Passivity-Based Control with a Generalized Energy Storage Function for Robust Walking of Biped Robots.

Area of Science:

• Robotics
• Control Systems
• Biomechanics

Background:

• Passivity-based control enhances robustness in bipedal walking by tracking a reference mechanical energy.
• Previous methods were limited by the assumption of a known, constant mechanical energy, restricting applications to simpler models.

Purpose of the Study:

• To generalize passivity-based, energy tracking control for robust bipedal walking.
• To enable the use of passivity-based controllers with arbitrary inner-loop controls that establish a limit cycle with constant generalized system energy.
• To accommodate systems with arbitrary degrees of underactuation.

Main Methods:

• Developed a novel generalization of a passivity-based, energy tracking controller.
• Integrated the controller with arbitrary inner-loop control strategies.
• Validated the approach through simulations on a 7-link bipedal robot model.

Main Results:

• The proposed control scheme successfully enlarges the basin of attraction for stable walking.
• Demonstrated an increased convergence rate to the desired limit cycle.
• Showcased improved robustness against disturbances such as uneven terrains and varying ground slopes.

Conclusions:

• The generalized controller expands the applicability of passivity-based methods to more complex bipedal robots.
• The approach offers enhanced stability, faster convergence, and greater resilience in dynamic walking scenarios.
• This work paves the way for more capable and robust legged locomotion systems.