Peter R. Grant

Motion Washout Filter Tuning: Rules and Requirements

Current motion-drive algorithms have a number of coefficients that are selected to tune the motion of the simulator. Little attention has been given to the process of selecting the most appropriate coefficient values. Final tuning is best accomplished using experienced evaluation pilots to provide feedback to a washout filter expert who adjusts the coefficients in an attempt to satisfy the pilot. This paper presents the development of a tuning paradigm and the capturing of such within an expert system. The focus of this development is the University of Toronto classical algorithm, but the results are relevant to alternative classical and similarly structured adaptive algorithms. This paper provides the groundwork required to develop the tuning paradigm. The necessity of this subjective tuning process is defended. Motion cueing error sources within the classical algorithm are revealed, and coefficient adjustments that reduce the errors are presented.

Driver Distraction: Evaluation with Event Detection Paradigm

The effects of eight in-vehicle tasks on driver distraction were measured in a large, moving-base driving simulator. Forty-eight adults, ranging in age from 35 to 66, and 15 teenagers participated in the simulated drive. Hand-held and hands-free versions of phone dialing, voicemail retrieval, and incoming calls represented six of the eight tasks. Manual radio tuning and climate control adjustment were also included to allow comparison with tasks that have traditionally been present in vehicles. During the drive the participants were asked to respond to sudden movements in surrounding traffic. The driver’s ability to detect these sudden movements or events changed with the nature of the in-vehicle tasks that were being performed. Driving performance measures such as lane violations and heading error were also computed. The performance of the adult group was compared with the performance of the teenage drivers. Compared with the adults, the teens were found to choose unsafe following distances, have poor vehicle control skills, and be more prone to distraction from hand-held phone tasks.

Effect of Simulator Motion on Pilot Behavior and Perception

A set of experiments were conducted on the University of Toronto Institute for Aerospace Studies flight research simulator to determine the effects of translational and yaw motion on pilot performance, workload, fidelity, pilot compensation, and motion perception for three helicopter yaw control tasks. The three control tasks were a yaw capture, a disturbance rejection task, and a tracking task. The yaw capture experiment was a duplication of an experiment previously run at a different simulator facility. The results of the yaw capture task were in general agreement with the previous study with the exception that, in the current study, yaw motion had a larger impact on pilot performance than the previous study. The current study found that translational motion improves performance and increases fidelity for all three tasks. Yaw motion increased performance for the yaw capture and disturbance rejection tasks. Translational motion generally improved fidelity and was easier to detect than yaw motion for all three tasks. Finally, if translational motion was present, the addition of yaw motion usually provided little additional benefit to performance, workload, compensation, or fidelity for all three tasks.

Pilot Behavioral Observations in Motion Flight Simulation

This paper summarizes key findings on how simulator platform motion affects pilotvehicle performance and workload. These measures are a subset of the broad topic of pilot behavior, namely those associated with fine motor skills. The findings include the effects of specific tasks, vehicle dynamics, interaction with visual cues, and cockpit manipulator cues. The results are in the context of vehicle systems development rather than training. A section reviews a set of motion fidelity criteria and compares it with the literature. The criteria allow an assessment of a simulator’s motion cueing strengths and weaknesses for a given task. The paper offers best practices for achieving pilot behavior in a flight simulator that is more akin to in-flight behavior. Three practices are most important: quantify all of the available cues analytically, evaluate the motion cues against available criteria, and strive to find relevant tasks that permit the motion cues to have at least adequate fidelity.

Motion-Visual Phase-Error Detection in a Flight Simulator

An experiment was conducted on the University of Toronto Institute for Aerospace Studies Flight Research Simulator to determine the minimum phase lead of pitch motion cues relative to pitch visual cues that can be consistently detected by a human observer. The effects of pitch frequency and amplitude, motion gain, and visual scene complexity on the detection threshold of the phase error between the visual and motion cues was determined. The mean detection threshold of the phase error averaged across all subjects and conditions was 57 deg. Pitch amplitude significantly affected the detection threshold of the phase error. Higher amplitudes led to lower detection thresholds. Motion gain also had a significant effect on the detection threshold of the phase error when the frequency was 0.2 Hz or the visual complexity was low. Higher motion gains led to lower detection thresholds. The frequency had a significant effect on the detection threshold of the phase error when the motion gain was 0.5 or the visual complexity was low. Higher frequencies led to lower detection thresholds. The direction of the frequency effect suggests that subjects perform more like motion-visual phase detectors than motion-visual time delay detectors. The results of the experiment were used to analyze pitch high-pass washout filters. The analysis suggests that the break frequency for a second-order washout filter should be lower than 0.13 rad/s and the break frequency for a first-order filter should be lower than 0.2 rad/s to keep the motion-visual phase error below the measured human perception limit.

