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TitleIntegrated extension sensor based on resistance and voltage measurement for a dielectric elastomer
Publication TypeConference Paper
Year of Publication2007
AuthorsO'Brien, B., Thode J., Anderson I., Calius E.P., Haemmerle E., and Xie S.
Conference NameProceedings of SPIE - The International Society for Optical Engineering
Date Published2007
KeywordsActuators, Amperometric sensors, Dielectric Elastomer Actuators (DEA), Elastomers, electric resistance, Feedback control, Feedback inaccuracy, Graphite electrodes, Integrated extension sensors, Loose carbon powder electrodes, MEMS, Networks (circuits), Pseudoinverse, Voltage measurement
AbstractThis paper presents a method for creating a smart Dielectric Elastomer Actuator (DEA) with an integrated extension sensor based on resistance and voltage measurement. Such a sensor can reduce cost, complexity, and weight compared to external sensor solutions when used in applications where external sensing is difficult or costly, such as Micro-ElectroMechanical Systems (MEMS). The DEAs developed for integrated feedback are 20mm by 70mm and 30 urn thick double layer silicone-dielectric actuators with reinforcing silicone ribs. Loose-carbon-powder electrodes produced the best electrical and mechanical characteristics out of several possibilities tried. Electrically isolated circuits were used to measure electrode resistance and driving voltage. These parameters were then related to experiment using a model to predict DEA length. An offline regression method was used to fit the model to within 2% of the full sensor range and the results were verified experimentally. The sensor feedback inaccuracy immediately after a position step disturbance was shown to be around 20% of the full sensor range. This improved over 5 seconds to less than 5% as the transient creep effects in the silicone membrane that introduced the initial inaccuracy decayed. Long term creep reduced the accuracy of the model, necessitating periodic retraining of the sensor. Overall the sensor-estimated extension shows a very good qualitative or 'shape' match with the actual extension in the system.

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