Aircraft Engineering and Aerospace Technology

Purpose – The purpose of this paper is to introduce a new danger-aware Operational Flight Program (OFP) for the unmanned helicopter's auto-navigation based on the well-known time-triggered message-triggered object (TMO) model.

Design/methodology/approach – In this design with the TMO, the danger-awareness means two things. First, an unmanned helicopter maneuvers on safe altitudes to avoid buildings or mountains when navigating to the target position. It is assumed that minimum safe altitudes are given on evenly spaced grids and on the center points of every four adjacent grids. A three-dimensional (3D) path-finding algorithm using this safe-altitude information is proposed. Second, a helicopter automatically avoids a zone with very high temperature caused by a fire.

Findings – Since the auto-flight control system requires componentized real-time processing of sensors and controllers, the TMO model that has periodic and sporadic threads as members, has been used in designing the OFP. It has been found that using the TMO scheme is a way to construct a very flexible, well-componentized and timeliness-guaranteed OFP.

Practical implications – As the RTOS, RT-eCos has been used. It was developed a few years ago based on the eCos3.0 to support the real-time thread model of the TMO scheme. To verify this navigation system, a hardware-in-the-loop simulation (HILS) system also has been developed.

Originality/value – Designing an OFP by using the real-time object model TMO and the proposed 3D safe path finding algorithm is a whole new effective deadline-based approach. And the developed OFP can be used intensively in the phase of disaster response and recovery.