Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part Two—Robust Control

2011 ◽  
Author(s):  
Sai-Kit Wu ◽  
Garrett Waycaster ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Robust Control ◽  
Nonlinear Model ◽  
Sliding Mode ◽  
Artificial Muscle ◽  
Control Approach ◽  
Actuation System ◽  
Highly Nonlinear ◽  
Pressure Dynamics ◽  
System Part ◽  
And Control

A robust control approach is presented in this part of the paper, which provides an effective servo control for the novel PAM actuation system presented in Part I. Control of PAM actuation systems is generally considered as a challenging topic, due primarily to the highly nonlinear nature of such system. With the introduction of new design features (variable-radius pulley and spring-return mechanism), the new PAM actuation system involves additional nonlinearities (e.g. the nonlinear relationship between the joint angle and the actuator length), which further increasing the control difficulty. To address this issue, a nonlinear model based approach is developed. The foundation of this approach is a dynamic model of the new actuation system, which covers the major nonlinear processes in the system, including the load dynamics, force generation from internal pressure, pressure dynamics, and mass flow regulation with servo valve. Based on this nonlinear model, a sliding mode control approach is developed, which provides a robust control of the joint motion in the presence of model uncertainties and disturbances. This control was implemented on an experimental setup, and the effectiveness of the controller demonstrated by sinusoidal tracking at different frequencies.

Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part One—Design Process

2011 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Controller Design ◽  
Artificial Muscle ◽  
The Other ◽  
Robotic Systems ◽  
Pneumatic Artificial Muscle ◽  
Actuation System ◽  
Torque Curve ◽  
System Part ◽  
New Feature ◽  
And Control

This paper describes the design and control of a compact and flexible pneumatic artificial muscle (PAM) actuation system for bio-robotic systems. The entire paper is divided into two parts, with the first part covering the mechanism design and the second part covering the corresponding controller design. This novel system presented in this part incorporates two new features, including a variable-radius pulley based PAM actuation mechanism, and a spring-return mechanism to replace the PAM in the “weak” direction. With the pulley radius as a function of the joint angle, this new feature enables the designer to freely modulate the shape of the torque curve, and thus achieves a significantly higher flexibility than the traditional configuration. The other new feature, the spring-return mechanism, is inspired by the fact that a large number of bio-robotic systems require a significantly larger torque in one direction than the other.

A Unified Force Controller for a Proportional-Injector Direct-Injection Monopropellant-Powered Actuator

2005 ◽  
Vol 128 (1) ◽  
pp. 159-164 ◽  
Author(s):  
Kevin B. Fite ◽  
Jason E. Mitchell ◽  
Eric J. Barth ◽  
Michael Goldfarb
Keyword(s):  
Sliding Mode ◽  
Direct Injection ◽  
Sliding Mode Controller ◽  
Nonlinear Controller ◽  
Single Input Single Output ◽  
Control Approach ◽  
Single Output ◽  
Human Scale ◽  
Actuation System ◽  
And Control

This paper describes the modeling and control of a proportional-injector direct-injection monopropellant-powered actuator for use in power-autonomous human-scale mobile robots. The development and use of proportional (as opposed to solenoid) injection valves enables a continuous and unified input/output description of the device, and therefore enables the development and implementation of a sliding-mode-type controller for the force control of the proposed actuator, which provides the stability guarantees characteristic of a sliding-mode control approach. Specifically, a three-input, single-output model of the actuation system behavior is developed, which takes a nonlinear non-control-canonical form. In order to implement a nonlinear controller, a constraint structure is developed that effectively renders the system single input, single output, and control canonical, and, thus, of appropriate form for the implementation of a sliding-mode controller. A sliding-mode controller is then developed and experimentally implemented on the proposed actuator. Experimental results demonstrate closed-loop force tracking with a saturation-limited bandwidth of approximately 6Hz.

