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1、外文参考文献原文Preventing collisions involving surface mining equipment:a GPS-based approachTodd M. Ruff a,*, Thomas P. Holdenba Spokane Research Laboratory, National Institute for Occupational Safety and Health, 315 East Montgometry Avenue, Spokane, WA 99207, USAbTrimble, Sunnyvale, 645 N. Mary Ave. 94088
2、, CA, USAReceived 28 June 2002; accepted 30 September 2002AbstractProblem: An average of three workers a year are killed in surface mining operations when a piece of haulage equipment collides with another smaller vehicle or a worker on foot. Another three workers are killed each year when haulage e
3、quipment backs over the edge of a dump point or stockpile. Devices to monitor the blind areas of mining equipment are needed to provide a warning to operators when a vehicle,person, or change in terrain is near the equipment. Method: A proximity warning system (PWS) based on the global positioning s
4、ystem (GPS) and peer-to-peer communication has been developed to prevent collisions between mining equipment, small vehicles, and stationary structures. Results: A final system was demonstrated using one off-highway haul truck, three smaller vehicles, and various stationary structures at a surface m
5、ining operation. The system successfully displayed the location of nearby vehicles and stationary structures and provided visual and audible warnings to the equipment operator when they were within a preset distance. Summary: Many surface mining operations already use GPS technology on their mobile
6、equipment for tracking and dispatch. Our tests have shown that it is feasible to add proximity warning to these existing systems as a safety feature. Larger scale and long-term tests are needed to prove the technology adequately. Impact on Industry:A PWSs that incorporates a combination of technolog
7、ies could significantly reduce accidents that involve collisions or driving over an edge at surface mining operations. Keywords: Proximity warning system; Collision; Global positioning system; Haulage equipment; Surface mining; Blind spots1.Introduction Each year, there are an average of 20 accident
8、s and three fatalities involving collisions between a piece of surface mining haulage equipment and either a smaller vehicle or a worker on foot or some other object. Another 21 accidents occur and three mining equipment operators are killed each year when their equipment backs over the edge of an e
9、mbankment,stockpile, or dump point (Fesak, Breland, & Spadaro,1996; Mine Safety and Health Administration MSHA,2002). These accidents are caused by the operators limited visibility from the cab of the equipment. In mining operations,these accidents most often involve large, off-highway dump trucks.
10、The areas that an equipment operator cannot see while seated in the cab of these trucks can be extensive,depending on the size and type of equipment. Fig. 1 shows the blind areas around a 50-ton-capacity dump truck common in construction and sand and gravel operations. The gray shaded area outside o
11、f the truck outline shows those areas where the truck operator cannot see a 1.8-m-tall person. Larger trucksup to 360-ton capacityare common in mining, and the blind areas for these trucks can extend 12 m in front of the truck.Blind areas to the rear and right side can be even larger. Researchers at
12、 the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to reduce accidents attributed to the lack of visibility around mining equipment. Many technologies exist that can provide an operator with information on unseen objects or workers near the equipment, includ
13、ing video cameras,sensors, and mirrors. Many of these technologies have been popular in other industries, such as ultrasonic sensors in the automotive industry and video cameras on recreational vehicles, but very few have been successfully applied to mining equipment. Other technologies are being de
14、veloped to address this problem and include electromagnetic signal detection and radar (Ruff, 2001). All of these technologies show promise for use on mining equipment; however, further development is needed to overcome the challenges associated with the harsh environment of mining and the size of t
15、he equipment being used. Global positioning system (GPS) technology also shows promise for this application. Many surface mines already use GPS on equipment for tracking, dispatch, and control. A logical next step for this technology is to use it to track equipment, workers, and stationary structure
16、s and provide a warning when the possibility of a collision exists. The NIOSH Spokane Research Laboratory, Spokane, WA, in cooperation with Trimble,1 Sunnyvale, CA, has developed a new system based on GPS technology that will provide an equipment operator with information on all other vehicles, stat
17、ionary obstacles, and dump points near the machine. T.M. Ruff, T.P. Holden / Journal of Safety Research 34 (2003) 175181Fig. 1. Gray areas indicate where driver cannot see a 1.8-m-tall person from cab of a 50-ton-capacity dump truck.2. System conceptThe concept for GPS-based proximity warning for mi
18、ning equipment entails the use of differential GPS receivers and radios on all equipment having reduced visibility, all smaller vehicles on the mine site, and all workers on foot.As illustrated in Fig. 2, the location of all moving objects must be determined and updated in real time, and this inform
