| Nuclear fusion research is a major scientific research project to build a clean energy for electricity generation.International Thermonuclear Experimental Reactor(ITER),one of the largest nuclear fusion projects in the world,is in the process of construction so far,monitoring and maintenance of the first wall of the Tokamak as its core equipment is achieved through remote operation.Considering that the properties of Tokamak were different scales and similar structure in different sizes of nuclear fusion projects in different countries,this paper classifies the Tokamak geometric structure into a class of key research.Tokamak-type facilities for nuclear fusion have several common features in small entryway,large radius of rotation,complex D-section,and so on.Therefore,this paper carried out parametrical study on the manipulator for the maintenance of the facility from two aspects,which is structural synthesis(also known as type synthesis)and motion planning of entering Tokamak,constructs the 1:10 Tokamak models and carries out the corresponding theoretical research and prototype experiments.It will provide theoretical basis and technical support for the development of Tokamak maintenance manipulator in the following full-scale ITER project.Based on the analysis and research for comprehensive development trend of type synthesis,this paper carries out an in-depth study on the determination of the degree of freedom(DOF),type synthesis,structure design of hyper-redundant manipulator for Tokamak maintenance task.The specific content of this paper is as follows:(1)Taking Tokamak-type facilities as the object of remote handling maintenance,this paper uses the parametric geometry analysis method to deduce “the DOF judgment equation of LCT-Robot(Load-Carrying and Transmit Robot)” used for the Tokamak-type maintenance task,and proposes the type synthesis method of hyper-redundant manipulator,which takes into account the classical mechanism configuration,POC(Position and orientation characteristic)set equivalence transformation and task space geometrical constraint factor,for Tokamak-type maintenance task based on configuration evolution method and POC equation theory.The higher the redundancy of degree-of-freedom for hyper-redundant manipulator,the better the efficiency of the method.Subsequently,this paper takes the 1:10 Tokamak model as the object of study,the revolution pair(R pair)and the prismatic pair(P pair)as the basic motion pair,carries out the type synthesis of 13 DOF Tokamak remote maintenance manipulator using the type synthesis of hyper-redundant manipulator,research results will contribute to configuration optimization of the subsequent Tokamak remote maintenance manipulator.(2)Taking one of all 13 DOF Tokamak hyper-redundant manipulator configurations by using type synthesis as the object of structural design,this paper proposes a structure design process of manipulator under the space geometric constraints of Tokamak-type maintenance tasks.This process fully considers the factors of the Tokamak maintenance manipulator structure design,such as the inherent geometric constraints of the maintenance space,the core parameter group quantization,the optimization of the transmission mechanism,the "lightweight" design of the key structural components,the relationship between the moment load and the joint output torque.Concurrently,based on parametric representation of Tokamak-type device and requirement of the collision avoidance during entering Tokamak,“the collision avoidance decision equation of Tokamak-type modular joint constrained by geometrical space” is deduced,and then the quantitative analysis and initially determines the modular joint length and width on the 1:10 Tokamak maintenance is carried out.(3)This paper presents a comprehensive design method of modular joint structure of redundant robots with differentiate strategies under Tokamak space constraints.This method considers the factors such as maintenance space geometric constraints,structural strength analysis and “lightweight” design.At the same time,the mutual correlations between structural strength analysis and “lightweight” design make the LCT-Robot joint having the function of parameterization and modularization under satisfying the geometric constraints of the maintenance space.And on this basis four types of modular robot joints,which is designed by using the comprehensive design method of modular joint structure of redundant robots with differentiate strategies and suited to the ITER 1:10 Tokamak first wall modle,is designed and developed.It will procide the scientific theoretical foundation and experimental basis for developing a full-scale Tokamak-type maintenance manipulator.(4)Taking the designed and developed 1:10 Tokamak LCT-Robot as the research object,the theoretical study and geometric analysis on trajectory determination,motion planning and collision avoidance during entering Tokamak is conducted.Then the “collision avoidance decision inequality during entering into Tokamak” respectively correspond to the fixed or arbitrary motion trajectory for Tokamak-type hyper-redundant manipulator is deduced.Based on the ten states of LCT-Robot entering Tokamak,the stage motion of 1T6 R LCT-Robot and configuration of mechanism freedom method is summarized,which effectively reduces the inverse kinematics problem of the hyperredundant to low-mobility and simplies the inverse kinematics problem of hyper-redundant manipulator oriented to special maintenance manipulator.In this research,all Tokamak maintenance problems is classified as a kind of parameterized maintenance task,which effectively reveals the characteristics of Tokamak maintenance.It provides a new research idea and application method for the analysis and research of hyper-redundant manipulator in the respects of configuration synthesis,structural design method under geometric constraints,motion planning and collision avoidance judgement during entering Tokamak.This paper provide a theoretical basis and technical support for expanding structural synthesis theory and method of hyper-redundant manipulator and the innovative design and practical application of Tokamak-type hyper-redundant manipulator. |
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