Juan Pedro Dominguez-Morales

Angel Jimenez-Fernandez, Daniel Gutierrez-Galan, Antonio Rios-Navarro et al.

In neuromorphic engineering, computation is commonly performed asynchronously, mimicking the way in which nervous systems process information: spike by spike. The Neuromorphic Auditory Sensor (NAS) has been implemented under this principle: applying different spike-based Signal Processing blocks. Computation in the spike domain requires the conversion of signals from analog or digital representation to the spike domain, which could present a speed constraint in many cases. This paper presents a spike-based system to convert audio information from low-power pulse density modulation (PDM) MicroElectroMechanical Systems (MEMS) microphones into rate coded spike frequencies. These spikes represent the input signal of the NAS, avoiding the analog or digital to spike conversion, and therefore improving the time response of the NAS. This conversion has been done in VHDL as an interface for PDM microphones, converting their pulses into temporal distributed spikes following a pulse frequency modulation (PFM) scheme with an accurate Inter-Spike-Interval, known as "PDM to spikes interface" (PSI). This was tested in two scenarios, first as a stand-alone circuit for its characterization, and then integrated with a NAS for verification. The PSI achieves a Total Harmonic Distortion (THD) of -39.51dB and a Signal-to-Noise Ratio (SNR) of 59.12dB, demands less than 1\% of the resources of a Spartan-6 FPGA and has a power consumption below 5mW.

Daniel Gutierrez-Galan, Juan Pedro Dominguez-Morales, Fernando Perez-Pena et al.

Initially, robots were developed with the aim of making our life easier, carrying out repetitive or dangerous tasks for humans. Although they were able to perform these tasks, the latest generation of robots are being designed to take a step further, by performing more complex tasks that have been carried out by smart animals or humans up to date. To this end, inspiration needs to be taken from biological examples. For instance, insects are able to optimally solve complex environment navigation problems, and many researchers have started to mimic how these insects behave. Recent interest in neuromorphic engineering has motivated us to present a real-time, neuromorphic, spike-based Central Pattern Generator of application in neurorobotics, using an arthropod-like robot. A Spiking Neural Network was designed and implemented on SpiNNaker. The network models a complex, online-change capable Central Pattern Generator which generates three gaits for a hexapod robot locomotion. Reconfigurable hardware was used to manage both the motors of the robot and the real-time communication interface with the Spiking Neural Networks. Real-time measurements confirm the simulation results, and locomotion tests show that NeuroPod can perform the gaits without any balance loss or added delay.