Studies in Surveying and Mapping Science (SSMS) Volume 3, 2015
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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
*1
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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Studies in Surveying and Mapping Science (SSMS) Volume 3, 2015
deviation value and makes it more proximate to the correct angle position. In the measurement process after the adjustment, the total station measured the deviation value from the center of the cross wire to the center of the image again to produce the final horizontal and vertical angle measurement value. The performance of ATR is influenced by many factors in the collimation and measurement process, such as distance, vertical angle, obstacles, observation time, terrain conditions, illumination conditions, and vertical angle. Therefore, this paper tests the ATR performance on different observation conditions taking LEICA TS30 total station for instance. The influence of different observation conditions on the performance of ATR will be studied by comparing multiple observed values of ATR and comparing the observed values of ATR with the manually observed values.
FIG. 1 THE WORKING PRINCIPLE OF ATR
Test and Analysis of ATR Performance In order to test ATR performance of the LEICA TS30 total station comprehensively, ATR automatic collimation and manual collimation are carried out respectively under the conditions of different distances, different observation time, different obstacles, different illumination, different terrain and different vertical angles. The directional values and the horizontal distance values are obtained no less than ten times to obtain the average value and the mean square error. The Influence of Different Distance on the Observation Precision of ATR[3] The experiment was carried out on a calm cloudy morning. The instrument was set up in an area that is flat and has a wide sphere of vision. The prism was set up away from the instrument about 5m, 10m, 30m, 50m, 100m, 150m, 200m, 300m, 500m, 750m, orderly. After collimating the same zero direction, ATR automatic collimation and manual collimation were carried out respectively to collimate the target. The observation values are read no less than ten times and the mean square errors were calculated. The results are shown in TABLE 1. TABLE 1 INFLUENCE OF DIFFERENT DISTANCE ON THE OBSERVATION ACCURACY OF ATR
ATR collimation Serial
Average
Average
Direction mean
Average
Distance mean
Average
Direction mean
square error
direction
square error
distance value
square error
direction
square error
(m)
(mm)
value(° ′ ″)
(″)
(m)
(mm)
value(° ′ ″)
(″)
1
5.2135
±0.15
91 42 00.8
±0.85
5.2133
±0.14
91 42 05.2
±4.65
2
10.1022
±0.11
91 15 11.3
±0.68
10.1021
±0.13
91 15 13.8
±4.02
3
28.7788
±0.08
92 03 06.5
±0.73
28.7787
±0.15
92 03 01.2
±3.37
number distance value
26
Manual collimation
Distance mean
4
51.1057
±0.07
91 47 58.2
±0.39
51.1056
±0.10
91 47 56.8
±5.39
5
102.0954
±0.13
91 43 36.8
±0.93
102.0953
±0.11
91 43 32.3
±4.85
6
151.2073
±0.10
91 44 22.1
±1.32
151.2701
±0.16
91 44 17.3
±2.01
7
201.9798
±0.25
91 51 35.9
±1.52
201.9795
±0.28
91 51 31.1
±2.53
8
304.0300
±0.20
91 47 13.7
±1.82
304.0299
±0.19
91 47 11.8
±3.24
9
514.9636
±0.25
91 49 10.8
±2.53
514.9640
±0.17
91 49 08.4
±4.01
10
747.3066
±0.14
92 20 30.6
±3.42
747.3064
±0.22
92 21 58.8
±4.60
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As shown in TABLE 1 , there is no obvious difference on precision between ATR collimation and manual collimation in distance measurement. The ranging measurement precision is basically the same in different distances. While for the direction measurement, the precision of ATR collimation is higher than that of manual collimation apparently when the distance is the same. When the distances are not the same, the precision of the direction measurement changes as a reversed parabola and the direction mean square error is minimum when the distance is about 50m which is only 0.39". With the distance shortening or lengthening, the mean square error increases gradually. When the distance is about 5m, the direction mean square error is 0.85", and when the distance is about 750m, the direction mean square error reaches 3.42". The Influence of Different