Electronic Toll Collection

This picture taken at the toll both on Sydney Harbour Bridge, around 1992. Tags were mounted on the vehicle windscreen, usually on the LHS or behind the blind spot of the rear vision mirror. There are two readers per lane (for redundancy), pointing down at the centre of the toll booth lane. The readers are pulsed, 3ms on, approximately 97 ms off. Readers are synchronised so that within any group of 24 such readers, only one is on at any time. (24 chosen due to the number of readers required, but theoretically 32 such readers could have been accommodated).

A vehicle sensor external to the reader senses a vehicle in the lane. If a tag is not read, or if the correct payment is not inserted in the coin basket, a video of the offending vehicle is recoded. RFID reading is continuous, i.e. it is NOT triggered by the vehicle sensor. Each reader outputs a heartbeat (defined packet of data on the serial port), so that the Host system knows that the reader is communicating. At any time, the host can issue a command, that sacrifices a read cycle, i.e. 100ms, and read an internal tag, to check that the reader is still operational.

The read range of the readers was reduced, so that tags in adjacent lanes would not be read. In addition, tag replies received due to multi-path reflections are characterised by a reduce power and subsequent reduced frequency of sub-carrier operation (sub-carrier frequency dependant upon excitation voltage), and such replies were rejected by the reader.

Extended Road Range

Usually RFID readers have a single antenna, which is used to transmit the interrogating signal and receive the weak reply. In order to extract the weak reply, about 50 dB of isolation is required between the transmitter output port and the receiver input port. This is usually achieved by the use a directional coupler on the antenna, that has about 10dB loss in the receive path. An alternative is to use two antennas. The antenna in the RFID reader box is usually the transmit antenna, and a separate box is used to house the receive antenna. If the two antennas are separated by approximately 1m, the required isolation can be achieved, and the read range increased. In this system, the read range doubled to 12m. Alternatively, the antennas could have been separated in the horizontal plane as opposed to the vertical plane. The system above was implemented at a shipping port, along with a weigh in motion system. The unique ID as obtained from the RFID tag, attached to the truck windscreen, was checked against the total vehicle load weight, and the driver alerted if the load exceeded his legal tare weight prior to exiting the facility.

Vehicle ID, Sugar Industry

This photo shows trucks, carrying sugar cane onto a weigh bridge. Trucks are identified both entering the sugar refinery and exiting. Hence the RFID reader is mounted in the centre on the road, so that a tag mounted on RHS of the vehicle, can be identified both when entering and leaving the facility. Since RFID reads were infrequent, a multiplexed antenna system was used, so that for one read cycle, RF energy would illuminate the entrance to the facility and for the next RF cycle, RF energy would illuminate the exit of the facility.

Steel Production

This photo shows RFID system being used to identify ladles carrying molten steel from the furnace to the casting facility. Due to the extreme temperatures the tags were located as far away as possible from the molten steel, encased in a Ultrason E2010 high temperature plastic housing. While the tag could be exposed to soak temperatures of around 200 °C, the tags were ROM tags and not EEPROM tags. EEPROM tags would have failed as any floating charge stored within an ID memory cell would have discharged over time at the elevated temperature. In addition, RFID reader were located as far as was practicably possible, by having the RFID antenna physically separated from the electronics by 10m of low loss cable.

Hot-Axle Detection and RFID

This photo shows a number of sensors connected to the RFID reader. In the centre of the tracks, an antenna can be seen underneath a laminated polycarbonate protective cover. It was important to use natural polycarbonate, as to protect polycarbonate usually carbon black is added. Unfortunately carbon black impedes the RF signal. Wood was originally used to protect the antenna from mechanical damage but was quickly replaced, since wood absorbs moisture, which also affects the RF signal. The antenna is connected to the reader located in the top RHS of the photo, with 6m of low loss cable. To the right of the antenna, one can see two infra-red sensors, in yellow. The large sensor at the bottom is used to identify wheel bearings that are hot. The smaller sensor at the top is used to identify when one carriage passes, i.e. it detects the gaps between the carriages. There is another large infrared sensor on the other side of the track, out of view of the photo. A peculiar facet of the sugar industry, is that during the wet season, the sugar cane wagons are placed out in the fields, normally covered in 1m of water. Unfortunately, wheel bearings do not survive well and many fail. With the hot axle box detector placed at the fastest part of the track bearings that are about to fail, or have indeed failed, can be detected. By knowing the side of the failed bearing, its relationship to the gap detector, and the ID of the bin, maintenance staff can be alerted inside the plant, and know exactly which bearing needs attention, If the system saved just one derailment, it would pay for itself.

Location ID

This photo was taken of the City Circle tram in Melbourne. The application consisted of tags buried in the pavement at interesting tourist locations. A reader was mounted upside down, and would identify tags. When a tag was read a commercial or video/audio announcement was made, indicating what tourist attractions/opportunities were available at the next stop. The major difficulty in this application was the extreme vibration the RFID reader was experienced to, and the fluctuation supply voltage. Transient suppressors, TRANSORBS were required on all supply lines to the reader, including serial communications. Readers were modified, to ensure that all components that had mass (Power Amplifier modules and capacitors), had multiple and rigid anchor points.

This photo shows another RFID application involving electrified vehicles. The RFID reader can be seen behind the window. Tags were mounted on rock bolts. Transorbs again were required to cope with fluctuating supply voltages on the vehicle.

Industrial Waste Management

This photo shows an RF ID Antenna (circular device mounted in the centre windscreen) and a tag mounted on the metal industrial waste bin

Domestic Waste Management

This photo shows a 27MHz RFID system, in which a small credit card sized tag was inserted in the lip of the bin, and the RFID antenna mounted on the side of the truck, the circular pipe emanating from the truck opening. Later this system was translate to 13.56 MHz

Manufacturing

This photo was taken at a vehicle seat manufacturing facility. Vehicle seat manufacture involves polyurethane being injected in to large steel moulds. Each mould type is for a particular vehicle, and various parameters of the polyurethane mix (including additives) are specified by vehicle manufacturers. As the polyurethane cures it releases heat (exothermic), and tags can reach 200°C. Tags seen as brown patches on the moulds, use a ROM technology, not EEPROM technology and are housed in Ultrason E2010 (natural). EEPROM tags would fail in this application as any RFID code stored on the floating gate of a memory cell, will disperse at the higher temperatures, and erase the stored identity. Also natural Ultrason was used, and UV stabilised material usually has carbon black, which impedes the RF signal.

Library

These photos show the first RFID Library in the world. Taken in 1998 at Butok Batik library in Singapore, a small half credit card sized tag was inserted into each book. Patrons could use self checkouts (LHS) to check the book out, and at the same time disarm the integrated EAS (Electronic Article Surveillance ) circuit. When the patron had finished with the book, they could be returned via the book drop (up to 4 at a time), and those books would be automatically logged as being available. The major advantage of the system was the use of a hand held RFID reader and the ability to complete library stock takes, without having to handle the books, and the ability to search for misplaced books, during such stock takes.

Warehouse Management

This photo shows RFID tags being suspended from the ceiling of a warehouse and an RFID reader mounted on top of the forklift. By reading the sequence of tags that the RFID reader identified, the system would know which bay or dock the forklift was operating on, thereby knowing where goods (in this case beer kegs) were being stored or retrieved.

A close up shot of the tags suspended from the ceiling.