Nonlinear dynamics and control of a set of robots for hunting and coverage missions

Abstract

The aim of this article is control of a set of 3-wheel robots with non-holonomic dynamics for hunting and covering around moving target. Robots have mass and inertia, and the wheel mass have been considered in the dynamic model of robots. The output of the controller is wheel’s torque and steering torque of the front wheel. The saturation and filtering effects of the actuators are also considered here. The robots in the group are controlled in such a way that each robot responds with an appropriate reaction, based on the control algorithm and the information passed down from other robots and the target (decentralized control). Moving target dynamics has been considered in a way that it is escaping from invader, and the target has holonomics dynamic, and it is assumed that the moving target hasn’t the wheel. To derive the equation of the motion, Kane dynamics procedure has been used. Robots are equipped with sensors for distance assessment, vision angle assessment and also signal receiver antenna. To estimate relative position and variables of another robot situation and target, Extended Kalman filter and Extended Kalman smoother (Extended Rauch–Tung–Strible smoother) had been used. To do a group maneuver using inertia analysis and optimizing the norm of error between desired and actual acceleration, controller was designed. The operation was implemented for three planes: ramp plane, spherical plane and cylindrical plane. The results include the hunting and the coverage of the target by four invader robot and relative distance diagrams between robots and the target, their velocity and corresponding to robots at three planes and also a comparison between real and estimated variables and moreover,comparison between estimations by Kalman filter and Kalman smoother. Based on the results, it can be seen that due to inertia effects in robots and non-holonomics feature of robots, designed controller and estimator are suitable for implementing to the operation to achieve appropriate results.