With the continuous exploration of the universe and astronomy’s development, the telescopes are bigger and bigger. Horizon structure is widely used in the modern large telescopes rack, which carries dozens, even thousands of tons of the rotary parts and demands high accuracy and good stability. Therefore, it is one of the key technologies for large telescope to develop the precision support technology integrated direct drive with large load, high stiffness, low friction, even frictionless. Magnetic suspension bearing has not only the advantage of non-contact, no friction, high rigidity, high precision, low power, low mechanical assembly requirements, but also is integrated with the driven torque motor, which simplifies the structure, reduces the cost. This paper explores one kind of active bias magnetic suspension bearing integrated with direct drive technology based on multidisciplinary design optimization (MDO), which provides a new choice and view for the modern large astronomical telescope tracking system.
The telescope tracking system is one big-inertia, multivariable, nonlinear, complex and strong coupling mechatronic system which is disturbed by some nonlinear disturbance such as torque ripple, wind disturbance and the cable drag force during the tracking process. In order to suppress the nonlinear disturbance and improve the tracking precision in large astronomical telescope, this paper explores one intelligent fuzzy control algorithm which contains engineers’ rich experimental experience and shows strong inductive ability. The simulation results show that the fuzzy controller is much stronger than traditional PID controller to suppress the nonlinear interference. The tests in the 1-meter telescope experimental platform also testify that it is very stable and the RMS of position tracking error is only 0.012″ in the superlow tracking speed 0.2″/s. While in the quick tracking speed, 6°/s with the acceleration 5°/s<sup>2</sup>, the RMS of position tracking error is only near to 1.8″. In conclusion, by the fuzzy control method designed in this paper, the dynamic response of the telescope tracking system has been improved effectively and the nonlinear interference has also been suppressed strong. What’s more, the tracking accuracy has been improved greatly.