Control of a mechatronic system containing a four bar mechanism by using intelligent methods

In this thesis, the intelligent and robust crank angular speed control of a four-bar mechanism driven by a externally excited DC motor is implemented. When the crank coupled with the motor rotates, the crank angular speed also changes periodically because of the changes in inertia forces of the rigid links. Due to the timing requirement, a constant crank angular speed is essential. The purpose of this study is to reduce angular speed fluctuations of the crank.It is thought that the use of fuzzy logic preferred for modeling the uncertainties in order to reduce the angular speed fluctuations of the crank is appropriate. Type-2 fuzzy logic is preferred where it is difficult to determine an exact membership function for a fuzzy set. A good control performance is obtained with type-2 fuzzy logic due to its effectiveness on nonlinearities and parameter variations. Type-2 fuzzy logic and Sliding Mode Control are combined to obtain both a simple algorithm and an effective structure against uncertainties. A new Nonsingleton Type-2 Fuzzy Sliding Mode Control method is developed to model also the input measurement uncertainties. The best results according to control performance are obtained using Nonsingleton Type-2 Fuzzy Sliding Mode Control structure for simulation studies. However, the control performances of both Nonsingleton Type-1 and Nonsingleton Type-2 Fuzzy Sliding Mode Control are superior. The error percentage and the difference between the absolute error values of these methods are very small so that it is not meaningful in the practice. For this purpose, as far as the industrial applications are concerned, it is thought that the use of Nonsingleton Type-1 Fuzzy Sliding Mode Control is suitable in order to have a simpler control algorithm. The advantages and disadvantages of these control structures are presented with simulation and experimental studies. The simulation and experimental results showing the effectiveness of the proposed control method is illustrated.