Adaptive Sliding Control of Six-DOF Flight Simulator Motion Platform

There is proposed an adaptive sliding controller in task space on the base of the linear Newton-Euler dynamic equation of motion platform in a six-DOF flight simulator. The uncertain parameters are divided into two groups： the constant and the time-varying. The controller identifies constant uncertain parameters using nonlinear adaptive controller associated with elimination of the influences of time-varying uncertain parameters and compensation of the external disturbance using sliding control. The results of numerical simulation attest to the capability of this control scheme not only to, with deadly accuracy, identify parameters of motion platform such as load, inertia moments and mass center, but also effectively improve the robustness of the system.

FUZZY GLOBAL SLIDING MODE CONTROL BASED ON GENETIC ALGORITHM AND ITS APPLICATION FOR FLIGHT SIMULATOR SERVO SYSTEM

To alleviate the chattering problem, a new type of fuzzy global sliding mode controller （FGSMC） is presented. In this controller, the switching gain is estimated by fuzzy logic system based on the reachable conditions of sliding mode controller（SMC）, and genetic algorithm （GA） is used to optimize scaling factor of the switching gain, thus the switch chattering of SMC can be alleviated. Moreover, global sliding mode is realized by designing an exponential dynamic sliding surface. Simulation and real-time application for flight simulator servo system with Lugre friction are given to indicate that the proposed controller can guarantee high robust performance all the time and can alleviate chattering phenomenon effectively.

Sliding Mode Controller Design for Position and Speed Control of Flight Simulator Servo System with Large Friction

Flight simulator is an important device and a typical high-performance position and speed servo system used in the hardware-in-the-loop simulation of flight control system. Friction is the main nonlinear resistance in the flight simulator servo system, especially in a low-speed state. Based on the description of dynamic and static models of a nonlinear Stribeck friction model, this paper puts forward sliding mode controller to overcome the friction, whose stability is

QFT control based on zero phase error compensation for flight simulator

To improve the robustness of high-precision servo systems, quantitative feedback theory （QFT） which aims to achieve a desired robust design over a specified region of plant uncertainty is proposed. The robust design problem can be solved using QFT but it fails to guarantee a high precision tracking. This problem is solved by a robust digital QFT control scheme based on zero phase error （ZPE） feed forward compensation. This scheme consists of two parts： a QFT controller in the closed-loop system and a ZPE feed-forward compensator. Digital QFT controller is designed to overcome the uncertainties in the system. Digital ZPE feed forward controller is used to improve the tracking precision. Simulation and real-time examples for flight simulator servo system indicate that this control scheme can guarantee both high robust performance and high position tracking precision.

ZERO PHASE ERROR REAL TIME CONTROL FOR FLIGHT SIMULATOR SERVO SYSTEM

Flight simulator is an important device and a typical high performanceposition servo system used in the hardware-in-the-loop simulation of flight control system. Withoutusing the future desired output, zero phase error controller makes the overall system's frequencyresponse exhibit zero phase shift for all frequencies and a very small gain error at low frequencyrange can be achieved. A new algorithm to design the feed forward controller is presented, in orderto reduce the phase error, the design of proposed feed forward controller uses a modified plantmodel, which is a closed loop transfer function, through which the system tracking precisionperformance can be improved greatly. Real-time control results show the effectiveness of theproposed approach in flight simulator servo system.

Realization of nonlinear PID with feed-forward controller for 3-DOF flight simulator and hardware-in-the-loop simulation

As friction, intrinsic steady-state nonlinearity poses a challenging dilemma to the control system of 3-DOF （three degree of freedom） flight simulator, a novel hybrid control strategy of nonlinear PID （proportionalintegral-derivative） with additional FFC （feed-forward controller） is proposed, and the hardware-in-the-loop simulation results are also given. Based on the description of 3-DOF flight simulator, a novel nonlinear PID theory is well introduced. Then a nonlinear PID controller with additional FFC is designed. Subsequently, the loop structure of 3-DOF flight simulator is also designed. Finally, a series of hardware-in-the-loop simulation experiments are undertaken to verify the feasibility and effectiveness of the proposed nonlinear PID controller with additional FFC for 3-DOF flight simulator.

Design and Analysis for a Three-Rotational-DOF Flight Simulator of Fighter-Aircraft

Most of researchers focused on traditional six degrees of freedom(DOF) Stewart flight simulator,which can not be adaptive in fighter?aircraft flight simulator. A three rotational DOF flight simulator of fighter?aircraft based on dou?ble parallel manipulator and hybrid structure is presented. The flight simulator is composed of two identical 3?RRS(revolute?revolute?spherical) spherical parallel manipulators and one cabin,called Twins. The cabin has an additional independent DOF for 360° continuous rotation,so it can be applied as a flight simulator for a fighter?aircraft to achieve spin maneuvering. Because of the introduction of the hybrid structure and double parallel manipulator of themechanism,the redundancy exists with respect to both kinematics and actuation. Kinematics is carried out and Jaco?bian matrix is established by means of screw theory. The inverse kinematics is given out by the analytical method. 64 groups inverse solutions are showed in a table by permutation. Forward kinematics is solved by an e ectively numeri?cal method. The forward numerical method is realized based on the analytically inverse kinematics and Jacobian matrix. The numerical examples show that the forward numerical method can be used in real?time control. The rollingmotion is considered in forward kinematics and a numerical example is given out. The proposed flight simulator can spin and there are three rotational DOF with a hybrid structure so that the novel flight simulator can be used in the field of the fighter?aircraft for pilots to train.

