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This paper presents the results of a quasi-transfer-of-training experiment performed in the SIMONA Research Simulator at Delft University of Technology. The goal of the experiment was to quantify the effects of simulator motion feedback on the training of skill-based human operator control behavior using multimodal human operator modeling techniques. In the experiment, 24 task-naive participants, divided over two groups, were trained in performing a skill-based compensatory pitch tracking task. The first group was trained in a fixed-base setting and transferred to a moving-base condition; the second group trained with motion feedback and then transferred to the fixed-base condition. The group that received initial moving-base training showed quick adaptation of their control behavior upon transfer to the fixed-base setting and limited further learning. The group that trained in the fixed-base condition showed only limited transfer of their learned control strategy to the moving-base setting. After transfer, this group initially continued to rely exclusively on visual feedback, as indicated by very low identified motion response gains, and required an amount of moving-base training identical to the other group to develop multimodal control behavior. These results suggest that motion feedback is required for effective initial simulator-based training of skillbased manual control. [ABSTRACT FROM AUTHOR]

Low-cost motion systems have been proposed for certain training tasks that would otherwise be performed on high-performance full-flight simulators. These systems usually have lower bandwidth and lower smoothness. The influence of these characteristics on pilot perception and control behavior is unknown and needs to be investigated. In this paper, this is done by simulating a model of a simulator with limited capabilities on a high-end simulator. The platform limitations, which consist of a platform filter, time delay, and noise characteristics, can then be removed one by one, and their effect on control behavior is studied in isolation. An experiment was conducted to identify pilot perception and control behavior in a closed-loop control task. The time delay and noise characteristics of the simulators did not have an effect. However, it was found that the bandwidth of the motion system had a significant effect on performance and control behavior. Results indicate that the motion cues were barely used at all in conditions with a low bandwidth, and that participants relied on the visual cues to generate lead to perform the control task. [ABSTRACT FROM AUTHOR]

To improve the tuning process of flight simulator motion cueing filters and support the development of objective simulator motion cueing requirements, a better understanding of how multimodal pilot control behavior is affected by simulator motion fidelity is required. To this end, all experiment is conducted in which seven pilots perform a pitch target-following disturbance-rejection task in a simulator under four different motion cueing settings. In addition, the task is performed in a real aircraft, which serves as the baseline condition. Differences between the simulator and aircraft experiment setup are minimized. Small remaining differences in the display and the sidestick setup slightly affected the experiment dependent measures. However, the effects introduced by the motion cueing settings are far more apparent. When motion fidelity improves to full aircraft motion, pilots are able to improve performance in attenuating the disturbance signal significantly. In addition, for improved motion fidelity, a change in multimodal pilot control behavior is observed by a decrease in pilot visual lead, while visual and vestibular perception delays increase. Pilot performance and control behavior in the simulator condition with full pitch motion and filtered pitch and center of gravity heave motion is most similar to the in-flight condition. [ABSTRACT FROM AUTHOR]

Knowledge about motion perception thresholds is essential for simulator motion cueing. Thresholds are generally measured in a passive experimental setup in which subjects do not actively influence their motion. For flight simulation applications, it is useful to also investigate thresholds during control tasks, where pilots actively influence the motion they sense. In this paper, thresholds were estimated during an active control task using a pilot model parameter identification method. A comparison with conventional passive threshold measurements was made. The threshold identification method was based on a multichannel pilot model extended with a nonlinear absolute threshold element. Two experiments were performed in a flight simulator: a passive experiment to measure the sensory pitch threshold, and an active experiment with a compensatory control task to identify the active pitch threshold. In the active experiment, the gain of the inertial motion amplitude was varied and two types of compensatory control tasks were considered. For both tasks, the pitch threshold was identifiable only for high motion gain levels. The measured passive threshold was lower than other values found in literature. The threshold identified from the active control task was higher than the measured passive threshold, but it was comparable with passive threshold values reported in other studies. [ABSTRACT FROM AUTHOR]

