Linear interpolation for a component placement robot

• US 4,922,434 A
• Filed: 06/16/1988
• Issued: 05/01/1990
• Est. Priority Date: 05/25/1988
• Status: Expired due to Fees

• Current Assignee: Control Data Corporation (Ceridian HCM Holding, Inc.)
• Original Assignee: Control Data Corporation (Ceridian HCM Holding, Inc.)
• Inventors: Fule, Andras G.
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US07/207,691
• Time in Patent Office: 684 Days
• Field of Search: 364/513, 364/468, 364/488-491, 364/559, 364/474.31, 318/640, 318/573, 318/568.11, 318/568.15, 358/101, 358/107, 356/399-401, 901/45, 901/47, 29/703, 29/740, 29/759, 29/832, 29/833, 29/834, 382/8
• US Class Current: 700/259
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: Y10T 29/53178 Chip component
• CPC Class Codes: Y10T 29/53261 Means to align and advance work part

Abstract

Linear interpolation is applied to each pair of placement coordinates in a data driven surface mount component placement robot in order to eliminate component misplacement due to board artwork dimensional inaccuracies. The linear interpolation algorithm is derived by measuring the actual dimensions of the artwork of a given board by an integrated vision system via a camera attached to the robot arm.

Claims

1. A component placement system for use with a component board of the type having component sites and at least two registration marks comprising:

(a) a robot arm;

(b) optical means associated with said robot arm for selectively generating signals;

(c) a component board mounting station for mounting a component board of the type having component sites and at least two registration marks;

(d) storage means for storing registration mark nominal position data representing the nominal location of said at least two registration marks, nominal distance data representing the nominal distance between at least one pair of registration marks, and nominal component site data representing the nominal position of said component sites on said component board;

(e) optical control means for retrieving said registration mark nominal position data from said storage means, for moving said robot arm in response to said registration mark nominal position data so that said optical means is positioned over the nominal position of consecutive ones of said at least two registration marks when said component baord is mounted on said component board mounting station, and for causing said optical means to generate a signal at the nominal position of consecutive ones of said at least two registration marks;

(f) interpolation determination means responsive to said signals from said optical means and said storage means for determining a measured distance between said at least one pair of registration marks and for comparing said measured distance with the corresponding nominal distance from said distance data for each of said at least one pair of registration marks in order to develop at least one interpolation factor;

(g) robot arm control means for, for each component site on said board, applying said at last one interpolation factor to the nominal component site data associated with a particular component site in order to generate corrected component site data representing the actual position of said particular component site on said component board and for controlling said robot arm to pick up a particular component intended for said particular component site and to place said particular component on said component board at the position indicated by said corrected component site data for said particular component site.

2. The component placement system of claim 1 wherein said component board has three registration marks and wherein said registration mark nominal position data comprises data representing the nominal location of said three registration marks.

3. The component placement system of claim 2 wherein said at least one pair of registration marks comprises two pair of registration marks, each pair defining a line perpendicular to the line defined by the other pair.

4. A component placement system for the positioning of components at pre-assigned sites on a component board of the type having registration marks, comprising:

(a) a robot arm;

(b) a component board mounting station for mounting a component board of the type having pre-assigned sites and registration marks;

(c) storage means for storing registration mark nominal distance data representing the nominal distance between at least one pair of said registration marks, nominal pre-assigned site data representing the nominal position of said pre-assigned sites on said component board, and a vision error correction factor;

(d) optical means for generating signals at the nominal position of said registration marks on said component board;

(e) interpolation determination means responsive to said signals from said optical means, said registration mark nominal distance data and said vision error correction factor for determining a measured distance between said at least one pair of said registration marks, for adjusting said measured distance with said vision error correction factor and for comparing said adjusted measured distance with the corresponding nominal distance between said at least one pair of registration marks in order to develop at least one interpolation factor;

(f) robot arm control means for, for each pre-assigned site on said component board, applying said at least one interpolation factor to the nominal pre-assigned site data associated with a particular pre-assigned site in order to generate corrected pre-assigned site data representing the actual position of said particular pre-assigned site on said component board and for controlling said robot arm to pick up a particular component intended for said particular pre-assigned site and to place said particular component on said component board at the position indicated by said corrected pre-assigned site data.