K Beykirch

MPI Motion Simulator: Development and Analysis of a Novel Motion Simulator

This paper discusses the technical issues that were required to adapt a KUKA Robocoaster for use as a real-time motion simulator. Within this context, the paper addresses the physical modifications and the software control structure that were needed to have a flexible and safe experimental setup. It also addresses the delays and transfer function of the system. The paper is divided into two sections. The first section describes the control and safety structures of the MPI Motion Simulator. The second section shows measurements of latencies and frequency responses of the motion simulator. The results show that the frequency responses of the MPI Motion Simulator compare favorably with high-end Stewart Platforms, and therefore demonstrate the suitability of robot-based motion simulators for flight simulation.

The importance of stimulus noise analysis for self-motion studies

Motion simulators are widely employed in basic and applied research to study the neural mechanisms of perception and action during inertial stimulation. In these studies, uncontrolled simulator-introduced noise inevitably leads to a disparity between the reproduced motion and the trajectories meticulously designed by the experimenter, possibly resulting in undesired motion cues to the investigated system. Understanding actual simulator responses to different motion commands is therefore a crucial yet often underestimated step towards the interpretation of experimental results. In this work, we developed analysis methods based on signal processing techniques to quantify the noise in the actual motion, and its deterministic and stochastic components. Our methods allow comparisons between commanded and actual motion as well as between different actual motion profiles. A specific practical example from one of our studies is used to illustrate the methodologies and their relevance, but this does not detract from its general applicability. Analyses of the simulator’s inertial recordings show direction-dependent noise and nonlinearity related to the command amplitude. The Signal-to-Noise Ratio is one order of magnitude higher for the larger motion amplitudes we tested, compared to the smaller motion amplitudes. Simulator-introduced noise is found to be primarily of deterministic nature, particularly for the stronger motion intensities. The effect of simulator noise on quantification of animal/human motion sensitivity is discussed. We conclude that accurate recording and characterization of executed simulator motion are a crucial prerequisite for the investigation of uncertainty in self-motion perception.

The Role of Visual Cues and Whole-Body Rotations in Helicopter Hovering Control

Helicopters in flight are unstable, and hovering at one spot requires the pilot to do a considerable amount of active control. To date, it is still under discussion which sensory cues helicopter pilots use for this stabilization task, and how these cues are combined. Here we investigated how cues from different sensory modalities (visual cues and body cues) are used when humans stabilize a simulated helicopter at a target location in a closed perception-action loop. Participants were seated inside a closed cabin on a Stewart platform equipped with a projection screen. They had to stabilize a simulated helicopter on a target spot. To investigate the influence of individual visual cues on the stabilization, a minimalistic visual scene was used. Two spheres in the scene represented the location of the target and the position of the helicopter. Optical flow was provided by world-stationary random dots, and a horizon was produced by a black ground plane and white sky. We measured stabilization performance in ten different conditions: black background, horizon, optical flow, both horizon and optical flow, and horizontal stripes; all of these both with and without platform rotation cueing. Physical pitch and roll body rotations were presented by tilting the platform exactly as the simulated helicopter tilted. Our results show that all manipulated cues – horizon, optical flow, and platform rotations – can help the participants to stabilize a simulated helicopter. In particular, adding physical rotation cues to visual stimulation in a simulator can significantly improve the ability of trained participants to stabilize the simulated helicopter at a target location.

Identification of Pilot Control Behavior in a Roll-Lateral Helicopter Hover Task

This paper focuses on the influence of different forms of motion feedback on the perception and control behavior of pilots in a roll-lateral helicopter hover task. To identify this influence, a combined target-following and disturbance-rejection task is carried out where the motion feedback is varied. The participants perform the control task with roll motion only, lateral motion only, combined roll-lateral motion, or with no motion. A cybernetic approach is taken to identify multi-loop pilot describing functions and estimate the parameters of a pilot model. Results show that participants perform significantly better at the control task with feedback of combined roll-lateral motion, and decrease their control activity. For the condition with feedback of roll motion a similar trend is observed. This is explained through the increased amount of information present in the inner roll stabilization loop.

Control of a lateral helicopter side-step maneuver on an anthropomorphic robot

Our society relies more and more on flight simulation for pilot training to enhance safety and reduce costs. But to meet the highest level of general technical requirements for simulators set forth by the FAA and EASA requires high-cost equipment. To make simulator use more accessible, reduced costs might be achieved with novel simulator designs and/or through research to improve the performance of existing designs. This report explores the use of such a novel design, based on an anthropomorphic robot arm to reproduce an experiment designed to evaluate flight simulator motion requirement for helicopter pilot training. Results compare promisingly well to those from a large, highperformance facility where the original work was performed.

