A Biodynamic Feedthrough Model Based on Neuromuscular Principles

Abstract

A biodynamic feedthrough (BDFT) model is proposed that describes how vehicle accelerations feed through the human body, causing involuntary limb motions and so involuntary control inputs. BDFT dynamics strongly depend on limb dynamics, which can vary between persons (between-subject variability), but also within one person over time, e.g., due to the control task performed (within-subject variability). The proposed BDFT model is based on physical neuromuscular principles and is derived from an established admittance model-describing limb dynamics-which was extended to include control device dynamics and account for acceleration effects. The resulting BDFT model serves primarily the purpose of increasing the understanding of the relationship between neuromuscular admittance and biodynamic feedthrough. An added advantage of the proposed model is that its parameters can be estimated using a two-stage approach, making the parameter estimation more robust, as the procedure is largely based on the well documented procedure required for the admittance model. To estimate the parameter values of the BDFT model, data are used from an experiment in which both neuromuscular admittance and biodynamic feedthrough are measured. The quality of the BDFT model is evaluated in the frequency and time domain. Results provide strong evidence that the BDFT model and the proposed method of parameter estimation put forward in this paper allows for accurate BDFT modeling across different subjects (accounting for between-subject variability) and across control tasks (accounting for within-subject variability).

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

“…Frequency response functions (FRFs) of the NMS can be estimated as "admittance", a measure of the allowed limb displacement due to an applied force [129]. HCs can adapt the admittance of their NMS -i.e., how "stiff" or "compliant" their response to forces is -which affects control performance in car driving [40], [45], aircraft control [24], and the impact of biodynamic effects in moving environments [130], [131].…”

Effects of Preview Time in Manual Tracking Tasks

“…In a few cases, when the best solution yielded clear outliers in the parameters, the second best solution was manually selected. The Variance Accounted For (VAF) was used as measure for the model's quality-of-fit: VAF = 1 − (σ 2 ε /σ 2 u ) × 100% [31]. A VAF of 100% reflects that the modeling error ε is zero and that model perfectly describes the measurements.…”

Design of Test Signals for Identification of Neuromuscular Admittance

“…the human's limb) in response to an external force. Knowledge of the neuromuscular admittance is particularly importance in situations where external disturbances act on the human's limb Venrooij et al (2014), and for situations where haptic support is given to the human operator through forces on a manipulator and/or modification of properties, such as stiffness, of the manipulator Abbink et al (2012).…”

“…This measurement is regularly performed for standard task conditions, such as the Force-Task (FT), in which the human operator is instructed to keep the force on the manipulator constant, the position task (PT), in which the instruction is to keep the manipulator in a set position and relax task (RT), in which the operator should suppress responses to manipulator movement. Using the data from the test signal, measured force on the manipulator and measured manipulator displacement, and possibly aided by EMG measurement, the NMS admittance properties can be identified in several possible approaches Damveld et al (2010) and Venrooij et al (2014). An example of the results of such a measurement is given in Figure 1.…”