Development of Inertial Sensors for AHRS considering DO-254

Abstract

This paper elaborates different aspects of the design and development of a MEMS-based sensor used in an Attitude Heading Reference System (AHRS) which has to be certified.Throughout the last decade the design and complexity of a typical inertial sensor has changed as well as the certification environment.For the inertial sensor, size, weight and power (SWaP) as well as cost pressure force the usage of complex electronic hardware (CEH) such as field programmable gate arrays (FPGA) and application specific integrated circuits (ASIC). These devices are typically used for processing and steering of one or more control loops of the inertial sensor. The overall performance does no longer depend only on the sophisticated design of the sensor chip, but also on the control-loops implemented in CEH. For CEH the standard RTCA DO254 has to be applied - therefore this paper focusses on this standard.On the certification side, the development standards DO-178 and DO-254 account for the high complexity of software (S/W) and hardware (H/W) in order to avoid systematic design errors. For AHRS development stringent compliance to the above processes must be shown, leading to additional development effort for AHRS and inertial sensor development (e.g., documentary task).While there are many examples for CEH for pure digital Airborne Electronic Hardware without sensors (e.g., H/W for I/F data processing), there is almost no guidance for design of inertial sensors in the framework of an AHRS development in accordance with DO-254.This paper explains based on simple examples how the development methodology has to be adapted, considering the complexity evolution of inertial sensors and current certification rules.