Gil Pratt

“That same gear that raises the torque, lowers the speed. Unfortunately, gear reduction causes something called reflected inertia. It's going to be as if the robot weighs a tremendous amount and it can really injure a person.”

“Putting a physical compliance, a spring, in series with the output of that gear train removes that reflected inertia at the very high frequencies.”

“Gil Pratt: Former MIT professor, later at Toyota Research Institute. Inventor of series elastic actuators — the insertion of a physical spring into a robotic joint to eliminate reflected inertia at high frequencies.”