The use of elastic elements has important benefits for human-machine interaction systems such as powered prostheses and rehabilitation exoskeletons. Elastic elements reduce the force due to impacts, simplify force control, store elastic energy and release it with tremendous power, and have the potential to reduce energy consumption and peak power when used in series with an electric motor. However, important questions remain unanswered with this technology. What is the maximum amount of energy that series elastic actuators can really save? How to design the elastic element in SEAs to guarantee maximum energy savings? How can I use dielectric elastomers to create a variable stiffness actuator? If you are interested in the answers to these questions feel free to check the papers below.
Lower-limb Kinematics and Kinetics During Continuously Varying Human Locomotion. E. Reznick, K. Embry, R. Neuman, E. Bolívar-Nieto, N. P. Fey, R.G. Gregg, Scientific Data, Under Review.
Intelligible Real-Time Activity Recognition for Lower-Limb Wearable Robots. Shihao Cheng, E. Bolívar-Nieto, and Robert D. Gregg, IEEE Robotics & Automation Letters, 2021, Under Review.
Extremum Seeking Control for Stiffness Auto-Tuning of a Quasi-Passive Ankle Exoskeleton. S. Kumar, M. Zwall, E. Bolívar-Nieto, R. Gregg, N. Gans, IEEE Robotics & Automation Letters, 2020, 5 (3), 4604-4611. (PDF)
Series Spring Design for Robust-Feasible Quasi-Direct Drives. E. Bolívar-Nieto, T. Summers, R.D. Gregg, S. Rezazadeh. Mechatronics, Under review.
Mechanical Simplification of Variable Stiffness Actuators Using Dielectric Elastomer Transducers. D. Allen, E. Bolívar, S. Farmer, W. Voit, and R. Gregg. Actuators, 2019, 8 (2), 44. (PDF)
Minimizing Energy Consumption and Peak Power of Series Elastic Actuators: a Convex Optimization Framework for Elastic Element Design. E. Bolívar, S. Rezazadeh, and R. Gregg. IEEE/ASME Transactions on Mechatronics, 2019, 24 (3), 1334-1345. (PDF)
Convex Optimization for Spring Design in Series Elastic Actuators: From Theory to Practice. Edgar A. Bolívar-Nieto, Gray C. Thomas, Elliott Rouse, and Robert D. Gregg. IEEE Int. Conf. Intelligent Robots & Systems, Prague, Czech Republic, 2021. Under Review.
Toward Phase-Variable Control of Sit-To-Stand Motion with a Powered Knee-Ankle Prosthesis. Daphna Raz, Edgar Bolívar-Nieto, Necmiye Ozay, and Robert D. Gregg. IEEE Conf. on Control Technology & Applications, San Diego, CA, USA, 2021.
Robust Optimal Design of Energy Efficient Series Elastic Actuators: Application to a Powered Prosthetic Ankle. E. Bolívar, S. Rezazadeh, T. Summers, and R. D. Gregg. IEEE Int. Conf. Rehab. Robotics, Toronto, Canada, 2019. (PDF)
A General Framework for Minimizing Energy Consumption of Series Elastic Actuators with Regeneration. E. Bolívar, S. Rezazadeh, and R. Gregg. In ASME Dynamic Systems & Control Conference, Tysons Corner, VA, USA, 2017. Best Student Robotics Paper Award. (PDF)
Towards a Series Elastic Actuator with Electrically Modulated Stiffness for Powered Ankle-Foot Orthoses. E. Bolívar, D. Allen, G. Ellson, J. Cossio, W. Voit, and R. Gregg. In IEEE Conf Automation Science & Engineering, Fort Worth, TX, USA, 2016. (PDF)
R. D. Gregg, E. Bolívar, D. P. Allen, and W. Voit, “Variable stiffness actuator with electrically modulated stiffness,” 2018. U.S. Patent, US 10,870,202 B2. (PDF)
How Much Energy Can Really Be Saved Using Series Elastic Actuators?. E. Bolívar, S. Rezazadeh, and R. Gregg. In IEEE Int. Conf. Intelligent Robots & Systems, Vancouver, BC, Canada, 2017. (PDF)