Effect of Jerk and Acceleration on the Perception of Motion Strength

In a flight simulator, the calculated aircraft motions are scaled down and filtered to fit within the envelope of the simulator motion system. A number of recent flight and ground simulation studies have reported that the simulator motion was too strong, when in fact, the motion was scaled down and filtered. This paper puts forth the hypothesis that this could be due in part to the motion drive algorithm and vehicle model exaggerating the jerk. To test the plausibility of this hypothesis a paired-comparison experiment was run to determine if the subjective impression of motion strength is a function of both the acceleration and jerk of the motion. The experiment found that the level of jerk and acceleration contributed to the perceived strength of motion, with larger jerks and accelerations leading to increased motion strength. In addition, the duration of the acceleration had a significant effect on the perceived motion strength, with longer durations leading to increased motion strength. Although the relationship between jerk and motion strength suggests that exaggerated jerk in the simulator could lead to the preference for scale factors less than one, the strength of the relationship strongly suggests that it does not entirely account for the preference.

PROTEST: An Expert System for Tuning Simulator Washout Filters

Current motion-drive algorithms have a number of coefficients that are selected to tune the motion of the simulator. Little attention has been given to the process of selecting the most appropriate coefficient values. Final tuning is best accomplished using experienced evaluation pilots to provide feedback to a washout filter expert who adjusts the coefficients in an attempt to satisfy the pilot. This paper presents the development of a tuning paradigm and the capturing of such within an expert system. The focus of this development is the University of Toronto classical washout algorithm, but the results are relevant to alternative classical and similarly structured adaptive algorithms. A set of relations between coefficient adjustments and motion cue errors are used to develop the expert system called PROTEST. PROTEST tunes the motion-drive algorithm based on a restricted set of comments given by the evaluation pilot. A set of experiments utilizing the University of Torontos Flight Research Simulator was conducted to test the performance of PROTEST. PROTEST was found to be a useful tool for motion tuning with performance matching that of tuning experts.

Analysing classes of motion drive algorithms based on paired comparison techniques

A paired comparison experiment using 23 subjects was run on the VIRTTEX driving simulator to compare a lane position based motion drive algorithm (MDA) with a classical MDA for a highway speed, lane change manoeuvre. Two different tuning states of the lane position algorithm and four different tuning states for the classical algorithm were tested. The subjective fidelity of the six different motion cases was compared with each other and a Bradley–Terry model was fit to find the fidelity merit of each case. In addition, the driving performance of the subjects for six motion cases was recorded and compared. The motion-tuning cases were selected such that the trade-off in motion quality between overall motion scaling and motion shape distortion (shape-error), as well as the trade-off between lateral specific force and roll-rate motion errors, could be studied. It was found that when the overall scaling is the same, drivers perform better with the lane position algorithm than with the the classical algorithm. A well-tuned, manoeuvre-specific, classical MDA, however, did achieve a subjective fidelity level on a par with the lane position MDA. A generically tuned classical MDA, however, has a significantly reduced fidelity and driving performance when compared with a lane position algorithm with the same scale factor. A strong trade-off between motion shape-errors and overall motion scaling was found. A small increase in motion cue shape-error, combined with an increase in the scale factor from 0.3 to 0.5, led to improved performance and increased subjective fidelity. The results of the experiment also suggest that simulator motion can be improved by reducing the angular-rate shape-error at the expense of the specific force shape-error (while keeping the total normalised shape-error constant).

Pre and Post Pilot Model Analysis Compared to Experimental Simulator Results

‡In 2003, a workshop on the use of pilot models to analyze the influence of visual and vestibular motion perceptio n on a pilot’s control behavior was held. As an example, an earlier experiment on the Vertical Motion Simulator ( VMS ) at NASA Ames was used to demonstrate that a pilot model analysis could reasonably explain the trends of the experimental results. Mo re importantly, the same analysis suggested an experimental configuration that, if tested, might have changed the general conclusions found in the NASA Ames study. Useful progress in research is enhanced when new studies and analyses build upon previous st udies and analyses. A new simulator experiment built upon the NASA Ames study and also evaluated all the new conditions analyzed with the pilot model during the workshop noted above. The results roughly correspond with the analysis. Although, the utmost w as done to produce the same motion cues in the University of Toronto research flight simulator as in the VMS experiment before, differences in the experimental results were found between the results of the NASA experiment and the University of Toronto experiment. The paper reviews the initial analysis, compares the analysis results with the new results from the new experiment, and readjust s the pilot mode l analysis with the new results. † ‡ p y

The Effect of Simulator Motion on Pilot's Control Behavior for Helicopter Yaw Control Tasks

A set of experiments were conducted on the UTIAS flight research simulator to determine the effects of translational and yaw motion on pilot performance, workload, fidelity, pilot compensation, and motion perception for three helicopter yaw control tasks. The three control tasks were a yaw capture, a disturbance rejection task, and a tracking task. The yaw capture experiment was a duplication of an experiment previously run at a different simulator facility. The results of the yaw capture task were in general agreement with the previous study with the exception that in the current study yaw motion had a bigger impact on pilot performance than the previous study. The current study found that translational motion improves performance and increases fidelity for all three tasks. Yaw motion increased performance for the yaw capture and disturbance rejection tasks. Translational motion generally improved fidelity and was easier to detect than yaw motion for all three tasks. Finally, if translational motion is present, the addition of yaw motion usually provided little benefit to performance, workload, compensation or fidelity, for all three tasks. p x f = specific force at pilots location in x-direction of pilot body frame, m/s 2 p y f = specific force at pilots location in y-direction of pilot body frame, m/s 2