Automatic correction of barometric altimeters using additional air temperature and humidity measurements

A GPS module is often combined with an atmospheric pressure sensor in onboard navigation systems. Thanks to this, using appropriate algorithms comparing the results obtained from GPS and from the barometric altimeter, it is possible to obtain much more accurate indications of the height above sea level. The authors analyzed the problem of correcting barometric altimeter errors caused by non-standard pressure and temperature conditions at sea level and the presence of water vapor in the air. The authors proposed methods of correcting the altimeter error using additional temperature and air humidity measurements. They also proposed a simple method for calibrating the altimeter prior to the mission to estimate the difference in pressure above the standard value. The paper discusses the influence of water vapor on the accuracy of the altimeter indications and the conditions for the applicability of the error correction method. The authors initially considered the possibility of using the method based on the concept of virtual temperature. However, this method was rejected because simulation studies showed that it did not give satisfactory results. Simulation tests were carried out in the MATLAB environment to assess the effectiveness of the proposed methods. The test results turned out to be satisfactory. They can be useful when designing low-cost navigation systems using simple sensors made in MEMS technology. The main envisaged application is in autonomous drone navigation systems.