Effective Viscous Damping Enables Morphological Computation in Legged Locomotion

Area of Science:

• Robotics
• Biomechanics
• Mechanical Engineering

Background:

• Physical damping is theorized to enhance stability in legged locomotion.
• Implementations of physical damping in compliant robotic locomotion are scarce.
• Sensor-free, adaptive force, and negative work capabilities of dampers are promising.

Purpose of the Study:

• Investigate energy dissipation from viscous and Coulomb damping in a simplified leg model.
• Explore effective viscous damping and adjustability in leg-mounted hardware.
• Quantify energy dissipated by mechanical dampers during simulated legged impacts.

Main Methods:

• Simulated vertical drops with ground-level perturbations using a numerical leg model.
• Engaged a parallel spring-damper from touchdown to mid-stance, auto-decoupling thereafter.
• Tested commercial hydraulic and custom pneumatic dampers mounted on a robotic leg.

Main Results:

• Numerical simulations indicated a need for adjustable, viscous dampers.
• The hydraulic damper demonstrated the most effective viscous damping in hardware tests.
• Adjusting the pneumatic damper's orifice had minimal impact on dissipated energy, contrasting simulation findings.

Conclusions:

• Physical dampers require characterization during actual legged impacts for effective use in compliant locomotion.
• The effectiveness of damping mechanisms may differ between simulations and real-world robotic applications.
• Further research is needed to bridge the gap between theoretical damping benefits and practical implementation in legged robots.