ECE 3642, Homework #4, Part 2 Due October 20, 2006.

1. a. Implement the simulink model shown in Fig. 7.8, Senturia. For the values given below, examine the time to contact (contact occurs at a gap of 50% of go). Yours does not have to look exactly like the one in the text, it just has to work correctly.
    b. Implement the simulink model shown in Fig. 7.9, Senturia. Note that some of the switches and the reset on the integrator may be connected differently than shown in Fig. 7.9, depending on how your elements are defined. In particular your switches may be completely different, or you may be able to completely eliminate them because we stop at half the gap with the contact. Here the idea is to also observe the opening behavior when the actuation voltage is removed.
    c. Put values into the models corresponding to a parallel-plate electrostatic actuator for a MEMS device (perhaps a microrelay). Actuator area=70x30microns, g₀=0.6 microns, volume of mass 50x70x6 microns, material Au, spring constant=300 N/m, pull-in stopped at g₀=0.3 microns by contact. Introduce just enough damping so that the device is somewhat underdamped.

What is the time to contact for voltages 1%, 10%, and 100% greater than the pull-in voltage? Note: The resistor in series with the voltage source must be fairly large for the simulation to converge. Changing the choice of solver under simulation -> parameters can help the simulator converge for smaller resistances (for example ODE23s).

Observe the opening behavior with the model from part b. You should see damped resonant behavior at the expected frequency is working correctly.