Advancements in robotics and prosthetics demand more sophisticated machinery capable of intricate and dynamic movements. However, traditional electric motors, designed for steady tasks, often prove inefficient for such demands. Addressing this challenge, researchers at Stanford University have developed a groundbreaking actuator that significantly enhances the efficiency of electric motors, as detailed in their recent publication in Science Robotics.
Associate Professor of Mechanical Engineering, Steve Collins, the senior author of the paper, elucidates the novel approach: “Rather than wasting lots of electricity… our actuator uses these clutches to achieve the very high levels of efficiency… without giving up on controllability…”
The actuator operates by leveraging the inherent force of springs, which require no energy to produce force but resist being stretched. When engaged in tasks like lowering heavy objects, the springs absorb some load, alleviating strain on the motor. By locking the springs in a stretched position, the energy can be stored for future use.
Electroadhesive clutches play a pivotal role in efficiently engaging and disengaging the springs. These clutches, consisting of electrodes, smoothly slide past each other when inactive. Application of a large voltage causes the electrodes to unite with an audible click, akin to static electricity attraction. Releasing the spring is a simple matter of grounding the electrode.
Lead author of the paper, Erez Krimsky, highlights the benefits of these clutches: “They’re lightweight, they’re small, they’re really energy efficient, and they can be turned on and off rapidly.”
The researchers’ prototype incorporates six identical clutched springs, offering versatility in task execution. Rigorous motion tests revealed remarkable energy savings, with the augmented motor consuming at least 50 percent less power than conventional models and, in optimal scenarios, reducing consumption by 97 percent.
Efficient motors hold significant implications for robotics, enabling extended operation and enhanced capabilities. A robot capable of prolonged activity without frequent recharging could undertake more meaningful tasks, particularly in hazardous environments where human presence is risky.
Krimsky underscores the impact on assistive devices like prosthetics or exoskeletons: “If you don’t need to constantly recharge them, they can have a more significant impact for the people that use them.”
While the actuator’s controller currently requires a few minutes to calculate the optimal spring combination for a new task, the researchers envision streamlining this process through artificial intelligence. This advancement could pave the way for commercial applications, potentially revolutionizing robotics and prosthetics industries.