Research On The Key Technologies Of Rotating Mirror Used On Imaging Ladar

According to the need of designing a new generation imaging ladar, the key technologies of scanning rotating mirror used on imaging ladar are researched in this dissertation for improving the location accuracy, speed stability and protracting the system life.The overall structure of the scanner is designed first. The influence of deformation and speed stability on laser's point location error is analyzed and the performance index is proposed. According to the design requirements, a brushless DC motor is selected to drive the system and a grating angular encorder is chosen to measure the location. The model of the rotating mirror and other components are completed using SolidWorks for mechanical analysis.According to the specific structure of the rotating mirror, static balance and dynamic balance are designed and optimized using rigid body equilibrium. A balance analysis method of rotating mirror is proposed based on SolidWorks, Which utilizes the quality assessment function of SolidWorks to get the centroid coordinates and the angle between rotation axis and center inertia main axis as the criterion of dynamic balance. A method of dynamic balance simulation of rotating mirror based on SolidWorks Simulation is proposed, and these methods generally applicable to the universal rigid rotor. The deformation of the rotating mirror is simulated and analyzed using ANSYS. The research results indicate that: when the velocity is 3600rpm, the deformation is less than 30nm, and the deformation angle is less than 0.1", the laser point's location error is less than 0.01mm far away from 10m.A brushless DC motor drive circuit is designed, which utilizes a brushless DC motor control chip Si9979Cs as it's core, and the three-phase MOSFET bridge is composed of three piece of Si9936DYs. The opto-isolation circuit, power supply circuit, and other peripheral circuits and protection circuits are also designed. The results show that the drive circuit is stable and reliable, and can effectively drive Maxon EC-max 40 283867 type brushless DC motor.Incremental digital PID based on the classical control theory is selected to control the system. The control circuit is composed of C8051F120 MCU and FPGA. The experimental system is built by a host computer, the control circuit, drive circuit and the rotating mirror scanner. The results show that the control method can regulate and control the speed effectively. The rotating mirror can operate stably at a predetermined speed. Standard deviation of speed error is about 10^-5.