Developing prosthetic artificial muscle actuator using dielectric elastomers (original) (raw)
Related papers
Dielectric elastomers as actuators for upper limb prosthetics: Challenges and opportunities
Medical Engineering & Physics, 2008
Recent research has indicated that consumers of upper limb prostheses desire lighter-weight, anthropomorphic devices. The potential of dielectric elastomer (DE) actuators to better meet the design priorities of prosthesis users is explored. Current challenges are critically reviewed with respect to (1) durability, (2) precision control, (3) energy consumption, and (4) anthropomorphic implementation. The key points arising from the literature review are illustrated with empirical examples of the strain performance and durability of one of the most popular DEs, VHB 4910. Practical application of DE actuators in powered upper extremity prosthetics is at present impeded by poor durability and susceptibility to airborne contaminants, unreliable control owing to viscoelasticity, hysteresis, stress relaxation and creep mechanisms, high voltage requirements, and insufficient stress and strain performance within the confines of anthropomorphic size, weight, and function. Our review suggests that the implementation of DE actuators in powered upper extremity prosthetics is not feasible at present but worthy of reevaluation as the materials advance.
Dielectric Elastomers as Electromechanical Transducers, 2008
Dielectric elastomer actuators (DEAs) whether used as artificial muscles or as replacements for traditional actuators show great potential for use in modern active orthotic and prosthetic therapeutic applications. Such actuators are roughly similar in function and biomechanics to natural muscle, including the ability to produce the high peak power density needed for muscle-like actuation that can simplifying biomimetic and bio-inspired design. Furthermore, DEAs are also capable of multidirectional actuation, enabling novel external and implantable designs not as suited to traditional actuation technology. Examples include artificial muscle-powered prosthetic arms, active ankle-foot orthoses, and ventricular assist devices. While challenges currently exist in using dielectric elastomerbased actuators for biomedical use, this technology shows great potential for the development of advanced orthoses and prostheses, leading to a substantial benefit for those with physical impairments and disabilities.
Modelling of High Output Force Dielectric Elastomer Actuator
International Journal of Mechanical Engineering and Robotics Research, 2017
Restoring the function of a lost limb for an amputee requires the generation of relatively large forces, which remains a challenge in current designs. Dielectric Elastomers (DE) have the desired properties of light weight, low cost, fast response, ease of control and low power consumption. Yet due to the elasticity of the material which requires mechanical support and low output force generation, DEs haven't been suggested for prosthetic devices that mainly require high output forces. This paper proposes a conceptual design for a prosthetic arm, where DE is used as a high output force actuator. A two-bar mechanism was assumed to represent the human arm, with one bar as the Humerus and another for the Radius and the Ulna bones. The flexion action of the mechanism was achieved by a slider-crank mechanism connecting the two bars. A Dielectric Elastomer (DE) was used to actuate the mechanism. In the proposed design, the DE membrane is configured as a planar linear actuator, with about 1000 parallel membranes to maintain the output force and reduce the tensile stress. An Analytic model for the specific configuration of DE materials was developed to analyze the output force of the designed mechanism for a range of input electric fields. The input electric field is below the dielectric strength of the material and induces 97 N of output force which is higher than reported actuator designs.
Dielectric elastomer artificial muscle actuators: Toward biomimetic motion
2002
To achieve desirable biomimetic motion, actuators must be able to reproduce the important features of natural muscle such as power, stress, strain, speed of response, efficiency, and controllability. It is a mistake, however, to consider muscle as only an energy output device. Muscle is multifunctional. In locomotion, muscle often acts as an energy absorber, variable-stiffness suspension element, or position sensor, for example. Electroactive polymer technologies based on the electric-field-induced deformation of polymer dielectrics with compliant electrodes are particularly promising because they have demonstrated high strains and energy densities. Testing with experimental biological techniques and apparatus has confirmed that these "dielectric elastomer" artificial muscles can indeed reproduce several of the important characteristics of natural muscle. Several different artificial muscle actuator configurations have been tested, including flat actuators and tubular rolls. Rolls have been shown to act as structural elements and to incorporate position sensing. Biomimetic robot applications have been explored that exploit the muscle-like capabilities of the dielectric elastomer actuators, including serpentine manipulators, insect-like flappingwing mechanisms, and insect-like walking robots.
