scholarly journals Design and implementation of robust controllers for a gait trainer

2009 ◽  
Vol 223 (6) ◽  
pp. 687-696 ◽  
Author(s):  
F-C Wang ◽  
C-H Yu ◽  
T-Y Chou
Keyword(s):  
Robust Control ◽  
Transfer Functions ◽  
Control Strategies ◽  
Control Algorithms ◽  
Robust Controllers ◽  
Robust Algorithms ◽  
Design And Implementation ◽  
Identification Techniques ◽  
Gait Trainer ◽  
Operating Points

This paper applies robust algorithms to control an active gait trainer for children with walking disabilities. Compared with traditional rehabilitation procedures, in which two or three trainers are required to assist the patient, a motor-driven mechanism was constructed to improve the efficiency of the procedures. First, a six-bar mechanism was designed and constructed to mimic the trajectory of children's ankles in walking. Second, system identification techniques were applied to obtain system transfer functions at different operating points by experiments. Third, robust control algorithms were used to design H∞ robust controllers for the system. Finally, the designed controllers were implemented to verify experimentally the system performance. From the results, the proposed robust control strategies are shown to be effective.

System Identification and Robust Control of a Pneumatic Muscle Actuator System

2013 ◽  
Vol 284-287 ◽  
pp. 1936-1940
Author(s):  
Liu Hsu Lin ◽  
Jai Yush Yen ◽  
Fu Cheng Wang
Keyword(s):  
Robust Control ◽  
Transfer Functions ◽  
Control Strategies ◽  
Robust Controller ◽  
Pneumatic Muscle ◽  
Actuator System ◽  
System Uncertainties ◽  
Pneumatic Muscle Actuator ◽  
And Performance ◽  
Identification Techniques

This paper describes the application of system identification techniques and robust control strategies to a pneumatic muscle actuator system. Due to the inherent nonlinear and time-varying characteristics of this system, it is difficult to achieve excellent performance using conventional control methods. Therefore, we apply identification techniques to model the system as linear transfer functions and regard the un-modeled dynamics as system uncertainties. Because robust control is well-known for its capability in dealing with system uncertainties, we then apply robust control strategies to guarantee system stability and performance for the system. This work is carried out in three parts. First, the pneumatic muscle actuator system was modeled as linear transfer functions. Second, robust control theorem were utilized to design a Hinf robust controller to deal with system uncertainties and performance requirements. Finally, the designed controller was implemented for experimental verifications and compared with a conventional PID controller. From the experimental results, the proposed Hinf robust controller is deemed effective.

ROBUST CONTROL FOR A PNEUMATIC MUSCLE ACTUATOR SYSTEM

2013 ◽  
Vol 37 (3) ◽  
pp. 581-590 ◽  
Author(s):  
Liu-Hsu Lin ◽  
Jia-Yush Yen ◽  
Fu-Cheng Wang
Keyword(s):  
Robust Control ◽  
Transfer Functions ◽  
Control Strategies ◽  
System Stability ◽  
Pneumatic Muscle ◽  
Guarantee System ◽  
Actuator System ◽  
System Uncertainties ◽  
Pneumatic Muscle Actuator ◽  
And Performance

This paper presents the modeling and robust control of a pneumatic muscle actuator system. Due to the inherent nonlinear and time-varying characteristics of this system, it is difficult to achieve excellent performance using conventional control methods. Therefore, we apply identification techniques to model the system as linear transfer functions and regard the un-modeled dynamics as system uncertainties. Because H∞ robust control is well-known for its capability in dealing with system uncertainties, we then apply H∞ robust control strategies to guarantee system stability and performance for the system. From the experimental results, the proposed H∞ robust controller is deemed effective.

The Use of Damping Based Semi-Active Control Algorithms in the Mechanical Smart-Spring System

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Wander Gustavo Rocha Vieira ◽  
Fred Nitzsche ◽  
Carlos De Marqui
Keyword(s):  
Active Control ◽  
Control Algorithm ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Flow Analysis ◽  
Coupled Systems ◽  
Control Technique ◽  
Control Algorithms ◽  
Control Techniques ◽  
Spring Mechanism

In recent decades, semi-active control strategies have been investigated for vibration reduction. In general, these techniques provide enhanced control performance when compared to traditional passive techniques and lower energy consumption if compared to active control techniques. In semi-active concepts, vibration attenuation is achieved by modulating inertial, stiffness, or damping properties of a dynamic system. The smart spring is a mechanical device originally employed for the effective modulation of its stiffness through the use of semi-active control strategies. This device has been successfully tested to damp aeroelastic oscillations of fixed and rotary wings. In this paper, the modeling of the smart spring mechanism is presented and two semi-active control algorithms are employed to promote vibration reduction through enhanced damping effects. The first control technique is the smart-spring resetting (SSR), which resembles resetting control techniques developed for vibration reduction of civil structures as well as the piezoelectric synchronized switch damping on short (SSDS) technique. The second control algorithm is referred to as the smart-spring inversion (SSI), which presents some similarities with the synchronized switch damping (SSD) on inductor technique previously presented in the literature of electromechanically coupled systems. The effects of the SSR and SSI control algorithms on the free and forced responses of the smart-spring are investigated in time and frequency domains. An energy flow analysis is also presented in order to explain the enhanced damping behavior when the SSI control algorithm is employed.

