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Elastic actuator for precise force control

United States Patent

*** EXPIRED ***
July 22, 1997
View the Complete Patent at the US Patent & Trademark Office
The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.
Pratt; Gill A. (Lexington, MA), Williamson; Matthew M. (Boston, MA)
Massachusetts Institute of Technology (Cambridge, MA)
08/ 496,419
June 29, 1995
GOVERNMENT RIGHTS IN THE INVENTION This invention was made with U.S. government support under contract No. 959333, awarded by the Jet Propulsion Laboratory of the U.S. Department of Energy. The U.S. Government has certain rights in this invention.