| In recent years,with the development of robotic technology,multi-robot system cooperative operation has been applied in various fields of production and life.Because of its advantages of high parallel work efficiency,strong cooperative work ability,good flexibility and fault tolerance,it has potential application value in remote operation,military operations,post disaster search and rescue,extraterrestrial base construction,intelligent manufacturing,agricultural production,education and entertainment and other fields.The operation accuracy of multi-robot system determines its task execution ability,and directly affects the breadth and depth of its application.However,the flexible forms of cooperation in multi-robot system make it more difficult to guarantee its operation accuracy in the long-time unmanned environment,which restricts the development of multi-robot system to the direction of autonomy,intelligence and high precision.The calibration and accuracy compensation of multi-robot system kinematics parameters are the key means to improve its operation accuracy.Based on the future development needs of multi-robot system,the design of independent and efficient calibration method of multi-robot system becomes an urgent problem to be solved.Based on the project of National Natural Science Foundation of China"Intelligent Online Self-Calibration Method for Deep Space Exploration Space Robot",this paper studies the kinematics parameters calibration and coordination accuracy compensation strategy of multi-robot system.The main results include:the analysis of the factors affecting the operation accuracy of multi-robot system,the design of the synchronous calibration method of kinematics parameters and the base pose of the multi-robot system,the cooperative accuracy compensation strategy of the multi-robot system and the physical experiment based on the actual multi-robot system.Firstly,the existing calibration methods of multi-robot system are based on the calibration of a single robot,which leads to complex calibration process,more manual participation,and only suitable for the current form of cooperation,which is difficult to give full play to the advantages of flexible and autonomous work of multi-robot system.Therefore,this paper designs a multi-robot calibration system using hand-eye camera for measurement to proposes a multi-robot autonomous calibration method,which is used to improve the accuracy of multi-robot cooperative work.According to the characteristics of cooperative tasks of multi-robot system,this paper combs the error sources and influence rules of the end pose accuracy of single robot and multi-robot system.A complete and continuous kinematics model of multi-robot system is established to provides the basis for subsequent calibration and accuracy compensation according to the characteristics of multi-robot calibration system.Secondly,the precision of multi robot cooperation is affected by the coupling of the precision of single robot and the pose error between robot bases.To avoid the influence of the error accumulation caused by the existing step-by-step calibration method on the precision of multi robot cooperation,a synchronous calibration method of multi robot system kinematics parameters and base pose is proposed.Due to the different kinematic modeling methods of master or slave robots in the closed-loop kinematic chain of multi robot calibration system,the kinematic error models of the two kinds of robots are studied respectively.The mapping relationship between the kinematic parameter errors of the two kinds of robots and the cooperative errors of the multi robots is deduced.The mapping relationship between the pose error of multi robot and its base and the end cooperation error of multi robot is established based on the two kinds of kinematic error models.Aiming at the problem that multi robot system parameters may lead to complex calculation,a two-step method is used to identify the kinematic parameters of multi robot and the pose relationship parameters of base coordinate system to realize synchronous calibration.Thirdly,a precision compensation strategy is designed to compensate the residual error after calibration,to further improve the precision of multi-robot cooperation and provide the possibility for the application of multi-robot system in higher precision operation scene.Based on the high-order kinematic error of multi-robot system,the discrimination condition of error compensation is designed as the evaluation standard of accuracy compensation.Aiming at the problem that it is difficult to obtain the pose of base coordinate system in multi-robot system,the solution method of base initial parameters and the compensation strategy of base pose error of multi-robot system are studied,which effectively improves the cooperation accuracy of multi-robot system.Finally,the multi-robot calibration system physical experiment platform is built,and the software control platform is designed to carry out the multi-robot system calibration experiment.It verifies that the multi-robot calibration system designed in this paper can realize the data acquisition and partial processing without the direct participation of human.Through the measurement of the multi-robot system coordination accuracy before and after the experiment,the results proved that the multi-robot system kinematics parameter calibration and accuracy compensation method proposed in this paper can effectively improve the multi-robot operation accuracy. |
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