CMAC-BASED VARIABLE STRUCTURE POSITION CONTROL OF A PNEUMATIC MUSCLE ACTUATOR SYSTEM

Pneumatic Muscle Actuator (PMA) has a broad application prospect in soft robotics. However, PMA has highly nonlinear and hysteretic properties among force, displacement, and pressure, which lead to difficulty in accurate position control. A phenomenological model is developed to portray the hysteretic behavior of PMA. This phenomenological model consists of linear component and hysteretic component force. The latter component is described by Duhem model. An experimental apparatus is built up and sets of experimental data are acquired. Based on the experimental data, parameters of the model are identified. Validation of the model is performed. Then a novel cascade position PID controller is devised for a 1-DOF manipulator actuated by PMA. The outer loop of the controller is to cope with position control whilst the inner loop deals with pressure dynamics within PMA. To enhance the adaptability of the PID algorithm to the high nonlinearities of the manipulator, PID parameters are tuned online using RBF Neural Network. Experiments are performed and comparison between position response of RBF Neural Network based PID controller and that of classic PID controller demonstrates the effectiveness of the novel adaptive controller on the manipulator.

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A computational simulated control system for a high-force pneumatic muscle actuator: system definition and application as an augmented orthosis

Computer Methods in Biomechanics & Biomedical Engineering ◽

10.1080/10255840802372052 ◽

2009 ◽

Vol 12 (2) ◽

pp. 173-183 ◽

Cited By ~ 4

Author(s):

Maria J. Gerschutz ◽

Chandler A. Phillips ◽

David B. Reynolds ◽

Daniel W. Repperger

Keyword(s):

Control System ◽

Pneumatic Muscle ◽

Actuator System ◽

Pneumatic Muscle Actuator

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Nonlinear Control of a Pneumatic Muscle Actuator System

IFAC Proceedings Volumes ◽

10.1016/s1474-6670(17)35335-1 ◽

2001 ◽

Vol 34 (6) ◽

pp. 1129-1134

Author(s):

Pablo Carbonell ◽

Zhong-Ping Jiang ◽

Daniel W. Repperger

Keyword(s):

Nonlinear Control ◽

Pneumatic Muscle ◽

Actuator System ◽

Pneumatic Muscle Actuator

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System Identification and Robust Control of a Pneumatic Muscle Actuator System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.284-287.1936 ◽

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.

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Sliding mode control of a pneumatic muscle actuator system with a PWM strategy

International Journal of Fluid Power ◽

10.1080/14399776.2014.893707 ◽

2014 ◽

Vol 15 (1) ◽

pp. 19-31 ◽

Cited By ~ 19

Author(s):

Ville T. Jouppila ◽

S. Andrew Gadsden ◽

Gary M. Bone ◽

Asko U. Ellman ◽

Saeid R. Habibi

Keyword(s):

Sliding Mode Control ◽

Sliding Mode ◽

Pneumatic Muscle ◽

Mode Control ◽

Actuator System ◽

Pneumatic Muscle Actuator

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Position Control of PWM-Actuated Pneumatic Muscle Actuator System

Volume 7: Dynamic Systems and Control; Mechatronics and Intelligent Machines, Parts A and B ◽

10.1115/imece2011-63370 ◽

2011 ◽

Cited By ~ 2

Author(s):

Ville Jouppila ◽

Asko Ellman

Keyword(s):

Position Control ◽

System Model ◽

Modeling Error ◽

Stick Slip ◽

Pneumatic Muscle ◽

Positioning Systems ◽

Highly Nonlinear ◽

Pneumatic Muscle Actuator ◽

Non Linear System ◽

Real Challenge

Pneumatic servo positioning systems have been in use for long time and subject to wide spectrum of studies due to their numerous advantages: inexpensive, clean, safe and high ratio of power to weight. However, the compressibility of air and the inherent non-linearity of these systems continue to make achieving accurate position control a real challenge. Conventional pneumatic servo systems are based on cylinder actuators that are difficult to control precisely due to the aforementioned nonlinearities as well as the nonlinear behavior of the air flow through the valve, the friction between the cylinder and the piston, and the stick slip effect at the low velocity of the system. In this paper, a position servo control system using a pneumatic muscle actuator is studied. Pneumatic muscle actuator is a novel type of actuator which has even higher force to weight ratio than the cylinder. In addition, muscle actuator introduces a stick slip free operation giving an interesting option for positioning systems. However, significant hysteresis and position dependant force result in a highly nonlinear system, a real challenge for good control performance. In this paper, pneumatic muscle actuator is controlled by a low-cost on/off valve with PWM-strategy instead of costly servo or proportional valve. The main processes of the system, including flow dynamics, pressure dynamics, force dynamics and load dynamics are derived to provide a full nonlinear model that captures all the major nonlinearities of the system. This model is used for analyzing and tuning the controller performances by simulations before implementing in the real system. In addition, a recently introduced method of using bipolynomial functions to model the valve flow rate is utilized to provide a continuous and invertible description of flow for controller designs. A proportional plus velocity plus acceleration controller with feed-forward component (PVA+FF) is designed based on the linearized system model. For a comparison, a sliding mode controller (SMC) based on linear as well as non-linear system model are designed. The performance of the designed controllers is studied by simulations. The stability and performance analysis includes the effects of friction modeling error and valve modeling error. The robustness of the controllers is tested by varying the payload mass of the system.

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