Stiffness Control of Surgical Continuum Manipulators

Area of Science:

• Robotics
• Control Systems Engineering
• Mechanical Engineering

Background:

• Continuum robots require advanced control strategies for precise interaction with environments.
• Existing controllers often lack the ability to directly manage robot stiffness, limiting their application in delicate tasks.

Purpose of the Study:

• To introduce the first stiffness controller specifically designed for continuum robots.
• To enable precise control over the tip stiffness of continuum robots.
• To leverage robot deflection sensing for both force sensing and stiffness control.

Main Methods:

• Developed a control law based on an accurate approximation of the continuum robot's coupled kinematic and static force model.
• Implemented the controller by driving actuators to specific positions that achieve a desired tip stiffness.
• Utilized robot deflection sensing to measure tip position and infer tip forces.

Main Results:

• The stiffness controller successfully achieved desired stiffness in steady-state conditions.
• Demonstrated good dynamic performance and stability during contact transitions.
• Validated the controller's effectiveness on a concentric tube robot experimental setup.

Conclusions:

• The proposed stiffness controller is the first of its kind for continuum robots.
• The approach allows for effective stiffness control through modification of existing position controllers.
• Robot deflection sensing serves a dual role in sensing and controlling tip forces, enhancing robot functionality.