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Date of Award


Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)


Graduate School

First Advisor

Robert H. Turpin

First Committee Member

David F. Besch

Second Committee Member

George Schroeder


A PID controller and a Fuzzy Logic controller were designed to balance an inverted pendulum system. Both controllers were implemented in a Digital Signal Processor (DSP). Measurements of the angular position of the pendulum (feedback signal) were taken from a precision potentiometer and transformed into digital by an Analog Interface Board (AlB) to be processed by the DSP. The DSP generated the digital control signal that was converted into analog by the AlB and then filtered and amplified to drive a DC motor. The DC motor provided the control force for the mobil base where the inverted pendulum was mounted. The PID controller was designed to move an unstable pole of the system from the tight side of the s-plane into the left side of the s-plane to provide stability and fast response. The Fuzzy Logic controller was designed using thirteen control rules that were generated using human intuition. It was found that the Fuzzy Logic controller required a considerably larger amount of memory than the PID controller. In general, the Fuzzy Logic controller performed better than the PID controller. It was concluded that nonlinearities present in some components of the system caused the PID controller not to perform as well. It was also found that the Fuzzy Logic controller was less sensitive to these nonlinearities, resulting in a better control of the inverted pendulum.



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