New Metrology Method For Geometrical Quantity Based On Electric Guiding And Error Correction And New Types Of Smart Displacement Sensors

Precise measurement technique is an important means to guarantee product quality and also an important tool for scientific researches. As the significant technical basis of S&T, economy and social development, the level of measurement and testing has become one of the important indexes to the national development of S&T. In traditional methods geometrical quantity is measured by using spatial reference quantity, and the relationship between measured quantity and reference quantity is space-to-space. It is necessary for traditional grating type displacement sensor and position encoder to have a high precision spatial reference quantity named dividing scale in order to achieve high precision measurement. The reticles of dividing scale must be divided proportionally and densely, which depends on precision machining technology. When number of reticles is not enough, reference quantity has to been further subdivided electronically. Therefore, machining technics is complex and requirement is high, which cause the cost of machining is high. Under the research of three projects funded by National Natural Science Foundation of China(NSFC) and one project funded by Important Natural Science Foundation of Chongqing, China, this paper theoretically and practically develops the study on a novel metrology method for geometrical quantity based on electric guiding and error correction and three new grating types of smart displacement sensors. The main contents and innovation are as follows:(1) A novel metrology method for geometrical quantity based on electric guiding and error correction is firstly proposed. Measurement precision depends on the precision of electric tracking and error compensation instead of the precision of manufacturing and installing.(2) The academic thought of measuring space with time and resolving mechanical problems with electric ways is discussed. Space quantity can be measured by using time as reference quantity and measuring spatial displacement can be changed to measuring time, which completely avoids precisely dividing reticles. Hence, machining cost can be largely decreased without the dependence of precision work.(3) Three new grating types of smart displacement sensors are studied based on the aforementioned novel method and idea. Including:1) The method of time-space coordinate transformation in precise displacement measurement and the principle of field type time grating displacement sensor aredeveloped.2) The new thought of developing differential grating displacement sensor with the novel signal subdivision method of slipper interpolating is described.3) The new research idea of developing laser grating displacement sensor based on electronic guiding and circular division multi-information fusing is firstly proposed. The precision of the sensor depends on auto control precision instead of precision of manufacturing and installment.(4) TG-E1 time grating angular displacement measuring system and a high precision time grating sensor sample both are successfully developed at the first time. A systematic means to achieve high precision of time grating is worked out after a mount of experiments. The result of testing time grating by National Institute of Measurement and Testing Technology (NIMTT), an institute of legal verification of China, is that indication error is ±0.8" in any 0°~360° range. The research finding, method of time-space coordinate transformation time grating displacement sensor, has passed the technical appraisement organized by NSFC. And the main conclusion is: ".... The characteristic of the sensor is that high precision can be achieved without high precisionmachining..... The novel method and technology proposed that can measure angulardisplacement very accurately without dividing scale are marked innovative and internationally advanced. The principle of time grating displacement sensor is initiative in the world and the sensor can be widely used. "(D The successful research on time grating is scientifically summarized. The key to realize using time to measure space is constructing a moving coordinate system with constant velocity. In the condition that it is hard to obtain real constant velocity, measuring the non-invariance of the velocity with certain ways and then correcting the non-invariance can realize high precision measurement. This is of great reference value in designing high precision measuring instrument in the future.(D Three new products named high precision time grating smart displacement sensor, circular division worktable with time grating digital display and time grating close-loop numerical control rotary table are developed. And a research scheme of automatic correcting system, serving the industrialization of the three new products, is presented. Using time to measure space and combined with microcomputer technologies, time grating possesses the unique advantage of achieving high precision without high precision machining, which endows the three new products with the advantages of easy manufacturing and low cost. Consequently the three new products have obvious priceadvantage. At present, time grating close-loop numerical control rotary table has been successfully applied in Chongqing Machine Tool Works of China. The cooperation with Chongqing Machine Tool Factory, Nanjing NO. 2 Machine Tool Works and Yantai Machine Tool Accessory Works is in process.In summary, after analyzing tradition metrology methods for geometrical quantity, this paper firstly proposes a novel metrology method based on electric guiding and error correction. Three new grating types of smart displacement sensors, time grating, differential grating and laser grating, are studied with the idea of using time to measure space. A time grating displacement sensor sample is successfully made out whose principle is initiative in the world and the technology has been applied in the market.