Artificial Muscles

Course material for "Artificial Muscles" e-course

Experimental investigation of characteristics of pneumatic artificial muscles

The characteristics of pneumatic artificial muscles (PAMs) make them very interesting for the development of robotic and prosthesis applications. The McKibben muscle is the most popular and is made commercially available by different companies. The aim of this research is to acquire as much information about the pneumatic artificial muscles as we can with our test-bed that was developed by us and to be able to adopt these muscles as a part of prosthesis. This paper presents the set-up constructed, and then describes some mechanical testing results for the pneumatic artificial muscles

Mechanical Testing of Artificial Muscles

This document focuses on the design and fabrication of a low cost instrument to measure the strain of the artificial muscles being researched and developed by Dr. Amanda Murphy and her team at Western Washington University. The instrument utilizes a laser displacement meter to measure the movement of the artificial muscles during actuation. All project objectives and goals were successfully met, and all deliverables completed. Instrument quality and strain testing results are analyzed and recommendations for future work are suggested based on the results of the project

High Fidelity Dynamic Modeling and Nonlinear Control of Fluidic Artificial Muscles

A fluidic artificial muscle is a type of soft actuator. Soft actuators transmit power with elastic or hyper-elastic bladders that are deformed with a pressurized fluid. In a fluidic artificial muscle a rubber tube is encompassed by a helical fiber braid with caps on both ends. One of the end caps has an orifice, allowing the control of fluid flow in and out of the device. As the actuator is pressurized, the rubber tube expands radially and is constrained by the helical fiber braid. This constraint results in a contractile motion similar to that of biological muscles. Although artificial muscles have been extensively studied, physics-based models do not exist that predict theirmotion.This dissertation presents a new comprehensive lumped-parameter dynamic model for both pneumatic and hydraulic artificial muscles. It includes a tube stiffness model derived from the theory of large deformations, thin wall pressure vessel theory, and a classical artificial muscle force model. Furthermore, it incorporates models for the kinetic friction and braid deformation. The new comprehensive dynamic model is able to accurately predict the displacement of artificial muscles as a function of pressure. On average, the model can predict the quasi-static position of the artificial muscles within 5% error and the dynamic displacement within 10% error with respect to the maximum stroke. Results show the potential utility of the model in mechanical system design and control design. Applications include wearable robots, mobile robots, and systems requiring compact, powerful actuation.The new model was used to derive sliding mode position and impedance control laws. The accuracy of the controllers ranged from ± 6 µm to ± 50 µm, with respect to a 32 mm and 24 mm stroke artificial muscles, respectively. Tracking errors were reduced by 59% or more when using the high-fidelity model sliding mode controller compared to classical methods. The newmodel redefines the state-of-the-art in controller performance for fluidic artificial muscles

Three-Dimensional Human iPSC-Derived Artificial Skeletal Muscles Model Muscular Dystrophies and Enable Multilineage Tissue Engineering

Summary: Generating human skeletal muscle models is instrumental for investigating muscle pathology and therapy. Here, we report the generation of three-dimensional (3D) artificial skeletal muscle tissue from human pluripotent stem cells, including induced pluripotent stem cells (iPSCs) from patients with Duchenne, limb-girdle, and congenital muscular dystrophies. 3D skeletal myogenic differentiation of pluripotent cells was induced within hydrogels under tension to provide myofiber alignment. Artificial muscles recapitulated characteristics of human skeletal muscle tissue and could be implanted into immunodeficient mice. Pathological cellular hallmarks of incurable forms of severe muscular dystrophy could be modeled with high fidelity using this 3D platform. Finally, we show generation of fully human iPSC-derived, complex, multilineage muscle models containing key isogenic cellular constituents of skeletal muscle, including vascular endothelial cells, pericytes, and motor neurons. These results lay the foundation for a human skeletal muscle organoid-like platform for disease modeling, regenerative medicine, and therapy development. : Maffioletti et al. generate human 3D artificial skeletal muscles from healthy donors and patient-specific pluripotent stem cells. These human artificial muscles accurately model severe genetic muscle diseases. They can be engineered to include other cell types present in skeletal muscle, such as vascular cells and motor neurons. Keywords: skeletal muscle, pluripotent stem cells, iPS cells, myogenic differentiation, tissue engineering, disease modeling, muscular dystrophy, organoid

Bioinspired Nanomaterials: Self Stiffening Artificial Muscles

Cytoskeletal organization and elasticity are greatly influenced by molecular stiffness and sterics as well as externally imposed and internally generated stresses or so it might be hypothesized. These dynamic networks are generally composed of stiff filaments of actin and flexible crosslinkers. Recent experiments have identified not only isotropic, nematic and raft phases of such structures but also affine and non-affine elastic regimes of protein-crosslinked actin networks. Synthetic materials lack the complexity of biological tissues, and man-made materials that respond to external stresses through a permanent increase in stiffness are uncommon. Here we report for the first time, the systems of nanotube-polydimethyl siloxane(CNT-PDMS) soft nanocomposite and analogous liquid crystalline elastomer (LCE) that mimic the actin filaments in muscle tissues. Polydomain nematic LCEs increase in stiffness by up to 90% when subjected to a low amplitude (5%), repetitive dynamic compression. Elastomer stiffening is influenced by liquid crystal content, the presence of a nematic liquid crystal phase and the use of a dynamic as opposed to static deformation. Rheological and X-ray diffraction measurements reveal that the stiffening can be attributed to a mobile nano-scale nematic director that rotates in response to dynamic compression. Dynamic stiffening, not previously observed in liquid crystal elastomers may pave the way for useful development of self-healing materials and for the development of biocompatible, adaptive materials for tissue replacement