Actuators

Actuators allow movement and convert commands into actions. There are 3 main types of actuators: electric, hydraulic and pneumatic.

Electric Actuators :

Electric actuators are simply electro-mechanical devices which allow movement through the use of an alectrically controlled systems of gears. Some common types are stepper motors, solenoids and an electric motor. Electric motors are the most common form of actuator.

Hydraulic Actuators

Hydraulic actuators allow a robot to move by the use of fluids moving under pressure through a series of valves by the use of pumps. The hydraulic fluids bused would normally consist of oils which are reasonably non-compressible. They are used where a lot of power is needed to move things. These would commonly be industrial robots possibly used on a car assembly line.

Pneumatic Actuators

Pneumatic actuators use compressed gas to force the movement of pistons through the use of pumps and valves and so allow movement of the robotic part. Pneumatic actuators work on the same principles as hydraulic actuators using a series of valves, pumps and pistons to gnerate movement in the robot. Grippers usually use compressed gas because electrics are too dangerous and hydraulics can become too messy if they were to leak.

How Are Pneumatic Actuators Used For Grippers?

The rotary actuator is a pneumatic actuator used to alternate the rotated position of an object. This is common with grippers. Just like the human wrist the actuator enables the rotation of an object. The energy for the rotation is provided by compressed gas (pneumatics). The rotary actuator is then able to convert the air pressure from a linear motion to a rotating motion.

How Is The Diection of The Force Changed?

This is done by a rack and pinion. Air pressure is pushes the piston in a linear motion, attached to the piston is a straight set of gears called a "rack". The rack is pushed forward as the piston moves. The rack is meshed with the circular gear teeth of a "pinion" forcing the pinion to rotate. The pinion can be rotated back into the original position by supplying air pressure to the opposite side of the air cylinder pushing in the same manner as discussed earlier for hydraulics. The pinion is connected to a shaft that protrudes from the body of the rotary actuator.  This shaft can be connected to various tools or grippers.