Automatic calibration of cameras and structured light sources
First Claim
1. In a work cell of the type containing one or more robots, each having a coordinate frame, and one or more video cameras, a method of calibrating at least one of the cameras, comprising the steps of:
- equipping one of the robots with one or more fiducials movable in three space;
moving the robot and/or the camera relative to one another through a series of offsets while observing and recording the image of each fiducial using the camera to be calibrated; and
determining the relationship between the relative position of the camera and the robot'"'"'s coordinate frame using only fiducial observations as the robot is moved through the series of offsets.
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Abstract
A work cell containing robot(s), video camera(s), and structured lighting source(s) is calibrated by observing targets with the camera(s) as a robot is displaced through a set of offsets. Complete information is recovered about the camera(s) calibration data and the structure of illumination from the light source(s). The robot is utilized to create known relative movements between the targets and the camera(s) and light source(s). Therefore, this technique is applicable to both the fixed and moving camera cases. Except for the target surface profile, there is no requirement to externally determine any absolute or relative positions, or any relationships either within or between the camera(s), targets, light source(s), and robot(s). Either single or multiple cameras (acting independently or in stereo) are calibrated to the robot'"'"'s coordinate frame, and then optionally used as measuring devices to determine the position and form of the structured light.
199 Citations
21 Claims
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1. In a work cell of the type containing one or more robots, each having a coordinate frame, and one or more video cameras, a method of calibrating at least one of the cameras, comprising the steps of:
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equipping one of the robots with one or more fiducials movable in three space; moving the robot and/or the camera relative to one another through a series of offsets while observing and recording the image of each fiducial using the camera to be calibrated; and determining the relationship between the relative position of the camera and the robot'"'"'s coordinate frame using only fiducial observations as the robot is moved through the series of offsets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of automatically calibrating a single camera having a field of view in work-cell environment including a robotic manipulator with an end effector, comprising the steps of:
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providing a calibration target relative to the end effector having at least three distinct features that can be resolved in the camera'"'"'s field of view; moving the target in three space while remaining in the field of view of the camera by sending a series of offsets to the robot; recording each offset position of the target in three space by observing the positions of the target features; computing a first set of camera calibration data with respect to a temporary coordinate frame and the three-dimensional offset target positions; aligning the temporary coordinate frame with the robot'"'"'s frame; displacing the target through a second set of offsets in three dimensions while keeping the target in the camera'"'"'s field of view; computing the positions of the features in three space; determining the origin of the robot'"'"'s frame in accordance with the recorded offsets and computed feature positions. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification