Development of a comprehensive finite element cervical spine model for studying neck injury of pilot

Introduction-The cervical spine is subjected to injury frequently,especially among pilots who are usually on the condition of high acceleration.Injuries of the cervical spine will be potential risk of damage to the spinal cord,which could be result in life threatening

Assessment of piloting behavior impact on landing risk of transport aircraft

The human factors and their interaction with other factors play an important role in the flight safety of transport aircraft.In this paper,a paradigm of risk assessment for transport aircraft interacting with piloting behaviors is proposed,with focus on landing which is the most accident-prone flight stage in aviation safety statistics.Model-based flight simulation serves as our data source for landing risk analysis under uncertainties.A digital pilot in the loop that reflects the human piloting behaviors is employed to facilitate simulation efficiency.Eight types of unsafe events in landing are identified from statistics.On this basis,the landing safety boundary is extracted via stochastic simulation to divide safety and hazardous flight status domains,which con-tributes to flight status management and risk warning.The simulation results indicate that appro-priate piloting behavior,which is active response and fast target acquisition with minimum overshoot and fluctuation,shows benefit to landing safety.The subset simulation technique is employed to further refine the boundary with less computational workload.Furthermore,the effect of airspeed,windspeed,and other factors on landing risk is also discussed.The proposed risk assess-ment method would help optimize operation procedure and develop targeted pilot training program.

Pilot time-varying control behavior modeling in refractory period with aircraft failures

Modeling human pilot control behavior aims to understand and describe how humans control aircrafts and devices,to provide a foundation for the study of the dynamic characteristics of the human-vehicle system.In the presence of aircraft failures,the human pilot has a control process of the refractory period,which may cause adverse aircraft-pilot couplings,and even lead to loss-of-control events.This refractory period will make the pilot emerge with time-varying and adaptive features.This paper investigates how pilot control behavior changes to adapt to the aircraft failure situation and develops a time-varying pilot model during the refractory period.Six aviation pilots performed a human-in-the-loop simulation experiment on a ground flight simulator to simulate the failure situations for a pitch-tracking task.To characterize the pilot’s time-varying response mechanism,a time-frequency-spectrum method was used to analyze the pilot control signal.Main innovations in the proposed model can be embodied in the description of the fuzziness,time-varying,and adaptation of the pilot for the failures in the refractory period.Based on fuzzy logic theory,the pilot’s judgment and identification of failures are described.The adaptation of manual control behavior to time-varying aircraft dynamics is depicted by adaptive model theory.Time-domain and time-frequency-spectrum analysis show that the simulation results of the pilot model are consistent with the human-in-the-loop experimental results.The model simulation evaluations are within the range of the experimental evaluation,which shows the rationality of the timevarying behavior model of the human pilot in a failure refractory period.The model has practical values for guiding the pilot to deal with abnormal conditions and predicting nonlinear aircraft-pilot couplings.

A Criterion Based on Closed-loop Pilot-aircraft Systems for Predicting Flying Qualities

During the process of aircraft design, the mathematical model of pilot control behavior characteristics is always used to predict aircraft flying qualities （FQ）. This is one of the important methods to avoid pilot-aircraft adverse coupling. In order to study the FQ criterion based on closed-loop pilot-aircraft systems, first, an experimental database is built, which includes 40 aircraft dynamics configurations and the corresponding flight simulation results. Second, the mathematical pilot models with a set of different aircraft configurations are obtained by this experimental database. Then, two FQ criteria, Neal-Smith criterion and Moscow Aviation Institute （MAI） criterion, are analyzed. And the relationship between the FQ level evaluated by actual pilot and the parameters of closed-loop pilot-aircraft systems is studied. Finally, an improved criterion of aircraft FQ is built based on the above two criteria. This new criterion is further used to predict FQ for four new aircraft dynamics configurations, and the prediction results verify its accuracy and practicability.

Prediction of nonlinear pilot-induced oscillation using an intelligent human pilot model

This paper proposes a method to predict nonlinear Pilot-Induced Oscillation(PIO)using an intelligent human pilot model.This method is based on a scalogram-based PIO metric,which uses wavelet transforms to analyze the nonlinear characteristics of a time-varying system.The intelligent human pilot model includes three modules:perception module,decision and adaptive module,and execution module.Intelligent and adaptive features,including a neural network receptor,fuzzy decision and adaptation,are also introduced into the human pilot model to describe the behavior of the human pilot accommodating the nonlinear events.Furthermore,an algorithm is proposed to describe the procedure of the PIO prediction method with nonlinear evaluation cases.The prediction results obtained by numerical simulation are compared with the assessments of flight test data to validate the utility of the method.The flight test data were generated in the evaluation of the Smart-Cue/Smart-Gain,which is capable of reducing the PIO tendencies considerably.The results show that the method can be applied to predict the nonlinear PIO events by human pilot model simulation.

