CAREER: A Prosthetic Elbow with Network of Soft and Modular Thermo-Active Actuators for Mobility Impaired Patients

There are about 15 million mobility impaired people in the United States who need assistance to move their limbs. Assistive robots have been proposed to help people with mobility impairments. Existing actuators for assistive robots are limited to rigid actuators and soft actuators.

Rigid actuators are powerful but may cause injury. Soft actuators can be safer, but not as powerful, portable, or responsive as their rigid counterparts. Soft actuators that use heat to stimulate actuation are portable and can be powerful.

However, their response can be too slow for many rehabilitation applications. This NSF Faculty Early Career Development (CAREER) project attempts to overcome these challenges by developing novel networks of flexible Peltier-based soft actuators designed for rehabilitation. The project will provide research opportunities to underrepresented pre-college, undergraduate, and graduate students and to students with disabilities.

The PI’s long-term goal is to create a wearable rehabilitation technology that is lightweight, portable, and soft but also quick to respond and powerful. Toward this goal, this project aims to optimally develop and control networks of modular thermo-active soft actuators with unprecedented properties for rehabilitation applications. Each actuator is composed of two modules, in which dramatic volume change due to the liquid-gas phase transitions leads to the axial expansion and contraction of a flexible tube inside each module.

Flexible Peltiers are placed between modules to absorb heat from one module and to deliver heat to the other module. One module expands when heated, and the other one expands when cooled. The research objectives of the proposal are to: (1) understand the underlying multi-physics (electro-thermo-mechanical) governing the operation of the actuator and the network, (2) create a framework for optimizing the network performance and establishing the effect of the actuator’s design parameters on the performance, (3) develop a versatile and robust control scheme, and (4) demonstrate the capabilities of the proposed networked actuators to be used as a drivetrain for a prosthetic elbow.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.