TY - JOUR
T1 - Modeling and Experimental Evaluation of a Variable Hydraulic Transmission
AU - Gan, Zhenyu
AU - Tang, Haoyue
AU - Treadway, Emma
AU - Gillespie, Richard Brent
AU - Remy, Christian David
N1 - Funding Information:
Manuscript received August 8, 2018; revised February 3, 2019 and November 2, 2019; accepted December 9, 2019. Date of publication January 3, 2020; date of current version April 15, 2020. Recommended by Technical Editor Prof. J. Mattila. This work was supported in part by the NIH under Grant 1-R01-EB019834-2014 “Wearable eMbots to Induce Recovery of Function” and in part by the National Science Foundation Graduate Research Fellowship Program under Grant DGE1256260. (Corresponding author: Zhenyu Gan.) The authors are with the Robotics and Motion Laboratory (RAMlab) and HaptiX Lab, Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 USA (e-mail: ganzheny@umich. edu; tonnytt@umich.edu; etreadwa@umich.edu; brentg@umich.edu; cdremy@umich.edu).
Publisher Copyright:
© 1996-2012 IEEE.
PY - 2020/4
Y1 - 2020/4
N2 - A low-loss hydraulic transmission offers an efficient and lightweight means to route power from a central source to distal actuators, with example applications in legged and wearable robots. For example, one could develop a completely passive hydraulic transmission for an exoskeleton that routes power from a healthy limb to a limb weakened by neurological injury to enable self-assist or rehabilitation. In this article, we introduce and model a variable hydraulic transmission that features rolling diaphragm cylinders and a discretely variable transmission ratio. The variable transmission utilizes digital hydraulics, wherein valves switch redundantly mounted cylinders in and out of the hydraulic circuit. The article discusses the impact of configuration on the available transmission ratios and passivity. Our modeling efforts focus on the parasitic effects that arise with power losses between the driving and driven joints, compliance and energy storage in the transmission, and drift during switching. We carefully validate the model, comparing analytically predicted fine and gross behaviors to experimental observations. Experimental results demonstrate the feasibility and utility of the proposed device and the associated model which serves as an important tool for the design and control of digital hydraulic transmission systems.
AB - A low-loss hydraulic transmission offers an efficient and lightweight means to route power from a central source to distal actuators, with example applications in legged and wearable robots. For example, one could develop a completely passive hydraulic transmission for an exoskeleton that routes power from a healthy limb to a limb weakened by neurological injury to enable self-assist or rehabilitation. In this article, we introduce and model a variable hydraulic transmission that features rolling diaphragm cylinders and a discretely variable transmission ratio. The variable transmission utilizes digital hydraulics, wherein valves switch redundantly mounted cylinders in and out of the hydraulic circuit. The article discusses the impact of configuration on the available transmission ratios and passivity. Our modeling efforts focus on the parasitic effects that arise with power losses between the driving and driven joints, compliance and energy storage in the transmission, and drift during switching. We carefully validate the model, comparing analytically predicted fine and gross behaviors to experimental observations. Experimental results demonstrate the feasibility and utility of the proposed device and the associated model which serves as an important tool for the design and control of digital hydraulic transmission systems.
KW - Actuators
KW - fluid flow
KW - hydraulic systems
KW - motion control
KW - variable speed drives
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U2 - 10.1109/TMECH.2019.2963880
DO - 10.1109/TMECH.2019.2963880
M3 - Article
AN - SCOPUS:85083987771
SN - 1083-4435
VL - 25
SP - 750
EP - 761
JO - IEEE/ASME Transactions on Mechatronics
JF - IEEE/ASME Transactions on Mechatronics
IS - 2
M1 - 8949563
ER -