A method to estimate nonlinear dynamics in pilot manual control behavior is described, and it is applied to estimating the magnitude of vestibular thresholds from experimental tracking data. The three-step identification procedure uses time-domain manual tracking data to identify the parameters of a multimodal pilot model that includes a nonlinear absolute motion perception threshold. The procedure is evaluated using experimental data and pilot model simulations. To vary the fraction of the applied simulator motion that is below threshold and the possible effects of the vestibular threshold on the adopted control strategy, values of 0.25, 0.5, 0.75, and 1 for the motion cueing gain were evaluated. For both the experimental and simulation data, the identification method yields the most consistent and accurate results for the unity motion gain. Reliable estimates of pilot motion perception thresholds from active manual tracking data require sufficient excitation of the vestibular modality. [ABSTRACT FROM AUTHOR]

The article focuses on a technique used in estimating real-time wind-data through Automatic Dependent Surveillance-Broadcast (ADS-B). ADS-B renders velocity vector data that were assessed through a global satellite navigation system, where it applies on the aircraft that is at the same altitude travel and true airspeed in all directions. Results of a study showed that ADS-B data and weather predictions by the Global Forecast System showed mean absolute errors of 9.5 kilotons and 30 degrees.

This paper presents the experimental behavior measurement method, a novel aircraft handling qualities evaluation method, that enables an objective evaluation and eliminates a number of the disadvantages of current handling qualities assessment methods. The experimental behavior measurement method tries to overcome the omissions of the handling qualities during tracking method and is complementary to the Cooper-Harper rating method. The experimental behavior measurement method determines the aircraft handling qualities based on measurement of the control behavior during target-tracking tasks with an increasing level of difficulty. The main metric of the experimental behavior measurement method is the crossover-regression frequency. This paper will provide the theoretical background of the experimental behavior measurement method and a case study that shows the application of the method. The case study evaluates the effect of the amount of aeroelasticity on the longitudinal handling qualifies of three aircraft models, although the experimental behavior measurement method is not limited to aeroelastic handling qualities. The experiment was performed in a motion-based flight simulator with eight Royal Netherlands Air Force test pilots. The results of the case study revealed significant changes in the crossover frequency matching the altered handling qualities. [ABSTRACT FROM AUTHOR]

In continuous manual control tasks, human controllers adapt their control strategy to the dynamics of the controlled element. This compensation for the controlled-element dynamics is performed around the pilot-vehicle system crossover frequency, in order to obtain satisfactory performance of the combined pilot-vehicle system, but is also seen to extend to frequencies well above crossover. For a controlled element representing the linearized pitch dynamics of a small conventional jet aircraft, an extension to the models for pilot equalization described in the literature was found to be needed for the modeling of the adopted pilot equalization dynamics over a wide frequency range. Measured pilot describing functions revealed that pilots use a combination of low-frequency lag and high-frequency lead equalization to compensate for the characteristics of these typical aircraft pitch dynamics around the short-period mode. An additional high-frequency lead term in the pilot equalization transfer function was found to allow for the modeling of these adopted equalization dynamics over a wide frequency range, thereby also yielding a significant increase in the percentage of measured control inputs that is explained by the pilot model. Furthermore, for this controlled element the extended model for the equalization dynamics was found to be important for the interpretation of the changes in pilot control behavior that occur due to the presence of physical motion feedback. [ABSTRACT FROM AUTHOR]

This paper investigates the extent to which target forcing functions consisting of multiple ramplike or steplike changes in target attitude can be used for identification of multimodal pilot models. The main question addressed is whether such signals provide enough excitation of the pilot-vehicle system to allow for reliable estimation of pilot model parameters from measured pilot control data. The compensatory control task from a previous human-in-the- loop experiment performed in a moving base flight simulator is used to define a typical multimodal pilot model identification problem. Using simulations of this control task, where different muitisine and ramp target forcing function signals are used to excite the pilot-vehicle system (in addition to a multisine disturbance signal), the accuracy and consistency of pilot model estimation results are evaluated. It is found that both the bias and variance of the pilot model parameter estimates decrease with increasing ramp signal steepness. If the steepnesses of the ramps in the target signals are higher than 3 deg/s, estimation results are found to be more accurate than those obtained using a quasi-random target forcing function. This indicates that reliable pilot model identification results can he obtained using such ramp target forcing function signals. [ABSTRACT FROM AUTHOR]

