hi am Kabil I would like to get details on speed control of DC motor using triac .....I need ur help

Introduction
The development of high performance motor drives is
very important in industrial applications. Generally, a
high performance motor drive system must have good
dynamic speed command tracking and load regulating
response. D.C motors have long been the primary
means of electric traction. D.C motor is considered a
SISO system having torque/speed characteristics
compatible with most mechanical loads. This makes a
D.C motor controllable over a wide range of speeds by
proper adjustment of its terminal voltage. Recently,
brushless D.C motors, induction motors, and
synchronous motors have gained widespread use in
electric traction. However, there is a persistent effort
towards making them behave like dc motors through
innovative design and control strategies. Hence dc
motors are always a good proving ground for
advanced control algorithm because the theory is
extendable to other types of motors. Many practical
control issues (motor control problems):
1) Variable and unpredictable inputs
2) Noise propagation along a series of unit processes
3) Unknown parameters
4) Changes in load dynamics
Under these conditions, the conventional constant gain
feedback controller fails to maintain the performance
of the system at acceptable levels. The incorporation
of feed forward in artificial neural networks is
important for several reasons the dynamical properties
of the system, and in practice it may improve the
performance. They are generally present in most nonlinear
dynamical system and can be used to implement
specific structures.
Speed Control of DC Motor Using TRIAC. DC motors
are widely used in industry because of its low cost, less
complex control structure and wide range of speed and
torque. With the increasing use of power
semiconductor units, the speed control of DC motor is
increasingly getting sophisticated and precise. A
TRIAC is a bidirectional thyristor with three
Terminals. Its three terminals are designated as MT1
(main terminal 1),MT2 & gate by G. Triac can
be turned on in each half cycle of the applied voltage
by applying a positive or negative voltage to the gate
with respect to the terminal 1. To successfully trigger
a TRIAC, Gate current must come from the main
terminal 2 side of the circuit