The Role of Motion Feedback in Manual Preview Tracking Tasks

Motion feedback has an important effect in many tasks performed by humans. In this paper, we aim to investigate the role of motion feedback in preview tracking tasks with double integrator dynamics, using results from a human-in-the-loop experiment performed in the SIMONA Research Simulator of the Delft University of Technology. Eight subjects performed the same yaw tracking task with a compensatory and preview display, both with and without motion feedback. System identification techniques and quasi-linear human controller models for preview and motion feedback are used to explain human controller’s behavior in tracking tasks. An extension to an existing human preview control model is proposed, in order to model the human in a preview task using motion feedback. It is found that, when motion feedback is available, human controllers adapt their behavior in a similar way for compensatory and preview tasks. Motion feedback allows human controllers to further improve their performance in preview tracking. This research shows for the first time that motion feedback still has an important effect on the human controller behavior, even if visual preview is available. I. I NTRODUCTION T HE topic of manual control has been widely studied in the scientific community. McRuer and his colleagues [1] developed the widely known "crossover model", which models how humans perform a task using a compensatory display. This enables obtaining a mathematical model for humans in a very simple task, where only the error is displayed. Obtaini ng such a model for more realistic tasks, where more informatio n is present (more visual feedbacks, motion feedback) would allow for a more complete understanding of manual control. Research has previously been conducted on the role of motion feedback in compensatory tasks ([2], [3], [4], [5], [6], [7]). Not only was motion feedback found to result in improved tracking performance, but also extensions to the crossover model including motion feedback were proposed. The main drawback of the compensatory task is that it translates poorly to real-life tasks. The preview task, in w hich the future movement of the target is also shown to the human, is closer to what can be seen in the real world, in tasks such as driving a vehicle along a road. Recent research at the Delf t University of Technology proposed a new empirical model for this kind of task ([8], [9]). This model allows to understand how humans use preview, by using both feedforward and feedback control. It is still not clear if human controllers use preview simila rly in tasks using motion feedback, and if motion feedback is sti ll beneficial in preview tracking tasks. This paper investigat es the role of motion feedback in preview tracking tasks, by analyzing how both feedbacks affect performance, and human tracking behavior. The main objective of the project is to understand what is the effect of motion feedback, and if we are able to model the human response to it. In order to do this, an experiment will be conducted in the SIMONA Research Simulator (SRS) at the Delft University of Technology. Subjects perform a yaw tracking task using a double integrator controlled element, with compensatory and preview displays, both with and without motion feedback. A number of parametric and nonparametric measures will be calculated in order to understa nd the influence of motion feedback on preview tasks. Coherence will be calculated as a measure of linearity of the human controller. Error and control output variances will be obta ined, and system identification methods will be used to identify th e pilot response. The van der El et. al model [8] will be tested to the experimental data, with an extension for the case of preview with motion feedback. The Variance Accounted For (VAF) will be calculated as a measure of the quality of the model fit. This paper is structured in six sections. In Section II, the control task is presented, along with the models used for compensatory tasks, with and without motion, and preview tasks. An extended model is proposed for the preview trackin g task with motion. The description of the human-in-the-loop experiment and the system identification techniques used ar presented in Section III. Section IV contains the experimen t results, and Section V the discussion of these results. This paper ends with the conclusions in Section VI. II. CONTROL TASK A. Task Characteristics The control task considered in this paper is a combined target-tracking and disturbance-rejection task. In a targ ettracking task, the human controller is asked to track a targe signal, designated by ft(t), minimizing the errore(t) between the outputx(t) and the current target [1]. This output can also be perturbed by a disturbance signal fd(t), which constitutes the disturbance-rejection part of the task. In this paper, control tasks performed with compensatory and preview displays are investigated. In the compensatory task, only the error is displayed. In the preview task, the hu man controller can see the future target signal up to τp seconds