Variable Stiffness Robot Joint System

Variable Stiffness Robot Joint System with Differential Gear for Combined Rotation and Stiffness Control

This technology is a differential gear-based variable stiffness robot joint system that uses two independent drive motor inputs to selectively perform joint rotation and stiffness adjustment based on the combination of the motors' rotational directions.

Conventional variable stiffness joints suffer from low drive efficiency and design redundancies, as one motor is dedicated solely to joint actuation while the other is dedicated solely to stiffness control.

This technology proposes a method where a first rotation module converts the motors' same-direction rotational force into joint rotation, while a second rotation module converts opposite-direction rotational force into linear motion to adjust the preload of an elastic member, thereby varying stiffness. Applicable to collaborative and rehabilitation robots, it maximizes both hardware efficiency and output by utilizing both motors.

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Key Features:

• First and second drive modules, each generating rotational force about a first direction axis
• A first rotation module that converts rotation to rotate the joint when both drive modules rotate in the same direction
• A stiffness provision module that elastically supports the rotational motion of the first rotation module to provide stiffness
• A second rotation module that converts motion into linear motion to adjust preload when the two drive modules rotate in opposite directions