Kalman Filter for Precise Altitude Estimation in FMCW Radar
Ayush Vardhan Jha, Ananya Ray, Umang Bhatia, Swastik Saini, Priyanka Mehrotra, BSVGR Jogeswara Rao, Pankaj Kanti Nath, Ch. V. N. Rao · 2023
Autonomous navigation is utilized in interplanetary landing missions to guide spacecraft towards specific destinations. For successful and soft landings, accurate altitude information is crucial. Radar altimeters are extensively employed in these missions to measure and determine precise altitudes. The Ka-band FMCW radar altimeter developed at SAC, ISRO will be used during upcoming landing mission [1]. This system is designed with a wide beam width, allowing it to measure the vertical distance to the ground (along nadir) accurately, even when the mounting platform experiences significant roll and pitch variations. However, the wide beam width results in the beam intercepting a large ground area. This means that any changes in the intercepted area can introduce variations in the characteristics of the return signal, posing challenges for precise altitude estimation. To mitigate the problem, a Kalman filter is designed and implemented. The system was then subjected to rigorous testing aboard a helicopter over different terrains. This paper discusses the filter design and the test results.