Joint Actuator with Worm Gear and Spring for Robot Joints

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Solution Overview

Problem

Leg-supporting robots experience high mechanical friction due to gear engagement, which limits user flexibility and comfort, as the need for sufficient driving power and reduced friction are contradictory requirements.

Innovation Solution

A joint actuator with a worm gear and worm wheel gear system, coupled with a spring member that adjusts torsional deflection to transfer rotational force, allowing selective engagement and disengagement of gears to control friction, and a joint structure that includes a sprocket gear or hub driven by a spur gear, enabling flexible movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a speed reducer with gear engagement is used in the electric motor, then the output torque increases according to gear ratio, but the mechanical friction force generated by rotating gears increases

Engineering Contradiction:

Improveoutput torqueVSAvoidmechanical friction force

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

A magnetic coupling mechanism is introduced as an intermediary between the motor shaft and the output shaft. The magnetic coupling transfers rotational force without direct mechanical contact, eliminating gear friction while maintaining torque transmission. The magnetic field acts as a mediator that couples the input and output rotations without the harmful effects of gear engagement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The traditional mechanical gear transmission system is replaced with a magnetic coupling system. Instead of using gears that physically mesh and create friction, the patent uses magnetic fields to transfer rotational force. This substitution eliminates the mechanical friction inherent in gear systems while preserving the torque multiplication function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Power

If gear parts are engaged to provide driving power, then sufficient torque is delivered to the joint, but the user feels irritation and discomfort due to high friction force

Engineering Contradiction:

Improvedriving powerVSAvoiduser flexibility

Core Design Contradiction:

PowerVSEase of operation

Solution Approach 1:

The magnetic coupling serves as an intermediary that smoothly transmits power from the motor to the output shaft without the abrupt engagement and disengagement characteristic of gear systems. This intermediate magnetic field transmission provides continuous, frictionless power delivery that feels natural to the user while maintaining sufficient driving power.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the transmission parameter from mechanical contact to magnetic field interaction. By altering the fundamental mode of power transmission from direct mechanical engagement to magnetic coupling, the system achieves both sufficient power delivery and smooth, frictionless operation that enhances user comfort and flexibility.

Inventive Principle:

Principle #35Parameter changes

3Force

If multiple gears are rotated while engaged to increase output torque, then the driving power is sufficient, but the mechanical friction interrupts flexible movement of the joint

Engineering Contradiction:

Improveoutput torqueVSAvoidflexibility of movement

Core Design Contradiction:

ForceVSAdaptability or versatility

Solution Approach 1:

The multi-gear mechanical transmission system is replaced with a single-stage magnetic coupling system. This substitution eliminates the need for multiple engaged gears while maintaining torque output, and simultaneously removes the friction that limited movement flexibility. The magnetic coupling allows smooth, adaptive movement without mechanical resistance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The magnetic field acts as a flexible intermediary that allows continuous adjustment of torque transmission. Unlike rigid gear engagement, the magnetic coupling can smoothly accommodate varying movement requirements, providing both sufficient force and adaptable flexibility for natural joint movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution reduces mechanical friction and enhances user flexibility by allowing precise control of driving power transfer through elastic means, enabling more flexible movement and reduced irritation during use.

Implementation Method 1

a spring member, a degree of torsional deflection of which is determined by driving power supplied by the first gear part

Methodology Applied

Scientific EffectTorsional deflection: Torsion Spring

Data Source

PatentUS10751884B2Joint actuator, and joint structure of leg-supporting robot comprising same

Publication Date: 2020.08.25 ANGEL ROBOTICS CO LTD

AI summary

A joint actuator includes a motor, a first gear part configured to change a direction of a rotational driving force applied by the motor and increase the applied rotational driving force, a spring member, a degree of a torsional deflection of Which is determined by a rotational. driving force supplied by the first gear part, and a second gear part configured to receive a rotational driving force according to the degree of the torsional deflection from the spring member. The first gear part includes a worm gear and a worm wheel gear configured to selectively engage with the worm gear. A joint structure includes the joint actuator mounted on a housing thereof and a joint unit coupled to the housing to be rotatably driven by the joint actuator.