A Pneumatic Artificial Muscle Actuated Above-Knee Prosthesis

2010 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Xiangrong Shen
Keyword(s):  
Sliding Mode ◽  
Mechanical Design ◽  
Knee Prosthesis ◽  
Artificial Muscle ◽  
Torque Control ◽  
Stair Climbing ◽  
Pneumatic Artificial Muscle ◽  
Control Approach ◽  
Energy Consuming ◽  
And Control

This paper describes the mechanical design and control approach for an above-knee (AK) prosthesis actuated by pneumatic artificial muscle. Pneumatic artificial muscle (PAM) affords great potential in prosthetics, since this type of actuator features a high power density, and similar characteristics to human muscles. However, there is no application of PAM in AK prosthetics in existing literature to the best knowledge of the authors. In this paper, a design of the prosthesis is presented, which provides sufficient actuation torque for the knee joint in energy consuming locomotive functions such as fast walking and stair climbing. The corresponding control approach is also presented, which combines an impedance-based locomotive controller with a lower-level sliding-mode torque control approach. Experiments on the proposed AK prosthesis have also been conducted to demonstrate the ability to mimic normal gait characteristics.

Design and Control of Chemomuscle: A Liquid-Propellant-Powered Muscle Actuation System

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Xiangrong Shen ◽  
Daniel Christ
Keyword(s):  
Liquid Fuel ◽  
Artificial Muscle ◽  
High Energy ◽  
Mobile Systems ◽  
High Energy Density ◽  
Effective Control ◽  
Future Application ◽  
Actuation System ◽  
Highly Nonlinear ◽  
And Control

This paper describes the design and control of a new chemomuscle actuation system for robotic systems, especially the mobile systems inspired by biological principles. Developed based on the pneumatic artificial muscle, a chemomuscle actuation system features a high power density, as well as similar characteristics to the biological muscles. Furthermore, by introducing monopropellant (a special type of liquid fuel) as the energy storage media, the chemomuscle system leverages the high energy density of liquid fuel and provides a compact form of high-pressure gas supply with a simple structure. The introduction of monopropellant addresses the limitation of pneumatic supply on mobile devices and thus is expected to facilitate the future application of artificial muscle on biorobotic systems. In this paper, the design of a chemomuscle actuation system is presented, as well as a robust controller design that provides effective control for this highly nonlinear system. To demonstrate the proposed chemomuscle actuation system, an experimental prototype is constructed, on which the proposed control algorithm provides good tracking performance.

scholarly journals Sliding mode control of the automobile electro-coating conveying mechanism with a nonlinear disturbance observer

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879574 ◽  
Author(s):  
Wei Yuan ◽  
Guoqin Gao
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Observer ◽  
High Performance ◽  
Sliding Mode ◽  
External Disturbance ◽  
Nonlinear Disturbance Observer ◽  
Control Approach ◽  
Mode Control ◽  
Highly Nonlinear ◽  
Nonlinear Disturbance

The trajectory-tracking performance of the automobile electro-coating conveying mechanism is severely interrupted by highly nonlinear crossing couplings, unmodeled dynamics, parameter variation, friction, and unknown external disturbance. In this article, a sliding mode control with a nonlinear disturbance observer is proposed for high-accuracy motion control of the conveying mechanism. The nonlinear disturbance observer is designed to estimate not only the internal/external disturbance but also the model uncertainties. Based on the output of the nonlinear disturbance observer, a sliding mode control approach is designed for the hybrid series–parallel mechanism. Then, the stability of the closed-loop system is proved by means of a Lyapunov analysis. Finally, simulations with typical desired trajectory are presented to demonstrate the high performance of the proposed composite control scheme.

scholarly journals CONTROL NOVEL MODEL OF KNEE CPM DEVICE

2009 ◽  
Vol 12 (4) ◽  
pp. 18-29
Author(s):  
Thanh Diep Cong Tu
Keyword(s):  
Weight Ratio ◽  
Artificial Muscle ◽  
Network Control ◽  
Continuous Passive Motion ◽  
The Novel ◽  
Highly Nonlinear ◽  
Cord Injury ◽  
And Control ◽  
Novel Model ◽  
Interesting Alternative

In recent years, CPM - Continuous Passive Motion has been proved to be one of the most effective therapeutic methods for patients who have problems with motion such as spinal cord injury, ankle and knee injury, parkinson and so on. Many commercial CPM devices are found in market but all of them use motors as the main actuators. The lack of human compliance of electric actuators, which are commonly used in these machines, makes them potentially harmful to patients. An interesting alternative, to electric actuators for medical purposes, particularly promising for rehabilitation, is a pneumatic artificial muscle (PAM) actuator because of its high power/weight ratio and compliance properties. However, the highly nonlinear and hysteresis of PAM make it the challenging for design and control. In this study, a PID compensation using neural network control is studied to improve the control performance of the novel model of Knee CPM device.

