Application of wireless sensor networks in field measurement

　　In the field of industrial measurement, wireless sensors often require long-term, large-scale, multi-channel data measurement systems. In the field of field environmental monitoring, due to the special environmental conditions, the monitoring system is often difficult to deploy effectively due to factors such as power supply and long-distance wiring. Wireless sensor networks are particularly suitable for field measurements in the industrial field due to their low power consumption, self-organizing routing, and no wiring required.

　　This article will introduce a wireless sensor network case deployed in a coastal city in southern my country. After a small modification, the system can meet many industrial measurement needs.

　　The city has a lot of mountainous landforms and a large population, which requires a high utilization rate of land. Therefore, a large number of buildings and roads are located near the mountains. The rainfall in the area is high all year round, especially in the rainy season in summer. Unstable mountainous landforms are prone to landslides after being eroded by rain, posing a huge threat to the safety of life and property of residents.

　　The local authorities have tried to deploy multiple wired monitoring networks to monitor and warn of landslides. However, since the monitoring areas are often in remote mountainous areas with few roads, field wiring and power supply are limited, making it very difficult to deploy wired systems. In addition, the wired method often uses dataloggers deployed nearby to collect data, requiring dedicated personnel to regularly go to the monitoring points to download data. The system cannot obtain real-time data and has poor flexibility.

　　In response to this, after many exchanges with geographical monitoring experts and several field visits, Crossbow proposed a complete wireless solution for landslide monitoring based on wireless sensor networks.

　　Basic measurement principle

　　The monitoring of landslides mainly relies on the functions of two types of sensors: liquid level sensors and inclination sensors. In areas where the mountains are prone to danger, multiple holes are set vertically along the direction of the mountain, as shown in Figure 1. Each hole will have a liquid level sensor deployed at the bottom and several inclination sensors deployed at different depths. Since the landslide phenomenon in the area is mainly caused by rainwater erosion, the depth of the groundwater level is the first indicator of the danger of landslides. The data is collected by the liquid level sensor deployed at the bottom of the hole and sent by the wireless network.

 

　　The movement of mountains can be monitored by tilt sensors. Mountains are often composed of multiple layers of soil or rock. Different layers have different movement speeds due to different physical compositions and erosion levels. When this happens, tilt sensors deployed at different depths will return different tilt data, as shown in Figure 2. After the wireless network obtains the data from each tilt sensor, professionals can determine the trend and intensity of the landslide and determine its threat level through data fusion processing.