A capacitive array for robotic proximity and feature sensing has been designed, modeled, and tested. The basic probe consists of alternating metallic strip electrodes. One set of strips makes up the drive plate. The other set consists of tiny receivers. Both sum and differential modes of operations are used to allow one to detect proximity and features, respectively. Modeling has encompassed calculation of admittance changes (ΔY) due to the introduction of materials with simple geometric configurations. The theory is developed in detail using the Lorentz reciprocity theorem. The relationship between the spatial frequency of the probe electrodes and the interrogation field penetration is also discussed. Testing has involved scanning a two-port configured probe system over a test piece with known features and flaws. Four capabilities of the probe have been examined: distance ranging, edge detection, field optimization (changing the electric field pattern of the probe to enhance output signal), and complex pattern recognition (filtering). Both dielectric and metal objects have been investigated.
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