Study On Method Of Dual-Robot Coordination

The development of modern industry and the improvement of robotic technology arefacilitating the performance of robots, therefore, the application field and scope of robots iscontinuously expanding and the application of them performing more works, which are evenmore complicated, instead of human, is increasing. In order to adapt to the increasingrequirement of work complexity, operation intelligent and system flexibility, the coordinationand collaborative operation of dual robot or multi-robots is the key technology, which iscritically need to be mastered, to promote and implement robotics in industrial environment.The closed chain system when multi-robot systemsoperate on objects restricted leads tomotion and redundancy control problems, which need to adress the issues in planning,analytic method and feasible control method in multi-robot system.The research object of this paper is the operation methods of kinematics coordination andforce control coordination by two6DoF industrial robots. Systematic and in depth study aremade on the collision avoidance path planning, coordinate system calibration, trajectoryplanning and its optimization method of coordinated motion by dual robots, the main contentsare as follows.In order to solve the problem of collision detection and collision avoidance path planningof dual robot systems, collision detection model of three layers’ sphere based on octree datastructure and the SAT-SDPD algorism, which is used to compute the shortest separationdistance and the shortest penetration distance between oriented bounding boxes, are proposed.Simulations are performed to verify the effectiveness and the feasibility of the algorism aswell as to compare and analyze the efficiency and accuracy of different modeling methodusing bounding box. Collision avoidance path planning and optimization methods, based onrepulsive velocity field, are proposed. It is proved by numerical simulation analysis that theimproved repulsive velocity field model has a good effect on collision avoidance pathplanning of dual robots.The study of trajectory planning method of coordinated welding by dual robots is thepremise to guarantee success of coordinated welding and the welding quality. This paperestablishes the coordinate systems of weld discrete points, non-master-slave trajectoryplanning methods for dual robots coordinated welding have been proposed, whose positionand pose planning are performed in the workpiece coordinate system{WP}under down handwelding constraints. Besides, optimal value search algorithm for the position of workpiececoordinate system in Cartesian space has been proposed. The effectiveness of the trajectory planning method of coordination welding and optimization algorithm for the position ofworkpiece coordinate system is verified by simulations.The kinematics coordination is not only the foundation of coordinated operation by dualrobot, but also the premise of realizing force control and coordination. In this thesis, athree-point calibration method, which is used to acquire the position and pose matrix betweenthe base coordinate of dual robots, has been proposed, its effectiveness is verified bynumerical simulation. The coordinated path generation method for slave robot’s coordinatedpath points are proposed, the slave robot’s path points of both coordinated following motionand mirror motion are generated through off-line computing. The results of the experimentsindicate that the accuracy of the motion trajectory by dual robots coordination can meet therequirements of industrial applications. Therefore, effectiveness of the proposed off-linecomputing method is verified.To solve the problem of internal force control in coordinated transportation by dualrobots, static analysis of dual robots’ grabbing an object collaboratively is presented. Anoptimized velocity damping PD control method, which is based on two existing typicalmechanical control methods, namely position/force hybrid control method and impedancecontrol, for coordinated transportation by dual robots based on genetic algorithm, has beenproposed. Experiment results indicate that the optimized control method has smaller controlerror than that of the common velocity damping PD control method, which justifies theeffectiveness of the proposed control methods and optimization algorithm.Finally, to verify the effectiveness and feasibility of the trajectory planning method andforce control method, two experimental platforms for dual robots kinematic coordination andforce coordination are respectively established. The experiments consists of two parts, thefirst part is kinematic coordination experiments, which includes off-line generatingslave-robot coordinating follow motion path experiments as well as off-line generating slaverobot’s coordinating mirror motion path experiment under the condition that motion path ofthe end of master robot is known. The second part is the experiment about coordinatedtransportation by dual robots based on force feedback damping control. The results of theexperiments show that the precision of trajectory of kinematic coordination, whose internalforce control has good transient performance, tracking accuracy and robustness, by dualrobots can meet the requirement of industrial robots operation.