How to Use Servos

Servos are used in a variety of hobbyist activities, mostly in radio controlled cars, boats and airplanes. There has also been an increasing interest in amateur robotics and servos play an integral role there. Learning to use and understand servos is key to the success of many of the hobbies people enjoy. In this how-to we'll explain how to use servos properly.

Difficulty: Moderate

Instructions

Things You'll Need:

• Servos, Servo specifications

1. First, regardless of whether you are trying to create a gigantic robot or a small remote control airplane, make sure you have the correct servo for the job. This means several things. Make sure that the servo's operating voltage matches the voltage supplied to it. Ensure that the servo will provide enough torque to move whatever needs to be moved. Verify that the servo operates at a high enough speed for your application. All of these figures are supplied by the manufacturer and can be easily referenced, usually via the internet.

2. When installing the servos make sure to allow room for the control arm to have sufficient clearance. Also don't forget to plan routing for the servo's leads. If they are not long enough to reach the receiver, servo extension leads can be purchased at most hobby shops. Also, depending on the application some servos might benefit from some form of dampening in their mounts, this can be as simple as placing small pieces of rubber or o-rings between the servo and the mounting surface.

3. Before installing the control arms attach all of the servos to the receiver or controller and apply power. Center the trim setting on all channels. Now disconnect power and each servo. From here you can install the control arms and all linkages. The idea behind this is to allow all of the servos to mechanically center before placing the control arms on. If you do not perform this step you may find that you have more or less travel in one direction with the servo.

4. Now that your servos are installed as well as centered, it is time to trim them and set their limits. In the radio system or controller you are using you can set both trims and total travel for the servo. The trim setting is where the servo is positioned from center when you turn it on. This allows you to have a preset position for the servo other than center. The travel volume adjusts the total distance the servo turns side to side, and you can reduce it from anywhere from full travel down to almost no travel if needed. In many cases travel distance needs to be set because the surface the servo is controlling is designed to move a certain distance, and the servo's total travel does not match this.

5. Now that all your adjustments have been made it is time to check for anything abnormal. Buzzing, binding, or sluggish servo response are all signs of abnormal servo operation. Common culprits are broken or worn teeth, stuck control rods and stripped gears. Also check to make sure that your servos are not drawing excessive current as this can cause a whole host of problems to other electronics in your project.