The precise positioning system of mica trough based on machine vision

Pan Yinsong; Li Zhengying; Wang Lifang; Ding Huihui; Pu Chunyu

doi:10.12086/oee.2018.170600

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Pan Yinsong, Li Zhengying, Wang Lifang, et al. The precise positioning system of mica trough based on machine vision[J]. Opto-Electronic Engineering, 2018, 45(7): 170600. doi: 10.12086/oee.2018.170600

Citation:

Pan Yinsong, Li Zhengying, Wang Lifang, et al. The precise positioning system of mica trough based on machine vision[J]. Opto-Electronic Engineering, 2018, 45(7): 170600. doi: 10.12086/oee.2018.170600

The precise positioning system of mica trough based on machine vision

1.
Key Laboratory of Optoelectronic Technique System of the Ministry of Education, Chongqing University, Chongqing 400044, China
2.
City College of Science and Technology, Chongqing University, Chongqing 402167, China

Fund Project: Supported by National Natural Science Fund (41371338) and Chongqing Fundamental and Frontier Research Program Fund (cstc2013jcyj A40005)

More Information

Corresponding author: Pan Yinsong, E-mail: panys@cqu.edu.cn

Received Date 05 November 2017

Revised Date 16 April 2018

Published Date 01 July 2018

Abstract

Abstract

In view of the issue that in the process of locomotive motor commutator maintenance and processing, laser modulation and positioning type mica slot engraving system are widely used in real applications. However, it has low precision and requires a lot of human intervention. To overcome this problem, this paper proposed a precise positioning method of mica slot based on machine vision, which can accurately extract the edge of the motor commutator. The system first independently designs the precision compensation algorithm and constructs the positioning error correction model. Based on this, the embedded system platform is built to realize the automatic, rapid and accurate positioning the center line of the mica slot. Then the system achieves accurate calculation the deviation between the knife and the center line and control the bit tool to move to the correct engraved position. Experimental results indicate that the instrument can accurately calculate the position of the mica slot center line. Through the servo motor control burin to adjustment and aim the midline, the knife positioning error has been controlled between the positive and negative 0.02 mm, achieving the entire operation process automation and precision.
- machine vision /
- precise positioning /
- precision compensation /
- error correction /
- automation

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References

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Overview

Overview

Overview: In the process of using locomotive motor commutator, due to the copper brush constantly rubbing, the copper scraps accumulate in the mica under the action of long time. In this case, the boundary between the copper and the mica slot becomes blurred, thus the motor commutator needs to be repaired on a regular basis. A traditional method is to use a laser-modulated positioning mica slotting system to perform engraving of the mica slot. However, the system detects the location of the mica slot depending on the reflectance of the laser, which is so different between copper bars and mica pieces. It can only get the approximate position of its center line and often appear missing and wrong situation. Therefore, it is necessary to perform error compensation by manual verification before each cutting to avoid unnecessary damage to the motor commutator, and at the same time, this method makes the work efficiency low. In order to improve the positioning accuracy and efficiency, this paper proposes an accurate positioning method of mica trough based on machine vision, which can effectively overcome the difficulties in precise extraction of the mica groove edges belong to motor commutator. In every working cycle, the system utilizes CCD camera to capture the current motor commutator surface image, then transfers the picture to the system’s numerical calculation module. Combing with the positioning error correction model constructed by the system, the self-designed precision compensation algorithm can accurately locate center line of the mica slot. After the positioning result transmitted to the main control unit, the servo system can control the burin to move to the designated position cutting the groove. When the above tasks are completed, the motor commutator can rotate into the next working cycle. The core part of the system is the precision compensation algorithm, which can precisely control each part of the center line positioning process of the mica slot, make precise positioning of the edge of the mica slot and avoid making the scratch mistaken for mica slot. Then finding out the correct location of the center line of the mica slot, the algorithm can also avoid the emergence of some extreme conditions to ensure the stable operation of the entire system. The experimental results show that the system can accurately calculate the midline position of the mica slot and control the positioning error of the knife between positive and negative 0.02 mm, which effectively improves the positioning accuracy and efficiency.