Study On The Motion Planning Of Multiple Crawler Crane Lifting System

With the development of Chinese economic construction, Ocean engineering, electric power construction, municipal construction and other industries promote a huge demand for lifting. This makes lifting toward modular and large-scale, so in order to meet the specific requirements, Multiple crane lifting together has become an indispensable trend. Because of the harmfulness of the accidents about multiple crane lifting, it’s necessary to ensure the safety of lifting. Therefore, the detailed and safe lifting scheme is essential before the catual lifting. At present, the traditional lifting scheme has the problems of safety analysis and large amount of calculation, it depends on the engineer’s experience. While there has been little research on the motion planning of the multi-crane lifting system, so in this paper, the research has important auxiliary function and significance.Firstly, the structure of the crawler crane is analyzed to get model of multi-crane lifting system from single and double crane lifting system. From this model, we find there are multi-closed-chain constraint and non-holonomic kinematic constraint in the system.Secondly, on above basis, we give the definition of the mathematical model of the motion planning of multi-crane lifting system. For multi-closed-chain constraint, combing with the RLG, a modeling method is proposed based on lifted object and crane carriage driving and the corresponding solving equations is given about the passive variables in this paper. For the non-holonomic kinematic constraint, the equation of state and action input collection are obtained from the crane walking model.Then a complete mathematical model of the motion planning is given to meet the requirements of the lifting constraints.Thirdly, because calculation of lifting force is a problem about statically indeterminate in multi-crane lifting system, a lifting force calculation method is given on the basis of ropes’ deformation in the premise that the ropes are used as flexible bodies and the lifted object and other crane’s parts of the system are used as rigid bodies. And five cases are analyzed to verify the correctness and applicability of the method by ANSYS.Fourthly, the RRT-Connect++ algorithm is used to simulate the four-carne and six-crane lifting cases based on the mathematical model of the motion planning of the multi-crane lifting system. According to these two cases, the method in this paper is feasible and applicable.Finally, a load distribution analysis software is designed to get the the change curve of lifting force in the planning path by MATLAB. The software can play a supporting role in the formulation of lifting scheme.