Universal application for contactless control
The first implementations of sensor devices for non-contact control, were used to detect an object approaching toward the sensor and in response send a trigger signal to start the appropriate process. Automatic gates, soap dispensers, porch lighting on building structures, hand dryers, or car parking assist devices all use contactless sensors as an input source. For this purpose, they use distance sensors, which resemble two-state switches from the wiring diagram, and gesture sensors, which recognize an operator's gestural movements in three dimensions and thus enable objects to be controlled in an intuitive way. Gesture control also allows the user to match the response of the controlled object to the range of motion seen by the sensor. This is one of the key features in video game systems.
Gesture recognition using infrared sensors
Non-contact control systems in sophisticated video game consoles, use lasers and special cameras to record the player's movements. With the ability to detect a variety of simple movements, simple motion sensors have found applications in consumer electronics, electric musical instruments, and automotive applications. For example, changing a radio station in a non-contact manner will require a swipe of the hand to the left or right, within the sensor's field of view. Adjusting the volume can be done by moving your hand closer or further away from the sensor. In such applications, among others, the most technically and economically advantageous solution is the use of infrared (IR) light sensors. In one of the simplest approaches, IR sensors consist of two infrared light emitting diodes (emitter) and an infrared receiver placed between them. The radiation coming from the IR emitter, typically has a highly directional characteristic. When you wave your hand in front of the IR emitter, the infrared light reflected by the IR receiver will change in intensity proportional to the movement you make - for example, if you move your hand from the left to the right side of the sensor, the amplitude of the signal from the IR emitter will increase, and similarly in the opposite direction of hand movement. Then, the IR sensor sends a signal to the microcontroller which, by means of the uploaded program, analyzes the input data in terms of the speed of the gesture and its type and direction, and then, depending on these factors, sends control signals to the appropriate output devices.
