Coding Target Design For Visual Measurement

With the continuous development of modern science and technology,computers,lasers,and CCD sensor technologies have also rapidly developed.In recent years,various research institutes at home and abroad have designed different shapes of targets,which can measure special surfaces combined with a vision measurement system.With the advantages of small size,light weight,easy to carry,etc.,more and more application of targets has been obtained.The vision-based target measurement system has a wide range of application,from visual detection and position of parts to machine assembly,besides in artifacts and sculptures,especially three-dimensional measurements of large-size free-form surfaces that cannot be achieved with a coordinate machine,such as the design of molds shape and turbine of aircraft and vehicle.In order to adapt to rapid on-site measurement and realize high precision and large-scale measurement,this paper used visual measurement system,the core of which is the target,to measure the target object through infrared-coding.This subject designed the encoding target,the encoding and marking points of which was LED infrared diode,because the clear image of the infrared LED code point can make the images collected by the CCD sensor be substantially consistent at different measuring distances by adjusting the brightness of the infrared LED light-emitting diodes.At the same time,a wireless communication system with CC2530 as the controller was designed to realize the intelligence,network and wireless of the target measurement system.In this paper,coding target is used as a detection tool and the following research is done:(1)Combining with domestic and foreign target encoding mode,a encoding target with infrared LED light-emitting diodes as the coding and marking points was put forward,and the shape of it was simulated and analyzed to determine the distribution of appropriate identification points and coding points.(2)The mechanical structure of the encoding target was designed,the advantages of linear target were determined,and the hardware circuit of the encoding target was designed.(3)For the convenience of operation,the encoding target was controlled wirelessly.In this paper,the STM32 series ARM controller developed by Italy France semiconductor company was used to adjust the duty ratio(PWM)of 12 infrared diodes to achieve the effect of infrared diode brightness change.At the same time,TI company's CC2530 wireless radio frequency chip was taken as the core to realize wireless,network and intelligence of the encoding target system using UART protocol.This topic comes from the National Natural Science Foundation of China's “A Study of Coordinate Measurement Method for Small Field of View Based on Coded Targets”.The design of the encoding target and the wireless intelligent object of the target measurement system is one of the important research subjects.We tested on the performance of the target,showing that the precision of encoding targets is higher than common targets,and through the simulation analysis the structure of the linear targets was determined.At the same time,infrared diode was used as the coding point and identification point of the target.The wireless intelligence of target measurement system was realized by using CC2530 as wireless transmission module.