Design And Realization Of The Clearance Measurement Device For The Electromechanical Actuator System

Electromechanical actuator system is an important executive structure of the aerospace craft. While, the clearance that produced during the machining and assembly has bad effects on the control accuracy, response time and reliability of the system. Too large clearance will lead the system to control phase lag and the dynamic performance of variation; and much too small clearance could causing the jam and friction increasing during operational process. So it’s necessary to measure the clearance of the system and adjust it to the proper size when producing and assembling them.Major of clearance measurement for mechanical structure is artificial at present, the measurement through hanging weight or using pressure meter to eliminate the clearance, combine the dial indicator to measure the displacement of the measuring rod, and calculate the angle by the value. The value of clearance is very tiny, it usually less than 10 minute arc. The measuring error is less than 1 minute arc, so it is hard to have a precise measurement, and traditional methods is unreliable and can’t meet the measuring requirement. This paper adopts a method that can measure the tiny angle using high precision displacement sensor and using the electric cylinder and pressure sensors to realize the continuous small torque output then realize the precise measurement of clearance angle. Experiment results verify the feasibility of the scheme design, and realize the automatic measurement for clearance and stiffness according to the mechanical structure design, electric system design and PLC programming.Achieving the clearance value under a variety of pressure through the grouping experiment for the electromechanical actuator system. And calculate the uncertainty of every group of clearance, the results indicate that the maximum uncertainty is 21?, less than the demand of system design 1?, and realize the automatic operation and reliable measurement process. The rigidity of output shaft can be converted into the measurement of force and variation of angle, and the high precision of angle measurement ensure the accuracy of stiffness calculation, according to the actual demand, the system can realize the measurement of rigidity.