Need a motor driver that can run at the lower voltages? The Didel 2 Motor Minishield can come to your rescue! Use your Arduino Uno (or form factor compatible) board with it to drive a tiny robot around.
Like some electronics, this linear motion Pico servo doesn't like running at over 5V. Even slightly less is better. This adapter board adds a bit of voltage drop to a 5/6V system to make your servo happy.