Biomimetic Bi-Pedal Humanoid: Design, Actuation, and Control Implementation with Focus on Robotic Legs

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Virginia Tech

The advancements made in technology over the past several decades have brought the field of humanoid robotics closer to integration into the everyday lives of humans. Despite these advances, the cost of these systems consistently remains high, thus limiting the environments in which these robots can be deployed. In this thesis, a pair of low-cost, bio-mimetic legs for a humanoid robot was developed with 12 degrees of freedom: three at the hip, one at the knee, and two at the ankle. Prior to developing the robot, a survey of the human-sized robotic legs released from 2006-2012 was conducted. The analysis included a summary of the key performance metrics and trends in series of human-sized robots. Recommendations were developed for future data reporting that will allow improved comparison of different prototypes. The design of the new robotic legs in this thesis utilized human anatomy data to devise performance parameters and select actuators. The developed system was able to achieve comparable ROM, size, weight, and torque to a six-foot tall human. Position and zero-moment point sensors were integrated for use in balancing, and a control architecture was developed. A model of the leg dynamics was created for designing balancing and walking algorithms. In addition, hydraulic actuators were evaluated for use in humanoid robotics, and testing was conducted in order to create a position control methodology. Finally, a predictive deadband controller was designed that was able to achieve accuracy of less than one degree using a valve with slow switching speed.

humanoid, biomimetic, legs, mechatronics, hydraulics