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In this paper, a bond graph model of a mobile robot with four Mecanum wheels is developed to extract a dynamic model of the robot. This is achieved using the BG_V21 tool box of MATLAB. The dynamic model thus obtained is used to derive the control law for trajectory tracking by the robot. There are two control algorithms that are used, namely, the flatness-based controller and the backstepping controller. From the simulation results, it is evident that the extracted dynamic model of the robot is accurate. Moreover, the flatness-based controller proved to have the upper hand in performance over the backstepping controller.

With the growing use of mobile robots in home applications, e-commerce warehouses, and so on it is necessary to pay attention to their object carrying capability for transferring objects from one location to another. The shape of the object to be carried may vary based on the type of surface (planar/nonplanar). For an instant, the surface of a cylinder is nonplanar. Thus, when the mobile robot tries to track a desired trajectory with a cylinder kept on its top surface, the cylinder may fall on the ground due to its uncontrolled rolling motion. Thus, in order to address the problem, this article presents a novel approach for a Mecanum wheeled mobile robot with a cylinder, for simultaneous balancing and tracking task. In this approach, first, the mathematical modeling of Mecanum wheeled mobile robot with the cylinder on its top surface is done using Newton-Euler approach. Then, to prevent the cylinder from falling, while Mecanum wheeled mobile robot is following a desired path, switching between two robust controllers is utilized to obtain a feasible reference trajectory. The robust control laws are derived using second-order sliding mode controller. In order to ensure the stability of the controller, Lyapunov stability proof of the established theorem has been provided. Later, the Mecanum wheeled mobile robot is made to follow a generated reference trajectory using the robust controller of the mobile robot. The proposed approach is implemented in MATLAB/Simulink. The simulation results proved the efficacy of the proposed approach such that Mecanum wheeled mobile robot followed the desired path with cylinder on its top surface. Moreover, results of statistical analysis have been presented, and comparison with proportional integral derivative (PID) controller is done to prove the superiority of the proposed approach.

comparing its performance with a priori approach. The experimental results indicate that the proposed method is reliable, quick and efficient to teach robot from task demonstrations.