Observation time on the Observation Precision of ATR The experiment was carried out on a sunny day in late March, the daily average temperature was 12℃, the wind force was 1~2 grade, and the weather condition was good. The instrument and prism were set up in an area without direct sunlight at noon. The observation was carried out respectively in five different periods of the day. After collimating the same zero direction, ATR automatic collimation and manual collimation were used respectively to collimate the target. The respective readings were obtained no less than ten times, and the mean square errors were calculated, as shown in TABLE 2. TABLE 2 INFLUENCE OF DIFFERENT OBSERVATION TIME ON THE OBSERVATION ACCURACY OF ATR
ATR collimation Average
Distance
distance
mean square
value
error
(m)
(mm)
6:30
52.0843
±0.18
Observation time
Manual collimation Direction
Average
Distance
mean square
distance
mean square
error
value
error
(″)
(m)
(mm)
22 26 52.0
±0.97
52.0844
±0.08
22 26 48.1
±1.94
Average direction value(° ′ ″)
Average direction value(° ′ ″)
Direction mean square error (″)
9:30
52.0844
±0.13
22 26 51.6
±0.85
52.0845
±0.11
22 26 50.3
±1.75
12:00
52.0843
±0.12
22 26 52.2
±0.69
52.0843
±0.06
22 26 51.8
±1.22
15:00
52.0846
±0.19
22 26 52.3
±0.87
52.0844
±0.13
22 26 51.5
±1.40
17:30
52.0844
±0.12
22 26 52.1
±0.86
52.0841
±0.10
22 26 50.5
±1.45
It can be seen from TABLE 2 that for the distance measurements there is no obvious difference on precision between ATR collimation and manual collimation, and the ranging measurement precision is basically the same in different observation time. While for the direction measurement precision, the precision of ATR collimation is higher than that of manual collimation. The precision of ATR collimation is the highest at noon, the precision in the late morning and in the afternoon is the second higher, and the lowest precision is in the early morning and in the evening. The Influence of Different Obstacles on the Observation Precision of ATR The experiment was carried out on a calm morning in a cloudy day on different experimental site. Making the survey line get through different obstacles vertically , ATR automatic collimation and manual collimation were carried out respectively to collimate the target and their readings were obtained no less than ten times.The mean square errors were calculated as shown in TABLE 3. TABLE 3 INFLUENCE OF DIFFERENT OBSTACLES ON THE OBSERVATION PRECISION OF ATR
ATR collimation Obstacles
Average
Distance
distance
mean square
value
error
(m)
(mm)
Average direction value(° ′ ″)
Manual collimation Direction
Average
Distance
mean square
distance
mean square
error
value
error
(″)
(m)
(mm)
Average direction value(° ′ ″)
Direction mean square error (″)
Glass
21.5174
±0.09
311 34 22.6
±0.82
21.5175
±0.11
311 34 26.2
±1.09
Leaves
29.8504
±0.21
82 03 35.8
±2.28
29.8504
±0.25
82 03 34.8
±1.28
Bushes
35.8219
±0.35
133 18 23.2
±2.83
35.8217
±0.38
133 18 21.1
±2.11
Wire
44.4234
±0.13
211 23 33.5
±1.03
44.4238
±0.32
211 23 34.9
±1.22
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It can be seen from TABLE 3 that for the distance measurements, there is no obvious difference between ATR collimation and manual collimation on precision, when getting through the same obstacle. But when through the trees, bushes and other intensive obstacles, the ranging measurement precision is obviously lower. For direction measurement precision, when getting through obstacles such as glass and wire which can not shut out sight serviously, the precision of ATR collimation is obviously higher than that of manual collimation; while when getting through trees, bushes and other obstacles which can shut out sight serviously, the precision of ATR collimation is lower than that of manual collimation. The Influence of Different Illumination Conditions on the Observation Precision of ATR The experiment was carried out at a sunny noon. The measuring line was set in a north-south direction, without any shelter around. Using ATR automatic collimation and manual collimation, the target was collimated under frontlighting and backlighting conditions respectively. The readings were obtained no less than ten times, and then the mean square errors were calculated, as shown in TABLE 4. TABLE 4 INFLUENCE OF DIFFERENT ILLUMINATION CONDITIONS ON THE OBSERVATION ACCURACY OF ATR
