An Operating Stiffness Controller for the Medical Continuum Robot Based on Impedance Control

Area of Science:

• Robotics
• Surgical Technology
• Control Systems

Background:

• Continuum manipulators offer advantages in minimally invasive surgery (MIS) due to their ability to navigate complex anatomical structures.
• Controllable operating stiffness is crucial for continuum manipulators during different surgical phases, balancing safe access with precise manipulation.

Purpose of the Study:

• To propose and validate an operating stiffness controller (OSC) for tendon-driven continuum manipulators.
• To enable dynamic adjustment of manipulator stiffness without altering its physical structure or materials.

Main Methods:

• Development of an OSC based on variable impedance control and Lagrangian dynamic modeling.
• Modification of driving forces along the manipulator's tendons to alter stiffness.
• Stability analysis using a Lyapunov function.

Main Results:

• The OSC successfully adjusted operating stiffness by modifying tendon driving forces.
• Experimental validation showed average errors of 7.82% for constant stiffness and 3.09% for time-varying stiffness.
• The controller demonstrated high accuracy, stability, and robustness.

Conclusions:

• The proposed OSC effectively controls the operating stiffness of continuum manipulators.
• This technology enhances the safety and precision of continuum manipulators in minimally invasive surgery.
• The controller's adaptability to dynamic stiffness requirements is a key advancement.