THE NEW METHOD FOR TESTING OF SPEED-MEASURING DEVICES IN ROAD TRAFFIC

Transcription

1 THE NEW METHOD FOR TESTING OF SPEED-MEASURING DEVICES IN ROAD TRAFFIC GORAN JANKOVIĆ ZLATAN TOPIĆ Military Technical Institute Belgrade, JOVICA CVETKOVIĆ J. MARENDIĆ-MILJKOVIĆ Directorate of Measurements and Precious Metals Belgrade, Abstract: In the area of measuring the speed of vehicles in traffic due to the occurrence of different types of speedometers with respect to the structure, methods of measurement and place of use, there is a need to create a unique method which aim (purpose) is to check all the metrological characteristics of measurement in terms of speed compared to the manufacturer's technical specification and metrology requirements of the by-laws for this type of measure. This method allows you to easily perform testing to measure the speed of any kind of speedometer (system) on the ground in real terms, regardless of road conditions and weather conditions. As a fully automated method is suitable for monitoring because it defines the parameters required for assessing the safety standards of speed and their proper use. Key words: velocity measurement, velocity standard, type test, verification, monitoring 1. INTRODUCTION Type testing, verification and monitoring of the vehicle speedometers in road traffic and their proper use (MBVS) are affairs in the jurisdiction of Directorate of Measurements and Precious Metals (DMDM) under Ministry of Economy and Regional Development. As the users of MBVS are Ministry of Internal Affairs and the Army of the Republic of Serbia, there is importance of these affairs bigger because the results of speed measuring together with video and photo record of controlled vehicle are data for Administration of justice to start adequate legal proceedings against traffic participants. That was the main request to define the method which will provide clear and simultaneous data checking regarding speed measuring at any place, because they are only evidence of law breaking. Before defining the method, requests to be meet was very rigid: Method must be simple and applicable for all types of MBVS. Must use accessible equipment. Must be valid regarding primary method. Must be cheap. Must be fully automated. Data must be protected and without possibility of erasing. Measuring could be done at every place and any weather conditions. Measuring on the usage place not need longer traffic blocking, what could cause problem of MBSV checking or bigger checking expenses. 2. TYPES OF SPEEDOMETERS Speedometers which are in the usage on the roads and crossroads in the territory of the Republic of Serbia are: Radar speedometers [1]. Laser speedometers (LIDARS) [2]. Devices with hard sensors [3]. Devices for speed measuring from vehicle at the move [4]. Before establishing the new method complete analysis has done concerning all types of MBVS regarding the way of speed measuring and place of use. Analysis helped to get information about signals which are coming from speedometers as a product of measuring process. Based on principle that all data was defined with further method must be able to check. These data are: Date and time of measuring. 746

2 Measured speed of controlled vehicle. Speed measuring photo or video record, with possibility recording number plate of controlled vehicle. 3. MEASURING EQUIPMENT 3.1. Primary speed etalon Description of etalon Primary etalon for vehicle speed measuring in traffic is system which consists of two etalon. First is time etalon and second is length etalon. Speed value is getting as relation of passed road and time, from measured values of time and length. Parts of the system are: Time etalon, LONGINES TL2000. Length etalon, Leica DISTO D5. Optical device with reflectors. Battery charge, stands, connecting cables and additional kit. Time etalon is device for the time measuring which during 23 hours, 59 minutes and 59,999 seconds could record time of passing vehicle with minimal scale of 1 ms. Frequency of time basis is 5 MHz. Relative error of time basis frequency is less than Stability of time measuring is 0,01 s in 24 h. Length etalon is laser range finder which measure distance in scope from 0,05 m to 200 m, resolution of presentation is 0,1 mm and maximal deviation during distance measuring is: in normal mod ± 1 mm for distances up to 10 m, ± 0,025 mm/m for distances between 10 m and 30 m, ± 0,1 mm/m for distances over 30 m; in long distance mod ± 0,15 mm/m for distances of 30 m; Time etalon is repeatable up to national time etalon and frequency UTC (DMDM), as well as up to international time scale UTC (BIPM). Length etalon is repeatable up to national length etalon DMDM Measuring method On precise defined distance, which is measured by length etalon, light beams are formed by optic devices with reflectors (optic gate). Time of passing controlled vehicle between two or more light beams is measuring. Controlled vehicle is running straight line and cutting light beams in adequate timing which is printing on paper track. This way data are permanent protected in unchangeable shape. Vehicle speed is getting trough the formula (1): Vehicle speed (m/s) = passed road (m) time(s) (1) Picture 1. Vehicle speed determining by the time and passed road measuring Measuring uncertainty For the scope of speeds from 30 km/h to 180 km/h and distance of 65 m, enlarged measuring uncertainty with factor overcome 2, starts from 0,01 km/h for 30 km/h to 0,1 km/h for maximal measured speed of 180 km/h Etalon purpose Primary etalon for vehicle speed measuring in traffic is intended for: Vehicle in traffic speedometer testing in the sense of type testing. Vehicle in traffic speedometer testing on terrain during first, periodical and special verification. For etalon-checking of working etalon for vehicle in traffic speedometer on terrain. Method validation for simulation vehicle speed in laboratory and terrain conditions Working speed etalon Working speed etalon is established in cooperation with Military technical institute of MoD (VTI). Regarding that VTI already has accreditation for motor vehicles speedometer homologous testing according to ECE R39 regulations, as well as adequate measuring equipment, DMDM asked VTI with proposal for the cooperation on the affairs of type testing and verification of the vehicle speedometers in road traffic. After inspection of VTI s laboratories and military airport in Kovin, was found out that all measure-technical conditions were fulfilled and the mentioned VTI personnel and laboratory capacities meet necessary requests for the testing Working etalon Working etalon for speed measuring, which is in possession of VTI, consists of measuring system CORREVIT L-350 Aqua producer CORRSYS-DATRON Sensorsysteme GmbH, and its parts are: Sensor head L-350 Aqua. 747

