Automated measurement of bulk material stockpiles

August 17th, 2015, Published in Articles: PositionIT

 

Through continuous product development, ABB ensures its customers always get the latest in technology and product benefits. New developments in the VM3D volumetric laser scanner system now enable it to provide faster results without any recurring data fees.

The 3D volumetric laser scanner (VM3D) provides a reliable automated solution to replace manual surveys of stockpiles. This non-contact laser scanner is designed to measure the volume of bulk material stockpiles stored in the open or in large structures like silos, bunkers, domes, and sheds. Whether measuring a few metres into the confined space of a small silo, or to the bottom of the largest warehouse, the VM3D with its long range, wide angular sweep and ability to function as a scanner network is a plug-and-play solution to stockpile volume measurement.

The system integrates high accuracy laser scanner with remote monitoring services for measurement of all visible surfaces, regardless of texture, granularity, slope, and/or colour. It delivers confident stock management and precise auditing of mineral ores, grains, and synthetic materials, from gold to sugar to fertilisers.

Fig. 1: Client stockpile in bunker.

Fig. 1: Client stockpile in bunker.

Volume estimation

Fig. 2: The volumetric laser scanner.

Fig. 2: The volumetric laser scanner.

The scanner transmits the raw point cloud over a 3G cell phone network to the company data centre where the point cloud is intelligently analysed to produce a picture of the stockpile and an estimate of the volume and mass it contains. It takes only ten minutes to get these results once the scan is complete. The analysis makes use of the building blueprints to determine the depth of the stockpile and avoid having to empty the building to baseline the scanner system. This analysis also eliminates artifacts like machinery and visible building structures from the volume estimate even if they move from scan to scan.

The complete data transmission chain uses highly secure encrypted data communications, and the company will enter into a legally binding agreement with the end user not to reveal any of their confidential inventory information. The ABB data centre service includes a daily scan for three years after which the customer can simply renew its 3G communications service to continue using the ABB data centre. Simple to use and maintenance free, the VM3D is said to provide accurate and repeatable results for years to come.

Distance measurement with laser technology

The scanner uses a high speed laser pulse to measure distance. The laser light is emitted towards the surface and some of it reflects back to the instrument where it is detected by a sensitive optical receiver. The time it takes for the light to travel to the surface and back to the instrument is directly proportional to the distance between the instrument and the surface. Using a time-of-flight calculation the scanner accurately measures the distance to the target surface using the equation below:

ABB-076-08-2015-equ1

The unique characteristics of laser light give the VM3D significant performance advantages over other technologies in terms of resolution and immunity from parasite reflections. The narrow, long range beam can measure both near and far distances and obstacles can be measured around by placing multiple scanners at different vantage points. This robust and reliable laser scanner performs a complete scan in under an hour and collects thousands of points per scan.

The scanner auto-ranges to measures a surface of 93 m. The narrow beam divergence of the laser combines with precise, mechanical scanning that covers a complete hemisphere. This creates a tight cloud of data points that are used to develop a surface map. Multiple scanners can be combined to determine the shape and volume of even the largest stockpiles. Dust tubes keep lenses clear and heated optics prevent condensation. The 3D volumetric laser scanner can operate in a temperature range from -20°C to +50°C and also provides volume estimates with less than 2% error.

Fig. 3: Volumetric measurement of stockpile.

Fig. 3: Volumetric measurement of stockpile.

The laser scanner is housed in a powder coated aluminum enclosure; the control box is offered in three options: mild steel for general purpose, painted mild steel for hazardous area (dust ignition protection) and stainless steel for hazardous area (dust ignition protection). The standard system includes laser scanner(s), control box, antenna and the free data centre service for a period of three years on daily basis (one scan per day).

No components to replace or adjust, no consumables and no calibration is required because of its permanently sealed and lubricated bearings. Also, this 3D volumetric laser scanner has the CSA, ATEX and IECEx potentially explosive atmosphere ratings certifications.

Contact ABB, Tel 010 202-5000, instrumentation@za.abb.com

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