The Design Of Inertial Measurement Unit Based On MEMS

An IMU (Inertial Measurement Unit) for mini-UAV (Unmanned Aerial Vehicle) based on MEMS (Micro-electromechanical Systems) was designed by this paper, aiming to measure the attitudes of UAV real time, such as triaxial accelerations, triaxial angular rates, roll angle and pitch angle. Firstly, the IMU scheme was developed based on MEMS with the view of applying to mini-UAV. The IMU was divided into three circuit boards which were vertical each other by the scheme. The three vertical circuit boards'scheme was satisfied to measure the triaxial attitude which was also accorded with the requirements of the low cost and miniaturization.Secondly, some often used filter algorithms were analyzed. The filter algorithms which were often used in the project were compared by their merit and demerit and scope. Then kalman filter and complementary were selected based on the features of MEMS sensor's signals.Thirdly, attitude fuse algorithm was designed in detail. Kalman filter was designed to remove noise and compensate drifts on account of the signals which were measured by MEMS sensors exists a lot of flaws, such as mixed with noise, drifts with temperature and time, and so on. Because of the attitude angles can not be obtained directly by the sensors, it developed fuse algorithm to get them.Fourthly, a scheme which the PWM (Pulse Width Modulation) signals of accelerometers were captured by the counters of MCU (Micro-programmed Control Unit) was designed to resolve the conflicts of which the channel of ADC (Analog to Digit Converter) was insufficient. With the requirements of the system, some base driving and communication protocol was designed.Lastly, the whole system was experimented. The results verified the availability and the correctness of the design.