Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1987-07-20
1989-05-09
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
356 5, G01J 132
Patent
active
048291722
ABSTRACT:
There is disclosed an optical ranging system adapted for use with widely varying return signal levels. Automatic signal level control is achieved in two parts, a passive optical part and an active electronic AGC part. The optical part is based on the coaxial arrangement of transmitting and receiving elements in which the shielded transmitting element is mounted in front of the receiving element, which includes Fresnel lens which comprises a plastic casting. The electronic AGC portion of the system includes means for providing a voltage drive (with low internal impedance) for the final AGC transistor when it would tend to be slow, so little phase shift in the control results from changes in the signal levels. Thereby, the determination of distance (the ranging) by phase shift measurement is kept reliable as signal level changes. This optical ranging system is especially adapted for mounting on autonomously guided vehicles (robot carts), which are important for material handling and inventory control in manufacturing systems in factory environments.
REFERENCES:
patent: 4346989 (1982-08-01), Gort et al.
patent: 4453825 (1984-06-01), Buck et al.
patent: 4639129 (1987-01-01), Hullein et al.
patent: 4712915 (1987-12-01), Kosakowski et al.
SPIE, vol. 230, Minicomputers and Microprocessors in Optical Systems, "Fully Integrated Microprocessor-Controlled Surveying Instrument", A. F. Gort, Jun. 1980, pp. 158-167.
"Redundant Sensors for Mobile Robot Navigation", Master's Thesis at the Massachusetts Institute of Technology by Anita N. Flynn, U.S. Government unclassified report No. AI-TR-859, Government accession No. AD-A101087.
American Telephone and Telegraph Company AT&T Bell Laboratories
Nelms David C.
Wisner Wilford L.
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