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In this paper, a fractional-order sliding mode controller (FOSMC) is designed and applied to a four-rotor unmanned aerial vehicle (Quadrotor) to perform trajectory tracking for different time-varying references. Because quadrotor's nonlinear system dynamics are effected by external disturbances and parameter variations easily, the FOSMC is used as a nonlinear controller to combine the flexibility of the fractional-order approach and the disturbance rejection characteristics of the integer-order sliding mode controller (IOSMC) to keep quadrotor on desired trajectory, as well as overcome parameter variations. In order to indicate the priority of the FOSMC, the IOSMC is also applied to quadrotor for the same references. The experimental results show that FOSMC is better than IOSMC in terms of error elimination and is good at dealing with parameter variations occurred while tracking the desired trajectory. [ABSTRACT FROM AUTHOR]

In this paper, speed and direction angle of a four wheel skid-steered mobile robot (4 WD SSMR) has been controlled via adaptive-fuzzy fractional-order sliding mode controller (AFFOSMC) under different speed and angle reference signals. The hybrid control method is designed to combine all advantages that controllers have such as flexibility realized by fractional order calculation, robustness to disturbances and parameters variations provided by sliding mode controller (SMC) as well as adaptation of G constant of SMC via fuzzy controller, simultaneously. Also, a fractionalorder SMC is applied to the system for the same reference speed and angle references to show the effects of the changes and adaptation of G constant. Experimental results show that the AFFOSMC has better trajectory tracking performance than the FOSMC. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear Continuous Sliding Mode control (CSMC) application is presented for trajectory tracking control of a four rotor unmanned aerial vehicle (UAV) called the Quadrotor, also known as micro helicopter. The proposed controller is tested with different time-varying reference routes to provide a stable flight for position control. To show the effectiveness of the designed CSMC, well-tuned PI controller is also applied to quadrotor for the same routes. The current position of the quadrotor is taken from accelerometer, gyroscope and ultrasonic sensors. The experimental results show that the CSMC is adequate to dealing with parameter uncertainties occur in the system dynamics while flying and has satisfactory performance in terms of robustness against to disturbances and error elimination when it compared with PI controller. [ABSTRACT FROM AUTHOR]

In this paper, speed and direction angle control of four-wheel drive skid-steered mobile robot (4WD SSMR) is realized by Fractional-Order Proportional Integral (FOPI) controller. Speed and direction angle of the mobile robot are calculated by using angular velocity of each motors. FOPI controller produces the torques of each motor of mobile robot for trajectory tracking and stabilization in the desired position. A well-tuned conventional PI controller is also applied to mobile robot for comparison with the FOPI. Experimental results prove that the FOPI shows better trajectory tracking performance than PI controller in terms of trajectory tracking accuracy and error levels. [ABSTRACT FROM AUTHOR]