Locomotion in mammals is controlled by a spinal central pattern generator (CPG) coupled to
a biomechanical limb system, with afferent feedback to the spinal circuits and CPG closing
the control loop. We have considered a simplified model of this system, in which the CPG
establishes a rhythm when a supra-spinal activating drive is present and afferent signals
from a single-joint limb feed back to affect CPG operation. Using dynamical system methods,
in a series of two papers we analyze the mechanisms by which this model produces …

In this paper we analyze a closed loop neuromechanical model of locomotor rhythm
generation. The model is composed of a spinal central pattern generator (CPG) and a single-
joint limb, with CPG outputs projecting via motoneurons to muscles that control the limb and
afferent signals from the muscles feeding back to the CPG. In a preceding companion paper
(Spardy et al 2011 J. Neural Eng. 8 065003), we analyzed how the model generates
oscillations in the presence or absence of feedback, identified curves in a phase plane …