System and method for joining workpieces to form an article
Workpieces are placed in the workstation so one is in registration with a fixed locator. Measurement data are obtained reflecting the positions of the respective features of the workpieces and represented in a common reference frame associated with the fixed locator. A processor uses the collection of assembly data and the measurement data to define and store ordered pairs of mating feature locations. The pairs are then reoriented using a computationally discovered best fit. The position of a feature demarked for registration with the adjustable locator is calculated and the adjustable locator is caused to move to the calculated position of the feature demarked for registration thereby establishing a best fit orientation of the mating workpieces in physical space. The mating workpieces are then positioned in said best fit orientation by registration with said fixed and adjustable locators and then mechanically joining the mating workpieces.
1. A method for forming a multi-piece assembly by joining mating workpieces in a workstation, the workstation having a frame with at least one fixed locator and at least one adjustable locator, wherein each workpiece has at least one physical feature, the position of which within the multi-piece assembly is expressed in a collection of assembly data, the method having a processor coupled to the workstation and one or more hardware-based fixtures that are mechanically operated and/or electronically controlled by the processor, comprising:
placing, by a positioning fixture, the workpieces in the workstation so that one of said workpieces is in registration with the fixed locator;
obtaining, at the processor, measurement data reflecting the positions of the respective features of the workpieces and representing the measurement data in a common reference frame associated with the fixed locator;
receiving and storing, by the processor, the collection of assembly data and the measurement data;
defining, by the processor, ordered pairs of mating features;
using the processor to define and store in memory, for each ordered pair of mating features, a test vector that connects a pair of mating features, where each test vector has vector components represented as variables stored in memory;
using the processor to computationally discover a best fit for the mating workpieces by collectively applying to the test vectors a computational optimization process that seeks to minimize the lengths of the test vectors while taking into account predefined weighting factors that give certain features locational preference over others; using the processor to reorient the data representing the feature locations of the respective workpieces in the common reference frameusing the computationally discovered best fit;
using the processor to calculate the position in the common reference frame of a feature demarked for registration with the adjustable locator;
moving the adjustable locator in relation to the frame to the calculated position of the feature demarked for registration with the adjustable locator and thereby establishing a best fit orientation of the mating workpieces in physical space, where the adjustable locator is moved by at least one of a motor or a robot controlled by the processor;
positioning said mating workpieces in said best fit orientation by registration with said fixed and adjustable locators and then mechanically joining the mating workpieces.
2. The method of claim 1 wherein the step of obtaining measurement data is performed optically while the workpieces are disposed in the workstation.
3. The method of claim 1 wherein the step of obtaining measurement data is performed at least in part prior to placing at least one of the workpieces in the workstation.
4. The method of claim 1 wherein the step of obtaining measurement data is performed at least in part prior to placing at least one of the workpieces in the workstation and transformed into said common reference frame by said processor.
5. The method of claim 1 further comprising supplying said collection of assembly data as computer aided design data.
6. The method of claim 1 wherein the computational optimization process employs a numerical optimization algorithm.
7. The method of claim 1 wherein the computational optimization process employs a priority-based numerical optimization algorithm.
8. The method of claim 1 further comprising obtaining second measurement data reflecting the positions of features of workpieces other than those placed in the workstation and including said second measurement data in the step of using the processor to computationally discover a best fit for the mating workpieces.
9. A method for forming a multi-piece assembly by joining mating workpieces in a workstation, the workstation having a frame with at least one fixed locator and at least one adjustable locator, wherein each workpiece has at least one physical feature, the position of which within the multi-piece assembly is expressed in a collection of assembly data, the method having a processor coupled to the workstation and one or more hardware-based fixtures that are mechanically operated and/or electronically controlled by the processor, comprising:
placing, by a positioning fixture, the workpieces in the workstation so that one of said workpieces is in registration with the fixed locator;
obtaining, at the processor, measurement data reflecting the positions of the respective features of the workpieces and representing the measurement data in a common reference frame associated with the fixed locator;
receiving and storing, by the processor, the collection of assembly data and the measurement data;
defining, by the processor, ordered pairs of mating features;
using the processor to reorient the pairs of mating feature locations using a computationally discovered best fit;
using the processor to calculate the position in the common reference frame of a feature demarked for registration with the adjustable locator;
moving the adjustable locator in relation to the frame to the calculated position of the feature demarked for registration with the adjustable locator and thereby establishing a best fit orientation of the mating workpieces in physical space, where the adjustable locator is moved by at least one of a motor or a robot controlled by the processor;
positioning said mating workpieces in said best fit orientation by registration with said fixed and adjustable locators and then mechanically joining the mating workpieces.
10. The method of claim 9 wherein the step of obtaining measurement data is performed optically while the workpieces are disposed in the workstation.
11. The method of claim 9 wherein the step of obtaining measurement data is performed at least in part prior to placing at least one of the workpieces in the workstation.
12. The method of claim 9 wherein the step of obtaining measurement data is performed at least in part prior to placing at least one of the workpieces in the workstation and transformed into said common reference frame by said processor.
13. The method of claim 9 further comprising supplying said collection of assembly data as computer aided design data.
14. The method of claim 9 wherein the computational optimization process employs a numerical optimization algorithm.
15. The method of claim 9 wherein the computational optimization process employs a priority-based numerical optimization algorithm.
16. The method of claim 9 further comprising obtaining second measurement data reflecting the positions of features of workpieces other than those placed in the workstation and including said second measurement data in the step of using the processor to reorient the pairs of mating feature locations using a computationally discovered best fit.