Sharp Corp’s new neural network-based microwave oven (CI No 2,497) will be in the shops next month. With the touch of a single button the user will be able to heat convenience foods to the correct temperature without having to key in a heating time manually, the company said. It works by using a multi-layer neural network that determines when the food is cooked, based on data received from humidity and gas sensors in the microwave. The microwave is aimed at the European market and originates from Sharp’s fuzzy logic microwave oven which costs around ú700 and is available only in Japan. Motivated by statistics showing that 80% of a microwave’s use is taken up reheating food and the fact that most people shun getting to grips with technology in the home, the Sharp R-4N76 microwave features two buttons for automatic heating, one for beverages and one for foods, although it can still be used as a conventional microwave if desired. Research began in October 1991 and was carried out over two years between the Department of Engineering & Science at the University of Oxford and Oxford-based Sharp Laboratories of Europe to decide if a microwave was a suitable application for a neural network. As the steam given off by drinks and by food is different, a separate button is necessary for each. The neural network was trained to recognise the different steam signatures of food and beverages. Some pre-processing of the data was necessary to account for noise factors.
No food was wasted
A cup or dish, for example, will rarely be placed centrally on the microwave turntable, so in training the network, a number of training patterns had to be accounted for. These included the effects different containers had on the heating of foods and the larger amounts of steam that are given off by food as it nears the end of the heating process. Despite the amounts of food needed to be heated during training, Sharp said that no food was wasted! Due to cost constraints, two buttons were finally decided on for the automatic heating function because the alternative of having a single button and more sensors in the microwave oven proved too expensive. Sharp said the controller chip being used is a non-standard 8-bit microprocesor. The research micr owave model was tested using an MS-DOS personal computer attached to the microwave coded using C, but this has to be rewritten from scratch for the final model. The algorithms were coded from scratch in Japan using assembly language. The microwave oven will cost ú250.
