This illstration shows the thermal displays indicate “READY” and “WAIT” to the robots. The thermal displays are composed of thermal switches (=thermal transistors) that heat flow occurs when the switch is on and it does not when the switch is off. In the steel factory, human cannot work because of high temperature. Therefore, high-temperature robots work instead of human. The robots can sense infared images using IR sensor. The light source of the thermal switch is waste heat. This is just idea…