A synthetic vision display is generally believed to support pilot terrain awareness. Many studies have shown, however, that the bias in perspective views can cause pilots to make judgment errors regarding the relative location, height, and ultimately the avoidance of terrain obstacles. Therefore, alerting systems are required to keep pilots at safe distances from the terrain. These systems provide explicit guidance commands to circumvent terrain conflicts, which is far from optimal regarding pilot terrain awareness as it fails to present the rationale of the terrain separation problem. Consequently, this can affect the trust in and the reliance on these systems and pose a potential safety risk. especially in events or situations unfamiliar to the alerting system. This paper presents the design and evaluation of an extension to a synthetic vision display that aims to make the constraints of the alerting automation more transparent in order to help pilots better understand why. how, and when they should act. A pilot-in-the-loop experiment, using 16 glass-cockpit pilots in a fixed-based flight simulator, showed that the constraint-based overlays indeed improved the overall pilot terrain awareness compared to a command-based display. The decision-making only improved in the unanticipated events introduced in the experiment. The utility of the energy angle was found to be important for recognizing the offnormal events and to prevent terrain crashes. However, the pilot response time, flight safety in terms of low-altitude flying, and pilot workload are better when using the command display. This indicates that a last-resort alerting and advisory system would still be required in operations at the periphery of safe system performance. [ABSTRACT FROM AUTHOR]

Flight simulators are widely used for research and training of pilots. However, in skill-based control tasks, pilots behave differently in the simulator compared to real flight, due to limited visual and physical motion cues. This warrants a method that quantifies simulator fidelity by the differences between pilot control behavior in real flight and in the simulator. This paper presents the results of in-flight experiments to determine multimodal pilot control behavior in real flight, the baseline in determining simulator fidelity. The experiment is performed in a Cessna Citation I! laboratory aircraft with a custom-built fly-by-wire system. To estimate pilots' visual and vestibular responses, two forcing functions need to be inserted into the control loop at different locations. The fly-by-wire system was used to physically disturb the aircraft with a disturbance forcing function, while pilots had to track a target forcing function on a display in the cockpit. Both a multisine and a ramp target signal were tested in roll and pitch control tasks, resulting in four experimental conditions. The results show that multimodal pilot control behavior can indeed be identified in real flight using the current fly-by-wire system setup. For two pilots, pilot model parameters could be estimated with high accuracy for all conditions. For some conditions of the two remaining pilots, however, no accurate parameter estimates could be found, as their control activity did not allow for a stable global optimum of the parameter estimation problem. [ABSTRACT FROM AUTHOR]

Human control behavior, as exercised during vehicle or aircraft control, can be identified by applying forcing functions with a specific frequency content to excite the human control system. The presence of these forcing functions may affect human control behavior as well, an effect which is not well-understood and might considerably affect the result of experiments. Common metrics, such as spectral shape and bandwidth, have been shown to be insufficient in predicting the forcing function's effect on human control behavior. This paper investigates the effect of forcing function phase on the control behavior, as well as the effect of the forcing function frequencies at which power is present, within a fixed spectral shape. These effects were tested in a human-in-the-loop compensatory tracking experiment. Our experiment showed that the effects of the frequencies were substantial. For this reason, a new metric was proposed to better predict the effects of forcing functions on the human control behavior, and to allow comparison between forcing functions with different spectral shapes and frequency contents. The metric considers the variance of the signal's derivatives. To test the validity of the metric, forcing functions with equal derivative variances were used in a compensatory tracking experiment. The outcome of the experiment reveals that the resulting behavior indeed can be considered equal when the variances are equal, even when the forcing function spectral shapes are considerably different. [ABSTRACT FROM AUTHOR]

An experiment was conducted in the SIMONA Research Simulator at Delft University of Technology to investigate the influence of sway, roll, and yaw motion cues oh pilot performance, control, and motion perception during decrab maneuvers. In the experiment, six pilots were instructed to perform manual decrab maneuvers in heavy crosswind conditions with a Cessna Citation 500 model. The contributions of yaw, roll, and sway motion stimuli were varied such that their effects on objective measures and subjective ratings could be examined. The results of this experiment show that yaw motion had a positive influence on performance in terms of lateral touchdown distance from the runway centerline. Roll motion significantly decreased roll rate variations during decrab. High workload and the relatively low intensity of lateral motion cues led to the fact that pilots were unable to give consistent fidelity ratings. This result emphasizes the need for an objective and quantifiable method to determine motion fidelity for such maneuvers. Pilot models can possibly be used to further investigate the influence of different motion cues in these transient control tasks. [ABSTRACT FROM AUTHOR]

