Studies in Surveying and Mapping Science (SSMS) Volume 3, 2015
www.as-se.org/ssms
Test and Analysis of Total Station’s ATR Performance Yan Wang1, Maohua Liu2, Fang Liu3 School of Traffic Engineering, Shenyang Jianzhu University, Shenyang, Liaoning, China, 110168 wyan413@126.com; 2liumaohua1115@126.com; 3499588584@qq.com
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Abstract Using ATR for automatic collimation is one of the most important performance of the new generation total station. This paper aims at testing the performance of ATR in different observation environments. Taking LEICA TS30 total station for instance, the variation of ATR’s observation accuracy is tested in the situations of different distances, different observation time, different obstacles, different illumination conditions, different terrain conditions, and different vertical angles. Then, the observation results are compared with the results of manual collimation. A series of practical conclusions are obtained through comparative analysis of the experimental data. Keywords ATR; TS30; Performance Test
Introduction Automatic Target Recognition(ATR) system is an automatic recognition system in intelligent total station which has great significances for improving the measurement precision and efficiency of the total station. In the observation process, a total station equipped with ATR system can automatically collimate the prism, so the collimating error is effectively weakened and the speed of observation is greatly improved. Moreover, the influence of meteorological conditions on the observation results is also weakened as the observation time is shortened using ATR. TS30 total station is the fourth generation high precision intelligent total station which is lauched as a substitute for TCA2003 in LEICA measurement system. Equipped with perfect ATR system, TS30 is one of the most advanced total stations in the world. The angle measurement precision of TS30 can reach 0.5", and the ranging measurement precision can reach 0.6mm+1ppm. This paper will take the TS30 total station as an instance to do a comprehensive testing on its ATR performance[1]. The Working Principle of ATR As shown in Fig. 1, the telescope of the total station has an automatic target recognition (ATR) component. When measuring with the activated ATR , the emitting diode (CCD optical source) emits a beam of infrared laser. The infrared laser is coaxially projected on the telescope axis through the optical components and launches out from the objective lens. The special spectroscope in the telescope separates the reflected ATR beam from the visible beam and the ranging beam, guides ATR beams to a CCD array to form a spot which is received by the built-in CCD camera. The position of the spot position is accurately determined through using the center of CCD camera as the reference point. The CCD array converts the received light signal into corresponding image and calculates the image center through image processing algorithms. The image center is the center of the prism[2]. Total station ATR precision measurement includes the searching process, the target collimation process and the measurement process. In the searching process, after roughly collimate the prism, ATR will check whether the prism is located within the telescopic field of view. If ATR can’t detect the prism, it will restart the searching process which will make the telescope do spiral motion continuously. After finding the prism, ATR will begin the target collimating process. The total station drives the telescope to approach the center of the prism, calculates the deviation value from the center of the cross wire to the center of the image , and then gives out the corrected horizontal and vertical angle value. The total station motor drives the telescope turn again according to the
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