Optical Position Sensor Based On A Digital Wavelength Encoding Grating

In this paper,a new type optical position sensor based on a digital wavelength-encoding grating is studied.As a key element,it is used in the Fly-By-Light control system,and the following research results are obtained.1.A system structure of digital wavelength-encoding optical position sensor is proposed.The sensor system structure is simple and compact.The system is composed by the reading system and demodulation system.The core element of the reading system is an encoding grating consisting of a number of equally spaced grating units which carry coding patterns corresponding to the position information.The resolution and ranger of optical position sensor depend on the structural design of the encoding grating.The encoding information is converted into wavelength information by self-collimating diffraction of the grating,transmitted to the subsequent demodulation system and the digital code is output,thereby completing the position measurement.And through the unique design of the encoding grating,the sensor's environmental adaptability is improved.2.Developed two kinds of multi-encoding grating,and formed a mature coding and decoding algorithm.The multi-encoding gratings adopts single-channel cycle and multi-channel combination,which can greatly improve the total coding amount of encoding grating without increasing the type of grating.By using the misalignment structure,the size of grating cells is not reduced,further improve the resolution.Three sets of coding algorithm program are compiled,which can be applied to the conceptual structure of combinational encoding raster quickly and effectively,and provide the key basis for optimization design according to different parameter requirements.According to the large number of calculation results,aiming at the design requirements of the optical position sensor for the aircraft,this paper chooses the "five gratings and three channels"or " six gratings and two channels " multi-encoding grating structure with thousands of coding quantities.By combining the structure of the encoding grating,we can get more than 100,000 coding amount,and subvert the coding mode of the traditional optical coding disc,which provides a new effective idea for the design of devices in large range applications.3.The establishment of a mature fabrication process of multi-encoding grating.The " five gratings and three channels " multi-encoding grating with a range of 100 mm and a resolution of 100 ?m were designed and fabricated by using a high-precision and repeatability fabrication process.And the replication technology significantly assists in the mass production of the multi-encoding grating.4.A systematic study on the whole structure of optical position sensor.Through the research on the production,selection and matching principle of all the components of the sensor system,the system build experience combining the theory and practice are formed.Based on the actual situation,the calibration method and significance of signal strength reference line are emphasized,and the calibration principle of dynamic signal strength reference line is put forward,which provides technical support for comprehensively improving the stability of sensor.5.The bench system of the optical position sensor is built and its performance is evaluated.The experimental results show that the fabrication precision of the "five gratings and three channels" multi-encoding grating and the selection and cooperation of the components of the system satisfy the requirements of the spectral response of the sensor.At the same time,the output signal of the demodulation system was tested in the temperature range of-55 ??70 ?.The results showed that the signal amplitude of the photosensitive element decreased with the increase of temperature,and the curve was similar Calibration of the reference line above,the digital signal can be accurately output,that is,the sensor system shows excellent resistance to high and low temperature performance.