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

2019-01-18T21:36:06Z (GMT) by Stuart Diller
Despite decades of academic and industry effort, achieving efficient and dynamic movement<br>of robots remains a significant challenge. Many robots, particularly humaniod robots<br>and wearable robots such as exoskeletons and prostheses, are quite limited in their versatility<br>and usefulness because of the force and speed limitations of actuators. Weight and<br>power consumption are particularly important factors in determining the operating range<br>and effectiveness of these devices. Geared electric motors are most commonly used in these<br>applications, but often result in slow, stiff, and halting operation. Other options include hydraulic<br>actuators, pneumatic actuators, electroactive polymer actuators, and shape memory<br>materials, but none of these are able to achieve the combination of high power output, high<br>efficiency, and low weight that would enable dynamic movement of untethered robots.<br>Many proposed solutions to this problem involve using clutches to improve the efficiency<br>and capability of actuation systems. However, conventional clutches such as electromagnetic<br>and magnetorheological clutches are themselves too heavy and power-hungry to be<br>practical. This thesis presents an electroadhesive clutch that has 10£ lower weight and<br>1000£ lower power consumption than conventional clutches. To inform a variety of possible<br>implementations, I extensively characterized the effects of design choices on the holding<br>force, responsiveness, and power consumption of the electroadhesive clutch. Next, I investigated<br>the use of the clutch in a walking assistance exoskeleton, demonstrating the reliability<br>and advantages of the electroadhesive clutch in a challenging robotics application. Finally, I<br>studied the use of electroadhesive clutches to harvest, store, and return mechanical energy<br>with rubber springs, and used multiple of these units in parallel to create a force controllable<br>energy recycling actuator. My aspiration is that the work in this dissertation will<br>lead to improved robotic hardware that enables exciting new capabilities in next generation<br>robotics.