Design, Characterization, and Implementation of Lightwieght and Energy-Efficient Electroadhesive Clutches for Robotics

Despite decades of academic and industry effort, achieving efficient and dynamic movementof robots remains a significant challenge. Many robots, particularly humaniod robotsand wearable robots such as exoskeletons and prostheses, are quite limited in their versatilityand usefulness because of the force and speed limitations of actuators. Weight andpower consumption are particularly important factors in determining the operating rangeand effectiveness of these devices. Geared electric motors are most commonly used in theseapplications, but often result in slow, stiff, and halting operation. Other options include hydraulicactuators, pneumatic actuators, electroactive polymer actuators, and shape memorymaterials, but none of these are able to achieve the combination of high power output, highefficiency, and low weight that would enable dynamic movement of untethered robots.Many proposed solutions to this problem involve using clutches to improve the efficiencyand capability of actuation systems. However, conventional clutches such as electromagneticand magnetorheological clutches are themselves too heavy and power-hungry to bepractical. This thesis presents an electroadhesive clutch that has 10£ lower weight and1000£ lower power consumption than conventional clutches. To inform a variety of possibleimplementations, I extensively characterized the effects of design choices on the holdingforce, responsiveness, and power consumption of the electroadhesive clutch. Next, I investigatedthe use of the clutch in a walking assistance exoskeleton, demonstrating the reliabilityand advantages of the electroadhesive clutch in a challenging robotics application. Finally, Istudied the use of electroadhesive clutches to harvest, store, and return mechanical energywith rubber springs, and used multiple of these units in parallel to create a force controllableenergy recycling actuator. My aspiration is that the work in this dissertation willlead to improved robotic hardware that enables exciting new capabilities in next generationrobotics