Visual motion tracking system
First Claim
1. An optical and electronic motion tracking system for measuring movement of an object comprisinga pattern of contrasting light and dark regions on the object for movement therewith,a lens focused on the pattern to produce an image of the pattern in an image plane, a linear array of equally spaced photosensor elements in the plane of the focused image wherein the element spacing corresponds to a certain object displacement, and each element is energized to a high or low state according to the brightness of the image focused thereon, whereby movement of the object effect a change of state of at least one of the elements,scan means for interrogating the energization state of the elements and generating output signals representing the states of the elements and for periodically repeating the interrogation for subsequent array scans,means responsive to the output signals for generating a transition signal representing each image transition between light and dark regions,a circuit responsive to the transition signals for comparing the transition signals for each scan with that of a preceding scan to thereby detect a difference in transition signals which denotes the amount and direction of movement of the focused image relative to the photosensor elements,and means responsive to said detected difference to produce a signal representing net object movement over a time period encompassing many scans.
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Abstract
The movement of an article such as a product carried by a conveyor is monitored by providing a patterned target, preferably striped with contrasting lines, to move with the object. A solid state line scan camera views the pattern of the target as it moves relative to the camera and the electronic output of the camera representing the light and dark areas of the target is analyzed by an electronic circuit to determined the movement of the target and therefore of the object being monitored. The resulting electronic signal representing the motion of the object is useful for coordinating the movement of a robot which is operating upon the object during its movement.
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Citations
4 Claims
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1. An optical and electronic motion tracking system for measuring movement of an object comprising
a pattern of contrasting light and dark regions on the object for movement therewith, a lens focused on the pattern to produce an image of the pattern in an image plane, a linear array of equally spaced photosensor elements in the plane of the focused image wherein the element spacing corresponds to a certain object displacement, and each element is energized to a high or low state according to the brightness of the image focused thereon, whereby movement of the object effect a change of state of at least one of the elements, scan means for interrogating the energization state of the elements and generating output signals representing the states of the elements and for periodically repeating the interrogation for subsequent array scans, means responsive to the output signals for generating a transition signal representing each image transition between light and dark regions, a circuit responsive to the transition signals for comparing the transition signals for each scan with that of a preceding scan to thereby detect a difference in transition signals which denotes the amount and direction of movement of the focused image relative to the photosensor elements, and means responsive to said detected difference to produce a signal representing net object movement over a time period encompassing many scans.
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2. An optical and electronic motion tracking system for measuring movement of an object comprising
a pattern of contrasting light and dark regions on the object for movement therewith, a solid state camera focused on the pattern, the camera including at least one linear array of equally spaced photosensor elements in the plane of the focused image wherein the element spacing corresponds to a certain object displacement, and each sensor is energized according to the brightness of the region focused thereon, the camera further including sensor scan means to interrogate serially the energization state of the elements and generate output signals representing the states of the elements and to periodically repeat the interrogation for subsequent array scans, counter means for serially producing an output of consecutive digital numbers representing the elements in synchronism with each scan, transition detector means responsive to the output signals for generating a transition signal each time the change in levels of adjacent output signals signifies an image transition between light and dark regions, memory means responsive to the transition signals and counter output for memorizing for each scan the numbers of the elements representing transition points, shift detector means for comparing the memorized numbers of each scan with those of the previous scan to detect the amount and direction of shift of the transition points thereby providing a measurement of object movement between scans, and accumulator means for accumulating the net object movement over a time interval encompassing many scans.
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3. An optical and electronic motion tracking system for measuring movement of an object comprising
a pattern of contrasting light and dark regions secured to the object for movement therewith, a solid state line camera focused on the pattern, the camera including at least one linear array of equally spaced photosensor elements in the plane of the focused image wherein the element spacing corresponds to a certain object displacement, and each sensor is energized according to the brightness of the region focused thereon, the camera further including sensor scan means to interrogate serially the energization state of the elements and generate output signals representing the states of the elements and to periodically repeat the interrogation for subsequent array scans, counter means for serially producing consecutive digital numbers representing the elements in synchronism with each scan, transition detector means responsive to the output signals for generating a transition signal each time the change in levels of adjacent output signals signifies an image transition between light and dark regions, memory means responsive to the transition signals and the counter produced digital numbers for memorizing for each scan the numbers of the elements representing transition points, shift detector means for comparing each of the memorized numbers of each scan with each of those of the previous scan to provide a plurality of difference signals including small and large signals representing valid shift and spurious values respectively, comparator means having a stored small reference value for comparing the absolute value of the difference signals with the small reference value to produce a valid shift signal when a given difference signal is equal to or less than the reference value, means responding to the valid shift signal and the difference signals for algebraically adding the valid difference signals to determine the net amount and direction of shift of the transition points, and means for signalling an increment of object movement when the said net amount attains the number of transitions per each array scan.
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4. An optical and electronic motion tracking system for measuring movement of an object comprising
a pattern of contrasting light and dark regions secured to the object for movement therewith, a solid state camera focused on the pattern, the camera including at least one linear array of equally spaced photosensor elements in the plane of the focused image wherein the element spacing corresponds to a certain object displacement, and each sensor is energized according to the brightness of the region focused thereon, the camera further including sensor scan means to interrogate serially the energization state of the elements and generate output singals representing the states of the elements and to periodically repeat the interrogation for subsequent scans, counter means for serially producing an output of consecutive digital numbers representing the elements in synchronism with each scan, transition detector means responsive to the output signals for generating a tansition signal each time the change in levels of adjacent output signals signifies an image transition between light and dark regions, memory means including two primary read/write memories responsive to the transition signals and counter output for alternately memorizing transition data comprising the numbers of the elements representing transition points, for each scan, and a secondary read/write memory, control means for effecting the storage of transition data from alternate scans in alternate primary memories and for loading the data from the one primary memory containing the lease recent transition data into the secondary memory to make available the said one primary memory for storage of subsequently generated transition data, shift detector means for comparing the memorized numbers of each scan in the other of the primary memories with those of the previous scan in the secondary memory to detect the amount and direction of shift of the transition points thereby providing a measurement of object movement between scans, and accumulator means for accumulating the net object movement over a time interval encompassing many scans.
Specification
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- Resources
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Current AssigneeGeneral Motors Corporation (General Motors Company)
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Original AssigneeGeneral Motors Corporation (General Motors Company)
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InventorsIadipaolo, Rene M., Dewar, Robert Jr.
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Primary Examiner(s)Britton, Howard W.
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Application NumberUS06/051,622Time in Patent Office617 DaysField of Search358/101, 358/105, 358/106, 358/107, 358/213, 358/125, 235/92 MPUS Class Current348/137CPC Class CodesG05B 19/4182 manipulators and conveyor onlyG05B 2219/45213 Integrated manufacturing sy...Y02P 90/02 Total factory control, e.g....
