A Cybernetic Approach to Assess the Longitudinal Handling Qualities of Aeroelastic Aircraft

The future demand for larger and lighter civil transport aircraft leads to more flexible aircraft, which bring their own controlling and handling problems. A review of established handling qualities methods showed that they were either unsuitable for aeroelastic aircraft, or had significant disadvantages. After consideration of the basic principles behind a number of handling qualities methods, a new handling qualities method was developed, the Experimental Behavior Measurement Method (EBMM). This new method is based on the principle that a satisfactory match between the aircraft characteristics and the human operator's behavioral characteristics is required to acquire proper vehicle handling qualities. The EBMM requires pilots to perform a number of pitch tracking tasks with a pursuit display, in the aircraft or a moving-base simulator. During these tasks the tracking signal bandwidth is increased, while the pilot's control behavior is determined using system identification techniques. A sudden decrease of the crossover frequency in the pilot's control behavior can be observed when the tracking signal bandwidth exceeds the pilot-vehicle capabilities. This phenomenon is called crossover regression, and the bandwidth at which crossover regression occurs is defined as the crossover-regression frequency. Since the crossover-regression frequency is dependent on the pilot-vehicle capabilities, it can be considered to be a measure of the handling qualities. The validity and applicability of the EBMM were investigated by conducting an experiment in the TU Delft SIMONA flight-simulator. Three aircraft models with varying levels of aeroelasticity were evaluated, using both the new EBMM as well as the well-established Cooper-Harper rating method, which assesses flying qualities as a surrogate for handling qualities. When the effects of the amount of aeroelasticity on the flying and handling qualities were compared, both a quantitative and qualitative correlation was seen between the results of the Cooper-Harper rating method and the new EBMM. In conclusion, the results suggest that the new EBMM method can contribute to the development of improved handling qualities of large and flexible future aircraft aircraft.Control and SimulationAerospace Engineerin

An Avionics Touch Screen based Control Display Concept

In many cockpits, control display units (CDUs) are vital input and information devices. In order to improve the usability of these devices, Barco, in cooperation with TU-Delft, created a touch screen control unit (TSCU), consisting of a high-quality multi-touch screen. The unit fits in the standard dimensions of a conventional CDU and is thus suitable for both retrofit and new installations. The TSCU offers two major advantages. First, the interface can be reconfigured to enable consecutive execution of several tasks on the same display area, allowing for a more efficient usage of the limited display real-estate as well as a potential reduction of cost. Secondly, advanced graphical interface design, in combination with multi-touch gestures, can improve human-machine interaction. To demonstrate the capabilities of this concept, a graphical software application was developed to perform the same operations as a conventional CDU, but now using a direct manipulation interface (DMI) of the displayed graphics. The TSCU can still be used in a legacy CDU mode, displaying a virtual keyboard operated with the touch interface. In addition, the TSCU could be used for a variety of other cockpit functions. The paper concludes with a report of pilot and non-pilot feedback.Control and OperationsAerospace Engineerin

Tuning Models of Pilot Tracking Behavior for a Specific Simulator Motion Cueing Setting

This paper describes the preliminary results of an effort to compile data from a large number of studies that investigated the effects of variations in motion filter settings on pilot behavior. The main objective of this study is to formulate a set of mathematical rules that will allow for the tuning of behavioral pilot models to a certain motion cueing setting. To achieve this, data for different dependent measures such as tracking performance, pilot-vehicle system crossover frequencies, and pilot model parameters, taken from ten different experiments that considered pilot tracking behavior under varying rotational or translational motion cueing settings, has been combined. By checking the correlation of the variation in any of these dependent measures and parameters that quantify the applied variation in motion cueing, a number of consistent relations has been identified. The most consistent and clear effects that are found from this analysis are variations in some important dependent measures with the motion filter gain at 1 rad/s. Over the full range of motion filter gains at 1 rad/s from 0 to 1, a reduction in pilot visual gain of around 20% is observed with reducing motion filter gain, in combination with a 30% increase in the amount of visual lead equalization adopted by pilots.Control & OperationsAerospace Engineerin

Estimation of Nonlinear Contributions in Human Controller Frequency Response Functions

