Discrete-Time Impedance Control for Dynamic Response Regulation of Parallel Soft Robots

Area of Science:

• Robotics
• Control Systems
• Soft Materials

Background:

• Soft robots, especially pneumatically actuated ones, exhibit significant vibrations and overshoots during deactuation due to their inherent flexibility.
• These vibrations reduce accuracy, increase settling time, and can compromise the structural integrity of soft robots.
• Existing literature lacks sufficient methods for vibration suppression in pneumatic soft robots.

Purpose of the Study:

• To develop and validate an effective impedance control strategy for regulating the dynamic response of pneumatic soft robots.
• To address the critical need for suppressing undesirable vibrations and overshoots in soft robot deactuation.
• To enhance the reliability and applicability of soft robots in industrial environments.

Main Methods:

• Formulation of a nonlinear discrete sliding mode impedance controller tailored for highly nonlinear soft robot systems.
• Implementation in discrete-time to allow efficient control of high-order system models without state-observers.
• Utilizing a 6-chambered parallel soft robot as an experimental platform for validation.

Main Results:

• The proposed discrete sliding mode impedance controller effectively limited the amplitude of undesirable vibrations in the soft robot.
• Comparative experiments demonstrated superior performance over existing state-of-the-art controllers in vibration suppression.
• The controller automatically calculates parameters, eliminating the need for manual tuning, and allows for fast embedded system implementation.

Conclusions:

• The developed nonlinear discrete sliding mode impedance controller offers a robust solution for vibration suppression in pneumatic soft robots.
• This approach significantly improves the dynamic control and reliability of soft robots for industrial applications.
• The controller's automatic parameter calculation and efficient implementation pave the way for wider adoption of advanced control strategies in soft robotics.