How to Build a Robot With a Linear Actuator

Linear actuators allow robots to lift objects.

Linear actuators are devices that generate force and motion. They are linear in that they travel in a straight direction, instead of moving in a rotational direction. Robots use linear actuators to perform motions that are not possible without the device. Some of the most advanced methods of building robots are extremely expensive and time-consuming. However, robot enthusiasts with some extra money can build more simplistic versions.

Things You'll Need

• Linear actuator
• DC motor (one that already has a gearbox attached)
• Sheet of aluminum
• Drill
• Servo motor controller
• Microcontroller
• Wheels, at least three
• Superglue

Instructions

1. Decide both the minimum and maximum distance the linear actuator can move. Determine how much force the actuator can place on objects and how fast you want the actuator to move. These are the primary characteristics of the linear actuator and will affect how you design it.

2. Install a DC motor, which is battery-powered and rotates quickly, while generating low torque. Screw the body of the motor to the robot frame. Take a sheet of aluminum, drill two holes in two of the corners of the motor, drill two more holes on the other side, and then bend the piece to create a 90-degree angle.

3. Connect the motor controller to the microcontroller -- the brain of the robot -- and the power supply. The motor controller is an intermediate device between the microcontroller, the power supply and the motor. The microcontroller tells the motor controller how much power the motor should run at, and the motor controller sends this power to the motor, from the power supply.

4. Make sure the controller operates at the same voltage range as the motor. Linear actuators use R/C servo input, so use a servo motor controller -- which usually operate at 4.8V to 6V, although some operate at other rates that are not standard.

5. Decide how many wheels the robot will have. Robots with three wheels or more are easier to build than two-wheeled robots, since they need gyroscopic stabilization. Drill holes into the wheels, so the axle connected to the motor has a place to go. Use an adhesive, such as superglue, to hold the wheels on.

Tips & Warnings

• A DC linear actuator relies on the rotation of a motor, which causes a screw to turn. The rotational movement of the screw causes the rotational movement to turn into linear movement. This type of actuator is useful for parts of the robot that lift objects.

• Pneumatic and hydraulic linear actuators have the most power, create long strokes and can move at high-speeds. These devices are ideal for situations where the robot must lift a heavy object, up to 500 lbs.

References

• Firgelli Automations: What’s a Linear Actuator?
• Robot Shop: How to Make a Robot – Lesson 3: Making Sense of Actuators
• Robot Shop: How to Make a Robot – Lesson 5: Choosing a Motor Controller
• Robot Shop: How to Make a Robot – Lesson 2: Choosing a Robotic Platform
• Society of Robots: Mechanics - Robot Chassis Construction