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Figure 1: Idealization: spring, mass and damper with step force input
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In Lab 4, we will use the same system that we studied in Lab 3. The objective of this lab is to observe the driven step response of a second order system and to tune the system's parameters to obtain a desired behavior. This can be done by adjusting the length of the spring rod and thereby changing the stiffness of the system. The voice coil that was short-circuited in Lab 3 is used to supply the input force. A function generator and power amplifier provide a step in voltage to the voice coil, which results in a step in force on the shaft. The damping is fixed at the short-circuit value of Lab 3.
By adjusting the stiffness, the rise time can be minimized for certain design specifications, like no overshoot, a specified percentage overshoot or no restrictions on overshoot. Another objective can be to minimize the settling time by aiming for a critically damped system.
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Figure 2: The power amplifier is an Apex PA21 power op-amp
in their EK21 evaluation kit.
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Figure 3: Circuit diagram of this lab
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See below for examples of prelab and lab assignments:
Prelab4.pdf
Lab4.pdf
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