Mechanical Analysis For POGO Stick In Measurement System Of Aircraft's Weight And Center Of Gravity

Aircraft's weight and center of gravity is an important parameter in the design and manufacture of aircraft.As flight attitude of turbojet aircraft tends to be complicated,aircraft's weight and center of gravity need to be accurately measured,which ensure flight safety.Based on measuring equipment for aircraft's weight and center of gravity,the traditional measurement equipment does not meet the current technical requirements in the key factors such as accuracy,efficiency and versatility.The operator's skill and experience is necessery for operating equipment highly.The new measurement system invented for aircraft's weight and center of gravity can solve the above problems.In the new system,the POGO stick is used as the positioning support component,the 3 axis force sensor is used as force measurement equipment,the aircraft's weight and center of gravity can be measured accurately by the combination of the measurement platform,the POGO stick and the central control system.The automatic detection and docking system is used to improve the automation degree of the system.The moment balance principle inventied for the measurement system specially now is adjusted for higher accuracy,as 3 axis force sensor with higher accuracy is utilized.Based on the related theorem of moment on axis moment of force and space force system,the system can accurately measure the center of gravity(x,z)of the aircraft.Based on the POGO stick linkage control function,a method of measuring the coordinates of the center of gravity in the Y direction is proposed.According to the method,the center of gravity(y)of the Y direction is measured accurately.The main bearing part of the measurement system invented for aircraft's weight and center of gravity is POGO stick,its quality directly affects the stiffness and dynamic characteristics of the measurement system.This paper presents a new type of POGO stick.According to the characteristics of use,the unloading mechanism is designed for the POGO stick.The structural design of the POGO stick model is carried out.The finite element analysis module and geometry optimization module aslo be invoked for 3D models' structural strength and the geometry of models' structural.The results show that: By using the design function of measurement system invented for aircraft's weight and center of gravity,the measurement progress and efficiency can be increased,and the automatic measurement process can be realized too.The actual value of the force and it's arm measured by force sensor is more precise and aceptable than force value of X,Z direction which is detected by platform.Due to the role of the POGO stick linkage control program,the barycentric coordinate measurement method in the Y direction can accurately measure the coordinates of the center of gravity in the Y direction.The structural strength,distortion and geometry of models' structural is optimal according to the simulation.The influence degree of each design variable on models' distortion was found by software's geometry optimization module.