Trajectory Tracking Control for a Stratospheric Airship Subject to Constraints and Unknown Disturbances

Abstract

This paper addresses the spatial trajectory tracking problem for a stratospheric airship with state constraints, input saturation and unknown disturbances. First, a Laguerre-based model predictive kinematic controller (LMPC) is proposed to tackle the state constraints and generate the desired velocity signal. To reduce the complexity of online optimization, Laguerre functions are applied to decrease the number of optimization variables by approximating the predicted control sequence. Second, in the dynamic loop, a sliding mode controller (SMC) with fast power rate reaching law (FPRRL) is introduced to track the desired velocity signal. The unknown disturbances in the dynamic model of airship are estimated and compensated by reduced-order extended state observer (ESO). An anti-windup compensator is incorporated into the FPRRL-based SMC controller to deal with the input saturation. Stability analysis implies that the tracking errors converge to a small neighborhood of zero. Comparative simulations about spatial straight and curve trajectory tracking are provided to evaluate the effectiveness and robustness of the proposed control scheme. INDEX TERMS Input saturation, model predictive control, state constraints, stratospheric airship, trajectory tracking, unknown disturbances.

Path Following Control for Underactuated Airships with Magnitude and Rate Saturation

“…For the target orientation control system, actuators saturation is an inevitable problem. Generally, the actuators saturation problem is handled by auxiliary systems and backstepping technique [ 28 , 30 , 48 , 49 ], smooth hyperbolic functions [ 27 , 50 ], model predictive control [ 9 , 19 , 51 , 52 ], or employing the generalized nonquadratic cost function [ 53 , 54 , 55 ] to guarantee the constrained control input. However, the consideration of system capability is always behind the consideration of achieving the control objective.…”

“…Once the constraints are violated, it may lead to performance deterioration or system instability [ 23 , 24 ]. Various control strategies are investigated to handle the saturation problem [ 25 , 26 , 27 , 28 , 29 ]. In Reference [ 30 ], a backstepping controller combined with auxiliary systems is designed to meet the input magnitude and rate constraints for a two-blade propeller system of an aircraft.…”

Robust Nonlinear Model Predictive Control for Ship Dynamic Positioning Using Laguerre Function

“…Furthermore, since the exponential decay factors are included in the Laguerre network, the increments of control signals expressed by Laguerre functions will converge to zero. Recently, the application of Laguerre function-based MPC (Lag-MPC) have received significant attention in various areas, e.g., permanent magnet synchronous machine [21], stratospheric airship trajectory tracking [22], non-minimal state space model [18], vehicle automation [23], [24], and autonomous underwater vehicle [25].…”

Unscented Kalman filter for airship model uncertainties and wind disturbance estimation

“…However, the complex dynamics of an airship and its vulnerability to wind disturbances pose a great challenge for designing an efficient control system. In literature, many nonlinear control approaches, such as Sliding Mode Control (SMC) [5,6], Back-Stepping Controller (BSC) [7], Model Predictive Control [8,9], and Nonlinear Model Predictive Controller (NMPC) [10], have been applied for the development of a control system for an airship and ground vehicles. Although they are robust control methods, they are usually designed for the worst-case scenario, sacrificing the nominal performance.…”