Mon 02 January 2017
There are many ways to control an RC servo and both the Arduino and the RPi have software libraries to do that. However, that consumes a small amount of overhead (processor power) and you may not want that.
Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface PCA9685 is a good hardware solution that is controlled via i2c. This is nice, because you can hook up a bunch of these and control more servos than you could ever want! The Adafruit tutorial does a great job of showing how to hook this up and the python library is here in their github account.
I used it to make a simple 4 legged (quadruped) robot.