This paper investigates the crossover-regression phenomenon in compensatory manual-control tasks. The adjustment, between-subject variation, and accuracy of linear human-operator models are analyzed in detail. A theoretical investigation into closed-loop error minimization will be presented. Our main hypothesis was that crossover regression is caused by an operator's inability to sufficiently decrease the time delays required to limit forcing-function resonance. To test the hypothesis and explore the use of linear-operator models in regressed conditions, an experiment very similar to McRuer's landmark 1965 experiment was conducted. A comparison between regressive and nonregressive conditions revealed that crossover regression is indeed a strategy to reduce forcing-function resonance. The bandwidth of the forcing-function signal at which participants regressed their n crossover frequency was found to vary considerably between participants. In regressed conditions, the between- subject variability in frequency-domain performance increased. Additionally, the operator control behavior became increasingly nonlinear, resulting in larger uncertainties and a higher between-subject variability in the linear-model parameter estimates. [ABSTRACT FROM AUTHOR]

This paper presents a new method for estimating the parameters of multichannel pilot models that is based on maximum likelihood estimation. To cope with the inherent nonlinearity of this optimization problem, the gradient-based Gauss-Newton algorithm commonly used to optimize the likelihood function in terms of output error is complemented with a genetic algorithm. This significantly increases the probability of finding the global optimum of the optimization problem. The genetic maximum likelihood method is successfully applied to data from a recent human-in-the-loop experiment. Accurate estimates of the pilot model parameters and the remnant characteristics are obtained. Multiple simulations with increasing levels of pilot remnant are performed, using the set of parameters found from the experimental data, to investigate how the accuracy of the parameter estimate is affected by increasing remnant. It is shown that the bias in the parameter estimates is only substantial for very high levels of pilot remnant. Some adjustments to the maximum likelihood method are proposed to reduce this bias. [ABSTRACT FROM AUTHOR]

This study investigates the use of haptic feedback to support the teleoperation of an uninhabited aerial vehicle with time delay. Two means of supplying the haptic feedback are investigated: first, an additional force on the control inceptor, and second, an additional force combined with an increased stiffness of the control inceptor. The advantage of combining the force feedback with stiffness feedback, over force feedback alone, is that the additional stiffness of the control inceptor increases the authority of the haptic feedback system in critical situations. The goal of this study is to increase the safety of teleoperation while reducing operator workload. A theoretical analysis shows that force--stiffness feedback improves the stability in the human control loop while allowing for lower force-feedback gain settings as compared with force feedback alone, which indicates that this could contribute to reducing operator workload. In an experiment, the two haptic feedback conditions were compared with a baseline condition without haptic feedback. The fidelity of the experiment was improved over an earlier experiment by introducing a time , penalty for collisions. The number of collisions was different for all three conditions, with the lowest number for the force-stiffness condition and the highest number for the baseline condition. Both haptic feedback conditions were rated equally on subjective workload metrics and scored better than the baseline. This finding is in contrast with results from earlier experiments, which indicated a higher workload with haptic feedback, and shows the importance of creating realistic test conditions when using subjective workload ratings. [ABSTRACT FROM AUTHOR]

During pitch rotation of the aircraft, a pilot, seated in front of the aircraft center of gravity, is subjected to rotational pitch and vertical heave motion. The heave motion is a combination of the vertical motion of the aircraft center of gravity and the heave motion as a result of the pitch rotation. In a pitch tracking task, all of these cues could potentially have a positive effect on performance and control behavior, as they are all related to the aircraft pitch attitude. To improve the tuning of flight simulator motion filters, a better understanding of how these motion components are used by the pilot is required. First, the optimal use of the different motion components was evaluated using an optimal control analysis. Next, an aircraft pitch attitude control experiment was performed in the SIMONA Research Simulator, investigating the effects of pitch rotation, pitch heave, and center of gravity heave on pilot control behavior. Pilot performance significantly improved with pitch motion, with an increased crossover frequency for the disturbance open loop. The increase in performance was a result of an increased visual gain and a reduction in visual lead, allowed for by the addition of pitch motion. Pitch heave motion showed similar but smaller effects. The center of gravity heave motion, although taking up most of the simulator motion space, was found to have no significant effects on performance and control behavior. [ABSTRACT FROM AUTHOR]

