Active Displacement Hydraulics for Mobile Robotics

One of the current limitations for mobile robotics walking is efficient actuation. The standard actuation technologies that have been used in mobile robotic platforms are servo-hydraulics, electro-hydraulics and electro-mechanical actuation. The hydraulic options have a high power density and pack well but are very inefficient leading to carrying extra batteries in mobile applications. The electro mechanical options improve on efficiency but require the actuation to be located at the point of actuation, leading to large masses on the legs and significant increases in power consumption. On top of that, these designs have limited success addressing the large ranges of power output found in legged locomotion in particular the range between walking and running. This work intends to develop a new method of actuation that is uniquely capable to meet the needs of mobile legged robotic applications. The proposed solution is a hydraulic based design that uses active control of pump displacement to manipulate its performance characteristics. The proposed solution will allow many joints to operate off a single motor without losses from valves. The proposed active displacement hydraulic power unit will provide system bandwidth comparable to servo-hydraulics and efficiencies better than electro-mechanical systems in an easy to package quite design.