The AX-12 servo actuator from Robotis is the most advanced actuator on the market in this price range and has become the defacto standard for the next generation of hobby robotics. The AX-12 robot servo has the ability to track its speed, temperature, shaft position, voltage, and load. As if this weren't enough, the control algorithm used to maintain shaft position on the ax-12 actuator can be adjusted individually for each servo, allowing you to control the speed and strength of the motor's response. All of the sensor management and position control is handled by the servo's built-in microcontroller. This distributed approach leaves your main controller free to perform other functions.