A programmable array of silicon neurons for the control of legged locomotion

The biological foundation of most natural locomotory systems is the central pattern generator (CPG). The CPG is a set of neural circuits found in the spinal cord, arranged to produce oscillatory periodic waveforms that activate muscles in a coordinated manner. A 2nd generation VLSI CPG emulator chip - with more and improved neurons, enhanced flexibility, and a higher degree of programmability - has been developed to synchronize oscillators with different frequencies and phases, also produced by the chip, through the coupling of integrate-and-fire (IF) silicon neurons. These oscillators are then used to control the movement of robot's limbs by using the IF neurons to set a specific phase difference between the oscillators. The chip's architecture is examined in detail, and the construction and implementation of the artificial neural networks that produce the waveforms required for locomotion is described.