Haptic feedback for flight envelope protection

Abstract

Improving the safety level of aviation is vital to prevent serious accidents. One key area where improvements can be made is the prevention of loss of control occurrences, by preventing the aircraft state to pass beyond the limits from which no recovery is possible. Such improvements can focus on improved monitoring of the main flight parameters and active automationmodes. The limits of an aircraft are typically expressed in terms of a flight envelope which represents the allowable region of load factor versus velocity. Modern day aircraft can support pilots in monitoring themain flight parameters by employing a flight envelope protection system: the inputs of the pilots are routed to the flight control computers which can impose limits on those inputs. In doing so, the computers are protecting the aircraft state fromleaving the flight envelope. When the control device is linked to the control surfaces, for example using cables and pulleys, any limit imposed by the flight control computer can be felt by the pilot. With the advent of fly-by-wire control devices, the mechanical link is replaced by an electrical connection, resulting in the loss of this information using the sense of touch. This haptic information was initially not included as it requires active control devices which had issues regarding the size, power and stability requirements. The lack of such haptic information on the flight envelope protection system might have been a contributing factor in some accidents. Nowadays active control devices do meet the requirements in terms of size, power and stability, and offer the possibility to re-introduce haptic feedback in fly-by-wire control systems. Therefore, this thesis looked at adding haptic feedback to the control device of a modern aircraft to increase pilot awareness of the flight envelope protection system...