The Research On Pick-Up Device Of An Towbarless Aircraft Tractor

Towbarless aircraft tractors(TBLT) have been widely used at the airport. The pick-up device is the key part of the TBLT. It's performance for the nosewheel determines the quality of the TBLT. But currently the level of the pick-up device's designing is lower than the foreign developed countries. To accelerate the research on pick-up device will provide technical supports for the rapid development of Chinese aviation industry.After have studied the patents and other relevant information of the pick-up device, this paper provides a novel pick-up device according to the SAE standards, ARP4852?ARP4853?ARP5284 and ARP5285. The three-dimensional model for this mechanism is built and it can do the movements of hoisting and lifting step by step. Then we do the kinematic analysis of this mechanism used the closed-loop vector method, and built the inverse kinematics and speed Jacobian matrix of the mechanism. The 4UPS-RPU parallel mechanism's stiffness model is constructed using deformation Jacobian matrix and principle of virtual work. In the process of constructing stiffness model, the stiffness of hydraulic cylinder and damping buffer are calculated completely. And also calculate the stiffness of spherical joints and universal joints using the software ANSYS. The stiffness distributes throughout the task workspace are simulated using the software of MATLAB.Also this paper analyzes the loads between the pick-up device and the nose landing gear, when the tractor, have picked up the nosewheel, starts, brakes, and corners. The influence for the change of center of aircraft gravity to the loads of the pick-up device is provided. This can provided a theoretical basis for the pick-up device's designing.