Many robotic joints powered by linear actuators suffer from a loss of torque towards the limits of the range of motion. This paper presents the design of a fully backdriveable, force controllable rotary actuator package employed on the Tactical Hazardous Operations Robot (THOR). The assembly pairs a ball screw-driven linear Series Elastic Actuator (SEA) with a planar straight line mechanism. The mechanism is a novel inversion of a Hoeken’s four-bar linkage, using the ball screw as a linear input to actuate the rotary joint. Link length ratios of the straight line mechanism have been chosen to optimize constant angular velocity, resulting in a nearly constant mechanical advantage and peak torque of 115 [Nm] throughout the 150° range of motion. Robust force control is accomplished through means of a lookup table, which is accurate to within ±0.62% of the nominal torque profile for any load case.
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ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference
August 17–20, 2014
Buffalo, New York, USA
Conference Sponsors:
- Design Engineering Division
- Computers and Information in Engineering Division
ISBN:
978-0-7918-4637-7
PROCEEDINGS PAPER
An Inverted Straight Line Mechanism for Augmenting Joint Range of Motion in a Humanoid Robot
Coleman Knabe,
Coleman Knabe
Virginia Tech, Blacksburg, VA
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Dennis Hong
Dennis Hong
University of California, Los Angeles, CA
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Coleman Knabe
Virginia Tech, Blacksburg, VA
Bryce Lee
Virginia Tech, Blacksburg, VA
Dennis Hong
University of California, Los Angeles, CA
Paper No:
DETC2014-35123, V05BT08A015; 6 pages
Published Online:
January 13, 2015
Citation
Knabe, C, Lee, B, & Hong, D. "An Inverted Straight Line Mechanism for Augmenting Joint Range of Motion in a Humanoid Robot." Proceedings of the ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. Volume 5B: 38th Mechanisms and Robotics Conference. Buffalo, New York, USA. August 17–20, 2014. V05BT08A015. ASME. https://doi.org/10.1115/DETC2014-35123
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