A Potential Flow Based Flight Simulator for an Underwater Glider

Underwater gliders are recent innovative types of autonomous underwater vehicles （AUVs） used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.

Zero phase error control based on neural compensation for flight simulator servo system

Using the future desired input value, zero phase error controller enables the overall system＇s frequency response exhibit zero phase shift for all frequencies and a small gain error at low frequency range, and based on this, a new algorithm is presented to design the feedforward controller. However, zero phase error controller is only suitable for certain linear system. To reduce the tracking error and improve robustness, the design of the proposed feedforward controller uses a neural compensation based on diagonal recurrent neural network. Simulation and real-time control results for flight simulator servo system show the effectiveness of the proposed approach.

Model identification of hydraulic flight simulator based on improved particle swarm optimization and wavelet analysis

A new model identification method of hydraulic flight simulator adopting improved panicle swarm optimization （PSO） and wavelet analysis is proposed for achieving higher identification precision. Input-output data of hydraulic flight simulator were decomposed by wavelet muhiresolution to get the information of different frequency bands. The reconstructed input-output data were used to build the model of hydraulic flight simulator with improved particle swarm optimization with mutation （IPSOM） to avoid the premature convergence of traditional optimization techniques effectively. Simulation results show that the proposed method is more precise than traditional system identification methods in operating frequency bands because of the consideration of design index of control system for identification.

Numerical Modeling of a New Flight Simulator Enabling Continuous 360⁃Degree Spinning and Translational Motion

This paper presents a new nine⁃degree⁃of⁃freedom parallel mechanism,which can be applied as a flight simulator.The mechanism is composed by Stewart turntable and another three⁃axis turntable.The Stewart platform can realize six⁃degree⁃of⁃freedom movement in space,but the working space is limited.After the three⁃axis turntable is installed,the rotation space can be increased to simulate more realistic flight conditions.This paper analyzes the new flight simulator from kinematics and dynamics aspects.In addition,the flight simulator is simulated and analyzed based on the MATLAB/Simulink simulation system.The results obtained from the numerical simulations is planned to be used for the practical manufacturing and applications of the new platform.

Bayesian Method Reliability of Flight Simulator

This paper introduces the basic viewpoints and characteristics of Bayesian statistics. Which provides a theoretical basis for solving the problem of small sample of flight simulator using Bayesian method. A series of formulas were derived to establish the Bayesian reliability modeling and evaluation model for flight simulation equipment. The two key problems of Bayesian method were pointed out as follows： obtaining the prior distribution of WeibuU parameter, calculating the parameter a posterior distribution and parameter estimation without analytic solution, and proposing the corresponding solution scheme.

The Relation between Mental Workload and Face Temperature in Flight Simulation

In this research, we study the relationship between mental workload and facial temperature of aircraft participants during a simulated takeoff flight. We conducted experiments to comprehend the correlation between work and facial temperature within the flight simulator. The experiment involved a group of 10 participants who played the role of pilots in a simulated A-320 flight. Six different flying scenarios were designed to simulate normal and emergency situations on airplane takeoff that would occur in different levels of mental workload for the participants. The measurements were workload assessment, face temperatures, and heart rate monitoring. Throughout the experiments, we collected a total of 120 instances of takeoffs, together with over 10 hours of time-series data including heart rate, workload, and face thermal images and temperatures. Comparative analysis of EEG data and thermal image types, revealed intriguing findings. The results indicate a notable inverse relationship between workload and facial muscle temperatures, as well as facial landmark points. The results of this study contribute to a deeper understanding of the physiological effects of workload, as well as practical implications for aviation safety and performance.

Research of Compound Controller for Flight Simulator with Disturbance Observer

A compound controller is proposed to alleviate the considerable chattering in output of zero phase error tracking controller （ZPETC）, when the flight simulator losses command data of simulation signal. Besides, the shortcomings, caused by conventional differential methods in retrieving velocity and acceleration signals, are avoided to a certain extent. The compound controller based on disturbance observer （DOB） is composed of a feed-forward controller and a feedback controller. It estimates velocity and acceleration of unknown tracking signal, and also velocity response with an approximate method for differential. The experiments on a single-axis flight simulator show that the proposed method has strong robustness against parameter perturbations and external disturbances, owing to the introduced DOB. Compared with the scheme with ZPETC, the proposed scheme possesses more simple design and better tracking performance. Moreover, it is less sensitive to position command distortion of flight simulator.

