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Vision System for Industrial Robots

 
14. System ready: accuracy measurements, total cost, conclusions
Update #10205  |  12 Jun 2015
 

System ready!


I am happy to announce that Robot-Vision system is ready! In this update I will include information about system accuracy and write about what I plan to do next.


User interface main window

 

Accuracy measurements


Robot-Vision system give very good results of object real position calculations. Maximum error measured is 2 mm for flat objects and 6,4 mm for cubic object (50 mm edge dimension). As an error (ΔE) I mean distance between real object mass center and the result from vision system in millimeters. Below you can see table with results and graphs representing error in relation to object position.


Accuracy of the system - measurements

 


Accuracy of the system - error graph for flat objects

 


Accuracy of the system - error graph for cubic objects (50 mm edge)

 

Conclusions


Achieved results are very satisfying, 2mm maximum error for flat objects can be considered as a measurement method error which proves very good accuracy of system. In case of cubic object error graph clearly shows that error come from object perspective influence because error is much higher in corners. That fact is caused by webcam, it provide only 10x digital zoom without any optic options so I can’t hang camera enough high to remove perspective error also digital zoom highly decrease quality of image. Replacing webcam with industrial camera with good optic lens probably would almost completely remove error. Another way to solve this problem is additional module responsible for recognition 3D objects edges and advanced mass center calculation.

 

Total cost of Robot-Vision system


Big advantage of my system is low cost compering to other vision systems. Prices of vision systems with similar aspects starts from 4000 euro and can cost even up to 9000 euro and more also this is cost of only processing unit and software excluding lens which can cost up to another 2000 euro, cables and development PC for system calibration. Total cost of my system which is ready to use and don’t need even development PC is 500 euro and can be decreased by choosing lower cost DVI display, keyboard and mouse. System own its low price thanks to Colibri T20 module along with Iris board which delivers very high performence and all functionality that is needed in order to create such a device. For now system offers object real position determination, color and size classification but with some more work on code could result additional functionality.

 

What next?


Robot-Vision project has been completed successfully and I am very happy of achieved results. Now I am planning to integrate system with industrial robot to create random placed objects sorting based on object color application. Soon I will post updates with robot technical details, robot program algorithm and video with result of sorting application.

Stay tuned it is not over yet!

 

 

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