Design of OTA-C Gaussian Function Generator

A novel method for analogue VLSI implementation of programmable Gaussian function generator is proposed in this paper, in which the Gaussian function is approximated by the OTA-C filter whose frequency response is Gaussian-shaped. OTA-C circuit is very suitable for this application since the programmability can be controlled by the transconductance of OTA precisely and easily. Based on the probability argument, the OTA-C biquadratic filters and OTA-C integrator which have the cascade connection are used as the building block. To elaborate the construction procedure, a seventh-order OTA-C Gaussian function generator is selected as an example. The simulation results verify the feasibility of the presented approach.

Controlling Underwater Robots with Electronic Nervous Systems

We are developing robot controllers based on biomimetic design principles. The goal is to realise the adaptive capabilities of the animal models in natural environments. We report feasibility studies of a hybrid architecture that instantiates a command and coordinating level with computed discrete-time map-based (DTM) neuronal networks and the central pattern generators with analogue VLSI (Very Large Scale Integration) electronic neuron (aVLSI) networks. DTM networks are realised using neurons based on a 1-D or 2-D Map with two additional parameters that define silent, spiking and bursting regimes. Electronic neurons (ENs) based on Hindmarsh–Rose (HR) dynamics can be instantiated in analogue VLSI and exhibit similar behaviour to those based on discrete components. We have constructed locomotor central pattern generators (CPGs) with aVLSI networks that can be modulated to select different behaviours on the basis of selective command input. The two technologies can be fused by interfacing the signals from the DTM circuits directly to the aVLSI CPGs. Using DTMs, we have been able to simulate complex sensory fusion for rheotaxic behaviour based on both hydrodynamic and optical flow senses. We will illustrate aspects of controllers for ambulatory biomimetic robots. These studies indicate that it is feasible to fabricate an electronic nervous system controller integrating both aVLSI CPGs and layered DTM exteroceptive reflexes.