Multi-Motor Force Synchronization With Dual-Loop Feedback Control

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Solution Overview

Problem

Existing multi-motor synchronization systems face challenges in achieving accurate force control and synchronization, particularly in high-power applications, due to the high cost and limitations of traditional torque measurement methods.

Innovation Solution

A dual-loop feedback control system is implemented, where an external loop adjusts for synchronization errors based on displacement and velocity, and an internal loop adjusts for output force errors using a spring to measure deformation, ensuring precise force control and synchronization among multiple motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional torque measurement methods (current or force sensor) are used, then torque can be measured, but the cost is high and application is limited

Engineering Contradiction:
Improvetorque measurementVSAvoidcost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical torque measurement methods (force sensors) with an electronic solution based on motor current detection and mathematical calculation. The torque is derived from the relationship between motor current, speed, and power characteristics, eliminating the need for expensive physical torque sensors while maintaining measurement accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces motor current as an intermediary parameter to indirectly measure torque. Instead of directly measuring torque with a sensor, the system uses current detection combined with motor characteristics models to calculate torque, serving as a cost-effective intermediary measurement approach.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If multi-motor hybrid force/position control is implemented, then accurate force control and synchronization can be achieved, but the control difficulty increases significantly

Engineering Contradiction:
Improvesynchronization precisionVSAvoidcontrol complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the control system into independent motor control units, each with its own force control loop. By dividing the multi-motor system into manageable modules with individualized control strategies, the overall control complexity is reduced while maintaining synchronization precision through coordinated control of each segment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements feedback control mechanisms where the actual force output of each motor is continuously monitored and compared with the desired force. The synchronization status and force errors are fed back to adjust control parameters in real-time, enabling accurate force control and synchronization without requiring overly complex open-loop control strategies.

Inventive Principle:
Principle #23Feedback

3Power

If multiple parallel motors are used for high-power output in limited space, then power requirement is met, but synchronization control becomes more difficult

Engineering Contradiction:
Improveoutput powerVSAvoidsynchronization control
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent merges the control strategies for multiple motors into a unified control framework that manages all motors simultaneously. By combining force control, position control, and synchronization control into an integrated system with shared control parameters and coordination algorithms, the patent achieves high-power output from multiple motors while managing synchronization complexity through unified management.

Inventive Principle:
Principle #5Merging (Combining)

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 for high-power applications.

Implementation Method 1

taking an actual output force of each of the plurality of motors as the feedback item of the internal feedback loop

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4340207B1Force control method and system for multi-motor synchronization
Publication Date: 2025.07.16 NINGBO GAUSS ROBOT CO LTD
  • EP4340207B1 patent drawingFigure 1
  • EP4340207B1 patent drawingFigure 2
  • EP4340207B1 patent drawingFigure 3

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.