Browsing by Author "Geta Menyechel"

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    Backstepping Fuzzy Sliding Mode Controller for Trajectory Tracking of Mobile Manipulator
    (Addis Ababa University, 2024-04) Geta Menyechel; Dereje Shiferaw (PhD)
    A Mobile Manipulator (MM) is essentially a robotic arm attached to a mobile platform, which could be designed for space, ground, aerial, or underwater environments. The mobile platform expands the reach of the manipulator, allowing it to access a larger workspace. This increased mobility enhances the ability to position the manipulator in various configurations, leading to more efficient task execution. Mobile Manipulators has complex system structure, highly coupling dynamics between mobile base and mounted manipulator arm, holonomic and nonholonomic kinematics constraints and highly nonlinear characters substantially increase the difficulty in designing a controller for the wheeled mobile manipulator. Designing a robust controller for mobile manipulator with the aim of simultaneous control of the velocity of the mobile platform and the motion of the end-effector is the aim of this thesis work. By employing the concepts of kinematic backstepping control and fuzzy sliding mode torque control, a two-step control approach is introduced for the nonholonomic mobile manipulator. In the first step, the kinematic velocity control is designed to ensure that all desired trajectories are achieved. In the second step, a fuzzy sliding mode torque controller, based on the dynamics of the mobile manipulator, is designed to ensure that the mobile platform’s velocity and the end-effector’s position converge to the reference trajectories generated in the first step. The proposed method stability is proved using Lyapunov theory, and its convergence is mathematically guaranteed. Comparision between BSMC and the proposed BFSMC is conducted in terms of tracking performance in the face of both disturbance and parameter variation and the proposed BFSMC has shown better performance in tracking the given trajectory by rejecting the external disturbances and tolerating the parametric uncertainties results in performance improvement of 31.6%. The effectiveness of the suggested control approach is confirmed through the creation of simulation outcomes using MATLAB/SIMULINK software.