Traditional Frequency Response Function (FRF) estimation techniques used for analysis of Human Controller (HC) dynamics in tracking tasks assume HC dynamics to be linear, but generally do not quantify or compensate for the effects of human nonlinearities. The robust and fast Best Linear Approximation (BLA) techniques for estimating an FRF do provide such quantification of nonlinear distortions caused by Period-In-Same-Period-Out (PISPO) nonlinearities and can reduce the effect of PISPO nonlinear operations on the FRF estimate. This paper investigates the application of these BLA techniques to both measured and simulated HC data. For the simulated data, a linear HC model was deliberately extended with a symmetric PISPO deadzone nonlinear operator and a realistic level of HC “remnant” noise. Overall, both the measured and the simulated data indicate that due to the high levels of remnant noise inherent to HC data, no consistent estimate of PISPO nonlinear contributions could be made. This also means that the improvement of using BLA techniques and averaging over multiple forcing function realizations does not result in a substantial improvement over the current practice of estimating HC FRFs from repeated measurements of a single forcing function.Control & SimulationControl & Operation

Analysis of Human Skill Development in Manual Ramp-Tracking Tasks

Human modelling approaches are typically limited to feedback-only, compensatory tracking tasks. Advances in system identification techniques allow us to consider more realistic tasks that involve feedforward and even precognitive control. In this paper we study the human development of a feedforward control response while learning to accurately follow a ramp-shaped target signal in the presence of a disturbance acting on the controlled element. An experiment was conducted in which two groups of eight subjects each tracked ramps of different steepnesses in a random or ordered fashion. In addition, ordered runs were followed by a 'surprise' run with a random ramp steepness. Results show that operators learn rapidly, continue to learn during the entire experiment, and can adapt very quickly to surprise situations. Experiments involving learning operators are challenging, as it is difficult to balance-out all experimental conditions and control for inevitable differences between (groups of) subjects.Industrial Design EngineeringControl & Simulatio

Effects of Simulator Motion on Driver Steering Performance with Various Visual Degradations

This paper investigates the effects of simulator motion on driver steering performance, and how this depends on the available visual information and external disturbances such as wind gusts. A human-in-the-loop driving experiment was performed in which twelve participants steered a fixedvelocity car to follow a winding road (target tracking, TT) while suppressing side-wind gusts (disturbance-rejection, DR). Driver performance with and without motion feedback is compared in six tasks: “regular” lane-keeping with optic flow, centerline tracking with optic flow, and centerline tracking without optic flow, all with both 5 and 100 m of preview. Performance is calculated in the frequency domain to separate TT and DR contributions. The results show that motion feedback always yields improved DR performance, but the actual improvement depends strongly on the available simulator visuals. TT performance is generally unaffected by motion feedback, except when preview is limited. We conclude that simulator motion is required to evoke realistic driver performance in tasks where substantial external disturbances are present, but not in disturbance-free tasks where a winding road is being followed.Control & Simulatio

Identification of the Feedback Component of the Neuromuscular System in a Pitch Control Task

This goal of this study is to understand which parts of the the neuromuscular system contribute during a pitch control task. A novel method developed at the Delft University of Technology allows us to determine the contribution of the neuromuscular feedback system by identifying the admittance, which is the frequency response function of the yielded displacement due to an external force perturbation which applied to control inceptor. In an experiment in a full-motion flight simulator, the neuromuscular admittance was identified during a longitudinal pitch tracking task with a side stick, for two different side stick configurations, an approach configuration with a relatively low stick stiffness, and a cruise configuration with a high stiffness. Besides the admittance, also the muscle activity of eleven muscles was measured. To validate whether the external force perturbation changed the control behavior of the pilot, the visual and vestibular response functions were identified as well. From the measured results it could be concluded that the variations of the control inceptor settings had a significant effect on the neuromuscular feedback system (admittance), although the overall lumped neuromuscular system did not change significantly. A very interesting finding were the very high levels of co-contraction measured during the pitch tracking tasks. And lastly it could be concluded that the required external force perturbation did not affect the control behavior.Control & OperationsAerospace Engineerin