FEATURE Conveyingy

Contrinex’s RFID tracks mobile conveyor position

Bulk material-handling equipment uses rugged RFID technology to sense the position of large rail-mounted reclamation conveyors operating in a harsh environment


ontrinex’s rugged RFID technology was used in bulk material handling equipment to sense the position of large rail-

mounted reclamation conveyors operating in a hot, dusty environment. A pair of read-write modules mounted on the machine structure interrogate a series of RFID tags, positioned at one-metre intervals along each travel rail. The control system identifi es each tag individually and determines the exact position of the machine and prevents crabbing.

Customer application

During surface-mining operations, large mobile reclamation machines are used to recover bulk materials. On each machine, a bucket wheel excavator collects material and deposits it onto a conveyor. As an area is cleared of material, the machine moves along parallel steel travel rails to the next area, allowing continuous operation without interruptions for machine repositioning. The distance between the travel rails

is around 100 metres (300ft) and travel speeds can reach 2m/s (4.5mph). If machine movement along the two rails is not controlled accurately, the two sides of the structure become misaligned, causing the machine to skew. In this event, production is halted whilst realigning the machine, but, in the worst case, there could be a costly damage. A sensing system is required that detects the position of each side of the machine structure accurately and reliably along the entire length of the travel rails, allowing coordinated control of the drive systems. Sensors must accommodate up to 10mm lateral movement of the machine structure across either rail, and must withstand the hot, dusty environment of a desert climate.


Contrinex high-frequency RFID read/ write modules and 30mm-diameter RFID transponder tags are ideal for this application. Rated to IP67, the M30-diameter read/write modules have PBTP sensing faces and V2A stainless-steel housings,

22 July/August 2020 | Automation Conveying machine

making them ideal for the demanding environment.

The ConIdent passive transponders

require no internal power source and, with PBTP synthetic housings, have the same IP67 rating. The selected combination provides read/write distances of up to 45mm (nearly 2in), ideal for the specifi ed operating conditions. Tags are mounted at one- metre intervals along each travel rail, each programmed with a unique identifi cation number. As the machine passes a tag, the read/write module reads its identifi cation number at high speed. This is transmitted via a PROFIBUS DP interface to the customer’s control system. A simple look-up table confi rms the location of the tag and thus the position of the machine, allowing movement of both sides of the structure to be synchronised without skewing. Operation is independent of the direction of travel.

Product advantages Product advantages include: • RFID sensing distances up to 60mm RFID; • Passive RFID transponder tags require no power source and minimal maintenance;

• Rugged RFID transponder tags with nylon or all-metal housings sealed to IP67 (washdown versions rated to IP69K);

• Choice of industry-standard control systems or IO-Link is ideal for Industry 4. Contrinex ConIdent RFID devices allow accurate and highly-reliable sensing of machine position, and the long sensing distance avoids any risk of collision damage. The customer enjoys extended service life and robustness not available from alternative position-detection systems, together with excellent value for money: • Uninterrupted production as positional identifi cation is highly reliable.

• No risk of skewing as movement of the machine structure is synchronised.

• Elimination of collision damage because of sensing distance up to 45mm.

• Passive RFID transponder tags require no power source and minimal maintenance.

• Rugged RFID transponder tags with nylon or all-metal housings sealed to IP67.

• ConIdent technology provides extended sensing range ≤ 45mm.

• Read/write units interface with a choice of industry-standard control systems or IO-Link.


Contrinex/PLUS Automation

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