Sliding Mode Observer for Drag Tracking in Entry Guidance

Finite-time super-twisting sliding mode control for Mars entry trajectory tracking

“…Taking into account the above-mentioned attractive features and challenges faced by the Mars entry mission, a great deal of control approaches including PID control [9], nonlinear control [10,11], active disturbance rejection control (ADRC) [12], adaptive control [13], model predictive control [14] and sliding mode control (SMC) [15], etc., have been proposed to address Mars entry trajectory tracking problem. A classical PID control scheme has been used to track the planned entry trajectory and demonstrate the effectiveness of the planning method in [9].…”

RBF neural network based second-order sliding mode guidance for Mars entry under uncertainties

“…(16) can be rewritten as the following error forṁ e 1 = e 2 e 2 = F + Gu + −ξ * 1 (19) Selecting the first sliding surface as follows (20) where ξ * 1 is the weighted nominal trajectory, which are a series of values that are stored as a function of time.…”

“…Entry vehicles are commanded to fly at a constant trim angle of attack, and the controlled guidance of the vehicle is achieved only through modulating the bank angle with a reaction control system (RCS). The three degree-of-freedom (DOF) dynamic equations of Mars entry vehicle, defined with respect to the Mars centered Mars-fixed coordinate system are given by [20][21][22] …”

“…Recently, the sliding control methodology has been considered as an elementary approach to robust control, and a perfect performance can be, in principle, achieved in the presence of parameter inaccuracy [17][18][19]. In order to suppress the adverse impact of uncertainties in atmospheric density and then improve entry guidance accuracy, standard sliding mode variable structure control (SMVSC) and multiple sliding surface guidance (MSSG) were respectively adopted to design the Mars entry guidance law [20][21][22]. Both theoretical analysis and simulation results show that the higher-order sliding mode (HOSM) has the desired property of practically eliminating the dangerous chattering often featuring the standard (first-order) sliding mode [17,22].…”

Mars atmospheric entry guidance for reference trajectory tracking

“…With this frame, we don't necessarily measure the atmospheric models and the vehicle's aerodynamic errors. In [14], a sliding mode state and perturbation observer (SMSPO) is used to estimate drag and drag rate as well as the modeling error, the SM-SPO was integrated with an FL tracking law to provide an estimate of the modeling error in the drag dynamics. The main contributions of this paper are: a) A novel Terminal Sliding Mode Control for tracking a reference trajectory is proposed.…”