Does jerk have to be considered in linear motion simulation

Perceptual thresholds for the detection of the direction of linear motion are important for motion simulation. There are situations in which a subject should not perceive the motion direction as, e.g., during repositioning of a simulator, but also opposite cases where a certain motion percept must intentionally be induced in the subject. The exact dependency of the perceptual thresholds on the time evolution of the presented motion profile is still an open question. Previous studies have found evidence for a sensitivity of the thresholds on the rate of change of acceleration, called jerk. In this study we investigate three motion profiles which differ in their jerk characteristics. We want to evaluate which profile can move people furthest in the horizontal plane in a given time without them noticing the direction. Our results suggest that a profile with a minimum peak jerk value should be chosen.

Intersegmental Eye-Head-Body Interactions during Complex Whole Body Movements

Using state-of-the-art technology, interactions of eye, head and intersegmental body movements were analyzed for the first time during multiple twisting somersaults of high-level gymnasts. With this aim, we used a unique combination of a 16-channel infrared kinemetric system; a three-dimensional video kinemetric system; wireless electromyography; and a specialized wireless sport-video-oculography system, which was able to capture and calculate precise oculomotor data under conditions of rapid multiaxial acceleration. All data were synchronized and integrated in a multimodal software tool for three-dimensional analysis. During specific phases of the recorded movements, a previously unknown eye-head-body interaction was observed. The phenomenon was marked by a prolonged and complete suppression of gaze-stabilizing eye movements, in favor of a tight coupling with the head, spine and joint movements of the gymnasts. Potential reasons for these observations are discussed with regard to earlier findings and integrated within a functional model.

Performance Measurements on the MPI Stewart Platform

The report AGARD-AR-144 provides a framework for systematically assessing the dynamic characteristics of flight simulator motion systems. Several measurements defined in the report were performed on the Stewart platform located at the Max Planck Institute for Biological Cybernetics. The measurements were performed with a setup consisting of real-time hardware and an off-the-shelf IMU. Results indicated that the motion platform describing functions were very similar to the standard platform filters implemented by the motion system manufacturer, but included a time delay of 100 ms. The total noise of the system mainly consisted of stochastic and high-frequency non-linear components, that were attributed to the IMU. The measurements defined by AGARD-144 proved to provide useful insight into the platform characteristics.

Using inertial information alone to estimate linear self-displacement with varying durations of constant velocity

[Extract] In conditional discrimination choice tasks, one learns to make a choice conditionally based on the presenting discriminative/cue stimulus. Prior research has shown that when each type of correct choice is followed by a cue-unique trial outcome (differential outcomes procedure), learning is faster and more accurate than when a single, common outcome is delivered for all types of correct choice. This learning effect has been termed the differential outcomes effect (DOE). Results are discussed here for brain regions that are active in mediating the DOE, while healthy young adults performed delayed conditional discrimination under event-related functional magnetic resonance imaging (fMRI).Based on two different work motivation theories, the relationships between personality traits (Big Five, CSE: core self-evaluation) and the importance of various job aspects was investigated. In Study I (N=118), graduates with high scores on Openness to experience and Agreeableness placed emphasis on Herzbergs motivation factors, whereas no relations were found for hygiene factors. In Study II (N=117 employees), the Big Five accounted for 30% of the variance in importance of the motivating potential of a job (Job Characteristics Model) and CSE showed incremental validity. Results are discussed regarding person-job fit and the practical utility of the CSE construct.Individual differences in learning nondeterministic relationships were investigated in samples with high mathematical proficiency. Probability Learning tasks were included within selection tests for admission to the French Air Transport Pilot Training. In Study 1 (N=401), two cues had positive and negative relationships with a target criterion. Four classes, homogeneous in mathematical performance, differed in learning the nondeterministic relationships. _ Fast-learners swiftly learned the relationships. _ Medium- and Slow-learners were slower but eventually succeeded. _ Nonlearners (12%) failed to learn even the positive relationship. These patterns replicated in Study 2 (N=448), including a third-irrelevant-cue. The irrelevant cue made the task more complex and degraded more the learning of the negative than the positive cue. Response time analyses confirmed that differences in the learning profiles went along with differences in the decision-making processes.