Design and Position Control of a Bionic Joint Actuated by Shape Memory Alloy Wires

Area of Science:

• Robotics
• Materials Science
• Mechanical Engineering

Background:

• Bionic joints are essential for robotic motion.
• Shape memory alloys (SMAs) offer muscle-like actuation but have limited axial stroke.
• Existing SMA actuators face challenges in achieving sufficient range of motion for complex robotic movements.

Purpose of the Study:

• To propose and evaluate a novel bionic joint design that overcomes the limited axial stroke of SMA actuators.
• To convert the axial displacement of SMA wires into amplified rotational motion for robotic joints.
• To demonstrate effective position control for the enhanced bionic joint.

Main Methods:

• Designed a bionic joint integrating SMA wires with a differential pulley set for stroke amplification.
• Developed a mathematical model for the bionic joint mechanism.
• Implemented and tested a proportional-integral (PI) controller for precise position control.

Main Results:

• The differential pulley system successfully amplified the axial stroke of SMA wires into rotational motion.
• The bionic joint achieved a notable rotation angle range from -30° to 30°.
• The PI controller demonstrated good position control performance for the joint.

Conclusions:

• The proposed bionic joint design effectively enhances the range of motion for SMA-actuated robotic joints.
• The integration of SMA wires and a differential pulley set presents an innovative solution for bionic joint actuation.
• This approach offers a promising method for developing more capable and versatile robotic systems.