Abstract:
A computer system for controlling a nonlinear physical process. The computer system comprises a linear controller and a neural network. The linear controller receives a command signal for control of the nonlinear physical process and a measured output signal from the output of the nonlinear physical process. The linear controller generates a control signal based on the command signal, a measured output signal, and a fixed linear model for the process. The neural network receives the control signal from the linear controller and the measured output signal from the output of the nonlinear physical process. The neural network uses the measured output signal to modify the connection weights of the neural network. The neural network also generates a modified control signal supplied to the linear controller to iterate a fixed point solution for the modified control signal used to control the nonlinear physical process.
Abstract:
The present invention discloses low noise, optically coupled optoelectronic and all-optical artificial neuron devices that can be configured in an array to simulate the function of biological neural networks, and methods for making the artificial neurons. In a first optoelectronic embodiment, the device employs the regenerative pulsation property of astable multivibrators as optical pulse generators. Prior art pulse-coupled artificial neurons are subject to undesirable noise interference because the interconnection of such prior art neurons is based on electrical signals conducted through a grid of wires. The present invention obviates the need for hard-wired interconnection of individual neurons in order to cofigure the neurons into a network. In an optoelectronic embodiment, the neuron receives an optical input signal from an external source. A photosensitive detector, disposed in a circuit to control the state of an astable or bistable multivibrator, converts the intensity of the input light into a train of light pulses having a frequency that is a function of the intensity of the input signal. In an all-optical embodiment of an artificial neuron, an input signal is first integrated and the integrated signal transmitted to an optical pulse generator comprised of a nonlinear material disposed within the cavity of a Fabry-Perot etalon. The output of the etalon is a train of light pulses having a frequency that depends upon the intensity of the integrated input signal. When a weak light signal reaches the neuron's input port, there is no light pulse emitted from the output port. By contrast, a strong signal, or a group of weak signals, triggers a short-lived light pulse. The output pulse frequency is a function of the summed input signal power.
Abstract:
An analog neural computing medium, neuron and neural networks comprising same are disclosed. The neural computing medium includes a phase change material that has the ability to cumulatively respond to multiple synchronous or asynchronous input signals. The introduction of input signals induces transformations among a plurality of accumulation states of the disclosed neural computing medium. The accumulation states are characterized by a high electrical resistance that is substantially identical for all accumulation states. The high electrical resistance prevents the neural computing medium from transmitting signals. Upon cumulative receipt of energy from one or more input signals that equals or exceeds a threshold value, the neural computing medium fires by transforming to a low resistance state that is capable of transmitting signals. The neural computing medium thus closely mimics the neurosynaptic function of a biological neuron. The disclosed neural computing medium may also be configured to perform a weighting function whereby it weights incoming signals and transmits modified signals. The neural computing medium may thus be configured to provide an accumulation function or weighting function and may readily be reconfigured from one function to the other. The disclosed neurons may also include activation units for further transforming signals transmitted by the accumulation units according to a mathematical operation. The artificial neurons, weighting units, accumulation units and activation units may be connected in a variety of ways to form artificial neural networks. Embodiments of several neural networks are disclosed.
Abstract:
Two neural networks are used to control adaptively a vibration and noise-producing plant. The first neural network, the emulator, models the complex, nonlinear output of the plant with respect to certain controls and stimuli applied to the plant. The second neural network, the controller, calculates a control signal which affects the vibration and noise producing characteristics of the plant. By using the emulator model to calculate the nonlinear plant gradient, the controller matrix coefficients can be adapted by backpropagation of the plant gradient to produce a control signal which results in the minimum vibration and noise possible, given the current operating characteristics of the plant.
Abstract:
A neural network includes a neuron, an error determination unit, and a weight update unit. The weight update unit includes an analog accumulator. The analog accumulator requires a minimal number of multipliers.
Abstract:
A neuronal network for modeling an output function that describes a physical system using functionally linked neurons (2), each of which is assigned a transfer function, allowing it to transfer an output value determined from said neuron to the next neuron that is functionally connected to it in series in the longitudinal direction (6) of the network (1), as an input value. The functional relations necessary for linking the neurons are provided within only one of at least two groups (21, 22, 23) of neurons arranged in a transverse direction (7) and between one input layer (3) and one output layer (5). The groups (21, 22, 23) include at least two intermediate layers (11, 12, 13) arranged sequentially in a longitudinal direction (5), each with at least one neuron.
Abstract:
A method of identifying features for a classifier includes identifying a set of elements that share a common characteristic, and then identifying a subset of elements within that set which share a second characteristic. Features are then selected that are more commonly possessed by the elements in the subset than the elements in the set but excluding the subset, and that are more commonly possessed by the elements in the set but excluding the subset, as compared to the elements outside the set. A further method of identifying features for a classifier includes defining a list of features, selecting a first feature from that list, identifying a set of elements that possess that first feature, and then identifying a subset of elements within that set which possess any other feature. A feature is then selected that is more commonly possessed by the elements in the subset than the elements in the set but excluding the subset, and that is more commonly possessed by the elements in the set but excluding the subset, as compared to the elements outside the set. If this feature is not already in the list of features, it is added to it. Another feature that has not already been selected is chosen from the list, and the process is repeated using this feature. This continues until every feature in the list of features has been selected.
Abstract:
A current-mode pulse-width-modulation (PWM) circuit converts analog current signals into pulse signals. The PWM circuit includes a first I-V converter and one or more second I-V converters, each of the one or more second I-V converters being coupled to one of the current signals. Each of the first and second I-V converters is also coupled to a current generator which generates a current that linearly changes with time. For each of the first and second I-V converters, when a polarity of the input current thereof changes, an output changes between a high voltage level and a low voltage level. A logic circuit is coupled to the first and each second I-V converter to obtain a pulse signal that has a pulse width linearly proportional to the current level of the respective current signal.
Abstract:
A PBNN for isolating faults in a plurality of components forming a physical system comprising a plurality of input nodes each input node comprising a plurality of inputs comprising a measurement of the physical system, and an input transfer function comprising a hyperplane representation of at least one fault for converting the at least one input into a first layer output, a plurality of hidden layer nodes each receiving at least one first layer output and comprising a hidden transfer function for converting the at least one of at least one first layer output into a hidden layer output comprising a root sum square of a plurality of distances of at least one of the at least one first layer outputs, and a plurality of output nodes each receiving at least one of the at least one hidden layer outputs and comprising an output transfer function for converting the at least one hidden layer outputs into an output.
Abstract:
A neural network includes a programmable template matching network and a winner take all network. The programmable template matching network can be programmed with different templates. The WTA network has an output which can be reconfigured and the scale of the WTA network can expanded.