A smart reheating and defrosting microwave oven based on infrared temperature sensor and humidity sensor

Microwave oven is widely used around the world since the functions of reheating and defrosting are convenient and efficient. However, these functions in traditional microwave oven are not intelligent for the control effects deeply rely on the users' experience. Besides, heating without food is very dangerous since there is no no-load detection. Therefore, in this paper, infrared array sensor and humidity sensor are combined together to achieve a smart microwave oven. Besides, no-load detection method, detection method for humidity sensor, pre-processing method for infrared sensor, location identification method for the food, and intelligent control methods for defrosting and reheating are proposed in detail. Experimental results demonstrate that the eigenvalues of load tests are all smaller than 1.5, while they are all larger than 1.5 in the no-load tests. The detection accuracy is 100% in the 200 test cases. In addition, the final temperatures of the meats (i.e. pork, fish, drumstick and chicken) after intelligent defrosting control are all between −2 °C and 25 °C, and the mean temperature ranges from 1 °C to 2.5 °C, which meets the expected target. Besides, the maximum control error of “Heating Target” is 3.5 °C, and the maximum difference between the mean temperature of multiple measurements and the corresponding target is 1.56 °C. The control error and control deviation of the temperature range for “Milk” are both less than 1 °C. As for “Reheating” control, the maximum control error and control deviation of the temperature range for the food with less moisture content are 0.18 °C and 2.5 °C, while they are 2.7 °C and 3.2 °C for the food with more moisture content. Moreover, the food quality after reheating or defrosting with the proposed smart microwave oven is better than that with the traditional microwave oven. In general, the proposed no-load detection method, and the intelligent control methods for defrosting and reheating are effective.