Re-optimization Contributes to the Adaption of External VF Field

The computational model of Franklin et al. (J. Neurosci., 28(44) 2008, 11165-11173) describes the adaptation of human arm movement to the external force field with lower-level feed-forward module for compensation. While this paper proposes another possible option that when the environment can be expressed in the internal model, the upper-level optimal control module can directly play the role of feedforward compensation merely via tuning two corresponding parameters: the co-contraction level r between a pair of antagonistic muscles and the parameter reflecting the force field during optimal calculation. To verify this idea, this paper imposes velocity -dependent force field in the simulation on the neruo-musculo-skeletal biomechanical model using optimal control method. Qualitatively, the outcome is consistent with the experimental references.