Methods for Multiloop Identification of Visual and Neuromuscular Pilot Responses

Abstract

In this paper, identification methods are proposed to estimate the neuromuscular and visual responses of a multiloop pilot model. A conventional and widely used technique for simultaneous identification of the neuromuscular and visual systems makes use of cross-spectral density estimates. This paper shows that this technique requires a specific noninterference hypothesis, often implicitly assumed, that may be difficult to meet during actual experimental designs. A mathematical justification of the necessity of the noninterference hypothesis is given. Furthermore, two methods are proposed that do not have the same limitations. The first method is based on autoregressive models with exogenous inputs, whereas the second one combines cross-spectral estimators with interpolation in the frequency domain. The two identification methods are validated by offline simulations and contrasted to the classic method. The results reveal that the classic method fails when the noninterference hypothesis is not fulfilled; on the contrary, the two proposed techniques give reliable estimates. Finally, the three identification methods are applied to experimental data from a closed-loop control task with pilots. The two proposed techniques give comparable estimates, different from those obtained by the classic method. The differences match those found with the simulations. Thus, the two identification methods provide a good alternative to the classic method and make it possible to simultaneously estimate human's neuromuscular and visual responses in cases where the classic method fails.

Manual Control Cybernetics: State-of-the-Art and Current Trends

“…This can be approached either by using small rapid transient perturbations [158], or by using continuous perturbations to estimate full-bandwidth admittance. The latter technique has been used to estimate the arm NMS admittance during aircraft control [159]. A particularly useful technique to design continuous force perturbations is the ReducedPower Method [129], which allows full-bandwidth admittance estimates while evoking unperturbed low-bandwidth control behavior.…”

Effects of Preview Time in Manual Tracking Tasks

“…2 were estimated, at the input frequencies ω i of the target and disturbance signals. An instrumental-variable multiloop system identification technique was used, based on Fourier coefficients [20], [30]. The same method was used to derive the preview tracking model, see [19], [20] for a complete derivation.…”

Pilot Adaptation to Different Classes of Haptic Aids in Tracking Tasks

“…Three different identification techniques are used in this paper: a CSD-based method, an ARX method, and a novel CSD-ML method [20,28]. These three methods were tested and compared in a previous study dealing with a compensatory tracking task without haptic aids [28].…”

“…The first is based on cross-spectral density analysis (CSD-based method) and has been commonly used for identifying pilot responses [21,27]. However, a recent work showed that the CSD-based method might provide a biased estimate of neuromuscular response if a noninterference hypothesis is not fulfilled [28]. In the same study two novel approaches were proposed to overcome this issue [20,28]: a method based on autoregressive models with exogenous inputs (ARX method), and an adapted version of CSD for a multiloop tracking task (CSD-ML method).…”

“…However, a recent work showed that the CSD-based method might provide a biased estimate of neuromuscular response if a noninterference hypothesis is not fulfilled [28]. In the same study two novel approaches were proposed to overcome this issue [20,28]: a method based on autoregressive models with exogenous inputs (ARX method), and an adapted version of CSD for a multiloop tracking task (CSD-ML method). Our paper extends the ARX and CSD-ML methods to a tracking task with haptic aids, and compares the results with those obtained by the commonly used CSD-based method.…”