Differential resistance feedback control of a self-sensing shape memory alloy actuated system

Area of Science:

• Materials Science
• Robotics
• Control Systems Engineering

Background:

• Miniaturization trends necessitate advanced sensors and actuators.
• Self-sensing actuation (SSA) is well-established in piezoelectrics but underexplored in Shape Memory Alloys (SMAs).
• External sensors are often impractical in confined or complex systems.

Purpose of the Study:

• To develop and validate a novel self-sensing actuation (SSA) scheme for Shape Memory Alloys (SMAs).
• To enable concurrent actuation and sensing using differential resistance measurements in antagonistic SMA wires.
• To implement a closed-loop control system for real-time tracking applications.

Main Methods:

• A differential resistance measurement scheme was devised for antagonistic SMA wires.
• A one-link manipulator arm was designed to experimentally verify the SSA scheme.
• A novel signal processing electronic circuit was employed for direct differential resistance feedback control.
• Fuzzy PID control was utilized, requiring no detailed SMA constitutive model.

Main Results:

• The SSA scheme was experimentally verified in a real-time tracking control scenario.
• The system achieved a closed-loop control bandwidth of up to 1.8 Hz.
• Angular tracking accuracy of ±0.06° was demonstrated over a ±15° movement range at 1 Hz operating frequency.

Conclusions:

• The proposed differential resistance measurement scheme effectively enables self-sensing actuation in SMAs.
• The fuzzy PID-based control system offers robust performance without needing complex SMA models.
• This approach is suitable for miniaturized, real-time control applications where external sensors are challenging.