Papers by Keyword: Artificial Muscles

Abstract: The evolution of the working potential, or that of the consumed electrical energy, of electrochemical artificial muscles based on electroactive materials (intrinsically conducting polymers, redox polymers, carbon nanotubes, fullerene derivatives, grapheme derivatives, porphyrines, phtalocianines, among others) and driven by constant currents senses, while working, any variation of the mechanical (trailed mass, obstacles, pressure, strain or stress) thermal or chemical conditions of work. One physically uniform artificial muscle includes one chemical motor and several chemical sensors working simultaneously under the same driving reaction. They fulfil the old dream of engineer and robot designers: one motor sensing by itself the working conditions. From basic polymeric, mechanical and electrochemical principles a basic equation is attained. It includes and describes, simultaneously, the polymeric motor characteristics (rate of the muscle movement and muscle position) and the working variables (temperature, electrolyte concentration and mechanical conditions). By changing working conditions experimental results overlap theoretical predictions. The ensemble computer-generator-muscle-theoretical equation constitutes and describes artificial mechanical, thermal and chemical proprioception (consciousness) of the system.

Abstract: Engineers, physicists and robot designers use to consider polymeric bilayer actuators (or artificial muscles) as low reliable devices for soft tools or soft robotic developments. Here we present the mechanical (movement rate and position) characterization of a polypyrrole/tape bilayer bending actuator. The polypyrrole film was synthesized in presence of dodecyl-benzene-sulphonate (DBS^-) and ClO₄^- anions: it exchanges cations during subsequent oxidation/reduction reactions. The angular rate of the movement results a linear function of the applied current and the described angle is a linear function of the consumed charge. The correlation coefficients overcame 0.99: electro-chemo-mechanical polymeric motors are full reliable for technological applications. The electrochemical model explaining the relationships between charge, film volume variation, mechanical work, force and displacement, strain and stress is also presented.

Abstract: Nonconventional actuators based on the pneumatic artificial muscles can be used in manipulators mainly for their lower energy consumption and higher performance at lower weight. In the paper there are compared the dynamic operating characteristics of the antagonistic actuator with the pneumatic artificial muscles obtained by simulation of the different muscle models in Matlab / Simulink environment with the real measured data on the experimental actuator. The results of these simulations and measurements confirmed highly nonlinear operating characteristics of such actuator and also right approach to the design of the actuator model using different muscle models.

Abstract: Sensor systems are an essential part of automated equipment. They are even more important in machines that come in contact with people, because they have a significant impact on safety. This paper describes the design of active feedback for rehabilitation device driven by pneumatic artificial muscles. Here are presented three methods for measuring the load of the robot. The first is a system composed of Force Sensitive Resistors (FSR) placed in the handle of the device. Two other methods are intended to measure the load of the actuator composed of artificial muscles. The principle of one method is to measure the difference in filling pressures of the muscles, second is based on strain measurement in the drive cables. The paper describes advantages and disadvantages of using each of these methods in a rehabilitation device.

Abstract: The paper describes basic characteristics of pneumatic artificial muscles (PAM) for using as actuator in mechatronic system. The previous parameters research of individually connected artificial muscles shows, that it is significantly nonlinear system with time delay. Availing these results, problem of using of static and dynamic characteristics of PAMs for control and modeling electropneumatic mechatronic systems based on the artificial muscles occurs. To solve this problems, the paper also deals with design of some models.

Abstract: Pneumatic position servo system with artificial muscles described in this paper represents feedback control system with non-linear compensation controller of state variables. The designed system demonstrates the operating characteristics that are significantly more favorable than the original characteristics without compensation and they are similar to the properties of the linear system. Such system has principally a shorter control time, significantly lower dynamic control error and it allows apply larger constants of the controller. Following an increased invariance of system against disturbances and also its parametric invariance (robustness) occur.

Abstract: The article contains information about the function and basic properties of the actuator based on pneumatic artificial muscles. It describes the design method of control structure of such actuator and shows the configuration of the non-linear actuator together with non-linear (compensation) control unit. The second upgrading method is based on the other mechanical configuration of the actuator. The artificial muscle force is transmitted by free pulley and has the practically linear static characteristic. The resulting position servosystem with linearized overall static characteristics has favorable results and better operation abilities. They are presented by experimentally measured step responses.

Abstract: Artificial muscle is a new style of actuator with novel working principle, which owns the advantages of compact structure, high power-to-weight ratio, compliance and easy application. Pneumatic artificial muscle (PAM) is usually used in robotics, medical auxiliaries and other small force output occasions nowadays. However, it suffers problems of small power, hysteresis and poor repeatability. A kind of artificial muscle working at high pressure was researched. Different muscle styles are compared and MicKibben structure is selected while fluid media is determined. Furthermore, factors of geometry and material properties, which limit the ultimate pressure, are analyzed. Formulas and simulations verify the influence of limitation and help to calculate key parameters of 18MPa artificial muscle. Data show that it is possible in theory to design high pressure artificial muscle by overall consideration of initial diameter, initial contraction angle and material properties, initial length only influent the stroke.

Abstract: Novel combined electrochemical and chemical synthesis methods for the preparation of Polypyrrole-based actuators are presented. Polypyrrole (PPy) actuators were electrochemically synthesized and after coating with a thin gold nano-layer, prepared into a Polyethersulfone (PI) substrate. Scanning Tunneling Microscopy (STM) and a potentiostat–galvanostat were used to confirm the actuation of PPy based actuators during the redox process. Three-layer actuator based on polypyrrole as electroactive material, Polyethersulfone as substrate and gold nanolayer in our proposed method have been realized. The structure strength and layer adhesion have been improved. This advancement in conducting polymer actuator technology will impact many engineering fields, where a stable, lightweight and large displacement actuator is needed.

Abstract: Several types of artificial muscles are actually able to mimic the active spring-like behaviour characterizing the tension-length diagram of the skeletal muscle but the natural damping expressed by the typical tension-velocity Hill’s relationship is not so easy to integrate in a simple way into the artificial muscle functioning. We discussed the use of a textile braided sheath, particularly in the case of the so-called McKibben structure to obtain a Hill’s model-like dynamic behaviour of the artificial muscle. Experiments are reported to compare “quick-release” experiments – as defined in muscular physiology – between artificial muscles whose braided weave is made of metallic strands and of rayon textile strands. It is shown that only in the second case a typical hyperbolic tension-velocity is highlighted with a curvature close to this of human skeletal muscle. It is also shown how the typical laws of friction in textile can explain this analogical behaviour with the Hill’s-model interpreted as a force model including a typical non-linear viscous component. An original interpretation of Hill’s model in terms of natural load-variations adaptation is given and so the advantage for an artificial muscle to get this biomimetic character.