Multi-Motor Force Synchronization With Dual-Loop Feedback
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Solution Overview
Problem
Existing multi-motor synchronization systems face challenges in achieving accurate force control and synchronization, particularly in scenarios requiring high power and limited space, with traditional torque measurement methods being costly and inefficient.
Innovation Solution
A dual-loop feedback control system is implemented, comprising an external loop for synchronization error and an internal loop for output force error, utilizing encoders and springs to measure and adjust motor displacement, velocity, and force, respectively, ensuring precise force control and synchronization among multiple motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional torque measurement methods (current or force sensor) are used, then torque can be measured, but the cost increases significantly
Solution Approach 1:
The patent uses motor current as a substitute (copy) for direct torque measurement through force sensors. By calculating torque from easily measurable current data through established relationships, the system achieves torque measurement functionality without the high cost of force sensors, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces the mechanical force sensor measurement system with an electrical measurement system based on motor current. This substitution eliminates the need for additional mechanical sensors while maintaining torque measurement capability, thereby reducing cost and device complexity while preserving measurement functionality
2Force
If multiple parallel motors are used to output large torque in limited height, then torque requirement is met, but synchronization control difficulty increases
Solution Approach 1:
The patent implements a master-slave synchronization control system where the master motor's position and speed are continuously monitored and fed back to control the slave motors. This feedback mechanism ensures all motors maintain synchronized operation despite individual variations, resolving the contradiction between achieving high torque through multiple motors and maintaining synchronization control
Solution Approach 2:
The patent employs different control modes (position control, speed control, torque control) for different motors in the parallel system. By assigning specific control characteristics to each motor based on its role (master or slave), the system achieves coordinated operation that maintains synchronization while delivering the required combined torque output
3Manufacturing precision
If position control mode is used for multi-motor synchronization, then displacement and velocity synchronization can be achieved, but accurate force control becomes difficult
Solution Approach 1:
The patent merges position control and force control into a unified master-slave synchronization system. The master motor operates in position control mode to ensure synchronization, while the slave motors operate in torque control mode with their torque commands derived from the master's position feedback. This combination allows the system to achieve both displacement/velocity synchronization and accurate force control simultaneously
Solution Approach 2:
The patent applies asymmetric control strategies to different motors: the master motor uses position control for synchronization reference, while slave motors use torque control for force accuracy. This asymmetric assignment of control modes to different motor roles enables the system to achieve both synchronization precision and force control accuracy that would be difficult to obtain with uniform control approaches
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves accurate force control and synchronization of multiple motors, reducing mechanical stress and deformation, and meeting industrial needs in limited spaces with improved efficiency and cost-effectiveness.
Implementation Method 1
measuring, by an encoder provided in each of the plurality of motors, the displacement and velocity of each of the plurality of motors in real-time
Implementation Method 2
acquiring an actual output force of each of the plurality of motors by measuring the deformation of a spring provided at a free end of each of the plurality of motors in real-time
Data Source
AI summary
A force control method and system for multi-motor synchronization is provided. The force control method includes: acquiring a total desired force of a plurality of motors; calculating the desired force of each of the plurality of motors according to a characteristic of each of the plurality of motors; setting an external feedback loop for controlling each of the plurality of motors to operate according to the desired force, and taking a synchronization error of each of the plurality of motors as a feedback item of the external feedback loop; and setting an internal feedback loop for controlling each of the plurality of motors to operate according to the desired force, and taking an output force error of each of the plurality of motors as a feedback item of the internal feedback loop. The force control method and system ensures multi-motor synchronization under the premise of accurate force control.