Pilot multi-axis control behavior modeling of receivers in probe-and-drogue aerial refueling

The probe-and-drogue aerial refueling(PDR)task is seriously disturbed by the wind field,so it is difficult to obtain accurate visual information of the probe and drogue position.Additionally,the pilot needs to control the vertical,lateral and forwardbackward positions of the receiver through the stick and throttle lever,and the pitch and roll manipulation actions of the stick should be reasonably distributed.To simulate the behavior of the pilot’s visual perception and the stick manipulation allocation in the PDR task,three modules are designed,including the visual information acquisition module(VIAM),strategy switching module(SSM)and pilot control and action module(CAM).Based on the coherence function analysis of the flight simulation test data,it is proven that the pilot’s multi-axis control behavior can be decoupled,and the flight states to be controlled are determined.Finally,the established multi-axis receiver pilot model(EPM)is developed.Combined with the motion models of the receiver,the tanker and the refueling equipment,a PDR flight task simulation model is established,and the evaluation indicators for the receiver’s flight performance during the PDR task,such as capture time and settling time,are proposed.The PDR flight simulation model was used to build the ground-based flight simulation test platform,and the flight simulation test of the PDR task was carried out.A comparison between the flight simulation test data and the numerical simulation results shows that the calculation error is less than 10%,which verifies the correctness of the established pilot model.The pilot model can be used to evaluate the design scheme of the refueling equipment and the receiver flight control law and provide a theoretical reference for the flight test design of the PDR task.

Airworthiness Compliance Verification Method Based on Simulation of Complex System

A study is conducted on a new airworthiness compliance verification method based on pilot-aircraft-environment complex system simulation. Verification scenarios are established by ＂block diagram＂ method based on airworthiness criteria. A pi- lot-aircraft-environment complex model is set up and a virtual flight testing method based on connection of MATLAB/Simulink and Flightgear is proposed. Special researches are conducted on the modeling of pilot manipulation stochastic parameters and manipulation in critical situation. Unfavorable flight factors of certain scenario are analyzed, and reliability modeling of impor- tant system is researched. A distribution function of small probability event and the theory on risk probability measurement are studied. Nonlinear function is used to depict the relationship between the cumulative probability and the extremum of the critical parameter. A synthetic evaluation model is set up, modified genetic algorithm （MGA） is applied to ascertaining the distribution parameter in the model, and a more reasonable result is obtained. A clause about vehicle control functions （VCFs） verification in MIL-HDBK-516B is selected as an example to validate the practicability of the method.

Water takeoff performance calculation method for amphibious aircraft based on digital virtual flight

Owing to the strong coupling among the hydrodynamic forces,aerodynamic forces and motion of amphibious aircraft during the water takeoff process,the water takeoff performance is difficult to calculate accurately and quickly.Based on an analysis of the dynamics and kinematics characteristics of amphibious aircraft and the hydrodynamic theory of high-speed planing hulls,a suitable mathematical model is established for calculating the hydrodynamics of aircraft during water takeoff.A pilot model is designed to illustrate how pilots are affected by the lack of visual reference and the necessity to simultaneously control the pitch angle,flight velocity and other parameters during water takeoff.Combined with the aerodynamic model,engine thrust model and aircraft motion model,a digital virtual flight simulation model is developed for amphibious aircraft during water takeoff,and a calculation method for the water takeoff performance of amphibious aircraft is proposed based on digital virtual flight.Typical performance indicators,such as the liftoff time and liftoff distance,can be obtained via digital virtual flight calculations.A comparison of the measured flight test data and the calculation results shows that the calculation error is less than 10%,which verifies the correctness and accuracy of the proposed method.This method can be used for the preliminary evaluation of airworthiness compliance of amphibious aircraft design schemes,and the relevant calculation results can also provide a theoretical reference for the formulation of flight test plans for airworthiness certification.

Human factors quantification via boundary identification of flight performance margin

A systematic methodology including a computational pilot model and a pattern recognition method is presented to identify the boundary of the flight performance margin for quantifying the human factors. The pilot model is proposed to correlate a set of quantitative human factors which represent the attributes and characteristics of a group of pilots. Three information processing components which are influenced by human factors are modeled： information perception, decision making, and action execution. By treating the human factors as stochastic variables that follow appropriate probability density functions, the effects of human factors on flight performance can be investigated through Monte Carlo（MC） simulation. Kernel density estimation algorithm is selected to find and rank the influential human factors. Subsequently, human factors are quantified through identifying the boundary of the flight performance margin by the k-nearest neighbor（k-NN） classifier. Simulation-based analysis shows that flight performance can be dramatically improved with the quantitative human factors.