US-based Roboteq has developed a sensor that can follow tracks created by sticking magnetic tapes onto a floor. It is aimed initially at creating a simple, low-cost steering system for AGVs (automatic guided vehicles), but could open up new applications such as rail-free tramways, patient transport systems for hospitals, and automated shelf-stacking systems for supermarkets.

The 160mm-wide MGS1600 sensor (above) uses advanced signal processing to measure its lateral distance from the centre of the magnetic track, from a height of up to 60mm above the track. It provides a position resolution of 1mm – claimed to be the most accurate available.

The passive magnetic guides are easy to lay and modify. The tape creates an invisible field that is immune to dirt and unaffected by lighting conditions. It can be hidden under non-ferrous flooring materials such as linoleum, tiles or carpet.

As well as following the guide track, the sensor can also detect the presence of magnetic markers next to the track. These markers, made of the same material as the tape but with an opposite polarity, can be used to signal forks in the path or the presence of a charging station. The sensor can handle two-way forks and can be instructed to follow the left or right track using commands to its digital inputs.

The sensor can be interfaced to a motor controller to create an AGV guidance system using just two components. It can also be linked to a PLC using analogue, PWM, RS-232 or CANbus interfaces. The sensor can also be interfaced to a PC via USB.

A PC utility is provided for configuring the sensor and updating its firmware. The utility also includes a strip chart recorder, and a window that shows the magnetic field seen by the sensor in real time. Users can add custom functions to the sensor using a programming language similar to Basic.

Initially, the sensor is being supplied as an open board module, but an enclosed, water-resistant version will be available in the second quarter of 2013.

A demonstration of the sensor being used to steer an AGV can be seen here, while a presentation of the technology is available here.