Lingyu Yang

Modeling and attitude control of aircraft with variations in mass and center of gravity

Large scale variations in the mass or center of gravity (C.G.) pose serious problems for the control of aircraft in situations as heavy load airdrop on cargo aircraft, the airliners which employ the active C.G. control technology, aircraft with structural damages during the flight. To solve the problem of attitude control of such aircraft, a general model for the aircraft is established and a disturbance rejection attitude controller is proposed. The proposed model comprises of a 6-DOF dynamics model and the mass and C.G. variation model, which can handle various mass or C.G. variations and can reflect the dynamic couplings introduced by such variations. For the attitude control of such aircraft, based on the framework of observation and compensation, an explicit model following controller with the extension of extended state observer (ESO) is established. Real-time simulations demonstrate that the proposed model can accurately reflect the aircrafts dynamic responses during the variations, and with the compensation from the ESO, the model following controller can improve the performance and meet the requirements of precision attitude control.

Modeling and attitude control of aircraft with center of gravity variations

Active center of gravity (C.G.) control is a key technology of vehicle management system, which has been extensively used in various types of aircraft. With active C.G. control system, aircraft may deviate from its known dynamics due to the C.G. offset, thus bringing new problems to the existing flight control system. A new design approach of the attitude control system of aircraft with C.G. variations is proposed in this paper.

Control allocation and management for aircraft with multiple effectors

This paper focuses on the control redundancy problem due to the increase of control effectors of advanced aircrafts. Based on the current control allocation research, this paper further puts forward the concept of control allocation and management system. The bases sequenced control allocation method is proposed firstly, and then some management strategies are introduced to the control allocation process of bases sequenced method. The candidate effectors and optimal indexes are managed according to the information of flight conditions, mission requirements and effectors working conditions, and engineering experience is also considered in this system. The key aspects of the proposed system are illustrated by a 6DOF nonlinear aircraft model. The simulation results show that the functions of control allocation system are extended and the system adaptability to the flight status, mission requirements and effectors failure conditions are improved.

Control Allocation Based Reconfigurable Flight Control for Aircraft with Multiple Control Effectors

A control allocation based reconfigurable flight controller is presented for aircraft with multiple control effectors because of the redundancy effectors feature. The main idea is to use the remaining control effectors to cancel or compensate the effects of the failure effectors. The control law was designed by trajectory linearization control method, which can provides robust performance at all stages of flight. And the desired moments are the outputs of the trajectory linearization controller. A novel optimal control allocation method, named bases sequence optimal control allocation (BSOCA) method, is proposed to distribute the deflections of control effectors of the aircraft to generate desired moments. A control effectors management system based on BSOCA method is presented to achieve flight reconfiguration under effector failures. The simulation results show that the control allocation based reconfigurable flight controller can adapt the effector failures and maintain stability and acceptable handling qualities.

A WiFi-enabled indoor air quality monitoring and control system: The design and control experiments

Particulate matter pollution becomes an increasingly important problem in developing countries and poses a hazard to human health especially in indoor environment. At the same time, modern buildings are equipped with advanced sensing and control technologies, offering control and optimization capabilities over a large range of parameters. This paper proposes an open platform of a WiFi-enabled indoor air quality monitoring and control system, which could be incorporated into such a ‘smart building’ structure. The complete software and hardware design of this system is presented, along with a series of control experiments. The proposed system operates over an existing WiFi wireless network utilizing the MQTT protocol. It is capable of monitoring the indoor air quality as well as controlling an air purifier to regulate the particulate matters concentration. Experiment results under a real world office environment demonstrate the effectiveness of the proposed design.

Online learning and inference based flight envelope estimation for aircraft loss-of-control prevention

Aircraft loss-of-control (LOC) is the major contributing factor to fatal accidents and is characterised by the manoeuvring of aircraft beyond the allowable flight envelopes. This paper proposes an online learning and inference based method for aircraft flight envelope estimation in order to prevent aircraft LOC. The lift and drag coefficients of the aircraft are identified online using an extended Kalman filter and the aircraft flight dynamics. A Gaussian process regression model then learns and infers the up-to-date form of the lift curve from both prior knowledge and the identification data. The extremum of the inferred lift curve, including the maximum lift coefficient and the critical angle of attack are used to compute the flight envelope estimate of the aircraft. Numerical simulation on the NASA generic transportation model (GTM) shows that the proposed method can effectively estimate the aircraft lift and drag coefficients, and by using the extremum on the up-to-date lift curve inferred, return the flight envelope under a wingtip impairment condition.

Model-based analysis of boundary layer ingestion effect on lateral-directional aerodynamics using differentiated boundary conditions:

The noteworthy feature of aircraft with distributed propulsion configuration is the integration of a blended-wing-body type airframe and an embedded distributed propulsion system, thus inducing the specific boundary layer ingestion effect. Different boundary layer ingestion effects on the distributed engines may generate asymmetric flow fields on the airframe surface, and then lead to the unique lateral-directional aero-propulsive close coupling. To investigate the lateral-directional aerodynamics influenced by boundary layer ingestion, a new comprehensive computational method based on the differentiated boundary conditions is proposed. This method uses a synthetic three-dimensional computational model including the airframe and multi-engine to analyze the aerodynamic characteristics, and the essential boundary conditions can be extracted from the thermodynamic distributed propulsion system model to represent the different boundary layer ingestion intensities on the left and right engines. Subsequently, detailed model-based analyses of boundary layer ingestion influences on the lateral-directional aerodynamic characteristics are conducted, and the influence regularities under different flight states are revealed. All the results demonstrate that the differentiated boundary layer ingestion intensities on distributed engines can certainly affect the roll and yaw aerodynamic performance of the distributed propulsion configuration aircraft.

Analysis of coupling effects between flight and propulsion systems for DPC aircraft

The noteworthy feature of aircraft with distribute propulsion configuration is the integration of the fuselage and semi-embedded distributed propulsion system, which brings strong coupling effects between flight and propulsion systems. The aim of this article is to systematically investigate the coupling effects due to boundary layer ingestion under different flight states. As the basis, the definition of boundary layer ingestion is put forward and the modeling process of distributed propulsion system is described in detail. An analysis method based on the distributed propulsion model and CFD computation is proposed. By using this method, the coupling characteristics between flight and propulsion system are generally analyzed under different flight heights and velocities. The results of this study demonstrate that the coupling effects can significantly improve the aerodynamic performance.

Aircraft centre-of-gravity estimation using Gaussian process regression models

Aircraft centre of gravity (C.G.) is important for aircraft safety and performance. This paper proposes the use of Gaussian process regression (GPR) models for the estimation of the C.G. location of fixed-wing aircraft. The major benefit of using a GPR model is that it is a data-based approach explicitly tackling uncertainties caused by the quality and quantity of the data as well as sensor measurement noise. The proposed method consists of two steps: the estimation of the fuel tanks C.G. using the GPR model trained with fuel weight property data, and the computation of aircraft C.G. by the C.G. equation. A numerical case study of a transport aircraft shows that the proposed method achieves small mean squared error and gives good estimate of the aircraft C.G. under simulated flight scenarios.

Research on robust control allocation for the advanced configuration aircraft

The accuracy of control allocation algorithms relies on control effectiveness matrix. To address this issue, this paper focuses on the robustness of control allocation. Several existing robust control allocation algorithms are analyzed at first. Then performance evaluation criteria for robust control allocation, which are designed for flight control, are proposed based on performance requirements of flight control system. Comparisons among existing robust control allocation algorithms are conducted via simulations. Finally, robustness of existing robust control allocation algorithms is evaluated according to the proposed robustness evaluation criteria.