US 4,044,377 A · Video target locator

Abstract

A closed circuit TV camera with a fixed focus lens, is used to measure the vertical displacement from and longitudinal distance from an industrial robot arm to checkered-row target pattern, i.e., a row of alternate black and white squares. The pattern is located in a fixed spatial relationship with a targeted object and is identified by the appearance of a burst of pulses in the video output during the horizontal scan. The vertical displacement of the target pattern from the optical axis of the camera is obtained by averaging the vertical deflection voltages, when the pattern is first acquired and when the pattern is just lost. The longitudinal distance to the target plane is obtained from the pulse repetition frequency within the burst, which increases linearly with distance. Harmonics of the fundamental burst frequency, which might result in ambiguity for far-to-near distance ratios exceeding two, are suppressed by a supplemental cylindrical lens which defocusses the image only along the line of scan without altering the top and bottom edge definition of the target.

Claims14

Dependent claims

A target locator for measuring the distance of a target from a station point comprising:

a. a target pattern of successive spaced-apart markings having a predetermined spatial relationship with the target;
b. video signal generating means including
i. a photosensitive medium,
ii. optional means located at the station point for imparting a light-value related, electrostatically charged image of the target pattern onto the photosensitive medium when the target is in the viewing plane of the optical means, the image being perspectively scaled with respect to the pattern in at least one direction and in accordance with the target distance from the station point,
iii. first scanning means for periodically directing a scanning beam over the imaged photosensitive material and along at least one scanning path having a generally parallel relationship with the direction of scaling, the video signal generating means being responsive to a scanned marking image to vary the video signal magnitude, whereby the duration of magnitude variation varies in accordance with the degree of perspective scaling;
and
c. means responsive to the varying duration to generate a signal indicative of the target distance from the station point.

4 more elements

A target locator for measuring the lateral displacement of a target from a longitudinal axis passing through a station point comprising:

a. a target pattern of successive spaced-apart markings having a predetermined spatial relationship with the target;
b. a video signal generating means including
i. a photosensitive medium,
ii. optical means located at the station point for imparting a light-value related, electrostatically charged image of the target pattern onto the photosensitive medium when the target is in the viewing plane of the optical means,
iii. first means for periodically directing a scanning beam over the imaged photosensitive material and along at least one scanning path crossing the imaged markings;
the video signal generating means being responsive to a scanned marking image to vary the video signal magnitude,
c. means for moving the scanning beam in an essentially perpendicular direction to the scan path;
d. means responsive to the video signal generating means to generate a signal indicative of the perpendicular displacement of the scanning beam when the pattern image is scanned.

5 more elements

Dependencies are inferred from the claim text.

Video target locator

Life of this patent

Video target locator

Life of this patent

Abstract

Claims14