Design and verification of a parallel elastic robotic leg

Area of Science:

• Robotics
• Mechanical Engineering
• Control Systems

Background:

• Robotic legs often face challenges in accurately replicating desired dynamic models due to non-linearities in elastic elements.
• Achieving linear dynamics is crucial for simplifying model-based control design and analysis in legged robots.

Purpose of the Study:

• To design and experimentally verify a parallel elastic robotic leg mechanism capable of emulating a linear mass-spring-damper model.
• To linearize the non-linear forces from elastic elements using a wrapping cam mechanism.
• To enable the application of analytical solutions from linear models in robotic control.

Main Methods:

• Design of a parallel elastic robotic leg incorporating a wrapping cam mechanism.
• Development of a system identification procedure to estimate leg mechanism parameters.
• Cross-validation of estimated parameters to assess performance against the target linear model.

Main Results:

• The wrapping cam mechanism effectively linearizes the non-linear elastic forces.
• Experimental verification confirms the passive dynamics of the robotic leg closely match the linear mass-spring-damper model.
• Successful parameter estimation and cross-validation demonstrate the mechanism's fidelity.

Conclusions:

• The developed parallel elastic robotic leg successfully achieves the intended linear dynamics.
• This mechanism provides a viable platform for parallel elastic actuation in robots.
• The findings facilitate the use of model-based controllers leveraging analytical solutions for linear systems.