Wireless application: Toyota plant monitors detention ponds wirelessly
Detention ponds are typically used to control the release of storm water runoff, especially if the runoff may contain contaminants from parking lots or building rooftops. Using a wireless monitoring system eliminates the need for someone to drive out to each pond to manually monitor the water levels.
With the passage of the 1972 Clean Water Act, the Environmental Protection Agency is responsible for regulating storm water runoff. The goal of this act was to restore the waters of the United States to a quality level that “provides for the protection and propagation of fish, shellfish, and wildlife and provides for recreation in and on the water.”
The Water Quality Act of 1987 expanded water regulations to include industrial storm water runoff and required that states be responsible for issuing National Pollution Discharge Elimination System (NPDES) permits to large manufacturing facilities. These manufacturing facilities must then regulate all runoff that enters directly into any waters of the United States or to a municipal storm sewer system.
Toyota Motor Manufacturing Kentucky, a large automotive manufacturer located in Georgetown, Ky., has four such detention ponds located up to a mile away from each other. These detention ponds are also separated by several large buildings.
The pond water must be tested after the first rainstorm of the month, and then the ponds’ drain gates are opened to allow the ponds to drain into local streams or creeks. At the end of the month the drain gates are closed until the next rainstorm occurs and the water is again tested prior to release. If it rains before the water has been tested for the month, Toyota’s employees must closely watch the pond levels until the water can be tested and released.
No line-of-sight needed
Because of the distance involved, and the location of several buildings between radios, Toyota Motor Manufacturing Kentucky collaborated with a vendor to decide to use radios that transmit data via multiple hops, back to a central location with a PC-based controller. Using the radios eliminated the need for line-of-sight between the ponds and the control location.
The wireless networks are made up of one master radio and many repeater or slave radios. The networks are self-forming and self-healing networks constructed around hierarchical communication architecture.
As the wireless network is first formed, the master radio “searches” for any repeaters or slaves within range. Repeaters and slaves that are outside the master radio’s range search for other repeaters to “connect” to, automatically forming the most efficient wireless network possible while still maintaining a strong enough radio signal to reliably transmit the data.
In addition to automatically forming complex radio networks, the networks can self-heal. If a radio loses synchronization to the wireless network, it may reconnect to the network using a different repeater radio.
For this detention pond monitoring application, submersible pressure sensors and a wireless radio with analog inputs were installed at each pond. Both devices were powered by a solar panel and backup battery pack. The pressure sensors were configured to sample the pond levels at five-minute intervals.
The pond level data was transmitted back to the master radio, which was installed on the roof of a building and powered from the available 10 Vdc to 30 Vdc. All radios use a high-gain omni-directional antenna to ensure a reliable long-range communication network was formed in all directions.
The master radio was connected to a host system that logged the pond level data and notified Toyota employees when the pond levels were rising.
Self-forming, self-healing radios
Four detention ponds have been successfully monitored using the radios.
Toyota Motor Manufacturing Kentucky and the employees responsible for gathering pond level information eliminated the manual process for several detention ponds and ensure environmental compliance. Because the networks are self-forming and self-healing, long-range, reliable networks are easy to install and maintain.
Before installing the wireless solution, monitoring detention pond levels required that someone drive out to each pond several times a day during storms. Using sensors and a wireless solution eliminated the need for someone to manually collect the pond level data. This automated solution also gathers more information from each pond, allowing employees to more accurately track their runoff pond levels and prevent the accidental release of untested water.
Susan Schnelbach is technical content architect, Banner Engineering, Wireless Product Division.
For more information about Banner Engineering, please visit http://www.bannerengineering.com.
Toyota Motor Manufacturing Kentucky uses Banner Engineering SureCross Wireless technology, including Banner Engineering SureCross MultiHop radios. Banner consulted with Toyota on the project.