Student Projects
Contact Information
University: Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Morelia. (Tecnológico de Monterrey campus Morelia).
Team Members (with year of graduation):
- Carlos Ignacio Ramírez Santillán (year of graduation: 2012)
Mail: nacho_989@hotmail.com
- Roman Antonio Saldaña Alcalde (year of graduation: 2012)
Mail: romanantony_sa@hotmail.com
- Claudio Carreño Martínez (year of graduation: 2012)
Mail: claudiyo_cm@hotmail.com
Faculty Advisers:
Dr. Salvador González García. ITESM Campus Morelia
Mail: sgg@itesm.mx
Submission Language
English
Project Information
Title: Automatic Sorting Machine for Mexican Lemon
Description:
The system is a real time lemon sorting machine based on a vision system which analyses the external features of the fruits to separate the poor quality lemons from the good quality ones. All this was designed so that the final product is cheap and adaptable to the traditional lemon packing lines.
Products
NI LabVIEW
NI Vision Development Module
NI Vision Acquisition Software
NI DAQ mx
NI DAQ USB 6008
Other products:
PLC Simatic Siemens s7 200 CPU 222
Step 7 Microwin
Logitech QuickCam Pro 9000
The Challenge
This project was developed in Michoacán México. Michoacán has the largest area of planted lemon in México, with 42,290.16 ha and 461,563.41 tons of production (last year), according to SIAP-SAGARPA 2012 information.
This great amount of production is packed in Michoacán and it is mostly sold in different states of México. The reality is most of the packers fail the quality test in lemon packing, and they are not able to export this product to other countries or to commercialize in better markets.
The poor quality of the packed lemon is due to the traditional way in which the good quality lemons are separated from the bad quality lemons, obtaining a mixed product with no constant good quality.
So the challenge was to create a mechatronics system, able to detect the surface features of all the lemons in the packing line and then do the automatic separation according to their quality, with a HMI with a control to change the sorting parameters in a very easy way and indicators with real time data about the lemons being processed.
This project is offering the increase of quality of selection of the fruit in a very cheap way, which will cause that the lemon packing companies be more competitive and then they will meet the strict requirements for exporting fruit and commercialize in better markets. This will be an important impact for the economy in Michoacán and México.
The Solution
The system was developed based on the manual sorting conveyor (Picture 1) existing in each lemon packing company. On this conveyor, poor quality lemons are manually removed from the packing line, leaving only the good quality lemons to continue the packing process.
Picture 1 - Traditional lemon sorting conveyor
Basically, the automatic lemon sorting machine is an adaptation to those traditional conveyors, turning the manual sorting section of the packing line, into an automatic sorting section. This is achieved adding the electronics, mechanical and electromechanical components that automate the fruit selection.
Because of its adaptable design of the system, the final product is cheap and doesn’t require more space in the packing line.
The picture 2 shows the elements installed on a small traditional sorting conveyor, so this conveyor can work as an automatic lemon sorting machine. Picture 3 shows another view of the machine.
Picture 2 – Automatic lemon sorting machine and its components.
Picture 3 – Another view of the automatic lemon sorting machine
The general process of the system is as follows:
The lemons are moving and rotating on the conveyor, they enter in the controlled light space where a webcam takes pictures of the whole surface of each lemon, these pictures are sent to a computer which processes the images and make the decisions depending on the external quality of the fruit and the parameters configured in the operator panel. When the lemons reach the end of the roller conveyor (this is detected by presence sensors), the computer sends the corresponding signals to the solenoids that perform the opening or closing action of the gates that remove poor quality lemons.
Information about the processing and control of the system using National Instruments products:
The National Instruments tools (hardware and software) were very important in the developing of this project. Basically, all the processing, analysis and control of the system is performed by a LabVIEW program running on a computer.
The vision software for LabVIEW was a very useful tool to perform the artificial vision part of the system. As said, the program needs to acquire the images and do the processing and analysis of the images to determine the kind of lemons that are passing on the conveyor. This task needs a lot of parallel programming and image processing techniques, LabVIEW gives an easy way to develop this kind of applications, offering very helpful tools to apply those techniques and solve the problem.
The following video shows the automatic lemon sorting machine working normally; it also shows us how the software is able to recognize in real time the surface poor quality features (this is more clearly shown at the final part of the video). That is an example of how the vision tools for LabVIEW helped to achieve this important part.
Automatic sorting machine for mexican lemon video.
Watch the detection of poor quality features in HD
http://www.youtube.com/watch?v=WLDbBlwfD-Q
Another important section to complete this system, are the signals that control the electromechanical actuation and the signals of the presence sensors at the end of the conveyor. In picture 2 is not shown, but the interface between the real world and the LabVIEW program is a National Instruments multifunction DAQ. The digital signals of a NI USB 6008 are used to acquire the sensors signals and generate the signals to control the solenoids in the separation part of the machine. Generating and acquiring signals was very easy using LabVIEW and the NI DAQ.
One of the requirements that packers told were important is that they need to be able to modify the defect tolerance level of selection. This has to do with the price of the lemon and with some of its customers; sometimes the price of the lemon is high and they want to sell more quantity to some customers who do not mind the selection is not so precise, so they need to modify the level of tolerance to the poor quality features of lemons.
The picture 4 shows the front panel of the application. There are some basic controls, including the control which makes possible to change the tolerance level of selection, as requested by the packers.
Picture 4 – Front Panel
Besides, the user interface shows a basic count of the processed lemons. With this information, the packer can monitor the quality of lemon brought to its packing line by each lemon producer.
Additional comments about the future of the project and revisions.
As it was shown, the sorting automation in this project was done on a small traditional conveyor, also, this machine uses a webcam instead an industrial vision camera for the machine vision application; so this is actually a beta prototype build in three months.
Nevertheless, the necessary things to do for the industrial adaptation in the packing line are not difficult. It will be necessary to add more separations lanes, solenoids, gates, sensors and cameras to cover the whole conveyor width. The industrial adaptation will be only to repeat (to a side) what was done in this project.
The industrial adaptation will require industrial components to handle in the best way the whole production. The final product will require industrial machine vision cameras; and also, there will be ideal to have a specific purpose system to perform the automation of the lemon sorting. The use of NI PXI platforms in the automatic lemon sorting machines will handle with very high performance the whole processing, analysis and control of the system. Its capacity to connect with industrial machine vision cameras and process the information with a real time controller makes the PXI platform ideal to perform the automatic lemon sorting section of the lemon packing lines.
