Sensory uncertainty and stick balancing at the fingertip

T. Insperger, John Milton

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The effects of sensory input uncertainty, ε, on the stability of time-delayed human motor control are investigated by calculating the minimum stick length, ℓcritℓ crit, that can be stabilized in the inverted position for a given time delay, τ. Five control strategies often discussed in the context of human motor control are examined: three time-invariant controllers [proportional-derivative, proportional-derivative- acceleration (PDA), model predictive (MP) controllers] and two time-varying controllers [act-and-wait (AAW) and intermittent predictive controllers]. The uncertainties of the sensory input are modeled as a multiplicative term in the system output. Estimates based on the variability of neural spike trains and neural population responses suggest that ≈ 7ε ≈ 7 -13 %. It is found that for this range of uncertainty, a tapped delay-line type of MP controller is the most robust controller. In particular, this controller can stabilize inverted sticks of the length balanced by expert stick balancers (0.25-0.5 m when τ ≈ 0.08τ ≈ 0.08 s). However, a PDA controller becomes more effective when ε > 15 %. A comparison between ℓcritℓ crit for human stick balancing at the fingertip and balancing on the rubberized surface of a table tennis racket suggest that friction likely plays a role in balance control. Measurements of ℓcrit, τ, and a variability of the fluctuations in the vertical displacement angle, an estimate of ε, may make it possible to study the changes in control strategy as motor skill develops.

Original languageEnglish
Pages (from-to)85-101
Number of pages17
JournalBiological Cybernetics
Volume108
Issue number1
DOIs
Publication statusPublished - Feb 2014

Fingerprint

Uncertainty
Controllers
Tennis
Motor Skills
Friction
Derivatives
Electric delay lines
Population
Time delay

Keywords

  • Control
  • Feedback delay
  • Sensory uncertainties
  • Stick balancing

ASJC Scopus subject areas

  • Biotechnology
  • Computer Science(all)

Cite this

Sensory uncertainty and stick balancing at the fingertip. / Insperger, T.; Milton, John.

In: Biological Cybernetics, Vol. 108, No. 1, 02.2014, p. 85-101.

Research output: Contribution to journalArticle

Insperger, T. ; Milton, John. / Sensory uncertainty and stick balancing at the fingertip. In: Biological Cybernetics. 2014 ; Vol. 108, No. 1. pp. 85-101.
@article{49d9ea5d0e69417d9f11f0864f67e3bf,
title = "Sensory uncertainty and stick balancing at the fingertip",
abstract = "The effects of sensory input uncertainty, ε, on the stability of time-delayed human motor control are investigated by calculating the minimum stick length, ℓcritℓ crit, that can be stabilized in the inverted position for a given time delay, τ. Five control strategies often discussed in the context of human motor control are examined: three time-invariant controllers [proportional-derivative, proportional-derivative- acceleration (PDA), model predictive (MP) controllers] and two time-varying controllers [act-and-wait (AAW) and intermittent predictive controllers]. The uncertainties of the sensory input are modeled as a multiplicative term in the system output. Estimates based on the variability of neural spike trains and neural population responses suggest that ≈ 7ε ≈ 7 -13 {\%}. It is found that for this range of uncertainty, a tapped delay-line type of MP controller is the most robust controller. In particular, this controller can stabilize inverted sticks of the length balanced by expert stick balancers (0.25-0.5 m when τ ≈ 0.08τ ≈ 0.08 s). However, a PDA controller becomes more effective when ε > 15 {\%}. A comparison between ℓcritℓ crit for human stick balancing at the fingertip and balancing on the rubberized surface of a table tennis racket suggest that friction likely plays a role in balance control. Measurements of ℓcrit, τ, and a variability of the fluctuations in the vertical displacement angle, an estimate of ε, may make it possible to study the changes in control strategy as motor skill develops.",
keywords = "Control, Feedback delay, Sensory uncertainties, Stick balancing",
author = "T. Insperger and John Milton",
year = "2014",
month = "2",
doi = "10.1007/s00422-013-0582-2",
language = "English",
volume = "108",
pages = "85--101",
journal = "Biological Cybernetics",
issn = "0340-1200",
publisher = "Springer Verlag",
number = "1",

}

TY - JOUR

T1 - Sensory uncertainty and stick balancing at the fingertip

AU - Insperger, T.

AU - Milton, John

PY - 2014/2

Y1 - 2014/2

N2 - The effects of sensory input uncertainty, ε, on the stability of time-delayed human motor control are investigated by calculating the minimum stick length, ℓcritℓ crit, that can be stabilized in the inverted position for a given time delay, τ. Five control strategies often discussed in the context of human motor control are examined: three time-invariant controllers [proportional-derivative, proportional-derivative- acceleration (PDA), model predictive (MP) controllers] and two time-varying controllers [act-and-wait (AAW) and intermittent predictive controllers]. The uncertainties of the sensory input are modeled as a multiplicative term in the system output. Estimates based on the variability of neural spike trains and neural population responses suggest that ≈ 7ε ≈ 7 -13 %. It is found that for this range of uncertainty, a tapped delay-line type of MP controller is the most robust controller. In particular, this controller can stabilize inverted sticks of the length balanced by expert stick balancers (0.25-0.5 m when τ ≈ 0.08τ ≈ 0.08 s). However, a PDA controller becomes more effective when ε > 15 %. A comparison between ℓcritℓ crit for human stick balancing at the fingertip and balancing on the rubberized surface of a table tennis racket suggest that friction likely plays a role in balance control. Measurements of ℓcrit, τ, and a variability of the fluctuations in the vertical displacement angle, an estimate of ε, may make it possible to study the changes in control strategy as motor skill develops.

AB - The effects of sensory input uncertainty, ε, on the stability of time-delayed human motor control are investigated by calculating the minimum stick length, ℓcritℓ crit, that can be stabilized in the inverted position for a given time delay, τ. Five control strategies often discussed in the context of human motor control are examined: three time-invariant controllers [proportional-derivative, proportional-derivative- acceleration (PDA), model predictive (MP) controllers] and two time-varying controllers [act-and-wait (AAW) and intermittent predictive controllers]. The uncertainties of the sensory input are modeled as a multiplicative term in the system output. Estimates based on the variability of neural spike trains and neural population responses suggest that ≈ 7ε ≈ 7 -13 %. It is found that for this range of uncertainty, a tapped delay-line type of MP controller is the most robust controller. In particular, this controller can stabilize inverted sticks of the length balanced by expert stick balancers (0.25-0.5 m when τ ≈ 0.08τ ≈ 0.08 s). However, a PDA controller becomes more effective when ε > 15 %. A comparison between ℓcritℓ crit for human stick balancing at the fingertip and balancing on the rubberized surface of a table tennis racket suggest that friction likely plays a role in balance control. Measurements of ℓcrit, τ, and a variability of the fluctuations in the vertical displacement angle, an estimate of ε, may make it possible to study the changes in control strategy as motor skill develops.

KW - Control

KW - Feedback delay

KW - Sensory uncertainties

KW - Stick balancing

UR - http://www.scopus.com/inward/record.url?scp=84894225571&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84894225571&partnerID=8YFLogxK

U2 - 10.1007/s00422-013-0582-2

DO - 10.1007/s00422-013-0582-2

M3 - Article

VL - 108

SP - 85

EP - 101

JO - Biological Cybernetics

JF - Biological Cybernetics

SN - 0340-1200

IS - 1

ER -