Research On Structural Design And Manipulation Method Of Continuum Aircraft Fuel Tank Inspection Robot Based On Rzeppa Universal Joint

Considering the difficulty for crew in aircraft fuel tank inspection,a continuum robot is designed to assist aircraft crew in inspecting fuel tank,which decreases the workload of fuel tank inspection and improve the efficiency of maintenance.Continuum robot can dynamically adapt to the environment with structural constraints and space complexity,and can carry the detection device to complete the related operations in complex environment.In order to enhance the load capacity of continuum robot and practicality of robot operation,the optimization design of the continuous robot structure and the control method based on the joystick are studied.Firstly,a continuum structure is designed according to the structural characteristics and movement mechanism of snake vertebrae.The continuum structure takes the rzeppa universal joint and the cylindrical helical spring as the main body of joint section,and takes the line actuation as the drive control mode.The continuum structure can perform bending motion and rotating motion based on the isokinetic feature of rzeppa universal joint and the restoring characteristic of the cylindrical helical spring.Secondly,based on the isokinetic feature of rzeppa universal joint,the kinematics analysis of continuum robot is conducted according to the unit load method of cylindrical helical spring.Then the influence of variable curvature bending properties of the plant is reduced,and the mapping relationship among the end position,joint variables and the length of driving cables is obtained.The mathematical expression of the driving cables length variation is deduced by the geometric model analysis of the single spring section,which lays the foundation for the control of the continuum structure.Thirdly,the Cartesian coordinates of each point of the manipulator are obtained based on the homogeneous transformation matrix among joints.The motion track of the end joint are obtained by interpolating calculation of the control input of the joystick in real time.And based on the idea that the end position of each joints follow the start position of preceding joint,the continuum robot realizes the joint continuous control based on the joystick.Finally,the hardware and software control systems of the continuum aircraft fuel tank inspection robot are designed with the joint body of the rzeppa universal joint and cylindrical helical spring.The prototype of the robot is built.The prototype experiments are performed,and the results prove the strong loading capacity of the continuum robot,the correctness of the kinematics model and the effectiveness of the control method.