Research On The Influence Of Encoder Resolution On Precision Of Strapdown Stabilized Platform

In recent years,with the rapid development of air combat,high precision,miniaturization,and fast response have become the main technical research directions for stabilized platforms.A stabilized platform is a mechatronics device that measures spatial angular velocity of the carrier or the platform load by using a gyroscope,so that the platform load can isolate the disturbance of the carrier and achieve stability in inertial space.The traditional direct stabilized platform has many advantages such as easily controlled,high precision.However,the gyroscope is installed on the inner frame in a direct stabilized platform,which limits the development of the miniaturization and fast response of the stabilized platform.Therefore,this paper proposes a scheme of strapdown stabilized platform.Because the gyroscope is not required to be installed on the inner frame of the strapdown stabilized platform,not only the cost is reduced,but also the volume is reduced,and the system's rapid response capability is also improved.However,the velocity measured noise of the encoder is introduced,which seriously affects the precision of the strapdown stabilized platform.To solve this problem,this paper proposes that improving the precision of the strapdown stabilized platform by increasing the resolution of the encoder.What's more,to study the influence of control parameters,gyro noise,and encoder resolution on the precision of the strapdown stabilized platform.Firstly,the coordinate system of the stabilized platform is defined according to the mechanical structure of the stabilized platform.Then,deduced and the stability equations of the direct stabilized platform and the strapdown stabilized platform by establishing the kinematics model of the system.Lastly,the stability principles of the two stabilized platforms are performed.On this basis,the control block diagrams of the two stabilized platforms are drawn and the transfer function of the system is derived.Secondly,the direct stabilized platform and the strapdown stabilized platform were modeled and simulated respectively in Matlab/Simulink to study the influence of carrier disturbance frequency and gyro noise on stabilized platform system and discover the critical value of encoder's resolution when the stability precision of the strapdown stabilized platform can reach the same level as the direct stabilized platform under impacts of different parameters.,which proved that the precision of the strapdown stabilized platform can be improved effectively by improving the resolution of the encoder.Then,the structural size of the combined magnetic encoder is modified,including the size of air gaps,magnetic rings,and hall slot,to perform finite element simulation of the magnetic field in JMAG-Designer and obtain the magnetic field spatial distribution map of the interior of the combined magnetic encoder,which will guides the structural optimization of the encoder.What's more,this paper introduces the subdivision algorithm of combined magnetoelectric encoder and the algorithm of preventing interval misjudgment,and compiles the corresponding algorithm program in Matlab to verify the algorithm's effect according to the encoder data collected by the upper computer software.The hardware circuit of the combined magnetic encoder is designed in the Altium Designer software,mainly including the circuit design of the Hall signal acquisition module,the CPU inter-communication module,the operational amplifier reference power module and the programming simulation module.Finally,the overall design of the hardware system of the strapdown stabilized platform is carried out,an experimental platform for the strapdown stable platform is set up.Calibration experiments are performed on the scroll axis encoder and on the pitch axis encoder of the strapdown stabilized platform,and the encoder precision is calculated.Then this paper test the current loop and speed loop on the motor of roller axis.