El-Cezeri Fen ve Mühendislik Dergisi, 2021
Dielectric Elastomer Actuator (DEA) consists of a thin dielectric elastomer membrane sandwiched between two electrode layers. When low current high voltage is applied to the two conductive layers, opposite loads occur on the surface which tends to pull one another. This voltage application causes thinning in width and expansion in surface area. DEAs are the favorite subject of research due to their low-cost advantages, fast response, high energy density, wide deformation, and softness. Due to the rigidity of the electric motors and the metal components of the robot, soft-acting robots using DEA are preferred to perform complex tasks instead of conventional robots. Robots with DEA have higher flexibility and better adaptability. Therefore, soft robots are popular topic in robotics research. DEAs are the best candidate materials for next-generation soft robot actuators and artificial muscles. In this study, simulation of the robotic systems has been realized by using DEAs calculation methods. Simulation results were compared with the data obtained from the application. This study will be the source of future studies on the subject. In the simulation, Matlab 2016 student and Labview Home and Students programs were used.
On the nature of dielectric elastomer actuators and its implications for their design
Proceedings of SPIE, 2006
Dielectric Elastomer (DE) actuators have been studied extensively under laboratory conditions where they have shown promising performance. However, in practical applications, they have not achieved their full potential. Here, the results of detailed analytical and experimental studies of the failure modes and performance boundaries of DE actuators are presented. The objective is to establish fundamental design principles for DE actuators. Analytical models suggest that DE actuators made with highly viscoelastic films are capable of reliably achieving large extensions when used at high speeds (high stretch rates). Experiments show that DE actuators used in low speed applications, such as slow continuous actuation, are subject to failure at substantially lower extensions and also have lower efficiencies. This creates an important reliability/performance trade-off because, due to their viscoelastic nature, highest DE actuators forces are obtained at low speeds. Hence, DE actuator design requires careful reliability/performance trade-offs because actuator speeds and extensions for optimal performance can significantly reduce actuator life.
Advanced Healthcare Materials, 2021
The inability to replace human muscle in surgical practice is a significant challenge. An artificial muscle controlled by the nervous system is considered a potential solution for this. Here, this is defined as a neuromuscular prosthesis. Muscle loss and dysfunction related to musculoskeletal oncological impairments, neuromuscular diseases, trauma or spinal cord injuries can be treated through artificial muscle implantation. At present, the use of dielectric elastomer actuators working as capacitors appears a promising option. Acrylic or silicone elastomers with carbon nanotubes functioning as the electrode achieve mechanical performances similar to human muscle in vitro. However, mechanical, electrical, and biological issues have prevented clinical application to date. Here materials and mechatronic solutions are presented which can tackle current clinical problems associated with implanting an artificial muscle controlled by the nervous system. Progress depends on the improvement of the actuation properties of the elastomer, seamless or wireless integration between the nervous system and the artificial muscle, and on reducing the foreign body response. It is believed that by combining the mechanical, electrical, and biological solutions proposed here, an artificial neuromuscular prosthesis may be a reality in surgical practice in the near future.
On the performance mechanisms of Dielectric Elastomer Actuators
Sensors and Actuators A: Physical, 2007
Dielectric Elastomer Actuators (DEAs) show promise for robotics and mechatronics applications. They are lightweight, low costs, and have shown good performance in laboratory demonstration. However, these actuators have not been widely applied commercially after more than ten years of development. One reason is that the mechanisms governing their performance are not completely understood. Hence designing practical actuators is difficult. This paper has the objective of understanding the dominant performance mechanisms of DEAs. To do so, an experimental characterization of actuator performance is conducted in terms of force, power, current consumption, work output, and efficiency. Key performance mechanisms of viscoelasticity and current leakage are identified from experimental observations and analytical models are developed. The models explain well the experimental observations and should aid designers in selecting applications that are appropriate for DEAs as well as designing effective DEAs.