Neuromechanical Model of Rat Hind Limb Walking with Two Layer CPGs and Muscle Synergies

We present a synthetic nervous system modeling mammalian locomotion using separate central pattern generator and pattern formation layers. The central pattern generator defines the rhythm of locomotion and the timing of extensor and flexor phase. We also investigated the capability of the pattern formation network to operate using muscle synergies instead of single muscle pairs. The result is that this model is capable of adjusting rhythm and muscle forces independently, and stepping is successfully produced using two synergies, one with the hip, and the other with the knee and ankle combined. This work demonstrates that pattern formation networks can activate multiple muscles in a coordinated way to produce steady walking. It encourages the use of more complex synergies activating more muscles in the legs for 3D limb motion.