Some basic facts about robots are they all have moving parts, they usually have metal or plastic components, and they use actuators to move segments or components of their bodies. All robots need an electrical power source to function.
Most robots use batteries or they plug into an electrical outlet. Hydraulic-powered robots require a fluid pump, while pneumatic-powered robots require an air compressor or compressed air containers. Hydraulic and pneumatic systems use pistons to pivot body segments.
Robots usually have movable body parts such as pivoting arm segments or spinning wheels. Body segments need joints in order to move, and they accomplish motion with an actuator. Robots can have a variety of actuators, including electric motors, solenoids, pneumatic systems and hydraulic systems. Actuators connect to electrical circuits that power motors and activate hydraulic and pneumatic systems.
Most robots have an onboard computer system that controls the robot's movements. An engineer or hobbyist can change the behavior of a robot by writing a new software program for the robot's computer system. Some robots have sensory systems, but very few are able to smell, hear, taste or see. The most common type of sensory system is a motion sensor that enables the robot to measure its own movements.