Proceedings ArticleDOI
An Inverted Straight Line Mechanism for Augmenting Joint Range of Motion in a Humanoid Robot
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TLDR
In this paper, the authors presented a fully backdriveable, force controllable rotary actuator package employed on the Tactical Hazardous Operations Robot (THOR), which used a ball screw-driven linear Series Elastic Actuator (SEA) with a planar straight line mechanism.Abstract:
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.Copyright © 2014 by ASMEread more
Citations
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Proceedings ArticleDOI
Compliant locomotion using whole-body control and Divergent Component of Motion tracking
TL;DR: Details leading to the successful implementation of optimization-based whole-body control on the hardware platform are discussed, including the design of a “simple” joint impedance controller that introduces inner-loop velocity feedback into the actuator force controller.
Proceedings ArticleDOI
Design of a series elastic humanoid for the DARPA Robotics Challenge
Coleman Knabe,John Seminatore,Jacob Webb,Michael A. Hopkins,Tomonari Furukawa,Alexander Leonessa,Brian Y. Lattimer +6 more
TL;DR: The mechanical design of ESCHER, a series elastic humanoid developed to compete in the DARPA Robotics Challenge (DRC) is described; by driving the single degree of freedom joint with two identical linear series elastic actuators (SEAs), the lower body is able to meet the necessary speed and torque requirements for locomotion on rough terrain.
Proceedings ArticleDOI
Embedded joint-space control of a series elastic humanoid
TL;DR: A distributed joint impedance control framework that leverages a custom dual-axis motor controller to track position, velocity, and torque setpoints for each pair of joints in THOR, a new series elastic humanoid.
Proceedings ArticleDOI
An unlumped model for linear series elastic actuators with ball screw drives
TL;DR: A new unlumped model specifically for linear series elastic actuators is proposed which uses a rack & pinion conceptualization to intuitively depict the mechanics of a linear ball screw drive.
Proceedings ArticleDOI
Design of a Compact, Lightweight, Electromechanical Linear Series Elastic Actuator
TL;DR: The THOR SEA as mentioned in this paper is an evolutionary improvement upon the SAFFiR SEA, which was designed to reduce the size and fixed length of the actuator while increasing its load capacity.
References
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Journal ArticleDOI
On the optimum synthesis of a four-bar linkage using differential evolution and method of variable controlled deviations
TL;DR: In this article, a four-bar Grashof linkage whose geometries allow minimum deviations from the problem given for different parts of the crank cycle has been chosen, where the motion of the mechanism crank point located in the prescribed environment of the given point on the observed segment is followed within the prescribed values of allowed deviation.
Journal ArticleDOI
A new family of deployable mechanisms based on the Hoekens linkage
TL;DR: In this article, a family of deployable prism mechanisms based on the Hoekens straight-line linkage is proposed, which can be deployed and compacted in a single dimension.
Proceedings ArticleDOI
Design of a Compact, Lightweight, Electromechanical Linear Series Elastic Actuator
TL;DR: The THOR SEA as mentioned in this paper is an evolutionary improvement upon the SAFFiR SEA, which was designed to reduce the size and fixed length of the actuator while increasing its load capacity.
Proceedings ArticleDOI
Early Developments of a Parallelly Actuated Humanoid, SAFFiR
TL;DR: In this paper, a shipboard autonomous fire fighting robot with a central lightweight skeleton actuated with modular ballscrew driven force controllable linear actuators arranged in a parallel fashion around the joints is presented.
Proceedings ArticleDOI
Design of a Human-Like Range of Motion Hip Joint for Humanoid Robots
TL;DR: In this article, the design of the hip joint of the Tactical Hazardous Operations Robot (THOR), which was created to perform disaster response duties in human-structured environments, was presented.