Research On Control Method In High Precision Turntables System

Three-axis turntable is one of the key measuring equipment of the inertial component. With the development of aerial industry, the requirement of performance of the three-axis turntable is to be highest. This thesis is written on the background of the research project of three-axis turntable. Inertial system is very important in aviation field and navigation field. With the improvement of inertial component and inertial system accuracy, the requirement of performance to the test equipment is to be highest. This dissertation is written on the background of a research project. It is mainly focused on many questions about control system design and control algorithms of three-axis simulating turntable that is a test equipment of inertial systems. The results verified in application.Firstly, inertia equations and dynamics equations are presented according to the structure of the three-axis simulating turntable, and torque equations of the motor controlled by PWM controller are presented. Mathematic model is given for the simulating turntable. The ability of uncoupling of the three-axis simulating turntable is proving by using adverse system theory, and nonlinear uncoupling network is also obtained. Using state feedback and dynamic compensating uncoupling, the model is transformed into three single-input and single-output linear systems and equivalent transfer formation. So the coupled system is uncoupled.The control system is designed to a digital system including, velocity-loop and position-loop, in order to meet the requests such as high precision, quick response wide velocity range and low velocity. At the same time the theory of sutra control and modern time control are applied to turn and compensate the control system. The control system apply nonlinear scaling fuzzy controller to improve quick response of positioning. A model reference adaptive system is applied to compensate the action of torque disturbance. A power converting circuit of H-bridge bipolar PWM control is designed to decrease the low velocity.The design methods is applied to the control system of three simulating turntable. The experimental results show that all the methods are effective and feasible. Every index of the system meets or surpassed the performance requirements. Now the three-axis simulation turntable is tested and used by the user.To make use of analysis and design on the theory of neural network, it mainly focuses on the analysis of frictional disturbance and designing neural-PID controller and the real time system software on the base of Windows 2000-RTX operation system. Firstly, the mathematical model of three-axis turntable is presented by the theory analysis, and is simplified according to practical parameters. The state equation of three-axis turntable is established. According to the adverse system theory the uncoupled ability of the network is proved and linear uncoupling network is also obtained. The model is transformed into three single input and single output linear systems, and then it can be analyzed and designed by the linear system theory. Secondly, based on affection of the machine and molecular the friction which is the mainly disturbance in the control accuracy is introduced. The useful friction model is given.After discussing the characteristic and algorithm of BP neural network, the applications of neural network, using in three-axis turntable system, are discussed. The method of compensation is discussed, and then made the theoretic analysis and simulation. The PID controller based on BP neural networks is designed to realize control parameter self-learning and self-adjusting. Both convergence and stability of this system are analyzed and simulation results are presented in the article.Finally, for the three-axis turntable real time control requirement the control software was specifically designed and accomplished on the base of windows2000 plus RTX real-time operating system.