History of turntable development
Some of the world's space technology developed countries, such as the United States, the former Soviet Union, Germany, France and so on the development of the turntable put a lot of energy. Their development level has been developed to a certain height. Especially the United States, it is the first turntable to develop one of the turntable, the turntable development technology has been in the world's leading position. At present, the United States in the turntable manufacturing, both in terms of quantity, variety, or measurement accuracy, test the degree of automation are the world's leading position on behalf of the world's highest level. In 1945 in the United States Massachusetts Institute of Technology instrumentation laboratory was born in the world's first turntable A-type turntable. Using ordinary ball bearings, with AC torque motor drive, angular position measurement components using ball micro switch. As the use of components is relatively low accuracy, and no experience can learn from this turntable a lot of shortcomings, the accuracy is very low, in fact, not put into use. Later in 1950, the successful development of the B-type servo turntable, 1953 developed a C-type turntable, with a precision gear instead of a direct drive device. 1954 D-type turntable put into use, this turntable uses a precision conical ball bearings, angular position readout device using photoelectric angle measuring system, marking the turntable into a high-level stage. In the late 1960s, the United States developed the turntable began to use computer control, such as the Fick Systems branch of the 3768 type, 3769 single-axis turntable and 5768 type, 5769 double-axis turntable; 5769 turntable also achieved a computer automatic test, which The turntable can operate in servo status, synchronous rate state, auxiliary rate state, digital position status and automatic program shift status, respectively. US CCJC company in the late 60s to the early 70s, developed and produced 51 series of dual-axis air bearing test bench. The late 1970s developed and produced 53 series three-axis turntable. It is worth mentioning that in this type of turntable using a modular precision angular position control system MPACS (Modular Presicion Angular Control System) 30H. 30H series of products combines modern electronic design and packaging technology, can provide a variety of control and coding functions. Since the minimum and maximum functional requirements are taken into account when designing each module of the MPACS, the system provides absolute angle or position control, position coding, and precision rate control. The system architecture is designed to provide maximum expansion capability for multi-axis test equipment, 30H series of modular features, showing a high degree of maintainability and flexibility. By the late 1970s, the US test turntable had reached a very high level, with high accuracy, high reliability, versatility, and computer control and data processing. Because in many cases, the technical level has reached the boundary or limit accuracy, while the technical development of continuity and habitual forces. Making it difficult to suddenly enter the new development is the use of air bearings, and advanced triaxial test bench with active magnetic levitation technology, which can shaft rotation accuracy from the O. 5 angle seconds to 0.03 angle seconds; structure of the test bench: some of the existing test bench using aluminum frame structure, and advanced triaxial test bench is a graphite composite spherical shell structure, This improves the symmetry and deflection characteristics; some of the existing models on the drive have a DC / AC torque motor, while the advanced triaxial test bench uses a multi-phase induction motor, eliminating the camber effect of the motor And torque fluctuation; angular position sensor: Some models of the existing test equipment using a single sensor synchronizer, and ITATT advanced three-axis test bench is used in the sensor synchronizer and optical encoder combination, so that the angle from the O. 5 angle seconds to less than O. Corner seconds, control: CGC some of the original test bench using analog / digital technology, and advanced triaxial test bench using digital state feedback technology, which can eliminate the offset, and create the conditions for the error compensation: the use of After the above technology, the improved advanced triaxial test bench ITATT integrated pointing accuracy up to O. 1 angle seconds, the positioning accuracy of the axis of 0.03 angle seconds, comprehensive technical indicators raised an order of magnitude.