Abstract:During the atmospheric entry phase of Mars probe, there exist uncertainties such as model parameters error. Based on direct feedback linearization theory, an active disturbance rejection sliding mode entry guidance method is proposed. Firstly, the tracking system model is linearized through the feedback linearization method. On this basis, the sliding mode control law is designed, and the linear extended state observer is used to estimate the unknown uncertain value of the system and compensate it in the control law. In addition, the lateral guidance law of the atmospheric entry phase is also given. The simulation results show that compared with the feedback linearization method, the guidance law designed by this method effectively reduces the influence of model parameters error on the guidance precision, and achieves good tracking effects of the reference trajectory and improves the accuracy of the probe's parachute deployment point.