Design and implementation of a practical control system for an air-conditioner with IoT sensor nodes

Recently, with the increase of global warming and electric energy waste, the cost of air-conditioning becomes a problem. However, standard products of air-conditioners are not capable on sophisticated temperature in an office room. In addition, a somewhat old air-conditioner does not keep the temperature of an office room as a human's request. The problem might caused by the structure of a thermo sensors of the old air-conditioner. Therefore, the authors design a practical control system for the air-conditioner as an add-on style. The system consists of a central control-detection unit and three detection nodes placed at different positions in the target room. Each detection node contains a temperature sensor and an infrared human detection sensor. The central control-detection unit contains a servomotor used to push the air-conditioner's power button. The data of each node is securely transmitted after encryption, and users can browse the node data and control the indoor temperature through the web page.