3 Signal processing electronic. Set of supports with vacuum connections, for fixing sensor head on the test vehicle. Set of cables for measuring system connections. Set of cables for electronic and sensor head power supply. Acquisition card NI USB6211. Software package ULvia6211-Lsw. Picture 3. Sensor head L-350 Aqua mounted on test vehicle Picture 2. Measuring system CORREVIT Technical specifications Speed range: 0,3 km/h 250 km/h. Distance measurement deviation: < ±0,1 % (with calibration on test surface at a distance of 200 m minimum). Speed linearity: < ±0,2 % (with calibration on test surface, v > 10 km/h). Working distance and range: 350 ±130 mm. Picture 4. Part of system CORREVIT inside test vehicle Before speed measuring it is necessary to determine correction factor for the test surface by distance measuring. Section length, not smaller than 200 m, of the chosen test track has to be measured by system CORREVIT L-350 Aqua, mounted on test vehicle Working principal Sensor head L-350 Aqua has halogen lamp for lighting test surface and optic ''eye'' which task is to magnify and to sharp surface picture passing under the sensor head. Measuring essence is in built-in CCD sensor, approximate density 600 x 500 pixels. In sensor are generating characteristic points of ''traveling'' surface and moving picture-surface from pixel to pixel. Regarding known pixels distance is getting to passed path, and calculated with generated time to derivative values of speed and accelerations Speed measuring Speed measuring needs test vehicle with mounted on working speed etalon and appropriate test track which provides safety testing in the whole scope of working speeds. Picture 5. Laser range finder Than the same track section has measured precisely by laser range finder. Complete procedure is repeating once more and results are average values of two measuring. 748

4 According to producers manual next step is calculating correction factor and applying it in sensors electronic by original software package CeCalWinPro, due to measured signals correction. During speed measuring, data are automatically updating and showing on PC display in the chart shape. It is possible to determine speed for any point or trajectory part Speed measuring method validation by CORREVIT system Speed measuring method validation speed measuring method validation is done by comparing with primary speed etalon. Before etalon-checking correction factor is determined for the testing road surface. Test vehicle with previously mounted on CORREVIT system are passing through pre-defined ''optic gates''. Every passing through optic gates produces interrupting lighting beam which cause electric impulse for real time printing on etalon tape of LONGINES TL2000. There were two optic gates, so we had printed two passing times for precise defined distance between gates. These data were elements for test vehicle speed calculation. Constant test vehicle speed was maintained between optic gates by original vehicle device tempomat. After measuring and data processing, average speed was displayed on monitor. These values were compared with values obtained by primary etalon TL TESTING METHOD 4.1. Radar and laser gauge testing Test vehicle, with previously mounted on CORREVIT L- 350 Aqua system, at precisely defined road distance are passing with assigned speed kept by original vehicle device tempomat. When vehicle reached assigned speed, then starts speed measuring by CORREVIT system. That way measuring synchronization is achieving between etalon and tested speedometer. Tested speedometer must be positioned close to vehicle trajectory because of cosine effect reduction Testing MBVS positioned on road crossing or near by road Test vehicle with previously mounted on CORREVIT system are passing through pre-defined road track with testing speedometers positioned at the same conditions as a real situation (height, angle and lateral distance) on the road crossing. Type testing are conducting at airport runway with testing speedometer positioned at specific height which is equal to mounted height of radar on the road crossing, where is vehicle speed control is performing. Radar mounting angle is checking too. This way we simulated real working operation conditions of speedometers. Table 1. CORREVIT system measured speed deviation Assigned test vehicle speed v v e v-v e 30 29,85 29,719 0, ,77 39,571 0, ,67 49,491 0, ,73 59,514 0, ,41 81,185 0, ,24 101,068 0, ,18 110,943 0, ,15 120,914 0, ,08 130,984 0, ,78 140,895-0, ,18 150,946 0, ,63 161,080-0, ,02 172,160-0, ,82 176,066-0,246 Picture 6. Testing MBVS beside road In all mentioned cases we simultaneous measure test vehicle speed by system CORREVIT (digital data) and testing speedometer. Testing is performing in the scope of speed from 30 km/h to 200 km/h, two times per every assigned speed. where is: v, speed measured by CORREVIT system; v e, speed measured by primary etalon; v-v e, speed measuring deviation. According to Table 1, speed measuring deviation is (0,12 ± 0,15) km/h. Picture 7. Testing - MBVS above road 749

