Max Mulder

Aeronautics and Astronautics

The Department of Aeronautics and Astronautics prepares students for professional positions in industry, government, and academia by offering a comprehensive program of undergraduate and graduate teaching and research. In this broad program, students have the opportunity to learn and integrate multiple engineering disciplines. The program emphasizes structural, aerodynamic, guidance and control, and propulsion problems of aircraft and spacecraft. Courses in the teaching program lead to the degrees of Bachelor of Science, Master of Science, Engineer, and Doctor of Philosophy. Undergraduates and doctoral students in other departments may also elect a minor in Aeronautics and Astronautics.

Using the SIMONA Research Simulator for Human-machine Interaction Research

The Delft University of Technology has developed a 6 degree-of-freedom flight simulator, the SIMONA Research Simulator (SRS). The design incorporates several advanced technologies, such as light-weight construction, high performance motion drive algorithms and a flexible, PC-based computer infrastructure. The simulator serves as a testbed for new technologies and as a tool for Human-Machine Interaction (HMI) research. Key components of the simulator that allow high quality Human-Machine Interaction research to be performed, are described. To ensure a sufficient level of accessibility for students and researchers, the software architecture of the SRS uses the Delft University Environment for Communication and Activation (DUECA), a middleware layer that shields the user from the complexities of the communication between PCs and the real-time scheduling of the different simulation modules. Through the use of DUECA, experiments are also easily portable between development workstations and different simulator environments. The concepts behind DUECA and its use in the research environment of SIMONA are discussed. Several research projects with the Faculty of Aerospace Engineering of the Delft University of Technology have been performed successfully using DUECA, on simulators of different fidelity, from standalone PCs, to a fixed base mockup and the SRS. __________________________________ * Associate Researcher, International Research Institute for Simulation, Motion and Navigation. Member AIAA. † Assistant Professor, Control and Simulation Division, Faculty of Aerospace Engineering. Member AIAA. ‡ Assistant Professor, Control and Simulation Division, Faculty of Aerospace Engineering. Member AIAA. INTRODUCTION Several groups within the Delft University of Technology (TU Delft) in the Netherlands have long been involved in research into flight simulation. For instance, the faculty of Design, Construction and Production has extensive experience with the design and control of hydraulic actuators for motion and control loading systems. The faculty of Aerospace Engineering has always been active in the field of modeling and simulation and has operated a threedegree-of-freedom flight simulator up until the early 1990s. At that time, a new co-operative initiative was set up to develop, build and operate an advanced sixdegree-of-freedom research flight simulator. These two faculties, together with the faculty of Information Technologies and Systems, initiated the International Research Institute for Simulation, Motion and Navigation (SIMONA). The SIMONA institute promotes fundamental and applied research in the fields of simulation technology and human-machine interaction. Available and newly generated knowledge on simulation technologies is applied to the development of the full-motion SIMONA Research Simulator (SRS, see Figure 1). This recently completed simulator stands at the heart of the SIMONA institute and provides an experimental facility for human-machine interaction research. An important aspect in both research fields is a close co-operation with industry and academia around the world. Figure 1 SIMONA Research Simulator AIAA Modeling and Simulation Technologies Conference and Exhibit 11-14 August 2003, Austin, Texas AIAA 2003-5525 Copyright

Haptic gas pedal feedback

Active driver support systems either automate a control task or present warnings to drivers when their safety is seriously degraded. In a novel approach, utilising neither automation nor discrete warnings, a haptic gas pedal (accelerator) interface was developed that continuously presents car-following support information, keeping the driver in the loop. This interface was tested in a fixed-base driving simulator. Twenty-one drivers between the ages of 24 and 30 years participated in a driving experiment to investigate the effects of haptic gas pedal feedback on car-following behaviour. Results of the experiment indicate that when haptic feedback was presented to the drivers, some improvement in car-following performance was achieved, while control activity decreased. Further research is needed to investigate the effectiveness of the system in more varied driving conditions. Haptics is an under-used modality in the application of human support interfaces, which usually draw on vision or hearing. This study demonstrates how haptics can be used to create an effective driver support interface.

