The dSPACE hardware is used to generate the step input and measure the output voltage as shown in Figure . A train of step input signals are generated by the digital-to-analog converter (DAC), and the analog-to-digital converter (ADC) measures both the input and the output voltage of the circuit.
Figure: Block diagram for connection of dSPACE hardware to the RC circuit.
The parameter estimation algorithm is implemented in a C program and downloaded into the dSPACE hardware. The simulated and real-time performance of the algorithm are shown in Figures and , respectively. The circuit component values in Figure are and with . The expected parameter values are A=1 and . The initial values of A and in both the simulation and the real-time execution are and , and the sampling rate is 1000 samples per second.
The simulation in Figure converges after only 6 time steps. The real-time execution in Figure converges to the values A = 0.98 and , but more than 6 iterations are needed due to measurement noise. Figure shows that the model in () with the parameter values A = 0.98 and obtained after convergence in Figure provides a good fit to the measured data. The measured data reaches a final value that is less than 1 volt because the DAC loads the circuit and produces an effective in the circuit of Figure .
Figure: Simulated convergence of A and alpha with noiseless data.
Figure: Trace of measured output voltage and convergence of A and during real-time execution.
The measured data presented in Figures 5 and 6 was acquired through an Internet connection to the dSPACE hardware, and the experiment itself was controlled through the Internet. Internet access to the experiment is currently available within the Bucknell University campus and through remote login (telnet) to a Bucknell University computer. The World Wide Web provides a more convenient interface for remote execution of the experiment, and we are currently developing a Web interface. The goal is to create a Web page that allows a remote user to execute the experiment, view the measured data, and download the measured data to the user's host computer.
Figure: Measured output voltage and the model () evaluated with A= 0.98 and obtained from the real-time trace in Figure after convergence.