Actuator Control With High-Efficiency Reducer for Backdrivability

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Solution Overview

Problem

Existing actuators with motors and speed reducers face challenges in improving overall backdrivability, with dominant backdrive resistance from the speed reducer part and unbalanced backdrivability due to cogging torque from the motor.

Innovation Solution

Combining a motor with reduced cogging torque and a high-efficiency speed reducer, where the speed reducer has an efficiency of 60% or more, and incorporating a control unit to suppress the cogging torque of the motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a speed reducer with high reduction ratio is used to reduce motor speed, then the output torque increases, but the backdrive resistance from the speed reducer dominates and worsens overall backdrivability

Engineering Contradiction:

Improveoutput torqueVSAvoidbackdrivability

Core Design Contradiction:

PowerVSEase of operation

Solution Approach 1:

The patent changes the efficiency parameter of the speed reducer to 60% or more, which is a significant improvement over conventional speed reducers. This parameter change reduces the backdrive resistance from the speed reducer, improving overall backdrivability while maintaining the torque multiplication benefit of the reduction mechanism.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional mechanical speed reducer with a high-efficiency speed reducer that has a fundamentally different mechanical design achieving 60% or more efficiency. This substitution reduces friction and backdrive resistance while maintaining the speed reduction and torque multiplication functions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If a motor with high torque density is used to reduce actuator size, then the motor dimensions are reduced, but cogging torque increases and creates unbalanced backdrivability

Engineering Contradiction:

Improvetorque densityVSAvoidbackdrivability

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent replaces the conventional motor with a control system that actively suppresses cogging torque. This substitution uses electronic control to eliminate the harmful mechanical effect of cogging while maintaining the high torque density benefits of modern motors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback control to detect and suppress cogging torque in real-time. The control unit monitors the motor operation and applies compensating forces to cancel out cogging torque, thereby eliminating its negative impact on backdrivability while allowing the motor to operate at high torque density.

Inventive Principle:

Principle #23Feedback

3Device complexity

If conventional speed reducers are used, then device complexity is reduced, but transmission efficiency is insufficient and backdrive resistance remains high

Engineering Contradiction:

Improvespeed reducer structureVSAvoidtransmission efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent changes the efficiency parameter from conventional levels (typically 30-50%) to 60% or more through fundamental design changes in the speed reducer. This parameter improvement reduces energy loss and backdrive resistance while the control unit suppresses cogging torque to achieve balanced backdrivability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250083307A1actuator

Publication Date: 2025.03.13 SUMITOMO HEAVY IND LTD

AI summary

An actuator includes: a motor; and a speed reducer that reduces rotation of the motor, in which the speed reducer has an efficiency of 60% or more, and the actuator includes a control unit that performs control to suppress a cogging torque of the motor.