5后 Both sdes Both sides 08 nele sid Single side 9 0 02 0.30.40.50.60.70.80.9 0.30.40.50.60.70.80.9 Scanning Range(m) Scanning Range(m) Fig.14.Deployment of RF-3DScan Fig.15. Accuracy for different Fig.16.Angle error for different scanning ranges scanning ranges VIII.PERFORMANCE EVALUATION A.Experiment Settings Orientation accuracy comparison with different distances We build a prototype of RF-3DScan,as shown in Fig.14. between the box and the antenna:We adiust the distance Hardware:Our system consists of one ImpinJ Speedway R420 between the antenna and the boxl as 0.8m,Im and 1.2m, reader,one Laird S9028 RFID antenna and multiple ImpinJ and let the antenna perform both sides scanning of 0.5m 40 times for each distance.The results are shown in Fig.19-20 E41-B tags.The antenna is fixed on a moving car.Soffware: We adopt LLRP protocol to communicate with the reader,and As the distance increases from 0.8m to 1.2m,the angle error decreases by 1.84 and the max error is below 4.9.The angle use a special module to control the moving of the car.Our algorithms are implemented in MATLAB and the language errors for the distances of Im and 1.2m are quite similar.For the bottom face accuracy,it decreases as well,but at least Java.Deployment:We let the antenna be above the boxes and 87.5%when the distance is 1.2m. move at a constant speed of 0.12m/s.For diversity,we use three different sizes of boxes.For each box,there are six tags Stacking accuracy:To evaluate the package stacking,we on it as shown in Fig.8(c).the tag spacing of the two tags on change the number of boxes from two to four,put the boxes the same surface is the same.The tag spacings of boxl,box2 along the antenna scanning direction,in front of the antenna and box3 are 23cm.17cm and 20cm. about Im.The boxes are close to each other.The antenna performs scanning from the end of the boxes to the other B.Micro-Benchmarks end.For multiple boxes,as we put them closely and limit the Metrics:To evaluate the package orientation accuracy,we scanning range,the data missing is serious,it is difficult to have two main metrics:bottom face accuracy,and angle error. determine the box's orientation,so the ordering accuracy is The bottom face accuracy is defined as the number of the not high (in Fig.21),around 73%for the case of three boxes. packages whose bottom faces are identified correctly out of the total package number.The angle error is the error between C.Marco-Benchmarks the estimated angle of the vertical faces against the antenna As STPP cannot handle the cases of limited scanning range, plane and the actual angle.For the package stacking.we use we compare RF-3DScan with STPP in the orientation accura- the metric ordering accuracy.The box is ordered correctly cies of different boxes and different box-antenna distances. only when its detected order is the same with the actual order. Different boxes:We randomly chooses box1,box2 or box3, Orientation accuracy comparison with different scanning and let the antenna be in front of the box about Im,perform ranges:The most advantage of our approach compared to both sides scanning of 0.5m 120 times.As shown in Fig.22.the STPP is that we do not require large range scanning,we adjust bottom face accuracy of STPP is about 81.7%,and RF-3DScan the scanning ranges from 0.3m to 0.9m on a single side or both achieves the accuracy about 92.5%,slightly outperforming sides.Taking the scanning range of 0.3m for example,in terms STPP by x1.13.According to the CDF of the angle error of a single side,it means the antenna starts scanning from the as shown in Fig.23,RF-3DScan performs better than STPP, box and moves 0.3m.while for both sides,the scanning range as the median angle error of STPP is about 3.58 and that of is 0.6m,centered on the box.The results are shown in Fig.15- RF-3DScan is 2.52. 16.From the results,we find RF-3DScan performs well as it Different distances:We choose boxl and let the antenna per- achieves the average bottom face accuracies about 95%for form both sides scanning of 0.5m 120 times.The distances are both sides scanning.and about 70%for one side scanning selected within [0.8m,1.2m]randomly.As shown in Fig.22. range of 0.7m.While the accuracy of the one side scanning is the bottom face accuracy of STPP is about 82.5%,while RF- not that good,STPP cannot deal with such limited scanning 3DScan achieves the accuracy about 93.3%,outperforming ranges. STPP by x1.13.Fig.24 shows the CDF of the angle error, Orientation accuracy comparison with different boxes:We from the figure,RF-3DScan still performs better than STPP, put the box in front of the antenna plane about Im,let the as its median error is about 2.13 and STPP's is 3.62 antenna perform both sides scanning of 0.5m 40 times for each Overall,our experimental results show that RF-3DScan box.As shown in Fig.17-18,the bottom face accuracy is above scales better than STPP for different boxes and box-antenna 87%,and the average angle error is below 4.4.Compared distances,as the average bottom face accuracies of RF-3DScan with boxl and box3,box2 has less accuracy due to its smallest and STPP are about 92.5%and 82.5%,while the average angle tag spacing. errors of them are about 4.08 and 5.05 separately.Fig. 14. Deployment of RF-3DScan VIII. PERFORMANCE EVALUATION A. Experiment Settings We build a prototype of