A bank angle protection method based on exponential potential functions

This paper presents a bank angle protection design for an aircraft model based on potential functions. In this design the envelope limit is treated as a virtual obstacle and an exponential repulsive potential function is proposed to generate the envelope protection command signal using a gradient descent law. The proposed design has a fixed triggering point at certain distance to the envelope limit. Comparison is made with the design employing quadratic potential functions to show the benefits of the new design. Results show that the new design has less interference in pilot operations, and the location of the triggering point has smaller effects on the performance. Moreover, a coeffcient can be added to the potential function as an additional tuning parameter which determines when the envelope protection law will modify pilot commands significantly. Simulation examples of bank angle protection design for linearized NASA’s Transport Class Model are provided to verify the efficacy of the proposed design.