High-Accuracy Surface-Perceiving Water Level Gauge With Self-Calibration for Hydrography

In a wide-range, long-time water-level measuring system, the absolute measurement error of gauges presently used increases with the increase of measurement range, which makes the gauges fail to satisfy the requirement of accuracy. Meanwhile, the cumulative error also increases after the system has been in operation for certain period of time so that the gauges need to be manually calibrated periodically. This paper presents a new type of water gauge with a wide measuring range (up to 150 m), which involves a minimum error about 2 mm. Based on the design scheme incorporating self-calibration and low power dissipation, the gauge combines an electric dc motor driving the mechanical structure to perceive the water surface and a rotary encoder detecting the distance between the benchmark and the water surface. The results and analysis of the experiments with the gauge demonstrate that this environmentally friendly device possesses the features of high accuracy, low power dissipation, and a wide range of applications.