Sensys: MAG2/Grind Resistant (GR) Sensor
The new MAG2/GR sensor developed by Sensys Networks utilizes the next generation of RF chipsets and circuitry.
- Superior accuracy
- Exceptional reliability
- Flush-mount in-pavement installation with no wires or lead-in cabling
- Extremely long battery life
- Advanced Magnetometer-Based Vehicle Detection
The Sensys Networks VDS240 Wireless Vehicle Detection System uses wireless magneto-resistive sensors to detect the presence and movement of vehicles. The sensors – installed in holes cored in the roadway and covered with epoxy – transmit detection data in real-time via low-power radio technology to a nearby Sensys Networks access point. Vehicle detections are further relayed to a traffic signal controller, remote traffic management center or other system.
The MAG2 sensors are installed flush with the roadway surface in plastic shells. The plastic shells enable the removal and replacement of sensors during roadway milling operations. The GR sensors are installed at depth of up to 8 inches below the top of the roadway surface without plastic shells. Sensors installed at these depths do not have to be removed and replaced during most roadway milling operations.
In typical traffic management applications, a sensor is placed in the middle of a traffic lane to detect the presence and passage of vehicles. Vehicle speeds and length are measured by two sensors installed in the same lane with the exact distance between them configured in software. The recommended distance between sensors depends on the range of expected speeds to be measured: for typical freeway applications, a separation of 20 to 24 feet (6.1 to 7.3 meters) is recommended; for typical arterial applications, a separation of 10 to 12 feet (3.1 to 3.7 meters) is preferred.
The state-of-the-art magneto-resistive sensing devices in each wireless sensor measure the x-, y- and z-axis components of the Earth’s magnetic field at a 128 Hz sampling rate. As vehicles come within range, changes in the x, y or z axes of the measured magnetic field become apparent. When no vehicles are present, sensors continually measure the background magnetic field to estimate a reference. Each sensor automatically self-calibrates to the local environment and to any long-term variations of the local magnetic field, by allowing this reference value to change over time.