ACTUATORS

Mechanical Movements

Actuators are an essential part of robotics,  they are the plant that drives the robots;  Provide the robot the ability to control  and  move its mechanical parts.


Types of Actuators

Generally, actuators can be classified into two category of movement; Linear and Rotary.


Linear Actuators

These actuators generate linear displacements, normally in sliding motion.

Rotary Actuators

Generate rotary displacements, normally in spinning motion

Pneumatic & Hydraulic Actuators


These are fluid powered actuators that are commonly used in industrial robotic applications to handle varies tasks from material handling to precision product manufacturing.


Pneumatic Actuators


Pneumatic Actuators uses compressed air to create movement.

Compressed air stored in storage cylinders or air compressors are pumped into the Pneumatic Actuator thus creating movements.

Hydraulic Actuators


Hydraulic actuators operates with incompressible liquid such as oil and water, they are normally used when large amount of force is required in operation.

The most common hydraulic actuators design is the piston type (Linear) actuators.

Electrical Actuators



These electromagnetic driven actuators are the most commonly used actuators used in robotics application. Their application ranges from industrial robotics all the way to hobbyist robotics.


The advantage of using electrical actuators over fluid powered one are:-

· ease of interfacing to electronic circuitry (not signal conversion is required)

· available in very small form

· electricity drive both the control circuitry and actuators (no extra power source     needed)

· easily and cheaply available


Electromagnetic Actuators


There are mainly two types of Electromagnetic Actuators;

Solenoids (Linear) and Electrical Motors (Rotary)



Solenoids

Solenoids produce linear motion when electricity is applied to its coil the ferromagnetic core is pull or push depending on the direction of the current flow

Electrical Motors


DC motors are the most commonly used electrical motors used in robots, various type of DC motors may be different in constructions but the basic working principal behind them is generally the same.


Guideline to Actuator selection

Here are some brief guidelines to the selection of actuators.

· Amount of power required?

· Difference actuators type delivers difference among of power

· Ease of power generation and driving actuators?

· Hydraulic actuator requires fluid tank

· Pneumatic actuator requires air compressor and high pressure storage tanks

· Electrical actuator requires batteries/electricity supply

· Size constraint?

· Availability?

   How easy is it to obtain the actuator?

· Price?

   How much does the actuator cost?