Modeling And Simulation For Rigid-flexible Coupling Dynamics Of The Tokamak Flexible In-vessel Inspection Robot

Tokamak flexible in-vessel inspection robot is a serial-link manipulator developed for the detection and maintenance tasks of the first wall of Tokamak. Because of the large range space and high precision detection tasks, the manipulator was made by lightweight materials, and has the characteristics of large working space, high load ratio and self-supporting, which is called as the typical slender flexible manipulator. Due to the high extent cantilever structure, the flexibility of the robot cannot be neglected. The existence of the flexible deformation will not only affect the accuracy of the terminal position and lead to collisions between the manipulator and Tokamak, but also cause the vibration and get unclear pictures from the camera. The modeling and control based on kinematics or multi-rigid-body dynamics have been unable to meet the practical requirements of the manipulator, so a rigid-flexible model of the manipulator is great significant to the safety and efficient working.The absolute nodal coordinate formulation is used to model the manipulator in order to meet the accuracy and computational efficiency requirements. For the special curved telescopic structure, a spatial curved beam element with hollow rectangular cross section using the absolute nodal coordinate formulation(ANCF) is presented in this paper. This element is based on Euler Bernoulli beam assumption, avoiding some complex problems caused from the deformation of the beam cross section. The nonlinear elastic force is obtained using the green strain which allows the curved element to model large deformation, large displacement and large rotation problems. Then the rigidflexible coupled dynamic model is established using this element.In order to meeting the high safety requirements of the manipulator, a realtime dynamic solver is developed. The dynamic equations of ANCF can be obtained by the incremental iterative method, the parallel processing algorithm based on Graphic Processing Unit(GPU) decrease the cycle of the solver to millisecond.For validating the control algorithm, combining with the 3d virtual reality module, a virtual simulation system is designed. This system can get the realtime control information and display the real-time motion of the manipulator, which greatly improve the reliability and safety of teleoperation. Simultaneously, the simulator also provides the interfaces for validating the control algorithm, which lays a good foundation for a better improvement, control and vibration suppression of the flexible inspection manipulator.Finally, the effectiveness and applicability of the dynamic model for the flexible in-vessel inspection manipulator is proved through the static and dynamic analysis and simulation.