Quasi-static rolling control for hybrid rolling-walking and climbing robots

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Publication Type thesis
School or College College of Engineering
Department Mechanical Engineering
Author Phipps, Cristian C
Title Quasi-static rolling control for hybrid rolling-walking and climbing robots
Date 2007-11-26
Description Motivated by the need for greater speed, efficiency and adaptability in climbing and walking robots, a class of legged robots have been developed which compliment their walking and climbing capabilities with rolling. Rolling capabilities are provided by innovative morphologies (including circular cross-section exoskeletons), without the need for additional resources beyond those required for walking and climbing. Herein is presented the design of two such robots, the development of quasi-static rolling locomotion controllers for them, and a comparison of experimentally obtained speed and energy data for walking versus rolling locomotion. Rather than basing the control law on simulated model based results as in previous work, the quasi-static control law developed here relies on the passive stability of a disproportionately weighted circular shape. On an even slope, such a shape will come to equilibrium where the center of gravity (CG) is on the line connecting the geometric center of the circle and the ground contact point. Sufficiently slow perturbations to the CG position will cause the circle to roll to restore equilibrium; therefore slowly moving the CG in some polar trajecotry of nonzero length from 0°->360° around the geometric center of the circular shape will cause it to roll a complete revolution. Joint paths to produce an orbit of the CG about the geometric center of the robot's circular shape are generated using a static optimization routine. The intent of this routine is to find smooth joint angle paths that produce a path of the CG at some specified distance L from the geometric center at angles from 0°->360°. Joint paths are generated offline for various L values and played back at different rates in order to evaluate the validity of the control. Experiments on the Rolling Disk Biped (RDB) robot show that in general, trajectory tracking of a linearly increasing rolling angle reference is improved as L increases and as the playback rate decreases which is in concert with our quasi-static assumption. This thesis will show that a feed-forward quasi-static rolling control law may be used to successfully increase the energy efficiency of a legged mobile robot on a level surface (by as much as 5.5 times that of walking on the RDB robot). It will also be shown that such a quasistatic control law may be used to reliably track a linearly increasing rolling trajectory for a limited range of rolling rates and slopes on the RDB.
Type Text
Publisher University of Utah
Subject Robot motion
Dissertation Institution University of Utah
Dissertation Name MS
Language eng
Relation is Version of Digital reproduction of "Quasi-static rolling control for hybrid rolling-walking and climbing robots" J. Willard Marriott Library Special Collections TJ7.5 2008 .P48
Rights Management © Cristian C. Phipps
Format Medium application/pdf
Format Extent 181,225 bytes
Identifier us-etd2,128540
Source Original: University of Utah J. Willard Marriott Library Special Collections
Conversion Specifications Original scanned on Kirtas 2400 and saved as 400 ppi 8 bit grayscale jpeg. Display image generated in Kirtas Technologies' OCR Manager as multiple page pdf, and uploaded into CONTENT dm.
ARK ark:/87278/s6th92c9
Setname ir_etd
Date Created 2012-04-23
Date Modified 2017-12-15
ID 193996
Reference URL https://collections.lib.utah.edu/ark:/87278/s6th92c9