The effect of random image perturbation on the measurement of line length and area using discrete photosensitive arrays is presented It is shown that two-dimensional independent Gaussian perturbation can linearize the response of area measurement systems employing arrays with elements of small active area

Area Measurement Using Random Image Perturbation with Discrete Arrays

A random perturbation about the true position of a target image is shown to improve the position-detection accuracy of systems which operate on quantized data. For a two-sensor receptor the random perturbation is shown to decrease the position error measurably. For a multisensor receptor the random perturbation is shown to drive the position error to zero.

The Effect of Random Perturbation on Position-Detection Accuracy

A position-detection system utilizing a chemical array is described. The array uses a continuous layer of inorganic compound in a resin material as the sensing medium, thus eliminating the element spacings that are the primary cause of error in discrete arrays with inactive gaps. The analysis of a one-dimensional chemical array with mechanical image perturbation is presented. Zero error-position detection is obtained with triangular image perturbation.

Chemical Array as a Position Detector

Improved position detection involving a one-dimensional photosensor array has been shown to be possible by applying a high-frequency perturbation signal to a normalized target image. A general analytical model which describes the receptor system with respect to receptor element threshold, perturbation amplitude (peak), and the deadspace between elements is presented. Functional-approximation theory is applied to determine necessary and sufficient conditions on the system parameters that optimize (Chebyshev) the system position transfer characteristic with respect to one that is linear.

Signal-Perturbation Model for Achievement of Optimal Position Transfer Characteristic

High-resolution position detection using a one-dimensional zero-dead-band photosensor receptor has been shown [1] to be possible by applying a high-frequency triangular perturbation to a normalized target image. It is shown here that for a nonzero dead-band ? between the receptor elements, position detection becomes increasingly uncertain as ? increases. By periodically changing the magnitude of the perturbation and the system gain, it is shown that accurate position detection is still possible for a receptor with nonzero dead-band.

Achieving Improved Position Detection Using a Modified Triangular Perturbation Signal

It is shown that a triangular perturbation signal provides increased position-detection accuracy over that provided by a sinusoidal perturbation signal [1]. Triangular perturbation is applied to a two-element photosensor receptor, resulting in perfect position detection within the dimensions of the receptor. It is also shown that perfect position detection can be obtained over as large a range as desired by using a many-element zero-deadband one-dimensional receptor subjected to triangular perturbation.

Jr. E.A. Parrish

Papers

On the Improvement of Position-Detection Accuracy Using Signal Perturbation Theory

The Effect of Random Perturbation on Position-Detection Accuracy