22-09-2012, 02:54 PM
Microcontroller Based RF Remote Controller Robot
1Microcontroller Based RF.pdf (Size: 267.87 KB / Downloads: 235)
Roboticists develop man-made mechanical
devices that can move by themselves, whose
motion must be modelled, planned, sensed,
actuated and controlled, and whose motion
behaviour can be influenced by programming.
Robots are called intelligent when they succeed in
moving in safe interaction with an unstructured
environment, while autonomously achieving their
specified tasks. A robot contains a movable
mechanism, influenced by sensing, planning,
actuation and control components. It does not
imply that a minimum number of these components
must be implemented in software. Here an RF
remote controlled robot is implemented with the
help of a At89S52 microcontroller.
Microcontroller
A micro-controller can be compared to a small
stand alone computer, it is a very powerful device,
which is capable of executing a series of preprogrammed
tasks and interacting with other
hardware devices. Being packed in a tiny integrated
circuit (IC) whose size and weight is usually
negligible, it is becoming the perfect controller for
robots or any machines requiring some kind of
intelligent automation. A single microcontroller can
be sufficient to control a small mobile robot, an
automatic washer machine or a security system.
Any microcontroller contains a memory to store the
program to be executed, and a number of
input/output lines that can be used to interact with
other devices, like reading the state of a sensor or
controlling a motor. Some machines and robots will
even rely on a multitude of microcontrollers, each
one dedicated to a certain task. Most recent
microcontrollers are 'In System Programmable',
meaning that you can modify the program being
executed, without removing the microcontroller
from its place.
IC voltage regulators
Voltage regulators comprise a class of widely used
ICs. Regulator IC units contain the circuitry for
reference source, comparator amplifier, control
device, and overload protection all in a single IC.
IC units provide regulation of either a fixed positive
voltage, a fixed negative voltage, or an adjustably
set voltage. The regulators can be selected for
operation with load currents from hundreds of milli
amperes to tens of amperes, corresponding to
power ratings from milli watts to tens of watts. Here
7805 regulator is used.
Motor Driver
An H-bridge is an electronic circuit which enables a
voltage to be applied across a load in either
direction. These circuits are often used in robotics
and other applications to allow DC motors to run
forwards and backwards. The term "H-bridge" is
derived from the typical graphical representation of
such a circuit. An H-bridge is built with four switches
(solid-state or mechanical). When the switches S1
and S4 (according to the below right figure) are
closed (and S2 and S3 are open) a positive voltage
will be applied across the motor. By opening S1 and
S4 switches and closing S2 and S3 switches, this
voltage is reversed, allowing reverse operation of
the motor. Using the nomenclature above, the
switches S1 and S2 should never be closed at the
same time, as this would cause a short circuit on the
input voltage source. The same applies to the
switches S3 and S4. This condition is known as
shoot-through.