Lower Limb Exoskeleton Control via Linear Quadratic Regulator and Disturbance Observer

<p>One of the dominant virtue of Steer-By-Wire (SBW) vehicle is its capability to enhance handling performance by installing Active Front Steering (AFS) system without the driver’s interferences. Hence, this paper introduced an AFS control strategy using the combination of Composite Nonlinear Feedback (CNF) controller and Disturbance Observer (DOB) to achieve fast yaw rate tracking response which is also robust to the existence of disturbance. The proposed control strategy is simulated in J-curve and Lane change manoevres with the presence of side wind disturbance via Matlab/Simulink sotware. Futhermore, comparison with Proportional Integral Derivative (PID) and Linear Quadratic Regulator (LQR) controllers are also conducted to evaluate the effectiveness of the proposed controller. The results showed that the combined CNF and DOB strategy achieved the fastest yaw rate tracking capability with the least impact of disturbance in the AFS system installed in SBW vehicle.</p>

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Estimation of Unknown Disturbances in Gimbal Systems

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.789-790.951 ◽

2015 ◽

Vol 789-790 ◽

pp. 951-956 ◽

Cited By ~ 3

Author(s):

Burak Kürkçü ◽

Coşku Kasnakoğlu

Keyword(s):

System Identification ◽

High Precision ◽

Disturbance Observer ◽

Linear Quadratic Regulator ◽

Linear Quadratic ◽

Stabilizing Controller ◽

Model Inversion ◽

Estimation Process ◽

Unknown Disturbances ◽

Unknown Disturbance

This paper presents a method for the estimation of unknown disturbances for high precision gimbal systems. Alternative to the classical methods of model inversion and filtering, we employ an asymptotically stabilizing controller which achieves the estimation process even in the presence of unstable zeros. The architecture provides an input equivalent disturbance which can be thought to capture all real disturbances in the system as well as virtual ones such as unmodelled dynamics and nonlinearities. The proposed method is illustrated on a 2-axis gimbal system where system identification is followed by the design on an integral linear quadratic regulator as the stabilizing controller which forms the base of the disturbance observer. It is seen that a random unknown disturbance is estimated successfully in the presence of additional gyro noise.

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Reachability Analysis for Robustness Evaluation of the Sit-to-Stand Movement for Powered Lower Limb Orthoses

Volume 1: Advances in Control Design Methods; Advances in Nonlinear Control; Advances in Robotics; Assistive and Rehabilitation Robotics; Automotive Dynamics and Emerging Powertrain Technologies; Automotive Systems; Bio Engineering Applications; Bio-Mechatronics and Physical Human Robot Interaction; Biomedical and Neural Systems; Biomedical and Neural Systems Modeling, Diagnostics, and Healthcare ◽

10.1115/dscc2018-9066 ◽

2018 ◽

Cited By ~ 2

Author(s):

Octavio Narvaez-Aroche ◽

Andrew Packard ◽

Pierre-Jean Meyer ◽

Murat Arcak

Keyword(s):

Lower Limb ◽

Center Of Mass ◽

Linear Quadratic Regulator ◽

The State ◽

Reachable Sets ◽

Linear Quadratic ◽

Initial State ◽

Worst Case ◽

Sit To Stand ◽

Finite Time Horizon

A sensitivity-based approach for computing over-approximations of reachable sets, in the presence of constant parameter uncertainty and a single initial state, is used to analyze a three-link planar robot modeling a Powered Lower Limb Orthosis and its user. Given the nature of the mappings relating the state and parameters of the system with the input, and output describing the trajectories of its Center of Mass, reachable sets for their respective spaces can be obtained relying on the sensitivities of the nonlinear closed-loop dynamics in the state space. These over-approximations are used to evaluate the worst-case performances of a finite time horizon linear-quadratic regulator for controlling the ascending phase of the Sit-To-Stand movement.

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