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Complete state regulator. Control structure from Fig.4. will ensure the system behaviour for the same mass m " extending ", according to Fig.5.
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At many motion control tasks, the problem of oscillations existence in multidimensional system with limited motion control and imperfect or complicated state quantities measurement possibility exists. Paper describes active damping simple possibility of these type systems and by two-dimensional system physical model shows active damping possibility...
Citations
Research into output-force tremor characteristics has a major part to play in preventing unstable and inefficient work of biocompatible Bionic Electric Actuator (BEA). Since its output force is small with a scale of mN level, it is susceptible to the surroundings during measurement, and then erratic continuous minor waves are not called the output-force tremor behavior. Precisely, it is defined as the unstable and obvious fluctuations in the BEA output force. In this paper, effects and active mechanisms of CaCl2 cross-linking and doping glycerol on output-force tremor characteristics of the BEA were researched in depth. And its structure was similar to 'sandwich', which was made up of the middle electrically actuating membrane made from Sodium Alginate (SA) and bilateral non-metallic electrode membranes blended with Multi-walled Carbon Nanotube (MWCNT). Furthermore, by microscopic picturing, Cyclic Voltammetry (CV) and tensile test, the micro morphology, specific capacitance and elastic modulus of BEA were acquired to clearly clarify its output-force tremor mechanism, and then the control methods were proposed. Experiments revealed that, in the quick growth phase, there was no tremor behavior occurring on the output force, except for a few slight fluctuations. Afterwards, the output force gradually increased and its tremor started to appear frequently, then the amplitude was larger and larger over time. Besides, all the BEA specimens occurred output-force tremors in varying degrees, where they were the slightest at 0.85 g L⁻¹ CaCl2. And as glycerol doping amounts increased, occurrence time of the maximum output force and its tremor was delayed greatly. Thus, by specifying working hours of the BEA, it was applied in the stage of steady growth of the output force before its tremors happening. Generally, our work presents practical approaches to the control of BEA capable of achieving both good output force properties and wide engineering applications.
Since Sodium Alginate (SA) hydrogel has disadvantages of poor controllability and low mechanical strength, it is difficult to satisfy the practical requirements when used alone. In this paper, with CaCl2 as the crosslinker, Calcium Alginate Hydrogel (CAH) was prepared as electric actuating membrane via ionic crosslinking. The non-metallic electrode membrane was fabricated from SA blended with Multi-walled Carbon Nanotube (MWCNT). Further, two electrode membranes were stuck on both sides of the actuating membrane to assemble a biodegradable Electroresponsive Biomimetic Actuator (ERBA). Moreover, an experimental platform was built for testing the output force of the ERBA cross-linked with different CaCl2 concentrations, and experimental test standards were developed according to preparation conditions and applied voltage. Then output force density was utilized to evaluate the output force characteristics. Based on in-depth analysis of the ERBA actuating mechanism, the influencing mechanisms of elastic modulus, specific capacitance and CaCl2 concentration on output force performance of the ERBA was illustrated respectively. The experimental results showed that suitable amount of the membrane solutions was 40 ml for preparing the ERBA, and its optimal test voltage was 3 V DC. When CaCl2 concentration was 0.9 g L⁻¹, the ERBA was best cross-linked, where its elastic modulus was large and ion migration rate was fast, which caused the maximum output force density of 26.534 mN g⁻¹. But as the CaCl2 concentration increased, the actuating membrane was cross-linked excessively, which resulted in blocked internal ion channel, small ion migration speed and reduced output force.
At present the Muscle-like Gel Actuator (MLGA), an emerging ionic Electro Active Polymer (EAP), has advantages of small driving voltage, low cost and good biocompatibility, so it is widely used in bionic engineering, marine equipment and medical science etc. But the small output force and slow response speed still seriously restrict further implementation of the MLGA in engineering applications. In this paper, using glycerol as the plasticizer, Calcium Alginate Hydrogel (CAH) was fabricated as electrically actuating membrane to promote its electromechanical properties, and the complete preparation process was proposed. The MLGA was a double-layer capacitor similar to 'sandwich' structure, which consisted of the middle actuating membrane and non-metallic electrode membrane on its bilateral surface, where the electrode membrane was made from Sodium Alginate (SA) blended with Multi-walled Carbon Nanotube (MWCNT). Furthermore, the output force performance of the MLGA doped with various glycerol contents was tested by an experimental platform, to obtain the effect law and optimum doping amount. By the tensile test and Cyclic Voltammetry (CV), elastic modulus and specific capacitance of the actuating membrane were acquired, and then from the microcosmic viewpoint, electrically actuating mechanism of the MLGA was deeply analyzed to further clarify the influencing mechanism. Experiments revealed that with the increase of glycerol amount, the elastic modulus decreased gradually but the specific capacitance increased first and then declined after 2 ml. When 1 ml glycerol was added, the output force reached the maximum and its density was 49.560 mN g⁻¹, which was 1.87 times larger than that of the sample without glycerol. Because the ion channel could be improved in a small amount of glycerol, which resulted in easy pass for internal ions. Instead, owing to the viscosity, large amounts of glycerol would block ion migration, which caused small output force density and poor electromechanical performance.
Bionic artificial muscle made from chitosan gel is an emerging type of the ionic electro active polymer with advantages of large deformation, low cost and environmental protection etc, which leads to a research focus and wide application in the fields of bionic engineering and intelligence material recently. In this paper, effects and improvement mechanisms of the direct casting and genipin cross-linking processes on response speed properties of the chitosan gel artificial muscle (CGAM) were mainly studied. Based on in-depth analysis of the CGAM response mechanism, a platform was built for testing the response performance of the CGAM, then its equivalent circuit and mathematical models were also established. Furthermore, control experiments were carried out to test and analyze several performances of the CGAM on response speed, electrical conductivity, mechanical properties and microstructure with different control variables. The experimental results illustrated that the CGAM assembled by direct casting enabled its electric actuating membrane and non-metallic electrode membrane tightly attached together with low contact resistance, which dramatically promoted the electrical conductivity of the CGAM resulting in nearly doubled response speed. Besides, different concentrations of genipin were adopted to cross-link the CGAM actuating membranes, and then it was found that the response speed of the uncross-linked CGAM was fast in the initial stage, but as time increased, it declined rapidly with poor steadiness. While there was no obvious decrease over time on the response speed of the CGAM cross-linked with low genipin concentration. Namely, its stability was getting better and better. In addition, the response speed of the CGAM cross-linked with low concentration of genipin was roughly the same as uncross-linked CGAM, which was quicker than that of high concentration. In this work, its internal mechanisms, feasible assembly technique and green modification method were provided to further explore the practical applications significantly.
