"How does Servo motors works " In this post
techmix.in is going to discuss how does
servo motors works.A servo is a small motor that you can position at any angle very
accurately. It contains internal circuits that will automatically
maintain that particular angle. However, you cannot do full revolutions
with a servo. You are restricted to a certain range, usually from
180-270 degrees. Servos are very powerful for their sizes.
Inside Servo Motors :
To fully understand how the servo works, you need to take a look under
the hood. Inside there is a pretty simple set-up: a small DC motor, potentiometer,
and a control circuit. The motor is attached by gears to the control
wheel. As the motor rotates, the potentiometers resistance changes, so
the control circuit can precisely regulate how much movement there is
and in which direction.
When the shaft of the motor is at the desired position, power
supplied to the motor is stopped. If not, the motor is turned in the
appropriate direction. The desired position is sent via electrical
pulses through the signal wire.
The motor's speed is proportional to the difference between its actual
position and desired position. So if the motor is near the desired
position, it will turn slowly, otherwise it will turn fast. This is
called
proportional control. This means the motor will only run as hard as necessary to accomplish the task at hand, a very efficient little guy.
Parts of Servo motors
How is the servo motors controlled?
Servos are controlled by sending an electrical pulse of variable width, or
pulse width modulation
(PWM), through the control wire. There is a minimum pulse, a maximum
pulse, and a repetition rate. A servo motor can usually only turn 90
degrees in either direction for a total of 180 degree movement.
The
motor's neutral position is defined as the position where the servo has
the same amount of potential rotation in the both the clockwise or
counter-clockwise direction.
The PWM sent to the motor determines position of the shaft, and based on the duration of the pulse sent via the control wire; the rotor
will turn to the desired position. The servo motor expects to see a
pulse every 20 milliseconds (ms) and the length of the pulse will
determine how far the motor turns. For example, a 1.5ms pulse will make
the motor turn to the 90-degree position. Shorter than 1.5ms moves it to
0 degrees, and any longer than 1.5ms will turn the servo to 180
degrees, as shown below.
When these servos are commanded to move, they will move to the position
and hold that position. If an external force pushes against the servo
while the servo is holding a position, the servo will resist from moving
out of that position. The maximum amount of force the servo can exert
is called the torque rating of the servo. Servos will not hold
their position forever though; the position pulse must be repeated to
instruct the servo to stay in position.
Servo Motor Applications
Servos are used in radio-controlled airplanes to position control surfaces like elevators, rudders, walking a robot, or operating grippers. Servo motors are small, have built-in control circuitry and have good power for their size.
WATCH WORKING HERE!!!!!!!!!!!!!!
In food services and pharmaceuticals, the tools are designed to be used
in harsher environments, where the potential for corrosion is high due
to being washed at high pressures and temperatures repeatedly to
maintain strict hygiene standards. Servos are also used in
in-line manufacturing, where high repetition yet precise work is necessary.
3/27/2013 01:22:00 pm
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