A Monopropellant-Powered Muscle Actuation System

2010 ◽  
Author(s):  
Xiangrong Shen ◽  
Daniel Christ
Keyword(s):  
Controller Design ◽  
Artificial Muscle ◽  
High Energy ◽  
Mobile Systems ◽  
High Energy Density ◽  
Robotic Systems ◽  
Effective Control ◽  
Future Application ◽  
Actuation System ◽  
Highly Nonlinear

This paper describes the design and control of a new monopropellant-powered muscle actuation system for robotic systems, especially the mobile systems inspired by biological principles. Based on the pneumatic artificial muscle, this system features a high power density, as well as characteristics similar to biological muscles. By introducing the monopropellant as the energy storage media, this system utilizes the high energy density of liquid fuel and provides a high-pressure gas supply with a simple structure in a compact form. This addresses the limitations of pneumatic supplies on mobile devices and thus is expected to facilitate the future application of artificial muscles on bio-robotic systems. In this paper, design of the monopropellant-powered muscle actuation system is presented as well as a robust controller design that provides effective control for this highly nonlinear system. To demonstrate the proposed muscle actuation system, an experimental prototype was constructed on which the proposed control algorithm provides good tracking performance.

Experimental Comparisons of Sliding Mode Controlled Pneumatic Muscle and Cylinder Actuators

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Ville Jouppila ◽  
S. Andrew Gadsden ◽  
Asko Ellman
Keyword(s):  
Sliding Mode ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Stick Slip ◽  
Servo Systems ◽  
Pneumatic Muscle ◽  
Positioning Systems ◽  
Actuation System ◽  
Highly Nonlinear ◽  
Muscle Actuators

Pneumatic muscle actuators offer a higher force-to-weight ratio compared to traditional cylinder actuators, and introduce stick-slip-free operation that offers an interesting option for positioning systems. Despite several advantages, pneumatic muscle actuators are commonly avoided in industrial applications, mainly due to rather different working principles. Due to the highly nonlinear characteristics of the muscle actuator and pneumatic system, a reliable control strategy is required. Although muscle actuators are widely studied, the literature lacks detailed studies where the performance for servo systems is compared with traditional pneumatic cylinders. In this paper, a pneumatic servo actuation system is compared with a traditional cylinder actuator. As the overall system dynamics are highly nonlinear and not well defined, a sliding mode control (SMC) strategy is chosen for the control action. In order to improve the tracking performance, an SMC strategy with an integral action (SMCI) is also implemented. The control algorithms are experimentally applied on the pneumatic muscle and the cylinder actuator, for the purposes of position tracking. The robustness of the systems are verified and compared by varying the applied loads.

Nonlinear Model-Based Control of Pulse Width Modulated Pneumatic Servo Systems

2005 ◽  
Vol 128 (3) ◽  
pp. 663-669 ◽  
Author(s):  
Xiangrong Shen ◽  
Jianlong Zhang ◽  
Eric J. Barth ◽  
Michael Goldfarb
Keyword(s):  
Canonical Form ◽  
Nonlinear Model ◽  
Pulse Width ◽  
Sliding Mode ◽  
Control Input ◽  
Model Based Control ◽  
Pulse Width Modulated ◽  
Time Dynamics ◽  
Model Based ◽  
Actuation System

This paper presents a control methodology that enables nonlinear model-based control of pulse width modulated (PWM) pneumatic servo actuators. An averaging approach is developed to describe the equivalent continuous-time dynamics of a PWM controlled nonlinear system, which renders the system, originally discontinuous and possibly nonaffine in the input, into an equivalent system that is both continuous and affine in control input (i.e., transforms the system to nonlinear control canonical form). This approach is applied to a pneumatic actuator controlled by a pair of three-way solenoid actuated valves. The pneumatic actuation system is transformed into its averaged equivalent control canonical form, and a sliding mode controller is developed based on the resulting model. The controller is implemented on an experimental system, and the effectiveness of the proposed approach validated by experimental trajectory tracking.

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