The ion engine works by giving an electrical charge, or ionizing, a gas called xenon. When the xenon ions are emitted at such a high speed as exhaust from the spacecraft, they push the spacecraft in the opposite direction. The ion propulsion system requires a source of energy and for DS1 the energy comes from electrical power generated by it's solar arrays. Power Power for industrial robots can be electric, pneumatic or hydraulic. Electric motors are efficient, require little maintenance, and aren't very noisy.
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. 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. Pneumatic and hydraulic robots require maintenance of the tubes, fittings and hoses that connect the components and distribute the energy.