Motion control by a highly maneuverable mobile robot in the task of following an object

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This article is devoted to the development of an algorithm for trajectory control of a highly maneuverable four-wheeled robotic transport platform equipped with mecanum wheels, in order to organize its movement behind some moving object. The calculation of the kinematic ratios of this platform in a fixed coordinate system is presented, which is necessary to determine the angular velocities of the robot wheels depending on a given velocity vector. An algorithm has been developed for the robot to follow a mobile object on a plane without obstacles based on the use of a modified chase method using different types of control functions. The chase method consists in the fact that the velocity vector of the geometric center of the platform is co-directed with the vector connecting the geometric center of the platform and the moving object. Two types of control functions are implemented: piecewise and constant. The piecewise function means control with switching modes depending on the distance from the robot to the target. The main feature of the piecewise function is a smooth change in the robot’s speed. Also, the control functions are divided according to the nature of behavior when the robot approaches the target. When using one of the piecewise functions, the robot’s movement slows down when a certain distance between the robot and the target is reached and stops completely at a critical distance. Another type of behavior when approaching the target is to change the direction of the velocity vector to the opposite, if the distance between the platform and the object is the minimum allowable, which avoids collisions when the target moves in the direction of the robot. This type of behavior when approaching the goal is implemented for a piecewise and constant function. Numerical simulation of the robot control algorithm for various control functions in the task of chasing a target, where the target moves in a circle, is performed. The pseudocode of the control algorithm and control functions is presented. Graphs of the robot’s trajectory when moving behind the target, speed changes, changes in the angular velocities of the wheels from time to time for various control functions are shown.

Keywords: mobile robot, the task of pursuit, control algorithms
Citation in English: Mikishanina E.A., Platonov P.S. Motion control by a highly maneuverable mobile robot in the task of following an object // Computer Research and Modeling, 2023, vol. 15, no. 5, pp. 1301-1321
Citation in English: Mikishanina E.A., Platonov P.S. Motion control by a highly maneuverable mobile robot in the task of following an object // Computer Research and Modeling, 2023, vol. 15, no. 5, pp. 1301-1321
DOI: 10.20537/2076-7633-2023-15-5-1301-1321

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International Interdisciplinary Conference "Mathematics. Computing. Education"