Robert A. Boie

Capacitive impedance readout tactile image sensor

The transduction of mechanical forces to representative electrical signals uses a three layer sandwich structure. The top layer is columns of compliant metal strips over a central elastic dielectric sheet. The bottom layer is a flexible printed circuit board with rows of metal strips and multiplexing circuits. Electrically, the sensor is a capacitor array formed by the row and column crossings with the middle layer functioning as a dielectric spring. A readout of the capacitor values corresponds to a sampled tactile image. The reasons for choosing this transduction method, the performance advantages of capacitive sensing and the design and integration of 64 element imagers into the fingers of a controlled compliance gripper are described.

An analysis of camera noise

The class of cameras that are based on ionization sensors, which includes the most common charge-coupled device (CCD) and vidicon cameras, is examined. Camera signals are shown to be corrupted by direction-dependent stationary electronic noise sources and fluctuations due to the statistical nature of the sensing process. The authors develop and test a model of the inherent noises in cameras. These results are confirmed by measurement, and they suggest a locally stationary model of noise for adaptive signal processing. >

Bar code recovery via the EM algorithm

The ubiquitous supermarket checkout scanner is indeed a well engineered and effective device. There is, nevertheless, demand for better devices. Existing scanners rely on simple and indeed low-cost signal processing to interpret bar code signals. These methods, nevertheless, fundamentally limit label reading and cannot be extended. A new method based on the deterministic EM algorithm is described. First results show a substantial improvement in label reading depth of field, which is an important performance parameter for bar code readers.

Noise-limited reading of bar codes

The ubiquitous supermarket checkout scanner is a well-engineered and effective device. Existing scanners rely on simple and low-cost signal processing to interpret bar-code signals, which imposes restrictions on the system noise power that they can tolerate. In this paper, the authors describe the relationships between engineering parameters of the system that limit reader performance. If the combined noise is Gaussian, they show that the reader error probability depends on a single parameter, which they call a timing signal-to-noise ratio.

Light Beam Stiffening Of Flexible Robot Arms

The structure and hence geometry of present day robots is outside the actuator control loop. Accuracy under changing load conditions requires a rigid and therefore massive structure. The performance may be improved by use of lighter structures with sensing and feedback control of the elastic modes and damping. This paper describes a sensing method based on a system of internal light beams and photodetectors that provides end-point sensing and structural deformation information necessary for high performance control.