Model-Based Experimental Development of Passive Compliant Robot Legs from Fiberglass Composites

Area of Science:

• Robotics
• Materials Science
• Mechanical Engineering

Background:

• Developing compliant robot legs is crucial for advanced locomotion.
• Composite materials offer tunable mechanical properties for robotic applications.
• Designing curved structures with specific stiffness presents a significant challenge.

Purpose of the Study:

• To present a methodology for creating compliant, half-circular composite robot legs with designable stiffness.
• To establish a predictive model for the stiffness of curved composite beams.
• To validate the methodology through experimental testing and robotic application.

Main Methods:

• Force-displacement experiments were conducted on flat cantilever composite beams (using fiberglass cloths).
• Cantilever mechanics were mapped to a virtual spring model to derive equivalent elastic moduli.
• A model linking curved beam mechanics to the virtual spring was used to estimate the stiffness of half-circular composites.

Main Results:

• The equivalent elastic moduli of fiberglass composites were successfully derived.
• The stiffness of half-circular composite structures could be estimated accurately using the developed model.
• The validated methodology enabled the fabrication of composite legs used on a hexapod robot.

Conclusions:

• The reported methodology provides an efficient way to design composite robot legs with tailored stiffness.
• The predictive model reduces the need for extensive experimental trials in designing curved composite structures.
• The successful application on a hexapod robot demonstrates the practical utility of the developed compliant legs.