19、ation must be transmitted to all nearby equipment so that the equipment operators are aware of other vehicles or workers nearby. In addition, the location of stationary structures, such as buildings, utility poles, and dump points, are stored in a database of potential obstacles. An alarm interface
20、in the cab is required to provide a visual and audible warning when another vehicle, worker, or stationary obstacle is within a preset danger zone around the equipment.Fig. 2. The PWS concept.The advantages of using GPS technology for proximity warnings at mining facilities include (a) the ability t
21、o use the existing GPS infrastructure at many mines, (b) the systems accurate location and tracking abilities, (c) low-to-zero occurrence of false alarms, (d) the capability of the system to identify obstacles, and (e) the ability to customize the user interface and warning zones.Development of a GP
22、S-based proximity warning system (PWS) by NIOSH and Trimble began in 2000. Prototypes were tested in an outdoor laboratory setting on passenger vehicles (Holden & Ruff, 2001). Development has progressed over the last 2 years, resulting in a mine-ready system that was demonstrated at the Phelps Dodge
23、 Morenci, copper mining operation in April of 2002.3. Prototype system3.1. System descriptionA prototype system was constructed to demonstrate that the idea of GPS-based proximity warning was feasible. Readily available components were used to keep costs at a minimum. Each system consisted of a lapt
24、op computer to:(a) collect, process, and transmit data, (b) run the PWS software, and (c) provide a display for the vehicle operator.A PCMCIA wireless network card (IEEE 802.11b) was used to communicate between laptops. An off-the-shelf, 12-channel, differential GPS receiver and antenna were used to
25、 determine location. A Coast Guard beacon was used to provide differential correction. Two complete systems were mounted in two different passenger cars for dynamic tests. 3.2. Test description and resultsAs described in Holden and Ruff (2001), the prototype system went through a series of operation
26、al and performance tests using two vehiclesa local vehicle and a remote roving vehicle. The goal of the operational tests was to verify the operation of the various pieces as compared to the defined specifications of the system. These specifications included the ability to set up, control, and monit
27、or the GPS receiver properly, and the ability to send and receive information over a wireless local area network (LAN) connection One key factor was to determine the reliable transmission range of the wireless LAN. Maximum (11 Mbps) and minimum (1 Mbps) signaling rates were tested using the PWS soft
28、ware running on two laptops with wireless LAN cards installed. Each LAN card had a dual-patch diversity antenna directly mounted on it. The system functioned very well and had no packet losses when the two vehicles were separated by distances under 60 m. Beyond 60 m, performance declined. The ranges
29、 where transmission completely stopped were 120 m for the 11-Mbps signal and 220 m for the 1-Mbps signal. It was evident that the quality of signal reception was a function of range, antenna properties, and line-of-sight to the transceiver. Note that the wireless network antennas were connected to t
30、he PCMCIA cards, so antenna type and placement was limited. Signal reception can be made more reliable by using a better antenna mounted on the exterior of the vehicle.Another important test of the wireless communications was the time-to-associate measure for a new vehicle entering a local area. At
31、ranges of up to 60 m, the new vehicle associated, or was recognized by the PWS, in less than 1 s. Outside 60 m, the vehicles time-to-associate was related to signal quality.A second set of tests evaluated the performance of thesystem and covered the following items:1. ability of the PWS to transfer
32、information accurately, which was measured by matching received data from a remote vehicle and data from the local vehicle using GPS time tags,2. latency of the remote vehicle information,3. accuracy of the real-time vehicle position,4. response to various dynamics of the remote vehicle, and5. respo
33、nse to various dynamics of the local vehicle.Provided that the communications link between the vehicles was functioning, the local vehicles PWS was able to follow the trajectory of the remote vehicle according to the transmitted information. Errors were determined by matching real-time data stored b
34、y the remote system with the perceived remote data recorded by the local PWS using a GPS time mark corresponding to the transmitted information. Essentially, the information was matched in time so all latency errors were removed. These results showed that the errors introduced to the system by corru
35、pt data transmissions were negligible, as no errors of significance were observed.The latency of the information presented to an operator corresponds to errors in the actual position of the remote vehicle. Latency-induced error is dependent upon the velocity of the remote vehicle. Latency can be det
36、ermined by special methods to roughly 0.2 s, assuming a broadcast rate of 4 Hz. In the tests, observed latency correlated well with this value. Additional sources of latency could be attributed to radio and processing delay. Overall, the system was measured to have a latency of less than 0.5 s.Fig.
