Micropositioning apparatus for a robotic arm

• US 4,808,064 A
• Filed: 12/05/1985
• Issued: 02/28/1989
• Est. Priority Date: 12/05/1985
• Status: Expired due to Fees

• Current Assignee: Odetics Incorporated (Iteris Incorporated)
• Original Assignee: Odetics Incorporated (Iteris Incorporated)
• Inventors: Bartholet, Stephen J.
• Primary Examiner(s): Spar, Robert J.
• Assistant Examiner(s): Doyle, Jennifer L.
• Application Number:
  US06/805,439
• Time in Patent Office: 1,181 Days
• Field of Search: 901/47, 901/9, 356/152, 73/763, 73/786, 73/862.04, 73/862.26, 73/862.33, 340/665, 340/685, 250/231 R, 250/231 SE, 414/730
• US Class Current: 414/730
• CPC Class Codes: B25J 9/1692 Calibration of manipulator
• CPC Class Codes: G05B 19/39 using a combination of the means covered by at least two of the preceding groups G05B19/21, G05B19/27 and G05B19/33
• CPC Class Codes: G05B 2219/39008 Fixed camera detects reference pattern held by end effector
• CPC Class Codes: G05B 2219/39176 Compensation deflection arm

Abstract

The present invention provides for precision micropositioning of a robotic structure. The micropositioning system includes a number of angular encoders indicating the angular orientations of various robotic elements with respect to one another and optical devices measuring the actual deflection of load bearing arm portions of the robotic structure. A separate optical device may be attached to each load bearing arm of the robotic structure. The optical device includes a target to be disposed at one end of the load bearing arms and an optical detecting system to be disposed at opposing ends of the load bearing arms. The target includes a plurality of light sources generally disposed in a plane and at least one light source disposed outside the plane. The optical detecting system includes first and second linear detector arrays adjacently disposed with longitudinal axes perpendicularly oriented. Each array senses target motion along a single line parallel to its longitudinal axis. An imaging lens and a cylindrical lens are provided for each array to focus images from the target light sources into lines oriented perpendicular to the longitudinal axes of the respective arrays. A portion of these images will remain focused on the detector arrays despite relative motion of the target perpendicular to the respective axes of the arrays. The optical detecting system resolves translational displacement of a target and associated robotic arm end along with pivotal changes in the orientations of the target and robotic arm end.

Claims

1. A micropositioning apparatus for a robotic device having a load bearing arm having a first end pivotally connected to a base and a second end for supporting a load, comprising:

means for detecting the angular orientation of the arm with respect to the base;

measuring means for optically measuring translational deflections of the arm, the measuring means having a target disposed at one end of the arm and means, disposed at the opposite end of the arm, for detecting displacement of the target, wherein the target comprises a plurality of light sources generally disposed in a common plane and at least one light source disposed outside said plane; and

means for pivoting the arm relative to the base to achieve a desired arm position based upon the detected angular orientation and the measured deflections.

2. The micropositioning apparatus of claim 1 further comprising means for individually activating the light sources in a repetitive sequence, wherein any particular target light source forming an image on the first and second detector array can be identified.

3. Apparatus for measuring the deflection of an extended beam, comprising:

a plurality of light sources disposed at a first end of the beam and generally aligned in a plane, and at least one additional light source disposed at the first end of the beam outside of said plane;

a first linear detector array, disposed at an opposing second end of the beam, having a plurality of light detecting elements arranged along a first longitudinal axis and sensing motion of the light source along the first longtiudinal axis;

a second linear detector array, disposed adjacent the first array, having a plurality of light detecting elements arranged along a second longitudinal axis, oriented perpendicular to the first longitudinal axis of the first array, and sensing motion of the light source along the second longitudinal axis;

first and second focusing lenses, respectively disposed adjacent the first and second detector arrays, respectively focusing light from the source onto the associated first and second detector arrays; and

first and second cylindrical lenses, respectively disposed between the first and second focusing lenses and the associated first and second detector arrays, respectively having a polar axis oriented parallel to the first and second longitudinal axes of the associated first and second detector arrays and respectively focusing a portion of a light source image onto the associated first and second detector arrays regardless of light source motion within the fields of view of the first and second detector arrays.

4. The apparatus of claim 3 further comprising means for individually activating the light sources in a repetitive sequence, wherein any particular light source forming an image on the first and second detector arrays can be identified.