Model-Based Feedforward Control of a Robotic Manipulator With Pneumatic Artificial Muscles

2012 ◽  
Author(s):  
Ryan M. Robinson ◽  
Norman M. Wereley ◽  
Curt S. Kothera
Keyword(s):  
Control Algorithm ◽  
Controller Design ◽  
Feedforward Control ◽  
Artificial Muscles ◽  
Specific Work ◽  
Pneumatic Actuators ◽  
Precise Control ◽  
Model Based ◽  
Pneumatic Artificial Muscles ◽  
Dynamics Simulations

Pneumatic artificial muscles (PAMs) are lightweight, flexible actuators capable of higher specific work than comparably-sized hydraulic actuators at the same pressure and electric motors. PAMs are composed of an elastomeric bladder surrounded by a helically braided sleeve. Lightweight, compliant actuators are particularly desirable in portable, heavy-lift robotic systems intended for interaction with humans, such as those envisioned for patient assistance in hospitals and battlefield casualty extraction. However, smooth and precise control remains difficult because of nonlinearities in the dynamic response. The objective of this paper is to develop a control algorithm that satisfies accuracy and smooth motion requirements for a two degree-of-freedom manipulator actuated by pneumatic artificial muscles and intended for interaction with humans, such as lifting a human. This control strategy must be capable of responding to large, abrupt variations in payload weight over a high range of motion. In previous work, the authors detailed the design and construction of a proof-of-concept PAM-based manipulator. The present work investigates the feasibility of combining output feedback using proportional-integral-derivative control or fuzzy logic control with model-based feedforward compensation to achieve improved closed-loop performance. The model upon which the controller is based incorporates the internal airflow dynamics, the geometric parameters of the pneumatic actuators, and the arm dynamics. Simulations were performed in order to validate the control algorithm, guide controller design, and predict optimal gains. Using real-time interface software and hardware, the controller was implemented and experimentally tested on the manipulator. Performance was evaluated for several trajectories, and different payload weights. The effect of varying the feedforward gain was also analyzed. Model refinement further improved performance.

Design and testing of a high-specific work actuator using miniature pneumatic artificial muscles

2012 ◽  
Vol 23 (3) ◽  
pp. 365-378 ◽  
Author(s):  
Robert D. Vocke ◽  
Curt S. Kothera ◽  
Anirban Chaudhuri ◽  
Benjamin K.S. Woods ◽  
Norman M. Wereley
Keyword(s):  
Angular Rate ◽  
Active Material ◽  
Small Scale ◽  
Artificial Muscles ◽  
Prototype System ◽  
Specific Work ◽  
Pneumatic Actuators ◽  
Actuation System ◽  
Angular Deflection ◽  
Pneumatic Artificial Muscles

Micro-air vehicle (MAV) development is moving toward smaller and more capable platforms to enable missions such as indoor reconnaissance. This miniaturization creates challenging constraints on volume and energy generation/storage for all systems onboard. Actuator technologies must also address these miniaturization goals. Much research has focused on active material systems, such as piezoelectric materials and synthetic jets, but these advanced technologies have specific, but limited, capability. Conventional servo technology has also encountered concerns over miniaturization. Motivation has thus been established to develop a small-scale actuation technology prototype based on pneumatic artificial muscles, which are known for their lightweight, high-output, and low-pressure operation. The miniature actuator provides bidirectional control capabilities for a range of angles, rates, and loading conditions. Problems addressed include the scaling of the pneumatic actuators and design of a mechanism to adjust the kinematic load-stroke profile to suit the pneumatic actuators. The kinematics of the actuation system was modeled, and a number of bench-top configurations were fabricated, assembled, and experimentally characterized. Angular deflection and angular rate output of the final bench-top prototype system are presented, showing an improvement over conventional servo motors used in similar applications, especially in static or low-frequency operation.

COMPARATIVE SURVEY OF VARIOUS STATIC AND DYNAMIC MODELS OF PNEUMATIC ARTIFICIAL MUSCLES

2017 ◽  
Vol 41 (5) ◽  
pp. 825-844 ◽  
Author(s):  
József Sárosi ◽  
Ján Piteľ ◽  
Mária Tóthová ◽  
Alexander Hošovský ◽  
István Bíró
Keyword(s):  
Dynamic Models ◽  
Geometric Model ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Force Model ◽  
Static Force ◽  
Pneumatic Actuators ◽  
Model Based ◽  
Pneumatic Artificial Muscles ◽  
Comparative Survey

A lesser known type of pneumatic actuators is pneumatic artificial muscle (PAM) although these pneumatic actuators play an important role in industrial, medical and other applications. In this study a PAM model based on the assumption Euler’s law is developed, some static force models (geometric model-based static force model, static force model using maximum force of PAM and static force model using a polynomial function) are compared to Sárosi’s force model and two dynamic models based on Sárosi’s static force model and Hill’s muscle model are presented.

