This Arduino Linear Actuator Tutorial shows how to control a Firgelli Small Linear Actuator using an Arduino compatible board and various input sensors, including a Slider and Rotation Knob for direct control, Joystick for incremental movement, and three buttons with preset positions (preset in the code with each position assigned to a button, so when a user pushes a button the small linear actuator moves to that position).
For Arduino Linear Actuator projects the small linear actuators by Firgelli are excellent. These linear actuators have an internal controller which allows them to be operated just like a servo. By using the Arduino Servo Library we can simply send out the desired position to the actuator and it moves to the position.
All of these parts can be found together in the RobotGeek Arduino Linear Actuator Experimenter's Kit, or obtained individually.