ATR collimation Average
Distance
distance
mean square
value
error
(m)
(mm)
Frontlighting
26.5356
±0.32
Backlighting
26.5372
±0.40
illumination conditions
Manual collimation Direction
Average
mean square
distance
error
value
(″)
(m)
136 16 07.1
±1.18
300 44 18.2
±1.28
Average direction value(° ′ ″)
Distance mean
Average
Direction mean square
square error
direction
(mm)
value(° ′ ″)
26.5360
±0.35
136 16 12.2
±1.57
26.5379
±0.48
300 44 21.3
±1.65
error (″)
It can be seen from TABLE 4 that for the distance measurements, there is no obvious difference on precision between ATR collimation and manual collimation whether the illumination condition is frontlighting or backlighting. For the direction measurements, the precision of ATR collimation is obviously higher than that of manual collimation. While in the frontlighting and backlighting conditions, the precision of ATR collimation doesn’t have obvious difference, the measurement precision in the backlighting condition is slightly higher. The Influence of Different Terrain Conditions on the Observation Precision of ATR The experiment was carried out at a sunny noon without wind under good weather conditions. Making the measuring line getting through grass, bushes, water fields, asphalt pavement and other areas that were covered by different vegetation, ATR automatic collimation and manual collimation were used to collimate the target respectively. The readings were obtained no less than ten times, and then the mean square errors were calculated, as shown in TABLE 5. TABLE 5 INFLUENCE OF DIFFERENT TERRAIN CONDITIONS ON THE OBSERVATION ACCURACY OF ATR
ATR collimation Average
Distance
distance
mean square
value
error
(m)
(mm)
Grass
30.1223
±0.28
Bushes
22.5368
Waters
Terrain conditions
Asphalt pavement
Manual collimation Direction
Average
Distance
mean square
distance
mean square
error
value
error
(″)
(m)
(mm)
101 34 43.9
±1.25
30.1241
±0.41
69 39 22.4
±2.06
36.3527
±0.21
75 44 23.5
42.7661
±0.33
133 45 20.0
Average direction value(° ′ ″)
Average
Direction mean
direction
square error
value(° ′ ″)
(″)
±0.33
101 34 47.1
±1.88
22.5377
±0.48
69 39 33.1
±3.47
±1.01
36.3538
±0.38
75 44 27.1
±1.31
±1.35
42.7692
±0.45
133 45 28.2
±2.01
It can be seen from TABLE 5 that for the distance measurements, there is no obvious difference on precision between ATR collimation and manual collimation in different terrain conditions. For the direction measurements, the precision of ATR collimation is obviously higher than that of manual collimation. In different terrain conditions, there are some differences among the measurement precision of ATR collimation. When measuring through bushes and on the asphalt pavement, the observation precision is slightly lower. While when measuring across the
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grass and the water fields, there is no visible change on the measurement precision of ATR collimation. The Influence of Different Vertical Angle on the Observation Precision of ATR The experiment was carried out in the environment without wind, and the weather condition was good. The total station was set up at a distance about 30m to the wall, and the prism was fixed on different height on the wall by a fixing device to adjust the vertical angle of collimating the target. Setting the vertical angle about 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35° respectively, ATR automatic collimation and manual collimation were used to collimate the target respectively. The readings were obtained no less than ten times, and then the mean square errors were calculated, as shown in TABLE 6. TABLE 6 INFLUENCE OF DIFFERENT VERTICAL ANGLE ON THE OBSERVATION PRECISION OF ATR
ATR collimation Vertical
Average
Distance mean
Average
angle
distance value
square error
direction
(m)
(mm)
value(° ′ ″)
0°
29.3258
±0.32
94 03 43.8
5°
29.3402
±0.28
10°
29.3338
15°
Manual collimation Direction
Average
Distance mean
Average
Direction mean
distance value
square error
direction
square error
(m)
(mm)
value(° ′ ″)
(″)
±0.42
29.3253
±0.42
94 03 45.3
±1.03
94 04 00.2
±0.39
29.3415
±0.45
94 03 57.2
±1.21
±0.35
94 03 32.9
±0.45
29.3351
±0.38
94 03 29.7
±1.13
29.3210
±0.30
94 03 40.2
±0.52
29.3235
±0.40
94 03 44.1
±1.25
20°
29.3971
±0.36
