The Modeling And Trajectory Planning Research Of The Tokamak Flexible In-Vessel Inspection Manipulator

Tokamak flexible in-vessel inspection manipulator is designed to inspect the first wall of Tokamak cavity.It is a 10-DOF redundant manipulator including macro arm part and micro arm part.The end-effector of this manipulator is a high-definition industrial camera which will collect the brick information of the first wall and feedback to the operator through 3D simulation system,then the brick can be judged whether it is in good condition.We can also see the real-time posture of the manipulator and the minimum distance between manipulator and the surrounding environment through the 3D simulation system.However,due to reasons such as machining error,the real kinematic parameters of the manipulator are different from the nominal kinematics parameters,which lead to the deviation between real manipulator and manipulator in 3D simulation system.On the one hand,the deviation can lead to error in the process of solving inverse kinematics,thus affecting the effect of trajectory planning;On the other hand,the deviation can lead to error in collision detecting,causing the uncertainty of the motion of real manipulator.In addition,the flexibility of the macro arm will cause vibration problem which affects the observation effect of the camera as a result of the use of lightweight materials.In order to improve the accuracy of motion and decrease the vibration of the manipulator,the kinematic calibration and trajectory planning of Tokamak flexible in-vessel inspection manipulator are researched in this paper.Due to the special structure of the manipulator,the traditional DH method is no longer applicable.In this paper,a complete kinematic model is established by introducing parameters such as the radius of the macro arm.Then the kinematic error model is established,the Levenberg-Marquardt algorithm is adopted to calibrate in order to avoid the singularity.Then we collect experimental data using Vicon motion capture system and calibrate,the experiment results show the effectiveness of the proposed calibration method.In addition,this paper uses the trajectory planning method to reduce the vibration of the manipulator during the movement.Considering the flexibility of the manipulator,traditional trajectory planning method based on kinematics or rigid body dynamics is no longer applicable.In this paper,the rigid-flexible coupling dynamics model is established by using the absolute nodal coordinate method and rigid body dynamics.Based on the rigid-flexible coupling dynamics model,the optimal trajectory planning problem is constructed to reduce the vibration,the optimal trajectory is realized by using the Pontryagin's minimum principle.Finally,the effectiveness of the method is verified by simulation.