The purpose of this research is to build and test a haptic rendering system using skin surface electro-tactile stimulation for a fingertip interface. A new driver output stage for delivering tactile signals is implemented to improve power inefficiency and reduce circuit area relative to traditional open-loop constant current driver (CCD)-based haptic renders. This will be realized in a constant voltage driver (CVD) method for haptic rendering. The challenge will be to make the system aware of the skin impedance loading conditions and to use this information to introduce a closed-loop solution that is necessary due to implementing this type of driver.The system will be made load-aware by identifying parameters of a proposed electronic impedance model of skin that is done online and in real-time with customized software and hardware. Output sensors will be used to measure the voltage and current at the loaded output. An extended least squares algorithm will identify the parameters from the measurements. The paper will introduce a model reference adaptive control law, using the direct method, with nonlinear feedback to test a closed-loop CVD design. To aid in determining normal operating conditions, and validating parameter estimation and simulated closed-loop control, related experiments will be carried out. This work is based on an older version electro-tactile haptic rendering system used in the laboratory.
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