Title
First steps toward translating robotic walking to prostheses: a nonlinear optimization based control approach.
Abstract
This paper presents the first steps toward successfully translating nonlinear real-time optimization based controllers from bipedal walking robots to a self-contained powered transfemoral prosthesis: AMPRO, with the goal of improving both the tracking performance and the energy efficiency of prostheses control. To achieve this goal, a novel optimization-based optimal control strategy combining control Lyapunov function based quadratic programs with impedance control is proposed. This optimization-based optimal controller is first verified on a human-like bipedal robot platform, AMBER. The results indicate improved (compared to variable impedance control) tracking performance, stability and robustness to unknown disturbances. To translate this complete methodology to a prosthetic device with an amputee, we begin by collecting reference locomotion data from a healthy subject via inertial measurement units (IMUs). This data forms the basis for an optimization problem that generates virtual constraints, i.e., parameterized trajectories, specifically for the amputee . A online optimization based controller is utilized to optimally track the resulting desired trajectories. An autonomous, state based parameterization of the trajectories is implemented through a combination of on-board sensing coupled with IMU data, thereby linking the gait progression with the actions of the user. Importantly, the proposed control law displays remarkable tracking and improved energy efficiency, outperforming PD and impedance control strategies. This is demonstrated experimentally on the prosthesis AMPRO through the implementation of a holistic sensing, algorithm and control framework, resulting in dynamic and stable prosthetic walking with a transfemoral amputee.
Year
DOI
Venue
2017
10.1007/s10514-016-9565-1
Auton. Robots
Keywords
Field
DocType
Transfemoral prosthesis control,Real-time optimal control,Hybrid systems,Quadratic program,Optimization problem
Control theory,Optimal control,Control-Lyapunov function,Simulation,Computer science,Nonlinear programming,Impedance control,Inertial measurement unit,Quadratic programming,Optimization problem
Journal
Volume
Issue
ISSN
41
3
0929-5593
Citations 
PageRank 
References 
9
0.80
17
Authors
5
Name
Order
Citations
PageRank
Huihua Zhao1325.02
Jonathan Horn2152.95
Jacob Reher390.80
Victor Paredes4182.41
Aaron D. Ames51202136.68