## 1 Introduction
[11] combined the model following the method with the \(H_{\infty}\) synthesis to construct a dynamic controller, which could improve the performance of the conventional ALS, even under severe weather conditions. [PERSON] et al. [12] presented a comprehensive autopilot for crosswind landing. The individual control loops were designed while using robust control methods and classical loophsaping, which provided a complete qualitative design strategy. A flare control law was exploited via multi-channel \(H_{\infty}\) synthesis [13]. The controller controlled the vertical speed of an aircraft while minimizing the influence of windshear and ground effects. Although the autonomous technologies can improve flight operations and overall aircraft performance, pilots will remain at the heart of operations in practice. Autonomous technologies are paramount to supporting pilots, thus enabling them to focus less on aircraft operation and more on strategic decision-making and mission management during landing. The energy approach to the flight control was used to access the current and predict the future states of an aircraft in order to improve the informational and situational awareness of the aircrew [14]. The landing maneuver was simulated with the ahead obstacle and the engine failure, which showed the correction of the algorithm. Another good project was Clean Sky 2 of European Clean Sky [15]. One of the themes of the project was to make use of advanced autonomous technologies and cockpit-navigation for large passenger aircraft to make the aircraft more reliable. Figure 1: Illustration of landing maneuver. Although the above works make great contribution to aircraft autolanding system, there are still some problems that have not been solved. During the landing phase, the velocity of the aircraft is lower than that under the least drag and the aircraft is in boundary flight condition. Hence, the aircraft easily becomes unstable and even becomes a non-minimum phase (NMP) system. Most of the aforementioned papers do not include analyses on this situation. Trajectory tracking problems of NMP systems are challenging. [PERSON] et al. (2016); [PERSON] et al. (2016) proposed the SI algorithm to solve the tracking problem of the NMP systems and got bounded solutions based on the inverse system and differential geometry theory. Subsequently, various studies for the application expansion of the SI algorithm have been implemented. [PERSON] et al. (2018) used the SI algorithm for feedforward control of flexible multibody systems. [PERSON] et al. (2019) applied a poles placement state feedback control of an induction machine system while using the stable dynamic inversion methodology. A new method to calculate the causal solution of SI was proposed to precisely track the airspeed and altitude for unmanned aerial vehicles ([PERSON] et al., 2020). This paper proposes an integrated control method that combines the SI algorithm and \(H_{\infty}\) synthesis for civil aircraft autolanding system in order to solve the trajectory tracking and disturbance rejection problem simultaneously, with the adaptive ways of thinking to propose some algorithms of control that are of wider application ([PERSON] et al., 2020). The main contributions of this paper are summarized, as follows:  
1. A robust autolanding controller (RAC) is designed based on \(H_{\infty}\) synthesis, which can handle with the disturbances during landing procedure, such as windshear and noise. 2. A stable inversion (SI) based robust autolanding controller (SIRAC) is proposed to improve the RAC scheme. The SI algorithm is used to enhance the trajectory tracking ability of aircraft autolanding system, which calculates the desired input and state through the desired landing trajectory. While the disturbance rejection ability is also increased due to the integration of the SI algorithm and \(H_{\infty}\) synthesis. The rest of the paper is organized, as follows: Section 2 deals with the models of the aircraft, actuator, windshear, and the desired landing trajectory used in this study.