94 04 25.1
±0.82
29.3922
±0.52
94 04 22.2
±1.66
25°
29.3168
±0.46
94 03 02.9
±1.55
29.3158
±0.48
94 03 05.3
±2.32
30°
29.3544
±0.58
94 04 11.1
±2.03
29.3532
±0.56
94 04 08.2
±2.85
35°
29.4048
±0.68
94 05 35.6
±3.15
29.4119
±0.75
94 05 38.2
±4.02
mean square error (″)
It can be seen from TABLE 6 that for the distance measurements, there is no obvious difference on precision between ATR collimation and manual collimation in different vertical angle impacts. But as the vertical angle increases gradually, the ranging precision decreases slightly. For the direction measurements, the precision of ATR collimation is obviously higher than that of manual collimation. When the vertical angle is less than 15°, the direction measurement precision does not change significantly. But when the vertical angle is larger than 15°, the direction measurement precision decreases significantly whether the ATR automatic collimation or manual collimation is used . Conclusion The following conclusions can be drawn from the above experimental results: 1) The ranging measurement precision of LEICA TS30 total station is higher, and there is no much difference on observation precision that under all kinds of observation conditions. 2) For the distance measurements, ATR has no obvious advantage, the mean square errors of ATR collimation is very close to that of manual collimation. 3) In the same conditions, when the distance is about 50m, the precision of ATR collimation is the highest. As the distance increases or decreases, the mean square errors both increase gradually. 4) When the weather conditions are the same, the performance of ATR collimation reaches the best at noon. 5) When the measurement line getting through obtacles, the observation precision of ATR collimation is impacted obviously. The more obtacles there are, the lower the ATR collimation precision is. 6) Direction of the sun doesn’t impact the direction measurement precision of ATR collimation obviously. 7) When the measurement line getting through different vegetation, the direction measurement precision of ATR collimation changes obviously. The greater the temperature gradient produced by the vegetation is, the lower the direction measuring precision is.
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8) The bigger the vertical angle of measurement line is, the lower the direction measurement percision of ATR collimation is. When the vertical angle no more than 15°, the direction measuring precision doesn’t change obviously. To sum up, it is more helpful to use the total station with ATR function to improve the observation precision and to shorten the time of observation in practical work. However, advantageous observation environment should be selected and adverse conditions should be avoided so as to improve measure precision to the highest degree. ACKNOWLEDGMENT
This work was supported by the general project of Shenyang Jianzhu University (Project Nos. 2014084) . REFERENCES [1]
Teng Huang, Guangbao Chen, Shufeng Zhang.Study of angle measurement accuracy of automatic recognition system ATR [J]. Hydropower automation and dam monitoring, 2004, 28(3):37-40.
[2]
Tenglong Guo, Jianping Yue. Analysis and test of ATR performance of surveying robot [J]. Bulletin of Surveying and Mapping, 2012, (8):92-94.
[3]
Zhen Jia, Zhipeng Xing ,Zhijian Wang. Test of ranging precision of different reflecting target by TS30 total station [J]. Beijing Surveying and Mapping, 2013, (6):46-49.
Yan Wang received the B.E. and M.E. degrees in geodesy and surveying engineering from Hohai University, Nanjing, China in 2002 and 2005. He is currently a lecture in School of Traffic Engineering, Shenyang Jianzhu University. His main research direction is the precise survey engineering. Mao-hua Liu received the B.E. and M.E. degrees in geographic information system from Liaoning Technical University, Fuxin, China in 2003 and 2006. He is currently a lecture in School of Traffic Engineering, Shenyang Jianzhu University. His main research direction is GIS. Fang Liu received the B.E. degree in surveying and mapping from Shenyang Jianzhu University, Shenyang, China in 2013. She is currently a postgraduate student in civil engineering surveying in Shenyang Jianzhu University.
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