Low Noise, High Efficiency Hydraulics for Mobile Robots

Biologically-inspired motions such as flapping, perching, walking, running, swimming, grasping and manipulating, are difficult for the most advanced robots today. The primary limitation comes from actuation technology in terms of stress/strain ratio delivered to the joint by the actuator overcoming specific resistance. Electromagnetic motors have low torque at high speeds and hence cannot be used directly on mobile robots without large transmission ratios. Transmission introduces weight, friction, reflected inertia and backlash. Most bioinspired robots such as running quadrupeds, bipeds, humanoids and exoskeletons need high-powered force control at moderate bandwidth. Conversely, hydraulic actuators provide extremely high power density but they are inefficient and noisy. To develop a highly efficient and low-noise hydraulic actuator for biologically-inspired robotics, this proposal will develop several high-level concepts for developing advanced pump, control and actuator subsystems. Specifically, we plan to build experimental compact valveless hydroelastic muscle to demonstrate high- fidelity force control with variable impedance and energy recovery. The primary focus will be to develop essential elements for integrating a high-efficiency, low noise variable impedance hydroelastic actuator prototype that can accurately mimic the mechanical behavior of biological animal or human limbs (arms or legs) resulting in applications in small- to medium-sized mobile robotic devices.