External Disturbance Compensation in the Problem of the Mobile Robot Visual Positioning

Abstract

The paper considers the problem of visual positioning of an all-wheel drive mobile omni-wheeled robot relative to an external visual marker in the form of a square described by the coordinates of four corner points. A video camera is rigidly fixed to the robot body. The robot is controlled by setting the thrust force in the longitudinal and normal directions, as well as setting the torque. The task is to ensure that the projection of the visual marker in the image plane is in the desired position, while a number of requirements are set for the dynamics of the controlled movement, in particular, in the presence of an external constant or periodic disturbance. The proposed solution consists of a combination of visual servoing control approaches and the use of a special multipurpose controller that allows you to break down an initially complex task into simpler ones that can be solved relatively independently of each other. The synthesis process of such a regulator is described to take into account the requirements in various driving modes. The resulting feedback provides asymptotic stability, astatism of the closed system with respect to a constant perturbation, as well as minimization of the intensity of the response of the control signal to polyharmonic perturbations with known frequencies. The effectiveness of the described approach is demonstrated by the example of experiments with a computer model of a mobile robot in its own motion mode, in the presence of a constant external disturbance and in the case of a polyharmonic disturbance with three harmonics.

Keywords

• control theory
• feedback
• multipurpose regulator
• filtering
• external disturbance
• computer vision