An LPV Approach to Obstacle-Sensitive Trajectory Regulation

2009 ◽  
Author(s):  
Mazen Farhood ◽  
Eric Feron
Keyword(s):  
Control Strategy ◽  
Design Parameter ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
And Performance ◽  
Three Degree Of Freedom ◽  
Parameter Dependent ◽  
Strategy Changes ◽  
Loop Stability

The paper focuses on the control of vehicular systems along trajectories in the presence of obstacles. We design parameter-dependent controllers which guarantee closed-loop stability and performance of the vehicle’s regulation loop. In addition, the control strategy changes depending on the position of the vehicle in the obstacle environment so that the critical outputs are given the most attention. We also provide a fast and easy-to-implement algorithm for online controller construction. Last, the proposed approach is applied to a three-degree-of-freedom helicopter.

Equivalent Kinematic Chains of Three Degree-of-Freedom Tripod Mechanisms With Planar-Spherical Bonds

2005 ◽  
Vol 127 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Patrick Huynh ◽  
Jacques M. Herve´
Keyword(s):  
Closed Loop ◽  
Degree Of Freedom ◽  
Robotic Device ◽  
Kinematics Analysis ◽  
Closed Loop System ◽  
Short Introduction ◽  
Kinematic Chains ◽  
Displacement Group ◽  
Three Degree Of Freedom ◽  
Moving Spheres

The paper aims to analyze the equivalent kinematic chains of a family of three-degree-of-freedom (3-DOF) tripod mechanisms with planar-spherical bonds in order to determine the platform motions generated by the mechanisms, and then to develop a prototype of a 3-DOF 3-RPS type parallel mechanism, which can be used as a wrist robotic device. After a short introduction to mechanical generators of Lie subgroups of displacement, the mobility formula of a general 3-DOF tripod mechanism based on the modified Gru¨ebler’s criterion is given. Using displacement group theory theorems, the analyzed closed-loop system becomes finally equivalent to three contacts between a rigid assembly of three moving spheres onto three fixed planes. As an application of the above method, a prototype mechanism is designed and fabricated based on the kinematics analysis, the force capability and the simplicity.

Multivariable Control Design for a Bilateral Telemanipulator

2003 ◽  
Author(s):  
Kevin B. Fite ◽  
Michael Goldfarb
Keyword(s):  
Impedance Control ◽  
Singular Values ◽  
Degree Of Freedom ◽  
Stability Robustness ◽  
Remote Environment ◽  
And Performance ◽  
The Stability ◽  
Three Degree Of Freedom ◽  
And Control ◽  
Control Methodology

This paper presents an architecture and control methodology for a multi-degree-of-freedom teleoperator system. The approach incorporates impedance control of the telemanipulator pair and formulates the system as a single feedback loop encompassing the human operator, telemanipulator, and remote environment. In so doing, multivariable Nyquist-like techniques are used to design compensation for enhanced stability robustness and performance. A measure of the transparency exhibited by the multivariable teleoperator system is attained using matrix singular values. The approach is experimentally demonstrated on a three degree-of-freedom scaled telemanipulator pair with a highly coupled environment. Using direct measurement of the power delivered to the operator to assess the system’s stability robustness, along with the proposed measure of multivariable transparency, the loop-shaping compensation is shown to improve the stability robustness by a factor of almost two and the transparency by more than a factor of five.

IDENTIFICATION OF THE BEST CONTROL STRATEGY FOR THE APPLICATION OF PROSTHETIC LIMBS

2016 ◽  
Vol 16 (07) ◽  
pp. 1650091 ◽  
Author(s):  
M. ASHMI ◽  
M. ANILA ◽  
S. JAYARAJ ◽  
K. S. SIVANANDAN
Keyword(s):  
Control Strategy ◽  
Closed Loop ◽  
Position Angle ◽  
Human Locomotion ◽  
Assistive Device ◽  
Driving System ◽  
Dc Motors ◽  
Prosthetic Limbs ◽  
And Performance ◽  
Mechanical Devices

Prosthesis is a part of the bio-mechanics field, the science of fusing electro-mechanical devices with human muscles, skeleton, nervous systems, etc. The prosthetic limbs are incredibly precious to amputees as it can improve mobility and help them stay independently. To actuate the assistive device, a real time closed loop driving system is developed comprising of Atmega328 microcontrollers and DC series motors which mimics human locomotion. The feedback corresponding to the rotation of the DC motors is fetched by optical encoders mounted on it and the error is computed. The controllers implemented will take corrective action so as to bring the motors to the desired position at the respective time. In this study P, PI, and PID control algorithms are incorporated in the closed loop driving system for better accuracy and performance. The gain constants ([Formula: see text], [Formula: see text], [Formula: see text]) are tuned manually and the suitable constants are determined by which the drive could be moved at the desired position (angle) in the ideal time of 1.4[Formula: see text]s for completing one gait cycle. The performance of P, PI, and PID controllers are compared and the best control strategy is employed in the driving system which exhibits least error and good stability.

Two Degree-of-Freedom Hysteresis Compensation for a Dynamic Mirror With Antagonistic Piezoelectric Stack Actuation

2013 ◽  
Author(s):  
James A. Mynderse ◽  
George T. C. Chiu
Keyword(s):  
Input Signal ◽  
Control Strategy ◽  
Closed Loop ◽  
Loop System ◽  
Degree Of Freedom ◽  
Closed Loop System ◽  
Loop Control ◽  
Hysteresis Compensation ◽  
Hysteresis Control ◽  
Two Degree Of Freedom

A methodology for designing a low-computation, high-bandwidth strategy for closed-loop control of a hysteretic system without a priori knowledge of the desired trajectory is presented. The resulting two degree-of-freedom hysteresis control strategy is applied to a dynamic mirror with antagonistic piezoelectric stack actuation. Hysteresis compensator is performed by a finite state machine switching polynomials for hysteresis inversion based on the input signal slope. Residual error after hysteresis compensation is corrected by an LQR feedback controller. Experimental results demonstrate effectiveness of the hysteresis compensator and closed-loop system under the proposed hysteresis control strategy. For the triangular input signal tested, the closed-loop system achieves a 91.5% reduction in hysteresis uncertainty with 60 kHz sample rate.

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