Engineering & Mining Journal

JUL 2018

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Page 52 of 75

SHOTCRETE JULY 2018 • E&MJ 51 Building tomorrow's technologies for today's mines WE DETECT so you can act COLLISION AWARENESS 360° Detection IN-CAB DISPLAY Warning: This Collision Awareness System (System) is designed to reduce the risk of certain accidents by providing visual and audio warnings to the driver of a potential collision. The System has limitations and cannot notify of all impending accidents. This System is not a replacement for proper safe and attentive driving. Please drive carefully at all times and do not rely on technology to prevent a collision. The System is only activated in certain circumstances and may not engage in all driving situ- ations, weather or road conditions. Accordingly, never wait for a collision warning. The driver is always responsible for proper operation of the vehicle and for maintaining the correct distance and speed - even when the Collision Awareness System is used. Failure to comply with these instructions could result in serious injury or death. Simple, intuitive in-cab display Minimized false alarms Developing Autonomous Shotcreting Systems At the 2018 Society for Mining, Metallur- gy and Exploration annual meeting, Tobi- as Hartmann presented "A Leap Toward Automation in Shotcreting." Hartmann is a Ph.D. candidate with the Institute of Advanced Mining Technologies (AMT) of the RWTH Aachen University. At many mines, the shotcreting machine is controlled by a remote operator near the machine. The amount of concrete applied to the surfaces and the quality control of the process is very subjective. That combined with the environmental conditions under- ground (i.e., dust, line of sight impair- ment, etc.), it is difficult to guarantee consistent concrete thicknesses through- out the process. To support the operator, AMT research- ers are developing a new concrete injec- tion vehicle, which will be equipped with sensors to monitor all steps of the pro- cedure, including an initial tunnel scan, concrete application and quality control (post tunnel scan). A laser scanner mounted on the vehi- cle's arm would scan the tunnel. During the concrete application, the system would monitor the nozzle positions and the concrete flow to create a virtual rep- resentation of the concrete thickness. The researchers are also using Ultra-Wideband (UWB) radio technology and an inertial navigation system (INS) to determine the position of the rig's application arm. After the application process, a second laser scan evaluates the concrete thickness. The arm is never in the same position twice so the scanner position must be localized to match the two scans to de- termine the layer thickness. Hartmann described the development of a local- ization-technology consisting of UWB and INS, including "sensorfusion." "The localization modules are used to deter- mine the arm position," Hartmann said. He said they preferred this method rath- er than placing encoders on every joint, which reduces the places where the sys- tem can fail. The UWB solution gives a good inital guess, which will generate more precision. While describing laser scanners, he re- minded the audience that it's important to determine the desired level of precision and accuracy. After testing several scan- ners, the AMT researchers found the accu- racy to be quite high, but precision varied between 4 mm and 10 mm. Ultimately, however, they opted to use a 2D scanner. Hartmann walked the crowd through several sweeping scans. "Because of the geometry, the system can't scan too far ahead," Hartmann said. "A good distance is 7 m or 8 m, scanning 15-m sections at a time, which is sufficient for shotcreting in tunnels." When it comes to digitalizing the shot- creting process, one of the major chal- lenges is the localization system, Hart- mann explained. "You may want to do that with lower cost hardware just to match the scan," Hartmann said. "Storing the data and post processing of the data in a timely fashion is another challenge. Then, there is need to develop a user-friendly interface." Hartmann believes that an af- fordable, robust system could eventually be developed.

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