Analysis And Research Of Turntable For Low Velocity Performence

Test turntable with high precision is a kind of significant apparatus for model calibration of inertial navigation systems and inertial instruments. The quality of test turntable determines the reliability and accuracy of experiments and is the foundation upon which the precision and performance of aeronautics and astronautics products and weapon systems is guaranteed. With the rapid progress of aeronautics and astronautics technologies, more excellent performance and accuracy of navigation and guidance is demanded, which in turn need improvement of the test turntable. However, the enhancement of the turntable in performance is limited by the disturbing torque, especially friction torque, while the reduction of friction is limited by technological level and experimental funds. Therefore, devising interrelated control laws to eliminate and compensate friction effect and in turn achieving high precision control contribute apparent theoretical significance and applicant value for the research of turntable with simple structure and high precision. For the problems mentioned above, relative researches are finished as follows:First, the research situations of turntable with low velocity are introduced and especially in the aspect of friction effect for turntable. Aiming at the problem of friction compensation, friction models in common use and compensation methods are presented. Based on the structure of turntable, the control model is constructed and linearization for actual system is finished, which in turn achieve the mathematic model of turntable. Also, the PID control law in tradition for turntable is recommended and the influence of parameters in PID for system is analyzed.For the low velocity performance of turntable, research is carried on about main factors which show clear effects on the low velocity performance, such as angel measuring error, disturbing torque of motor and friction torque, and relative researches are completed by simulation and experiments. In foundation of the theoretical analysis for restraining environmental disturbance by acceleration negative feedback, the control law for acceleration negative feedback which based on filter and observer are designed, and more simulations and researches are carried out, especially for sinusoidal signals with low frequency and ramp signals with small slope.By analyzing theoretical simulation and actual experiment, the tracking error of system is a series of signals with the same frequency as the order signal, based on which, the character of forward-back control method and self-adaptive control method are analyzed. In turn, self-adaptive and forward-back control law is conbined. The simulation indicates that this method performs apparent control capability in restraining the effect of friction torque for turntable performance in low velocity.Based on the research of a kind of turntable, hardware of angel measuring system and interface circuits is devised. For the decentration and pitched error in the process of grating application, relative researches are carried out, and of which, the correctess is poroved by experiment. Also, the software of industrial control computer is accomplished and the self-adaptive and forward-back control law is tested by turntable with single shaft. Finally, the experiment results significantly suppose the validation of the control law designed.