marvin:lab4
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====Tuning PID Parameters==== | ====Tuning PID Parameters==== | ||
The easiest way to tune the parameters would be if it was possible to do a simulation and see the phasemargin, | The easiest way to tune the parameters would be if it was possible to do a simulation and see the phasemargin, | ||
+ | A PID controller is based on three controllers placed in a cascade and they are very often shown in the Laplace domain, where the characteristics in terms of bandwith are more prominent. In our situation an in-depth analysis of the phase-margin is not available and therfore finetuning these controllers are made via the trial and error concept. The three figures from the wikipedia secton on PID controllers are very useful in order to get an intuitive understanding of the three controllers. These figures are shown here for convenience. | ||
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By inspection we summarize the following. An increase in the proportional gain will create a larger overshoot, but reduce the steady state error and rise time. An increase in the integral controller also increase the overshoot, while eliminating the steady state error. (This is actually depending in how many poles we have in the system). If we increase the differential controller, we decrease the overshoot with no affect on the steady state error, but the bandwith of the system will be reduced. | By inspection we summarize the following. An increase in the proportional gain will create a larger overshoot, but reduce the steady state error and rise time. An increase in the integral controller also increase the overshoot, while eliminating the steady state error. (This is actually depending in how many poles we have in the system). If we increase the differential controller, we decrease the overshoot with no affect on the steady state error, but the bandwith of the system will be reduced. | ||
The deafault parameters in the program caused Marvin to oscillate to much, so based on the observed behavior of Marvin, we decided to increase the differential controller in proportion to the other controllers, | The deafault parameters in the program caused Marvin to oscillate to much, so based on the observed behavior of Marvin, we decided to increase the differential controller in proportion to the other controllers, |
marvin/lab4.txt · Last modified: 2008/10/03 11:39 by rieper