Sliding mode lateral stand-off tracking control of finless airship

The paper addresses the stand-off tracking control problem for an underactuated finless airship having uncertainties and wind disturbances. The outer loop design sliding surface is based on the line of sight angle rate and its distance from a target, for the inner control loop, generates the reference heading angle commands, the proposed backstepping sliding-mode controller based on the yaw error angle generating commands by actuating the yaw-gyro propulsion. Theoretical results show that the closed loop system is globally asymptotically stable. With the assumption of target movement as disturbances, this framework is also applied to linear and variable direction moving targets. The numerical simulations are conducted for stand-off tracking control for a stationary and a moving target or targets, having servos dynamics and sensor models with measurement noises and external disturbances, and the results verify the effectiveness of the proposed framework for stand-off target tracking. The results obtained by comparing traditional proportional navigation and LQR design demonstrate the capability of the airship to execute a stand-off trajectory tracking with uncertainties and wind disturbances.