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Real-Time Implementation and Internet

The dSPACE hardware is used to generate the step input and measure the output voltage as shown in Figure gif. 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 gif and gif, respectively. The circuit component values in Figure gif are tex2html_wrap_inline311 and tex2html_wrap_inline313 with tex2html_wrap_inline315 . The expected parameter values are A=1 and tex2html_wrap_inline319 . The initial values of A and tex2html_wrap_inline223 in both the simulation and the real-time execution are tex2html_wrap_inline325 and tex2html_wrap_inline327 , and the sampling rate is 1000 samples per second.

The simulation in Figure gif converges after only 6 time steps. The real-time execution in Figure gif converges to the values A = 0.98 and tex2html_wrap_inline331 , but more than 6 iterations are needed due to measurement noise. Figure gif shows that the model in (gif) with the parameter values A = 0.98 and tex2html_wrap_inline331 obtained after convergence in Figure gif 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 tex2html_wrap_inline337 in the circuit of Figure gif.

Figure: Simulated convergence of A and tex2html_wrap_inline341 alpha with noiseless data.

Figure: Trace of measured output voltage and convergence of A and tex2html_wrap_inline223 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 (gif) evaluated with A= 0.98 and tex2html_wrap_inline331 obtained from the real-time trace in Figure gif after convergence.

next up previous
Next: Summary Up: No Title Previous: Recursive Parameter Estimation Algorithm

Kozick Rich
Fri Jun 21 11:03:19 EDT 1996