Blind Identification of Impact Forces From Multiple Remote Vibratory Measurements

2000 ◽  
Author(s):  
J. Antunes ◽  
P. Izquierdo ◽  
M. Paulino
Keyword(s):  
Explicit Knowledge ◽  
Transfer Functions ◽  
Dynamical Behavior ◽  
Practical Interest ◽  
Operating Conditions ◽  
Blind Identification ◽  
Minimum Entropy ◽  
Response Measurement ◽  
Identification Techniques ◽  
The Impact

Abstract Structures and mechanical components are often subjected to impulsive forces. There is a need for identification techniques which enable monitoring of such loads under operating conditions. For safety reasons and convenience, force identification must often be based on response motions sensed at accessible locations, remote from the impact points. In our previous work we presented techniques for the experimental identification of both isolated impacts and complex rattling forces on a beam, generated at a single and also at several impacting supports. The system dynamical behavior was modeled using traveling flexural beam waves. Although successful, these techniques obviously assume a good understanding of the system dynamic parameters. This is not always the case, a fact that highlights the practical interest of blind identification techniques. This relatively recent field, connected with higher-order statistics, avoids any explicit knowledge of the system transfer functions or impulse responses. Our previous work, based on a single response measurement, is extended in this paper to include several simultaneous responses. We develop a multi-trace version of Wiggins minimum-entropy blind deconvolution algorithm. From numerical simulations and experiments, it is shown that the robustness to noise contamination is increased by using multiple response data. These results suggest that blind identification techniques will prove very useful in practical situations.

Robust vibration control of flexible panel: modeling and simulation

2017 ◽  
Vol 14 (5) ◽  
pp. 433-442
Author(s):  
Aalya Banu ◽  
Asan G.A. Muthalif
Keyword(s):  
Robust Control ◽  
Vibration Control ◽  
Controller Design ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Parametric Uncertainty ◽  
Design Algorithm ◽  
Content Type ◽  
And Performance

Purpose This paper aims to develop a robust controller to control vibration of a thin plate attached with two piezoelectric patches in the presence of uncertainties in the mass of the plate. The main goal of this study is to tackle dynamic perturbation that could lead to modelling error in flexible structures. The controller is designed to suppress first and second modal vibrations. Design/methodology/approach Out of various robust control strategies, μ-synthesis controller design algorithm has been used for active vibration control of a simply supported thin place excited and actuated using two piezoelectric patches. Parametric uncertainty in the system is taken into account so that the robust system will be achieved by maximizing the complex stability radius of the closed-loop system. Effectiveness of the designed controller is validated through robust stability and performance analysis. Findings Results obtained from numerical simulation indicate that implementation of the designed controller can effectively suppress the vibration of the system at the first and second modal frequencies by 98.5 and 88.4 per cent, respectively, despite the presence of structural uncertainties. The designed controller has also shown satisfactory results in terms of robustness and performance. Originality/value Although vibration control in designing any structural system has been an active topic for decades, Ordinary fixed controllers designed based on nominal parameters do not take into account the uncertainties present in and around the system and hence lose their effectiveness when subjected to uncertainties. This paper fulfills an identified need to design a robust control system that accommodates uncertainties.

scholarly journals Control Strategies and Artificial Intelligence in Rehabilitation Robotics

AI Magazine ◽  
2015 ◽  
Vol 36 (4) ◽  
pp. 23-33 ◽  
Author(s):  
Domen Novak ◽  
Robert Riener
Keyword(s):  
Artificial Intelligence ◽  
Control Strategies ◽  
Rehabilitation Robotics ◽  
Control Algorithms ◽  
Assistive Robots ◽  
Socially Assistive Robots ◽  
Rehabilitation Robots ◽  
Exercise Adaptation ◽  
Dominant Paradigm ◽  
Do So

Rehabilitation robots physically support and guide a patient's limb during motor therapy, but require sophisticated control algorithms and artificial intelligence to do so. This article provides an overview of the state of the art in this area. It begins with the dominant paradigm of assistive control, from impedance-based cooperative controller through electromyography and intention estimation. It then covers challenge-based algorithms, which provide more difficult and complex tasks for the patient to perform through resistive control and error augmentation. Furthermore, it describes exercise adaptation algorithms that change the overall exercise intensity based on the patient's performance or physiological responses, as well as socially assistive robots that provide only verbal and visual guidance. The article concludes with a discussion of the current challenges in rehabilitation robot software: evaluating existing control strategies in a clinical setting as well as increasing the robot's autonomy using entirely new artificial intelligence techniques.

scholarly journals Modeling and Controlling the Cooling System of an IC Vehicle

2021 ◽  
pp. 80-85
Author(s):  
C. Mureșan ◽  
◽  
G. Harja
Keyword(s):  
Mathematical Modeling ◽  
Heat Exchangers ◽  
High Performance ◽  
Cooling System ◽  
Control Strategies ◽  
Positive Influence ◽  
Control Algorithms ◽  
Performance Control ◽  
Ic Engines ◽  
Physical Phenomena

The performance and efficiency of internal combustion (IC) engines can be greatly improved by using a high-performance cooling system. This can be achieved by implementing robust control strategies and, also by building the cooling system with high-performance elements. The mechanical execution elements can be replaced with electrically controllable elements such as the pump and the thermostat valve. This will have a positive influence on the degree of controllability of the system. In order to develop high-performance control algorithms, it is necessary to have a model that best reflects the behaviors of the physical system. Thus, this paper presents a mathematical modeling approach for the cooling system using the principles of heat exchangers and the physical phenomena present in them.

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