Twisted string actuator for hybrid actuation

Hybrid Twisted String Actuator with Auxiliary Drive

This technology relates to a twisted string actuator for hybrid operation, which drives robot joints by combining a twisted string drive unit with an auxiliary drive unit.

Conventional twisted string actuators suffer from asymmetric contraction and relaxation, leading to complex control and performance limitations due to the trade-off between force and speed.

By placing an auxiliary drive unit in parallel, this technology minimizes interference and compensates for the trade-off relationship, thereby improving the control performance and response speed of robot joints.

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Key Features:

• A twisted string drive unit where a pair of string twisting units rotate in opposite directions to create string tension.
• A joint member and cam pulley that receive power from the twisted string drive unit to control bidirectional movement.
• An auxiliary drive unit connected to the output shaft of the joint member to directly control the bidirectional movement of the output shaft.
• A load cell that slides on a linear guide to detect the torque generated by the twisted string drive unit.

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This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of core technologies for compact, lightweight, high-performance, and highly durable safe drive modules based on string twisting, utilizing string surface reinforcement, variable radius pulleys, and hybrid drive control, as well as the Ministry of Trade, Industry and Energy's Engineering Graduate School Support Program (Plant Engineering field).