Characterization of action optimality criteria as a complementary assessment of pilot workload
Creators: name:  K. STEINER 
name:   B. BERBERIAN 
name:   N. LANTOS 
name:   C. SCHULTE  
name:   T. RAKOTOMAMONJY 
name:   N. PELEGRIN 
name:   S. HALIYO 
name:   J. SARRAZIN 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: SYSTEM INTEGRATION
AERONAUTICS

description: In the aeronautical industry, the specification and design choices of flight assistance functions are strongly guided by the control of the workload (WL) that their use induces. In fact, the WL is often defined as a criterion determining the success or failure of the function and must be taken into account from the first steps of design. Quantifying WL through physiological measures is not straightforward and few models exist to explain the mechanisms behind it [1]. Indeed, the effectiveness of assistive devices depends on the understanding of the sensorimotor system, specifically, movement optimality (OPM). OPM represents how the nervous system manages the trade-off between action performance and the cognitive cost (or cognitive WL) related in its execution. It can be quantified through biomechanical criteria also called \"cost functions\" [2] The objective of this study is twofold. It aims (1) to identify the relationship between task difficulty (ID) and OPM, and (2) to compare biomechanical criteria of OPM to subjective measures of WL, more classically used in the field of ergonomics, in different ID conditions. To do this, two groups of 20 participants performed a reciprocal version of Fitts\' task [3]. Placed in a speed-accuracy trade-off situation, the participants were instructed to control the movement of an object in a virtual environment by operating a sidestick along the medial-lateral axis. Each group controls the movement of the object according to a specific law (position or speed). During two sessions, each participant performs the experiment in a specific frame of reference (geocentric vs egocentric). For each session (geocentric or egocentric), 5 levels of ID are tested. Several cost functions are calculated from kinematic and EMG recordings made on the participant\'s arm. The main results show that with the increase of the ID we observe (1) a decrease of the performance (increase of the movement time, undershoot and overshoot), (2) the appearance of nonlinearities in the kinematics of the object, (3) a more important quantity of noise in the distribution of coactivation of the EMG signal. These results verify Fitts\' law and validate the hypothesis that biomechanical criteria of movement can be used to quantify more accurately cognitive workload at different levels of analysis in addition to the subjective measures of WL classically used in system design ergonomics. References [1] Zhang, X., Qu, X., Xue, H., Zhao, H., Li, T., Tao, D. (2019). Modeling pilot mental workload using information theory. The Aeronautical Journal, 123(1264), 828-839. doi:10.1017/aer.2019.13. [2] Berret, B., Chiovetto, E., Nori, F., Pozzo, T. (2011). Evidence for composite cost functions in arm movement planning: an inverse optimal control approach. PLoS computational biology, 7(10), e1002183. [3] Fitts P.M., Peterson J.R.,(1964), Information capacity of discrete motor responses, Journal of Experimental Psychology 67, 103112.