RF-3DScan, as shown in Fig.14. Hardware: Our system consists of one ImpinJ Speedway R420 reader, one Laird S9028 RFID antenna and multiple ImpinJ E41-B tags. The antenna is fixed on a moving car. Software: We adopt LLRP protocol to communicate with the reader, and use a special module to control the moving of the car. Our algorithms are implemented in MATLAB and the language Java. Deployment: We let the antenna be above the boxes and move at a constant speed of 0.12m/s. For diversity, we use three different sizes of boxes. For each box, there are six tags on it as shown in Fig. 8(c), the tag spacing of the two tags on the same surface is the same. The tag spacings of box1, box2 and box3 are 23cm, 17cm and 20cm. B. Micro-Benchmarks Metrics: To evaluate the package orientation accuracy, we have two main metrics: bottom face accuracy, and angle error. The bottom face accuracy is defined as the number of the packages whose bottom faces are identified correctly out of the total package number. The angle error is the error between the estimated angle of the vertical faces against the antenna plane and the actual angle. For the package stacking, we use the metric ordering accuracy. The box is ordered correctly only when its detected order is the same with the actual order. Orientation accuracy comparison with different scanning ranges: The most advantage of our approach compared to STPP is that we do not require large range scanning, we adjust the scanning ranges from 0.3m to 0.9m on a single side or both sides. Taking the scanning range of 0.3m for example, in terms of a single side, it means the antenna starts scanning from the box and moves 0.3m. while for both sides, the scanning range is 0.6m, centered on the box. The results are shown in Fig.15- 16. From the results, we find RF-3DScan performs well as it achieves the average bottom face accuracies about 95% for both sides scanning, and about 70% for one side scanning range of 0.7m. While the accuracy of the one side scanning is not that good, STPP cannot deal with such limited scanning ranges. Orientation accuracy comparison with different boxes: We put the box in front of the antenna plane about 1m, let the antenna perform both sides scanning of 0.5m 40 times for each box. As shown in Fig.17-18, the bottom face accuracy is above 87%, and the average angle error is below 4.4◦. Compared with box1 and box3, box2 has less accuracy due to its smallest tag spacing. 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Scanning Range (m) 0 0.2 0.4 0.6 0.8 1 Accuracy Both sides Single side Fig. 15. Accuracy for different scanning ranges 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Scanning Range (m) 0 5 10 15 Angle Error (deg.) Both sides Single side Fig. 16. Angle error for different scanning ranges Orientation accuracy comparison with different distances between the box and the antenna: We adjust the distance between the antenna and the box1 as 0.8m, 1m and 1.2m, and let the antenna perform both sides scanning of 0.5m 40 times for each distance. The results are shown in Fig.19-20. As the distance increases from 0.8m to 1.2m, the angle error decreases by 1.84◦ and the max error is below 4.9◦. The angle errors for the distances of 1m and 1.2m are quite similar. For the bottom face accuracy, it decreases as well, but at least 87.5% when the distance is 1.2m. Stacking accuracy: To evaluate the package stacking, we change the number of boxes from two to four, put the boxes along the antenna scanning direction, in front of the antenna about 1m. The boxes are close to each other. The antenna performs scanning from the end of the boxes to the other end. For multiple boxes, as we put them closely and limit the scanning range, the data missing is serious, it is difficult to determine the box’s orientation, so the ordering accuracy is not high (in Fig. 21), around 73% for the case of three boxes. C. Marco-Benchmarks As STPP cannot handle the cases of limited scanning range, we compare RF-3DScan with STPP in the orientation accura￾cies of different boxes and different box-antenna distances. Different boxes: We randomly chooses box1, box2 or box3, and let the antenna be in front of the box about 1m, perform both sides scanning of 0.5m 120 times. As shown in Fig.22, the bottom face accuracy of STPP is about 81.7%, and RF-3DScan achieves the accuracy about 92.5%, slightly outperforming STPP by ×1.13. According to the CDF of the angle error as shown in Fig. 23, RF-3DScan performs better than STPP, as the median angle error of STPP is about 3.58◦ and that of RF-3DScan is 2.52◦. Different distances: We choose box1 and let the antenna per￾form both sides scanning of 0.5m 120 times. The distances are selected within [0.8m, 1.2m] randomly. As shown in Fig. 22, the bottom face accuracy of STPP is about 82.5%, while RF- 3DScan achieves the accuracy about 93.3%, outperforming STPP by ×1.13. Fig. 24 shows the CDF of the angle error, from the figure, RF-3DScan still performs better than STPP, as its median error is about 2.13◦ and STPP’s is 3.62◦. Overall, our experimental results show that RF-3DScan scales better than STPP for different boxes and box-antenna distances, as the average bottom face accuracies of RF-3DScan and STPP are about 92.5% and 82.5%, while the average angle errors of them are about 4.08◦ and 5.05◦ separately