5 These data are elements for calculation of speed measuring deviation tested speedometer in comparison to the speed measured by system CORREVIT. Testing results are presented in table and they must be inside boundaries allowed error according to article 7. of the Regulations book of measuring conditions for vehicle speedometers in road traffic ("Sl. glasnik RS", br. 40/2009) (in further text Regulations book). To certify vehicle speedometers in traffic, testing is performing on the road crossing and the road traffic is completely blocked. is necessary to secure testing according the way shown in the picture 9. Vehicles disposition during testing is very important regarding testing process safety ''Interceptor'' testing Vehicle speed gauges from the moving vehicle "interceptors", (interceptor is common name for the police vehicle which has built in speedometer with possibility of recording video data) are adjusting according to the producers manual before testing. ''Interceptor'' is crossing pre-defined path and at the same time speedometer system software are implementing (using specific commands and procedure) with calibration factor which is involved in speed data calculation. Test vehicle with previously mounted on CORREVIT system are moving with constant speeds, which are maintained by original vehicle device tempomat, in front of the testing vehicle ''interceptor''. Testing is performing in the scope of speed from 60 km/h to 200 km/h, two times per every assigned speed. Picture 8. Checking interceptor speed Measuring synchronization is conducting by radio link or by switching light signals. Up today interceptors could measure vehicle speed when is standing still beside the road. In that situation test vehicle with mounted on CORREVIT system is passing by parked interceptor keeping constant assigned speed. Interceptor should be positioned as closer as possible to the vehicle trajectory because of cosine effect reduction. During every single measuring video data record is producing which shows measured speed and number plate of test vehicle. Every data are automatic lodged on gauge hard disc. Testing results are presented tabular. If there are no conditions to test gauge regarding testing road or runway, testing could be conducted on highway. It Picture 9. Vehicles disposition during testing: 1-guard police vehicles; 2-testing interceptor; 3-test vehicle with Correvit system 4.4. Testing results Speed testing results are presented tabular as is shown in Table 2. Table 2. Speed measuring deviation Assigned speed Allowed deviation v E v x G 30 31, ,15 ± , ,13 ± , ,12 ± , ,24 ± , ,31 ± , ,29 ± 3, , ,80 ± 4,2 160* 157, ,71 ± 4,8 180* 177, ,26 ± 5,4 200* 197, ,20 ± 6,0 * if the weather, vehicle and safety conditions allows. where is: v E, speed measured by CORREVIT system; v x, speed measured by testing gauge; G = v x - v E, speed measuring deviation. If the speed measuring results are inside allowed boundaries it will be considered that speedometer fulfills measuring authoritative conditions according to article 7. of Regulations book. During every single speed measuring testing speedometer generates photo and video record. Visual checking of next data (article 14. of Regulations book) is performing: Date and time of measuring Measured speed of controlled vehicle Number table of controlled vehicle Example of picture from speedometer display with explanation of presented indications are shown in picture 10.: 750

6 with completely automatic manner. This gives possibility to control usage of speedometers in traffic in real conditions direct without warning from speedometer possessor. Considerations that speed testing are conducting on terrain in real traffic conditions; method provides maximal safety of man and equipment which presents priority and main request. Further development of this method by application suitable devices for global position (GPS) and communication together with new test vehicles, will enable testing remote control and wireless transfer of measured data. Picture 10. Photo-record of speed measuring If the all mentioned data shown in photo-record are clear and legible it will be considered that requests are met according to article 14. of Regulations book. 5. CONCLUSION Until now testing have shown that described testing method is very reliable and applicable in the various road and weather conditions. Speed testing results got by using this method is identical or very close to measuring results using primary method. Advantage of this method is its applicability for testing every type of speedometer disregarding of usage place References [1] OIML R91, Radar equipment for the measurement of the speed of vehicles, [2] IACP, NHTSA, Speed-measuring device, Perfomance specifications: Lidar module, USA, [3] NHTSA, IACP, Speed-measuring device, Perfomance specifications: Down-The-Road Radar Module, USA, [4] NHTSA, IACP., Speed-measuring device, Perfomance specifications: Across-the-Road Radar Module, USA,