You can use radio frequency identification technology (RFID) technology to control a servomechanism and move a load in response to a signal. This is seen in practical applications such as automatic door openers and radio-controlled toys. RFID uses radio waves to transmit and receive data, while a servo is a system in which many units operate together to perform an action in response to a signal. The two types of technology work well together and can be used for projects that the average home-based hobbyist engineer can undertake using readily-available parts and materials.
The term “servomechanism” or “servo drive” refers to a function or a task rather than to a machine. A servo system consists of a power supply, load, positioning controller, servo control (amplifier), servo motor and a feedback mechanism. The positioning controller is a device that stores information regarding a specific function or task and that activates a motor or load according to a specific program. The command signal goes to the positioning controller and then passes to the servo control, which amplifies the power to a level necessary to move the motor or load. The power supply converts the power required to move the load from AC to DC and supplies power to the integrated circuits. As the load moves, a feedback signal is sent by another device to the controller, which compares the feedback to the command signal and makes any necessary adjustments to the movement of the load by the servo motor.
RFID is a wireless technology in which radio waves are used to transmit information between an RFID reader and an RFID tag. The RFID signals can only be transmitted over a limited range, which depends on both the technology and the operating environment. Both the RFID reader and tag transmit radio frequency electromagnetic energy, with active RFID tags requiring an external power supply. They can interfere with radio signals in the area and are subject to legal controls. The reader and the tag each have an antenna in order to transmit energy between each other. The antenna helps to power passive RFID tags which are not connected to a power supply. RFID transmits in limited frequency ranges.
RFID signals are used to control servomechanisms and power motors and move loads. You can try your own DIY RFID/servo project using materials from your local RadioShack store. For example, you can try passing an RFID signal through a smartcard into a servomechanism that opens a door automatically when your user ID is received. This will require some technical and engineering knowledge, but is relatively simple in terms of parts and materials. A radio-controlled car is another example of RFID controlling a servo and is another good DIY project to try.
RFID equipment transmits radio signals at frequencies that could interfere with medical equipment and is therefore subject to legal limitations. You need to check whether you need a license to operate RFID technology and ensure that your projects comply with power and frequency limitations within your area.