Biological Cybernetics

, Volume 78, Issue 2, pp 119–132

The generation of handwriting with delta-lognormal synergies

  • Réjean Plamondon
  • Wacef Guerfali

DOI: 10.1007/s004220050419

Cite this article as:
Plamondon, R. & Guerfali, W. Biol Cybern (1998) 78: 119. doi:10.1007/s004220050419

Abstract.

This paper presents a handwriting generation model that takes advantage of the asymptotic impulse response of neuromuscular networks to produce and control complex two-dimensional synergistic movements. A parametric definition of a ballistic stroke in the context of the kinematic theory of rapid human movements is given. Two types of parameters are used: command and system parameters. The first group provides a representation of the action plan while the second takes into account the temporal properties of the neuromuscular systems executing that plan. Handwriting is described as the time superimposition of basic discontinuous strokes that results in a continuous summation of delta-lognormal velocity vectors. The model leads to trajectory reconstruction, both in the spatial and in the kinematic domain. According to this new paradigm, the angular velocity does not have to be controlled independently and continuously; it naturally emerges from the vectorial summation process. Several psychophysical phenomena related to two-dimensional movements are explained and analyzed in the context of the model: the speed/accuracy trade-offs, spatial scaling, the isochrony principle, the two-thirds power law, effector independence, etc. The overall approach also shows how basic handwriting characteristics (dimension, slant, baseline, shape, etc.) are affected and controlled using an action plan made up of virtual targets fed into a neuromuscular synergy that is governed by a delta-lognormal law.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Réjean Plamondon
    • 1
  • Wacef Guerfali
    • 1
  1. 1.École Polytechnique de Montréal, Laboratoire Scribens, Département de génie électrique et de génie informatique, C.P. 6079, Succursale Centre-Ville, Montréal QC H3C 3A7, Canada CA

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