Design and Experiments of Model-free Compound Controller of Flight Simulator

A model-flee compound controller design method is proposed to achieve the wide frequency bandwidth requirement of flight simulators. The method based on quantitative feedback theory, acquires system uncertainty under different working conditions through closed-loop identification with power spectrum estimation. Then in controller designing, it makes a trade, off between the strict requirements for magnitude-frequency characteristics and those for phase-frequency characteristics of flight simulators, by converting the indices of magnitude-frequency characteristics of flight simulators into quantitative feedback theory-based tracking specification bounds and using feedforward controller to attain the required phase-flequency characteristics. Simulation and experimental results indicate that, when used to design inner flame controller of flight simulator, the proposed method can fulfill the requirements for wide frequency bandwidth indices. Compared with other controller design methods, it has the property of model-free and transparency.

Modeling and software implementation of flight system for simulator of a new fighter

Real-time modeling and simulation of flight system are the key parts of simulator. After describing the architecture of simulator for a newer fighter, author presents the composition of flight system and its mathematic models. In this paper, aircraft is regarded as an elastic flight body. And a new integrated algorithm which can remedy the shortcoming of Euler method and four-element method is used to calculate the Eulerian angles of aircraft. Finally, the software implementation of the flight system is given in the paper.

ADAPTIVE BACKSTEPPING SLIDING MODE CONTROLLER FOR FLIGHT SIMULATOR BASED ON RBFNN

For flight simulator system,a kind of Adaptive Backstepping Sliding Mode Controller(ABSMC)based on Radial Base Function Neural Network(RBFNN)observer is presented.The sliding mode control theory is famous by its characteristic that it is insensitive to the external disturbances and parameters uncertainties.Combining this characteristic with Backstepping method can simplifies the controller design.And the addition of the terminal attractor can make the arrival time shorten greatly.However,too large external disturbances and parameters uncertainties are still not allowed to the system,and the design process of ABSMC does not have the upper bound information of disturbance until a RBFNN observer is designed to solve the problems.The simulation results show that the proposed scheme can improve the tracking precision and reduce the chattering of the control input,and the system has a higher robustness.

PARAMETER IDENTIFICATION OF LUGRE FRICTION MODEL FOR FLIGHT SIMULATION SERVO SYSTEM BASED ON ANT COLONY ALGORITHM

In light of the high nonlinearity of LuGre friction model, a novel method based on ant colony algorithm(ACA) for identifying the friction parameters of flight simulation servo system is proposed. ACA is a parallelized bionic optimization algorithm inspired from the behavior of real ants, and a kind of positive feedback mechanism is adopted in ACA. On the basis of brief introduction of LuGre friction model, a method for identifying the static LuGre friction parameters and the dynamic LuGre friction parameters using ACA is derived. Finally, this new friction parameter identification scheme is applied to a electric-driven flight simulation servo system with high precision. Simulation and application results verify the feasibility and the effectiveness of the scheme. It provides a new way to identify the friction parameters of LuGre model.

Dynamic flight stability of a bumblebee in forward flight

The longitudinal dynamic flight stability of a bumblebee in forward flight is studied. The method of computational fluid dynamics is used to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvector analysis are employed for solving the equations of motion. The primary findings are as the following. The forward flight of the bumblebee is not dynamically stable due to the existence of one （or two） unstable or approximately neutrally stable natural modes of motion. At hovering to medium flight speed [flight speed Ue = （0-3.5）m s^-1; advance ratio J = 0-0.44], the flight is weakly unstable or approximately neutrally stable; at high speed （Ue = 4.5 m s^-1; J = 0.57）, the flight becomes strongly unstable （initial disturbance double its value in only 3.5 wingbeats）.

Dynamic flight stability of hovering model insects:theory versus simulation using equations of motion coupled with Navier-Stokes equations

In the present paper, the longitudinal dynamic flight stability properties of two model insects are predicted by an approximate theory and computed by numerical sim- ulation. The theory is based on the averaged model （which assumes that the frequency of wingbeat is sufficiently higher than that of the body motion, so that the flapping wings＇ degrees of freedom relative to the body can be dropped and the wings can be replaced by wingbeat-cycle-average forces and moments）; the simulation solves the complete equations of motion coupled with the Navier-Stokes equations. Comparison between the theory and the simulation provides a test to the validity of the assumptions in the theory. One of the insects is a model dronefly which has relatively high wingbeat frequency （164 Hz） and the other is a model hawkmoth which has relatively low wingbeat frequency （26 Hz）. The results show that the averaged model is valid for the hawkmoth as well as for the dronefly. Since the wingbeat frequency of the hawkmoth is relatively low （the characteristic times of the natural modes of motion of the body divided by wingbeat period are relatively large） compared with many other insects, that the theory based on the averaged model is valid for the hawkmoth means that it could be valid for many insects.