Anthropomorphic finger antagonistically actuated by SMA plates

Area of Science:

• Robotics
• Materials Science
• Biomimetics

Background:

• Traditional robotic actuators often use linear or spring-shaped shape memory alloys (SMAs).
• Designing biomimetic robotic systems requires actuators that can replicate complex human movements.

Purpose of the Study:

• To develop a novel robotic finger utilizing thermomechanically trained SMA plates for biomimetic flexion and extension.
• To evaluate the force application capabilities and control performance of the SMA-based robotic finger.

Main Methods:

• Fabrication of a robotic finger using SMA plates trained into a flexed human finger shape.
• Integration of antagonistic flexor and extensor actuators for finger movement.
• Development of a nonlinear antagonistic controller with nested current and position control loops.
• Utilizing 3D printing for mold fabrication and a multi-stage casting process for assembly.

Main Results:

• The best NiTi-based SMA plate achieved an average maximum fingertip force of 9.01N.
• The robotic finger demonstrated minimal tracking errors for sine and square wave inputs.
• The system exhibited recovery from unexpected disturbances and a closed-loop bandwidth of 6.4 rad/s (intermittent) and 1.8 rad/s (continuous).

Conclusions:

• Thermomechanically trained SMA plates can effectively actuate a biomimetic robotic finger.
• The developed antagonistic control system provides precise and robust finger actuation.
• This approach offers a promising method for creating compact and powerful robotic actuators inspired by human anatomy.