In the teleoperation of an uninhabited aerial vehicle, haptic feedback can be used to provide useful information through the sense of touch. Although this can improve performance and enhance situation awareness, time delays caused by signal transmission generally induce control problems with haptic feedback, causing unsafe operations. Wave variables have been suggested to cope with the control problems in bilateral human--machine systems with time delay. Very little has been reported, however, on effects related to human control activity and workload when using wave variables. This paper describes a theoretical analysis of using wave variables to enhance a collision-avoidance system for visual and haptic uninhabited aerial vehicle teleoperation with time delay. An experiment was conducted to evaluate its effectiveness regarding operator performance, control activity, workload, and the safety of operation. Results indicate that wave variables are indeed successful in improving human performance. The number of collisions, operator control activity, and workload all decreased. Whereas performance and control activity were equivalent to the situation of haptic feedback without time delay, workload remained higher. [ABSTRACT FROM AUTHOR]

In this paper, the effects of peripheral visual and physical motion cues on manual control of second-order roll dynamics are investigated. In particular, the differences between the use of these cues in compensatory target-following and disturbance-rejection tasks are considered. Tracking performance, control activity, and measures of control behavior are determined from recent measurements and compared with results from an earlier experiment. Most previously reported effects of peripheral visual and physical motion cues in target following and disturbance rejection are confirmed. A comparison of tasks with varying levels of difficulty is found to reveal reduced effectiveness of peripheral visual and physical motion cues in the less difficult target-following tasks only. Observed differences in measured control behavior for target following and disturbance rejection are related to effective strategies for reducing tracking errors introduced by the forcing-function signals in both tasks. [ABSTRACT FROM AUTHOR]

A current trend in aircraft noise abatement around airports is exploiting the benefits of revised arrival and approach procedures with computational aids, such as onboard and ground-based trajectory prediction algorithms and displays. The challenge for these upcoming advanced noise abatement procedures is to mitigate the noise impact without sacrificing runway capacity. A proposed solution, implemented in the three-degree decelerating approach, is to delegate the task of spacing the aircraft to the cockpit during the approach. To assist the pilots, a flap scheduling algorithm with complementary interface has been developed that takes noise nuisance and in-trail spacing into account. The design and functionality of this support system is presented and evaluated with three experiments. Monte Carlo simulations indicated adequate and consistent performance and robustness of the self-spacing algorithm for various wind and traffic scenarios. A pilot-in-the-loop simulator experiment verified that, with the aid of the algorithm, pilots were able to execute the noise abatement procedure consistently while maintaining safe-spacing. The support system reduced pilot workload up to an effort level comparable to current standard approaches. The concept was demonstrated in flight, which confirmed the conflict-free performance benefits and the feasibility of self-spacing during continuous decelerating/descent approaches under actual flight conditions. [ABSTRACT FROM AUTHOR]

The majority of information sources on the flight deck are visual displays. An example is the flight director display that improves pilot manual aircraft control performance but also involves a visually demanding task. Tactile, or haptic displays use the human tactile modality as an information channel. This paper discusses how the visual information of the flight director can be presented through providing force-feedback on the control stick. The haptic flight director gives pilots a constant stream of tactile information on the state of the flight director command bars, also when visual attention is not directed at the primary flight display. It was hypothesized that the shorter latencies in the tactile motor loop allow pilots to control aircraft at a higher bandwidth, increasing performance. It was further hypothesized that using two modalities, instead of one, to conduct the aircraft manual control task, would reduce pilot workload, also when a secondary, visually distracting side task is present. To test these hypotheses, an experiment was conducted in a fixed-base simulator. Professional pilots conducted approaches with the visual and haptic flight director displays, while simultaneously a secondary task had to be conducted. Results show that the haptic flight director indeed yields improved pilot performance and lower workload. [ABSTRACT FROM AUTHOR]