging necessary motion state information, achieving comprehensive control without time loss.
Data Source
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AI summary
A system for distributed multi-axis motion control includes a controller having a memory configured to store a control program and a processor configured to execute the control program. A desired motion trajectory is determined for a multi-axis system having multiple axes, and an axis command is generated for each of the axes as a function of the desired motion trajectory. The system also includes multiple motors and multiple motor drives. Each of the motors corresponds to one axis for the multi-axis system, and each of the motor drives controls at least one of the motors responsive to receiving the axis command for the corresponding motor. Each of the motor drives also determines a motion state for a link driven by the motor as a function of the axis command and transmits at least a portion of the motion state to another motor drive controlling another axis.