ROBOT ACTUATORS

Motors

In order to perform any action robots make use of actuators. The drive motors are the most important actuators of mobile robots. In a three-wheeled robot there are two drive wheels that are located at the front. The third wheel of the robot acts as a caster. To make the robot run forward or backward the drive wheels normally run at the same level of speed. If the left wheel is made to turn faster than the right wheel, the robot can pursue a course for turning it to the right. If the right wheel is made to run at faster speed, the robot turns its direction to the left. If left wheel runs in forward direction and the right wheel runs in backward direction, the robot perform a spin to the right. If the right wheel moves in forward direction and the left wheel moves in backward direction the robot spins in the opposite direction. The motors used in the robots are controlled by a fine arrangement of transistors that is known as an H-Bridge. This usually contains four MOSFET transistors that are controlled by two MOSFET inverter gates. Motors are also installed in robots to enabling them to move their arms.

Loudspeaker

A robot can communicate to events and people by making sound. There are many different types of buzzer or siren that can be switched digitally. An oscillator can be used for generating a tone of the required frequency. The LEGO Mindstorms robots contains a good collection of sound files which can be played when required for interaction. These include frequently-used words in our daily life and phrases, such as ‘well done’, ‘goodbye’, ‘left’, ‘right’, and the numerals ‘one’ ‘two’ ‘three’ and so on, and an additional number of useful sound effects, for example, the sound of an applause.

DISPLAYS

The simplest form of display that is used in robots is an LED display. Such displays can be easily driven directly from an output pin of the microcontroller, so there are no interfacing considerations. A robot can also be engineered to play an LCD display, though this is more complicated process than using only a few number of separate LEDs.