Experimental Validation of Nominal Model Characteristics for Pneumatic Muscle Actuator

2013 ◽  
Vol 460 ◽  
pp. 1-12 ◽  
Author(s):  
Alexander Hošovský ◽  
Kamil Židek
Keyword(s):  
Control System ◽  
Nonlinear Differential Equations ◽  
Model Performance ◽  
Weight Ratio ◽  
Open Loop ◽  
Artificial Muscles ◽  
Pneumatic Actuators ◽  
Intelligent Control System ◽  
Pneumatic Artificial Muscles ◽  
The One

Pneumatic artificial muscles belong to a category of nonconventional pneumatic actuators that are distinctive for their high power/weight ratio, simple construction and low price and maintenance costs. As such, pneumatic artificial muscles represent an alternative type of pneumatic actuator that could replace the traditional ones in certain applications. Due to their specific construction, PAM-based systems have nonlinear characteristics which make it more difficult to design a control system with good performance. In the paper, a gray-box model (basically analytical but with certain experimental parts) of the one degree-of-freedom PAM-based actuator is derived. This model interconnects the description of pneumatic and mechanical part of the system through a set of several nonlinear differential equations and its main purpose is the design of intelligent control system in simulation environment. The model is validated in both open-loop and closed-loop mode using the measurements on real plant and the results confirm that model performance is in good agreement with the performance of real actuator.

scholarly journals Powered Upper Limb Orthosis Actuation System Based on Pneumatic Artificial Muscles

2018 ◽  
Vol 48 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Dimitar Chakarov ◽  
Ivanka Veneva ◽  
Mihail Tsveov ◽  
Pavel Venev
Keyword(s):  
Upper Limb ◽  
Joint Stiffness ◽  
Artificial Muscles ◽  
Joint Motion ◽  
Robot Interaction ◽  
Pneumatic Actuators ◽  
Joint Torques ◽  
Actuation System ◽  
Pneumatic Muscles ◽  
Pneumatic Artificial Muscles

AbstractThe actuation system of a powered upper limb orthosis is studied in the work. To create natural safety in the mutual “man-robot” interaction, an actuation system based on pneumatic artificial muscles (PAM) is selected. Experimentally obtained force/contraction diagrams for bundles, consisting of different number of muscles are shown in the paper. The pooling force and the stiffness of the pneumatic actuators is assessed as a function of the number of muscles in the bundle and the supply pressure. Joint motion and torque is achieved by antagonistic actions through pulleys, driven by bundles of pneumatic muscles. Joint stiffness and joint torques are determined on condition of a power balance, as a function of the joint position, pressure, number of muscles and muscles

Miniaturized Pneumatic Artificial Muscles Actuating a Bio-Inspired Robot Hand

2013 ◽  
Author(s):  
Thomas E. Pillsbury ◽  
Ryan M. Robinson ◽  
Norman M. Wereley
Keyword(s):  
Degrees Of Freedom ◽  
Full Scale ◽  
Constitutive Relationship ◽  
Force Density ◽  
Human Hand ◽  
Artificial Muscles ◽  
Specific Work ◽  
Robotic Hand ◽  
Robot Hand ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are used in robotics applications for their light-weight design and superior static performance. Additional PAM benefits are high specific work, high force density, simple design, and long fatigue life. Previous use of PAMs in robotics research has focused on using “large,” full-scale PAMs as actuators. Large PAMs work well for applications with large working volumes that require high force and torque outputs, such as robotic arms. However, in the case of a compact robotic hand, a large number of degrees of freedom are required. A human hand has 35 muscles, so for similar functionality, a robot hand needs a similar number of actuators that must fit in a small volume. Therefore, using full scale PAMs to actuate a robot hand requires a large volume which for robotics and prosthetics applications is not feasible, and smaller actuators, such as miniature PAMs, must be used. In order to develop a miniature PAM capable of producing the forces and contractions needed in a robotic hand, different braid and bladder material combinations were characterized to determine the load stroke profiles. Through this characterization, miniature PAMs were shown to have comparably high force density with the benefit of reduced actuator volume when compared to full scale PAMs. Testing also showed that braid-bladder interactions have an important effect at this scale, which cannot be modeled sufficiently using existing methods without resorting to a higher-order constitutive relationship. Due to the model inaccuracies and the limited selection of commercially available materials at this scale, custom molded bladders were created. PAMs created with these thin, soft bladders exhibited greatly improved performance.

scholarly journals Flatness-Based Control of a Two Degrees-of-Freedom Platform With Pneumatic Artificial Muscles

