A New View on Biodynamic Feedthrough Analysis: Unifying the Effects on Forces and Positions

Abstract

When performing a manual control task, vehicle accelerations can cause involuntary limb motions, which can result in unintentional control inputs. This phenomenon is called biodynamic feedthrough (BDFT). In the past decades, many studies into BDFT have been performed, but its fundamentals are still only poorly understood. What has become clear, though, is that BDFT is a highly complex process, and its occurrence is influenced by many different factors. A particularly challenging topic in BDFT research is the role of the human operator, which is not only a very complex but also a highly adaptive system. In literature, two different ways of measuring and analyzing BDFT are reported. One considers the transfer of accelerations to involuntary forces applied to the control device (CD); the other considers the transfer of accelerations to involuntary CD deflections or positions. The goal of this paper is to describe an approach to unify these two methods. It will be shown how the results of the two methods relate and how this knowledge may aid in understanding BDFT better as a whole. The approach presented is based on the notion that BDFT dynamics can be described by the combination of two transfer dynamics: 1) the transfer dynamics from body accelerations to involuntary forces and 2) the transfer dynamics from forces to CD deflections. The approach was validated using experimental results.

Mathematical Biodynamic Feedthrough Model Applied to Rotorcraft

“…To understand this choice and the capabilities of the resulting model, first the complete BDFT system model needs to be discussed. Descriptions of the full BDFT system model, provided in [11], [23], and [24] are briefly repeated here. Fig.…”

“…Admittance is a dynamic property of a limb characterized by the relation between force (input) and position (output) of a limb [26]. It is known that BDFT dynamics depend on neuromuscular admittance [11], [24].…”

“…These blocks are, therefore, of interest when studying, e.g., the stability of the human-vehicle interaction [18], however, they do not influence the BDFT dynamics themselves. It is reasonable to assume that the processes that underly BDFT are the same in open-loop and closed-loop systems [24]. This allows for studying BDFT in an open-loop fashion, i.e., exposing a subject to a predetermined acceleration signal M dist (t) and measuring the forces and control device deflections, without having to close the loop by feeding these inputs into a vehicle model.…”

Admittance-adaptive model-based cancellation of biodynamic feedthrough

“…The BDFT response can separated in several related dynamical relationships [11], [15]. The first distinction that can be made is that BDFT causes both involuntary positions (deflections) of the control device and involuntary forces applied to the control device.…”

Vehicle Active Steering Control System Based on Human Mechanical Impedance Properties of the Arms

“…They [13] developed the driver model with LQR path-following controller and NMS to analyze the robustness of driver steering control with measured mechanical impedance parameters, and demonstrated the differences of pass-following performance between the relax condition and the co-contraction stiffness of NMS. Abbink and Mulder et al [14], [15] estimated the admittance of NMS in the manual control task by analyzing involuntary limb motion of the driver caused by vehicle accelerations, called biodynamic feedthrough (BDFT), in the limited experimental conditions on muscle co-contraction level. They described the BDFT system composed of the transfer function from body acceleration to involuntary force and the function from force to position.…”