Research On Control Method For Gyro-based Stabilization Of Shipboard Electro-optical Theodolite

In order to track the target stably,electro-optical theodolite needs to isolate the interference brought by carrier shaking.For shipboard theodolite is located on the deck of a ship,it is easily disturbed by the movement of roll,pitch,and yaw of the ship caused by wind,wave and current.As the theodolite on the deck sways with the ship,it makes line of sight(LOS)unstable and even the target lost.So in the presence of ship shaking,ship isolation methods must be applied to ensure the LOS stabilization of theodolite.The conventional method of theodolite LOS stabilization used in the past is using feed forward control with the data provided by ship inertial navigation system.This method is limited by ship inertial navigation system because it takes quite long from inertial navigation system starting to the stable operation and the isolation degree is limited at around 40 d B.Modified through this method still remaining jitter,and could have inverse effect on imaging quality and measurement of optical camera with long lens.Therefore,this thesis intends to install rate gyro on the theodolite to realize autonomous measurement,making a gyro calibration loop after self stabilizing correction based on marine inertial navigation system.And then establish isolation model of gyroscope through coordinate transformation.The encoder and gyroscope constitutes dual-rate loop in order to optimize the control effect of LOS stabilization and to improve the isolation so as to reach LOS jitter control purposes and improve the imaging resolution and measurement capability.At the same time,in the case of without inertial navigation system,using the rate gyro autonomous measurement can also achieve the stability of the ship.Therefore,based on previous studies of LOS stabilization,carrying out gyro-based measurement of marine carrier theodolite Los jitter control method research has very important significance.Firstly,through coordinate transformation,this essay establish mathematical model of ship stability based on INS attitude data of ship swaying provided by inertial navigation system and adopt method of target feed forward along with velocity feed forward method to isolate the ship swaying.And the effectiveness of the proposed scheme was verified through the simulation of MATLAB.The isolation degree was calculated and the limitation of the scheme was point out.Secondly,the establishment of the rate-gyro-based ship self stable mathematical model was followed in this paper and common gyro installation mode was discussed.Then a method of gyro based stabilization mathematical model was established after the correcting of ship shaking based on inertial data.The effectiveness of the proposed scheme was verified through MATLAB simulation and results show that this method has higher a isolation degree.In order to improve the tracking precision of control system of carrier-based electro-optical theodolite and overcome the shortcoming of single rate-loop servo control structure,a dual rate-loop cascade control method was presented in which the measuring signals of encoder and rate gyro were respectively employed to constitute the inner rate loop and the outer rate loop and two controllers were designed to reject inner disturbance and insulate carrier turbulence.Finally,as was proven by simulation,with KVH DSP1760 high precision fiber optic gyroscope(FOG)as inertial space velocity components,the data testing work of FOG was tested with high accuracy aerospace three-turn turntable.And the future work prospect was put forward in the end on this essay.The basis of theoretical work is ready for carrying out the practical engineering application later in the future.