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
David Bou Saba ◽  
Paolo Massioni ◽  
Eric Bideaux ◽  
Xavier Brun
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Volume Ratio ◽  
Open Loop ◽  
Control Technique ◽  
Artificial Muscles ◽  
Two Degrees Of Freedom ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are an interesting type of actuators as they provide high power-to-weight and power-to-volume ratio. However, their efficient use requires very accurate control methods taking into account their complex and nonlinear dynamics. This paper considers a two degrees-of-freedom platform whose attitude is determined by three pneumatic muscles controlled by servovalves. An overactuation is present as three muscles are controlled for only two degrees-of-freedom. The contribution of this work is twofold. First, whereas most of the literature approaches the control of systems of similar nature with sliding mode control, we show that the platform can be controlled with the flatness-based approach. This method is a nonlinear open-loop controller. In addition, this approach is model-based, and it can be applied thanks to the accurate models of the muscles, the platform and the servovalves, experimentally developed. In addition to the flatness-based controller, which is mainly a feedforward control, a proportional-integral (PI) controller is added in order to overcome the modeling errors and to improve the control robustness. Second, we solve the overactuation of the platform by an adequate choice for the range of the efforts applied by the muscles. In this paper, we recall the basics of this control technique and then show how it is applied to the proposed experimental platform. At the end of the paper, the proposed approach is compared to the most commonly used control method, and its effectiveness is shown by means of experimental results.

scholarly journals A Biomechatronic Device Actuated by Pneumatic Artificial Muscles for the Automatic Evaluation of Nociceptive Thresholds in Rheumatic Patients

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 78
Author(s):  
Luigi Randazzini ◽  
Alessia Capace ◽  
Carlo Cosentino ◽  
Rosa Daniela Grembiale ◽  
Francesco Amato ◽  
...  
Keyword(s):  
Pain Sensitivity ◽  
Qualitative Evaluation ◽  
Control Unit ◽  
Automatic Measurement ◽  
Artificial Muscles ◽  
Embedded Control ◽  
Pneumatic Actuators ◽  
Diagnostic Protocol ◽  
Pneumatic Artificial Muscles ◽  
Rheumatic Patients

In the current clinical practice, the diagnosis of Rheumatoid Arthritis (RA) draws on the qualitative evaluation of pain sensitivity thresholds which is affected by several source of uncertainties, due to an operator-dependent diagnostic protocol. Taking our cue from the diagnostic shortcomings, we have explored the possibility of automating the measurement of mechanical nociceptive thresholds through the adoption of soft pneumatic actuators controlled by an embedded control unit. In this work, we want to show that a purpose-made biomechatronic device actuated by soft and pneumatic actuators is potentially a boon both for rheumatologists and biomedical researchers involved in nociception and physicophysical studies. In the full breadth and scope of the objective diagnosis of RA, the first prototype of a novel biomechatronic device for quantitative and automatic measurement of mechanical nociceptive thresholds has been designed and tested through nociception experiments on 10 subjects. The experimental results show that the designed device can reliably generate the controllable and repeatable nociceptive stimuli needed for the objective diagnosis of RA.

Contractile Pneumatic Artificial Muscle Configured to Generate Extension

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Benjamin K. S. Woods ◽  
Shane M. Boyer ◽  
Erica G. Hocking ◽  
Norman M. Wereley ◽  
Curt S. Kothera
Keyword(s):  
Compressive Loading ◽  
Compressive Force ◽  
Artificial Muscle ◽  
Specific Power ◽  
Artificial Muscles ◽  
Specific Work ◽  
Operational Characteristics ◽  
Pneumatic Artificial Muscles ◽  
High Specific Power ◽  
Internal Mechanism

Pneumatic artificial muscles (PAMs) are comprised of an elastomeric bladder surrounded by a braided mesh sleeve. When the bladder is inflated, the actuator may either contract or extend axially, with the direction of motion dependent on the orientation of the fibers in the braided sleeve. Contractile PAMs have excellent actuation characteristics, including high specific power, specific work, and power density. Unfortunately, extensile PAMs exhibit much reduced blocked force, and are prone to buckling under axial compressive loading. For applications in which extensile motion and compressive force are desired, the push-PAM actuator introduced here exploits the operational characteristics of a contractile PAM, but changes the direction of motion and force by employing a simple internal mechanism using no gears or pulleys. Quasi-static behavior of the push-PAM was compared to a contractile PAM for a range of operating pressures. Based on these data, the push-PAM actuator can achieve force and stroke comparable to a contractile PAM tested under the same conditions.

A Survey on the Evolution of Nonconventional Pneumatic Actuators

2012 ◽  
Vol 463-464 ◽  
pp. 1069-1072
Author(s):  
Alexandra Liana Visan ◽  
Nicolae Alexandrescu
Keyword(s):  
Medical Devices ◽  
Mechanical Engineering ◽  
Artificial Muscles ◽  
Technical Literature ◽  
Pneumatic Actuators ◽  
Pneumatic Artificial Muscles ◽  
Main Operating

In this article will be presented the evolution of the nonconventional pneumatic actuators, in general Pneumatic Artificial Muscles known in the technical literature as PAM’s that were patented as well as their main operating principles and area of activity. These types of actuators have been applied in all kinds of applications from mechanical engineering, robotic, alimentary industry, special equipments, diagnostic medical devices and prostheses.

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