June 18, 2020
Luis Sentis, an associate professor in the Department of Aerospace Engineering and Engineering Mechanics, and a team of researchers received the IEEE/ASME Transactions on Mechatronics best paper award published in 2018. The paper titled “Investigations of a Robotic Test Bed with Viscoelastic Liquid Cooled Actuators” was selected for its innovative approach to actuator design.
The paper features the invention of a novel type of actuator — a mechanism that controls movement — that can be used in robotic applications, known as a viscoelastic liquid cooled actuator (VLCA). The researchers designed, built and thoroughly tested the new actuator and implemented it into their newly designed legged robot, DRACO, which was built for this project.
The team’s main goal of this project was to show that their VLCA excels in five critical axes that enhance a legged robot’s movement and performance: energy efficiency, torque density, impact resistance, joint position and force controllability.
The new VLCA actuator design consists of elastomers with a piston-like ball screw drive that can be used in multi-DOF (multiple degrees of freedom) robots and was tested thoroughly for its robotics performance.
After developing design objectives for the new actuator and investigating the properties and performance of viscoelastic materials, the team designed and built DRACO using the new actuator. Testing of the new VLCA robotic system demonstrates that the robot is capable of lifting large payloads with high output power and can also change its trajectory quickly while carrying moderate payloads. Experiments were also performed to test DRACO’s response to impacts by hitting it with a hammer and through other human-induced external forces.
The legged robot DRACO, tested and controlled using algorithms from the Human Centered Robotics Lab at UT Austin and designed and built by engineers from Apptronik, is shown here dynamically walking using its tiny feet. The robot was built to feature a new kind of actuator — the mechanism that controls the robot — known as a viscoelastic liquid cooled actuator (VLCA).
Sentis said the importance of this new type of actuator for robotic control will ultimately allow for more robots to be used in a number of commercial applications due to their light weight, which makes them more portable and affordable.
“Our liquid cooled viscoelastic actuation technology contributes to a significant reduction on the size of motors needed to control legged robots. The lighter robots are, the more portable and affordable they become,” Sentis said. “Legged robots, such as the latest Boston Dynamics quadrupedal robot, are starting to become commercial for logistic support, door-to-door delivery, and industrial inspection. Liquid cooled viscoelastic actuators will allow future generations of legged robots to be significantly lighter than current ones.”
The research featured in the winning paper was conducted in the Human Centered Robotics Laboratory, which is directed by Sentis.
Sentis holds the General Dynamics Endowed Faculty Fellowship at the Cockrell School of Engineering. He is also co-founder and scientific advisor of Apptronik Systems Inc., a company focusing on human-centered robotic augmentation systems and educational robotic laboratories.
