A magneto-elastic model for soft magnetic concentric tube robots

Area of Science:

• Robotics
• Materials Science
• Biomedical Engineering

Background:

• Conventional concentric tube robots face limitations due to material stiffness and instability.
• Existing designs rely on pre-curved elastic energy storage for actuation.
• Soft robotic systems require novel actuation methods for complex environments.

Purpose of the Study:

• To present a numerical solution for a reduced-order analytical energy formulation of a soft, magnetically actuated concentric tube continuum robot.
• To introduce a new design using softly magnetic rings for direct deformation generation.
• To enable new classes of highly compliant robotic systems for constrained environments.

Main Methods:

• Derivation of a complete magneto-elastic formulation coupling magnetic torque and sleeve curvature.
• Utilizing softly magnetic rings adhered to braided sleeves for actuation.
• Experimental validation using a 7T pre-clinical MRI scanner.

Main Results:

• The model accurately captures mechanical hysteresis, bistability, and nonlinear tip pose relationships.
• Experimental results show strong agreement with simulated deformation, with an overall RMS error of 4.4°.
• The proposed design principle is applicable to magnetic fields above 1T.

Conclusions:

• The developed framework supports closed-loop control, design optimization, and self-sensing capabilities.
• This innovation facilitates the development of highly compliant soft continuum robots.
• The magnetic actuation approach offers a promising alternative for delicate medical procedures and constrained environments.