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.