Theoretical Foundations for a Total Energy-Based Perspective Flight-Path Display

One of the most difficult aspects of manually controlled flight is the coupling between the control over the aircraft speed and altitude. These states cannot be changed independent of each other through the aircraft control devices, the elevator and the throttle. Rather, to effectively change an aircrafts speed and altitude, the controls have to be coordinated. The mediating mechanism that underlies the coordination of the controls is the management of the aircrafts energy state. This article shows that the abstraction hierarchy (AH; Rasmussen, 1986) framework can be effectively used to gain more insight into the underlying structure of the aircraft energy management problem. The derived AH representation is based on the analysis of the energy constraints on the control task. It reveals the levels of abstraction necessary to link the aircrafts physical controls to the speed and altitude goals and also how the aircraft energy is a critical mediating state of the control problem. Energy awareness can be increased by presenting explicit energy management information. The powerful and novel concepts of the total energy reference profile and energy angle are introduced in this article and applied in the context of a perspective flight-path display. The resulting display presents energy management information fully integrated with the tunnel-in-the-sky display and reveals 5 new and important energy cues, intuitively linking the controls and the goals.

Measuring the Performance of the SIMONA Research Simulator's Motion System

A hardware and software system is presented that is used to measure the motion performance of Delft University’s SIMONA Research Simulator. It uses the simulator’s operational software environment and an onboard Inertial Measurement Unit to measure motion performance metrics that are based on AGARD report no. 144. The metrics can be used to assess the simulator’s motion capabilities, but can also serve to evaluate different control algorithms for the motion base. An example of this last use is presented in this paper. The measured data shows that the effort put into the lightweight design of the simulator cab and the advanced motion control algorithms, has resulted in good motion performance in terms of time delay and bandwidth. Also, increased motion performance is expected to be possible with further tuning of the control algorithms and enhancements in the driving software.

A Cybernetic Approach to Assess Flight Simulator Fidelity

This paper presents the results of an experiment in which a cybernetic approach has been used to investigate the effect of motion filter setting changes and display type on simulator fidelity. Pilot control behavior, pilot remnant, open loop behavior, open loop performance and subjective evaluations in a real jet-aircraft were compared with that in a high-fidelity motion base simulator. The task studied was a pitch-tracking following task. Peripheral information was omitted from the experiment. The results from the flight tests, in the first phase of the experiment, were used to tune and validate simulator models and settings for the simulator tests in the second phase of the experiment. These flight test results are also used as a base-line condition to which the results from the simulator tests are compared. Two types of displays were used in the experiment, a compensatory and pursuit display, and in the simulator, a set of nine different motion filter settings. Results show only slight differences in pilot control behavior and open loop behavior between the aircraft and the simulator, between the different motion filter settings in the simulator, and between the two display types used. A more significant effect is found on the pilot injected noise level and consequently on the open loop performance. Analytical biases and variances are calculated for the estimated open loop describing functions. The applied cybernetic approach has provided objective and accurate results, which makes this technique suitable for more extensive research on simulator fidelity in the future.

Evaluation of Vestibular Thresholds for Motion Detection in the SIMONA Research Simulator

This paper presents the results of an experiment in which motion perception thresholds in the SIMONA Research Simulator are measured. Selfmotion perception is the result of perceived visual, vestibular, tactile, and proprioceptive cues. In this experiment, motion perception is based on vestibular cues only. Below a certain value, the vestibular cues will not be perceived by humans. This value is called the threshold for motion perception. Two different thresholds exist, an upper threshold and a lower threshold. The upper threshold is the stimulus value at which the stimulus switches from not perceived to perceived. The lower threshold is the value the stimulus reaches when the stimulus changes from perceived to not perceived, i.e. with decreasing stimulus amplitude. Knowledge of these thresholds is important for the use of motion simulators. The motions presented to the subject in this experiment are linear or angular accelerations in all six motion directions. The results from the experiment correspond well with known motion perception thresholds and vestibular models.

