Method of calibrating a vial autosampler
First Claim
1. In a vial autosampler having a plurality of vial holding stations and a robotic arm to carry a vial between the vial holding stations, a method of positioning the robotic arm relative to at least one of the vial holding stations comprising the steps of:
- providing a position reference feature disposed at a fixed location with respect to the autosampler;
storing in memory a first nominal position for the at least one of the vial holding stations and a second nominal position for the position reference feature;
measuring an actual position of the position reference feature;
calculating a first difference between the second nominal position and the measured position of the position reference feature;
calculating a corrected position of the at least one of the vial holding stations as a function of the first nominal position and the first difference; and
positioning the robotic arm as a function of the corrected position.
1 Assignment
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Accused Products
Abstract
A modular vial autosampler has a storage area for vials containing samples to be analyzed and at least one modular sampling station. A vial transfer mechanism includes an arm having a gripper that lifts a sample vial from the storage section, and the arm moves it to a station for identification and then to a sampling station, and under central control activates the sampling station for obtaining a sample for analysis. The vial transfer mechanism gripper is movable in X, Y, and Z directions to capture and move a selected vial and includes an alignment guide for the vials. Potentiometers are used for providing signals indicating arm position and the control is provided with updated information for calibration of the potentiometers and also updated position information for the arm relative to a fixed home position is obtained.
117 Citations
18 Claims
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1. In a vial autosampler having a plurality of vial holding stations and a robotic arm to carry a vial between the vial holding stations, a method of positioning the robotic arm relative to at least one of the vial holding stations comprising the steps of:
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providing a position reference feature disposed at a fixed location with respect to the autosampler;
storing in memory a first nominal position for the at least one of the vial holding stations and a second nominal position for the position reference feature;
measuring an actual position of the position reference feature;
calculating a first difference between the second nominal position and the measured position of the position reference feature;
calculating a corrected position of the at least one of the vial holding stations as a function of the first nominal position and the first difference; and
positioning the robotic arm as a function of the corrected position. - View Dependent Claims (2, 3, 4, 5)
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6. A method of calibrating movement of a robotic arm in a vial autosampler, the method comprising:
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a) moving the robotic arm along a first axis until a first known location is reached;
b) obtaining an initial first sensor signal related to the first known location;
c) moving the robotic arm along the first axis until a second known location is reached;
d) obtaining a successive first sensor signal related to the second known location;
e) computing a first axis scale related to a difference between the initial and successive first sensor signals; and
f) storing data based upon the first axis scale, wherein said data is used to calibrate movement of the robotic arm. - View Dependent Claims (7, 8, 9, 10, 11)
moving the robotic arm along a second axis orthogonal to the first axis until a third known location is reached;
obtaining an initial second sensor signal related to the third known location;
moving the robotic arm along the second axis until a fourth known location is reached;
obtaining a successive second sensor signal related to the fourth known location;
computing a second axis scale related to a difference between the initial and successive second sensor signals; and
storing data based upon the second axis scale.
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12. A method of calibrating movement of a robotic arm in a vial autosampler, the method comprising:
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providing stored location information of a calibration feature disposed in a fixed location relative to the autosampler;
moving the robotic arm to the calibration feature;
measuring an actual location of the calibration feature; and
calculating a calibrated home position based upon a comparison of the stored location information and the measured actual location. - View Dependent Claims (13)
bringing the robotic arm into contact with the calibration feature;
moving the robotic arm in a first direction while contacting the calibration feature until loss of contact is registered;
bringing the robotic arm into contact with the calibration feature again; and
moving the robotic arm in a second direction orthogonal to the first direction while in contact with the calibration feature until loss of contact is measured.
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14. A method of calibrating movement of a robotic arm in a vial autosampler, the method comprising:
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positioning a calibration bar relative to at least two vial storage locations;
bringing the robotic arm into contact with the calibration bar;
monitoring contact between the bar and the robotic arm while the robotic arm is moved relative to the bar in order to detect loss of contact between the bar and the robotic arm; and
calculating a calibration parameter based upon the movement of the robotic arm relative to the bar, and the detected loss of contact. - View Dependent Claims (15, 16, 17)
moving the robotic arm to a first position on the bar;
moving the robotic arm along a first axis until a sensor signal registers loss of contact between the bar and the robotic arm at a second position;
moving the robotic arm to a third position spaced from the first position along an axis orthogonal to the first axis; and
moving the robotic arm along the first axis until a sensor signal registers loss of contact between the bar and the robotic arm at a fourth position.
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17. The method of claim 16, wherein the calibration parameter is relative skew between a tray containing the at least two vial storage locations and the robotic arm.
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18. A method of calibrating motion of a robotic arm in a vial autosampler, the method comprising:
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measuring axis scaling factors in at least two orthogonal axes;
determining a calibrated home point using the axis scaling factors and a calibration reference feature;
measuring relative skew of a sample tray with respect to the vial autosampler; and
compensating stored vial receptacle position information based upon the home point and the measured skew.
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Specification