Automatic Color Inspection for Colored Wires in Electric Cables

作者：Ghidoni Stefano^*; Finotto Matteo; Menegatti Emanuele

来源：IEEE Transactions on Automation Science and Engineering, 2015, 12(2): 596-607.

DOI：10.1109/TASE.2014.2360233

• Cable crimping
• wire color measurement
• wire color sequence
• wire detection
• visual inspection

In this paper, an automatic optical inspection system for checking the sequence of colored wires in electric cable is presented. The system is able to inspect cables with flat connectors differing in the type and number of wires. This variability is managed in an automatic way by means of a self-learning subsystem and does not require manual input from the operator or loading new data to the machine. The system is coupled to a connector crimping machine and once the model of a correct cable is learned, it can automatically inspect each cable assembled by the machine. The main contributions of this paper are: (i) the self-learning system; (ii) a robust segmentation algorithm for extracting wires from images even if they are strongly bent and partially overlapped; and (iii) a color recognition algorithm able to cope with highlights and different finishing of the wire insulation. We report the system evaluation over a period of several months during the actual production of large batches of different cables; tests demonstrated a high level of accuracy and the absence of false negatives, which is a key point in order to guarantee defect-free productions.
Note to Practitioners-This work is motivated by the need of performing an accurate quality control on cable production: an automated inspection method is necessary for effectively assuring a quality check on 100% of the produced parts. The vision system exploits a compact acquisition hardware enabling the system to be easily integrated in existing cable crimping machines. The software system is composed by two main modules: the first one localizes the wires, while the second performs color measurements. This paper explains how it is possible to segment wires also when they are bent in many different ways; moreover, a reliable method for identifying colors, which is robust to wire markings and highlights, is described. The proposed system is able to automatically adjust tolerances in color measurement depending on the colors of the wires to be checked. This represents a strong point of the system, and it can be applied also in other contexts where color analysis on noisy data needs to be performed.

• 出版日期2015-4