The Effect of Concurrent Bandwidth Feedback on Learning the Lane-Keeping Task in a Driving Simulator

Objective: The aim of this study was to investigate whether concurrent bandwidth feedback improves learning of the lane-keeping task in a driving simulator. Background: Previous research suggests that bandwidth feedback improves learning and that off-target feedback is superior to on-target feedback. This study aimed to extend these findings for the lane-keeping task. Method: Participants without a driver’s license drove five 8-min lane-keeping sessions in a driver training simulator: three practice sessions, an immediate retention session, and a delayed retention session 1 day later. There were four experimental groups (n = 15 per group): (a) on-target, receiving seat vibrations when the center of the car was within 0.5 m of the lane center; (b) off-target, receiving seat vibrations when the center of the car was more than 0.5 m away from the lane center; (c) control, receiving no vibrations; and (d) realistic, receiving seat vibrations depending on engine speed. During retention, all groups were provided with the realistic vibrations. Results: During practice, on-target and off-target groups had better lane-keeping performance than the nonaugmented groups, but this difference diminished in the retention phase. Furthermore, during late practice and retention, the off-target group outperformed the on-target group. The off-target group had a higher rate of steering reversal and higher steering entropy than the nonaugmented groups, whereas no clear group differences were found regarding mean speed, mental workload, or self-reported measures. Conclusion: Off-target feedback is superior to on-target feedback for learning the lane-keeping task. Application: This research provides knowledge to researchers and designers of training systems about the value of feedback in simulator-based training of vehicular control.

Active Deceleration Support in Car Following

A haptic gas pedal feedback system is developed that provides car-following information via haptic cues from the gas pedal. During normal car-following situations, the haptic feedback (HF) cues were sufficient to reduce control activity and improve car-following performance. However, in more critical following situations, drivers use the brake pedal to maintain separation with the lead vehicle. A deceleration control (DC) algorithm is designed that, in addition to the HF, provided increased deceleration upon release of the gas pedal during car-following situations that required faster deceleration than releasing the gas pedal alone would do. For the design, a driver model for car following in different situations was estimated from driving simulator data. A Monte Carlo analysis with the driver model yielded subjective decision points, where drivers released the gas pedal to start pressing the brakes. This enabled the definition of a reaction field, which determined the needed deceleration input for the DC algorithm. The tuned DC algorithm was tested in a fixed-base driving simulator experiment. It was shown that the active deceleration support improved the car-following performance while reducing the driver brake pedal input magnitude in the conditions tested.

Ecological Interface Design for Terrain Awareness

Advanced terrain warning systems, such as the enhanced ground proximity warning system, and safety-enhancing displays, like the synthetic vision system, have proven to play an important role in reducing the number of controlled flight into terrain accidents. Research indicated, however, that terrain collisions may still occur for aircraft equipped with these systems. Synthetic vision allows for perception of the environment, but lacks properties to support understanding and extrapolation of the perceived data. A terrain warning system provides elementary meaning to the environment, but is not well integrated into synthetic vision displays. To further increase terrain awareness and, ultimately, eliminate terrain collisions, synthetic vision should be integrated with a terrain awareness functionality that allows the pilot to be continuously informed about how the external constraints (imposed by the terrain) relate to the internal aircraft constraints (e.g., climb performances). Based on that information, pilots can judge for themselves what an obstacle actually means to them in terms of possibilities to fly over it, and if not, what the alternatives for action are. In this article, the paradigm of ecological interface design is used to analyze the aircraft manual control task in the vertical plane and to develop a more meaningful interface for (vertical) terrain awareness. An abstraction hierarchy is presented, developed for the task of guiding an aircraft through a terrain-challenged environment. The design and experimental evaluation of a vertical situation display are discussed, enhanced with ecological overlays to increase terrain awareness.