Effects of underestimating the kinematics of trunk rotation on simultaneous reaching movements: Predictions of a biomechanical model

Martin Simoneau, Étienne Guillaud, Jean Blouin
Journal of NeuroEngineering and Rehabilitation. 2013-01-01; 10(1): 54
DOI: 10.1186/1743-0003-10-54

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Simoneau M(1), Guillaud É, Blouin J.

Author information:
(1)Faculté de Médecine, Département de kinésiologie, Université Laval, Québec,

BACKGROUND: Rotation of the torso while reaching produces torques (e.g., Coriolis
torque) that deviate the arm from its planned trajectory. To ensure an accurate
reaching movement, the brain may take these perturbing torques into account
during movement planning or, alternatively, it may correct hand trajectory during
movement execution. Irrespective of the process selected, it is expected that an
underestimation of trunk rotation would likely induce inaccurate shoulder and
elbow torques, resulting in hand deviation. Nonetheless, it is still undetermined
to what extent a small error in the perception of trunk rotations, translating
into an inappropriate selection of motor commands, would affect reaching
METHODS: To investigate, we adapted a biomechanical model (J Neurophysiol 89:
276-289, 2003) to predict the consequences of underestimating trunk rotations on
right hand reaching movements performed during either clockwise or counter
clockwise torso rotations.
RESULTS: The results revealed that regardless of the degree to which the torso
rotation was underestimated, the amplitude of hand deviation was much larger for
counter clockwise rotations than for clockwise rotations. This was attributed to
the fact that the Coriolis and centripetal joint torques were acting in the same
direction during counter clockwise rotation yet in opposite directions during
clockwise rotations, effectively cancelling each other out.
CONCLUSIONS: These findings suggest that in order to anticipate and compensate
for the interaction torques generated during torso rotation while reaching, the
brain must have an accurate prediction of torso rotation kinematics. The present
study proposes that when designing upper limb prostheses controllers, adding a
sensor to monitor trunk kinematics may improve prostheses control and

Auteurs Bordeaux Neurocampus