Developing a better ‘Plan B’ for airline safety
While current system architectures include a primary and a back-up or stand-by channel (so-called redundancy) for monitoring aircraft speed, the systems consist of similar equipment with similar failure mechanisms. Thus, the redundancy is not always real as failure of the primary channel may mean failure of the back-up channel as well. The ‘New standby lidar instrument’ (Neslie) project was designed to develop a multi-axis laser with new signal processing algorithms for the stand-by channel, thus increasing aircraft safety by decreasing the probability of failure of both aircraft speed monitoring channels. The researchers first specified the desired characteristics of efficient signal processing algorithms for measuring true air speed (TAS), angle of attack (AOA) and side-slip angle (SSA). The algorithms were developed and extensively tested using appropriately modelled data. Given the requirement for real-time processing of a huge amount of data, the researchers implemented the algorithms on powerful field-programmable gate array (FPGA) boards, with special attention to data collection time and processing speed of the FPGA processor. Neslie project efforts resulted in design of the optical air data system (OADS) with integrated laser, integrated optics, optical head and windows, real-time signal processing and an air density acquisition theoretical study. In addition, the researchers produced and flight-tested a lidar mock-up validating the OADS concept and producing promising results. Along the way, they created a large signal database that should prove quite useful for further research in signal processing. Results of the Neslie project should have a significant and positive impact on the future of European airline safety.
