We all know if a company wants to stay in business then it has to manufacture quality products. Visual inspection of products is well known method to check quality. Earlier days trained human beings were used for inspection. Nowadays machine vision systems are employed. The reasons are many. It can work throughout day and night without a sign of fatigue. It can surpass the human inspection speed. It can have a wide dynamic range camera which will help to differentiate even a small change in colour. With human inspection system to check all the manufactured products is not cost effective. Few samples from a batch of products are taken and quality testing on the samples are carried out. Statistical methods are employed to estimate the amount of failed products from the failed samples. But with online one can check each product individually [1].
Consumers expect high quality biscuits to have consistent size, shape, colour and flavour. Size and shape improves the aesthetics of biscuits. Colour and flavour has role on the taste of biscuits. Electronic nose can be used detect flavour. In tea processing industry electronic nose is employed and reported in scientific papers. Articles related to employability of electronic nose in biscuit manufacturing are to be found in Internet. It is a common knowledge that any biscuit that is over baked will be in dark brown in colour and under baked will posses light brown colour. It is technically called as 'Baking Curve'. Image processing techniques are used find the shades of biscuit colour and classification is carried out by artificial neural networks. This method was developed in way back of 1995 by Mr. Leonard G. C. Hamey [8]. In a typical cream sandwiched biscuit, top and bottom layers are biscuits and middle layer is made up of filling like cream or chocolate. Cost of filling is more than the biscuits. Over filling means less profit for the company. So much care is taken to maintain correct size of biscuit and filling height.
Consumers expect high quality biscuits to have consistent size, shape, colour and flavour. Size and shape improves the aesthetics of biscuits. Colour and flavour has role on the taste of biscuits. Electronic nose can be used detect flavour. In tea processing industry electronic nose is employed and reported in scientific papers. Articles related to employability of electronic nose in biscuit manufacturing are to be found in Internet. It is a common knowledge that any biscuit that is over baked will be in dark brown in colour and under baked will posses light brown colour. It is technically called as 'Baking Curve'. Image processing techniques are used find the shades of biscuit colour and classification is carried out by artificial neural networks. This method was developed in way back of 1995 by Mr. Leonard G. C. Hamey [8]. In a typical cream sandwiched biscuit, top and bottom layers are biscuits and middle layer is made up of filling like cream or chocolate. Cost of filling is more than the biscuits. Over filling means less profit for the company. So much care is taken to maintain correct size of biscuit and filling height.
In a typical production line, every minute 30 rows (120 biscuits form a row) of baked biscuits passes on a conveyor and all of them has to be inspected. This results in checking of 3600 biscuits per minute. Length, width and thickness are measured with an accuracy of ± 0.17 mm. In addition to this check for cracks and splits are carried out. If a biscuit fails to qualify the then it is discarded.
In a typical biscuit inspection system, three cameras will be used to grab the image of moving biscuits which are illuminated by special fluorescent lights. Grabbed images are processed to get size and shape. A fourth camera that is in 45 degree angle used to capture the laser light that falls on the biscuits. When multiple laser line images are combined it gives a 3D shape of biscuit. [2, 4]. For sample inspection pictures go to [7] and download the pdf file. The cameras are required to operate in a 45 degree centigrade ambient temperature. The captured images are transferred via GigE to the inspection room which is 100m away from the baking system. Special software displays the captured images on the computer screen with necessary controls. The images are stored for four years.
List of Vision system manufacturers
o Machine Vision Technology in United Kingdom [2] ,
o Hamey Vision Private Limited in Australia [4]
o Q-Bake from EyePro systems [6]
In India way back in 2002, CEERI (Central Electronics Engineering Research Institute) present in CSIR Madras complex developed a Biscuit Inspection system with a budget of Rs. 20.7 Lakhs. (1 Lakh =100,000 and Rs. 50 approx. 1US$). It got the fund from Dept. of Science and Technology, Govt. of India and partnered with Britannia Industries, Chennai to get requirements [5].
Source
2. Keeping Biscuits with Good Shape, http://www.baslerweb.com/9/8/5/0/BAS1011_Bisquit_Inspection.pdf
3. Biscuit Bake Colour Inspection System - Food Colour Inspection, http://www.hameyvision.com.au/biscuit-colour-inspection.html
4. Simac Masic, http://www.simac.com
5. CMC News, July – December, 2002, http://www.csirmadrascomplex.gov.in/jd02.pdf
6. Q-Bake, Inspection Machine for Baked Goods, http://www.eyeprosystem.com/q-bake/index.html
8. Pre-processing Colour Images with a Self-Organising Map:Baking Curve Identification and Bake Image Segmentation, http://www.hameyvision.com.au/hamey-icpr98-som-baking.pdf
Courtesy
I want to thank Dr. A. Gopal, Senior principle scientist, CEERI, CSIR Madras Complex, Chennai, who gave a lecture on Biscuit inspection system in National level workshop on “Embedded Processors and Applications” held at SRM University, Chennai on 31-Aug-2012. He inspired me to write this article.
