Formation Control Of Mobile Robots Based On Visual Servo

With the increasing requirement for solving complex tasks, multi-robot cooperation is attracting more and more attention for its many remarkable characteristics, such as low cost, parallelism and redundancy. As a common cooperation strategy, multi-robot formation can improve efficiency, flexibility and robustness of system. This thesis discusses the visual-based multi-robot formation in the indoor environment. Main contents are as follows: building the visual formation model; estimating the leader’s relative position, orientation and velocity designing visual servo controllers. The controllers are designed with using inverse dynamics and sliding mode control technologies. Particularly, fixed-front-corner and parallel approach methods of missile guidance law are introduced into controller design of multi-robot formation.Firstly, this thesis derives a visual tracking model of mobile robot, which combines the kinematics model of two-wheel mobile robot with an on-board camera. With the aid of transformations of image space and inertial space, the differential equations of visual tracking model are finally obtained. This model is the foundation of mobile robot control and multi-robot formation control. Moreover, it also can be used to estimate the relative position, orientation and velocity of the leading robot.With the visual tracking model in hand, different control laws are designed with using sliding mode method, parallel approach method and fixed-front-corner method. In the servo process, image information is used to calculate the leader’s position and orientation. Then, they are compared with the desired trajectories such that the closed-loop feedback controller is realized.Numerical simulations are carried out to verify the developed model and control algorithms. The simulation results demonstrate that the developed model and control algorithms are correct and effective.