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Power source for robots can be electric, pneumatic or hydraulic. Usually, a power source drives the robot through the use of actuators (constitute as part of the robot body).

For electrical driven robots, four major types of electric drive can be used:

• Stepper Motors: These are used mainly for simple pick and place mechanisms where cheapness is more important than power or controllability.
• DC Servos: For the early electric robots the DC servo drive was used extensively. It gave good power output with a high degree of control of both speed and position.
• AC Servos: In recent years the AC servo has taken over from the DC servo as the standard drive. These modern motors give higher power output and are almost silent in operation. As they have no brushes they are very reliable and require almost no maintenance in operation.
• Solenoids Actuator: A major advantage of solenoid actuator is their quick operation. Also they are much easier to install than pneumatic or hydraulic actuators. However, solenoid can only fully open or closed and they don't produce much force.

Pneumatic robots use compressed air and come in a wide variety of sizes. A pneumatic robot requires another source of energy such as electricity, propane or gasoline to provide the compressed air. Many of the simple pick and place arms are driven by pneumatics. This makes them cheap but has the disadvantage of being difficult to control.

Hydraulic robots use oil under pressure and generally perform heavy duty jobs. This power type is noisy, large and heavier than the other power sources. A hydraulic robot also needs another source of energy to move the fluids through its components. Hydraulic drives were used on a large number of the early robots as it was more rigid and controllable than pneumatics and it could provide more power than the electric drives then available. The problems with hydraulics are that it tends to be fairly slow in operation and that due to the high pressures involved leaks can be very messy.

Most robots require a plug into the wall. Hydraulic robots also need a pump to pressurize the hydraulic fluid, and pneumatic robots need an air compressor or compressed air tanks. Furthermore, Pneumatic and hydraulic robots require maintenance of the tubes, fittings and hoses that connect the components and distribute the energy.

For mobile robots, two other important sources of electric power, solar cells and batteries, are used. There are lots of types of batteries like carbon-zinc, lithium-ion, lead-acid, nickel-cadmium, nickel-hydrogen, silver zinc and alkaline to name a few. Battery power is measured in amp-hours which is the current (amp) multiplied by the time in hours that current is flowing from the battery. For example, a two amp hour battery can supply 2 amps of current for one hour. Solar cells make electrical power from sunlight. If you hook enough solar cells together in a solar panel you can generate enough power to run a robot. Solar cells are also used as a power source to recharge batteries.

There are other forms of power source for special robot application. For example, power for deep space probes is traditionally generated by radioisotope thermoelectric generators or RTGs, which use heat from the natural decay of plutonium to generate direct current electricity.

Robots may use all these actuator types.