Calibration technology of length measurement accuracy of total station in automatic air refractive index compensation system

Abstract

In order to realize high precision calibration of total station, an automatic compensation system for air refractive index has been developed, including sensor array system and data processing system. The sensor array system consists of 82 temperature, humidity and air pressure sensors, forming a dense sensor array, monitoring the changes of environmental parameters along the baseline. The data processing system automatically compensates the air refractive index for different measurement sections in real time. Based on the Changping baseline of National Institute of Metrology,China, real-time and time-delay experiments were carried out to compensate the refractive index of air for the measured distance of the total station.. The experimental results show that the maximum measurement error is about 1 mm when the environmental parameters with 14 seconds delay are compensated, nearly 10% of the data reach the error of 0.5mm. The time-delay compensated measured distance will affect the accuracy. It shows that the calibration accuracy of total station can be effectively improved by using the developed automatic air refractive index compensation system.