37、3 shows that radio coverage for these particular wireless network cards was excellent within a 100-m range. The position of the stationary local vehicle is near the middle right of the figure (black dot). The thin line is the actual trajectory of the remote vehicle, and the dots are the perceived po
38、sitions. Areas where the line is not covered resulted from communications interference from large obstacles. This demonstrates the line-of-sight nature of the short-range radios. Note that the communication gaps occurred over 100 m from the origin of the grid.Fig. 3. Top view of remote vehicles path
39、 as perceived by local stationaryvehicle.Fig. 4 shows the computed position errors of the moving remote vehicle as perceived by the stationary local vehicle. Errors of less than 2 m are evident. The graphs show that the errors were very small when the remote vehicle was stationary (flat line), but l
40、arger when it was in motion. The errors can be attributed to position update latency, but are within the desired specifications. Fig. 4. Geodetic position error of moving vehicle computed at local vehicle.4. Mine-ready system4.1. System descriptionTests of the prototype system showed that the concep
41、t of a GPS-based PWS was feasible; however, the system had to be redesigned using components that could be used on mining equipment. The mine-ready PWS consisted of the following Trimble components: (a) a GPS antenna, (b) a Windows CE-based computer with LCD display to run the PWS software, (c) an e
42、ight-channel, single-frequency, differential GPS receiver (integrated into the computer enclosure), and (d) a SiteNet 900-MHz Internet Protocol (IP) radio. All of these components were designed for mounting on heavy equipment.The mine-ready PWS operates in a similar manner to the prototype system, b
43、ut with a few modifications. As before, GPS is used to determine the location of the vehicle on which a system is mounted. Differential correction information from a base station is also received by the PWS. The corrected location of that vehicle is then transmitted once per second via the IP radio
44、to all other vehicles in the area equipped with a PWS. The locations of other vehicles are also received by the IP radio and shown on the computers display if they are within a specified range. The location of stationary obstacles, such as dump points, power lines, and mine buildings, does not have
45、to be transmitted. Their coordinates can be entered into the system database so that they show up on the vehicles display.4.2. Test description and resultsFor tests at the Phelps Dodge Morenci Copper Mine, a complete PWS was installed on each of the following equipment: Caterpillar 797 360-ton capac
46、ity haul truck (Fig. 5), Caterpillar rubber-tire dozer (Fig. 5), and two service trucks (pickups). A base station was also installed on a nearby hill to provide differential correction information to the individual systems on the vehicles. Fig. 5. PWS equipment installed on a Caterpillar haul truck
47、and dozerThe GPS antennas and IP radios were temporarily, but securely, mounted on the mining equipment and service trucks in typical locations, usually on or near the cab roof. The computer was securely mounted in each vehicle in a fashion similar to a final, permanent installation. The PWS softwar
48、e ran on this computer and displayed a screen for the equipment operator that showed his/her equipment in the center, the detection zone radius, the warning zone radius, system status, and icons representing other vehicles or stationary obstacles in the area (Fig. 6). Fig. 6. PWS computer display.Ea
49、ch vehicles warning and detection zones were adjusted according to the vehicles size. The display in Fig. 6 was mounted in the Caterpillar 797 haul truck and had a 30-mradius warning zone and a 60-m-radius detection zone. The zones for the dozer and service trucks were set at 20 and 40 m. Audible alarms were generated whenever another vehicle or stationary obstacle was detected in either zone. In addition, the color of another vehicles icon changed from green (ou
