Multiple Underwater Spherical Robot Formation Control Research

With the declining of global resources, underwater robots have been designed in order to develop marine resourse meanwhile protect the matitime rights. The underwater spherical robot, with its flexible movements and high intensity of pressure working , is widely applyed in under water operation.This paper got the inspiration from natural animal cluster movement which can overcome the disadvantage brought by a single robot.It began at multiple underwater spherical robot formation movement and the formation of multiple robot working together to complete the wide and full range tasks, such as underwater collaboration to round up the enemy target, comprehensive monitoring,etc.This paper based on BYSQ-3 type spherical underwater robot. The control strategy and methods of several spherical robots is studied.The concrete research contents are as follows:Firstly, this paper analyses both the software and hardware structure and kinematic characteristics of the BYSQ-3 type of spherical robots,which established foundation for the formation process and control method. A mathematic model of the multiple underwater spherical robot formation and a pilot robots for reference the origin of the spherical coordinate system was established,which can simplify the control of robot team formation to involve in the process of matrix calculation.Secondly, the control methods of multiple underwater spherical robot formation is studied.The analysis of task allocation algorithm and path planning algorithm for robot system from the initial disorder state to the process formation is conducted.Meanwhile,the logic strategy of the formation process is studied.In addition,the research propose task allocation algorithm in three-dimensional space based on two dimensional tangent circle method robot which is indicated by simulation.Thirdly, the multiple underwater spherical robot formation process control methods, multiple underwater spherical robot from formation shape to the formation of obstacle avoidance of the control used in the process of formation control algorithm is analyzed. The research studied the logical strategy in the process of formation keeping, meanwhile the formation keeping control algorithm based on iterative learning method is improved. Iterative learning control law was designed, and in the same time, the research designed a robot path tracking control algorithm based on sliding mode control algorithm. The simulation results verify the algorithm the research proposed.Finally, this paper analyzed the formation process control method of obstacle avoidance, the control method when robot encounter obstacles,and the formation process logic of obstacle avoidance strategy. In order to make the obstacle avoidance of robot team formation to shape constraint still maintain the original formation in the process of formation, the formation based on traditional artificial potential field method is improved. On this basis, a fuzzy control algorithm of formation obstacle avoidance based on artificial potential field method is proposed which can improve the security of multi robot system obstacle avoidance, and the simulation of obstacle avoidance for multi robot is carried out. Taking BYSQ-3 underwater spherical robot as the experimental control object,the effectiveness of the formation control algorithm of multi robot is verified by underwater spherical robot experiment.