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ELECTRICAL
CIRCUITS
All circuits in this robot
are custom built except RF Transmitter & Receiver. The RF Transmitter
and Receiver were taken from a standard cordless telephone and were adapted
for use in control of robot.
Power
Robot uses 12 Volts 4 Amphere
lead acid battery to drive the whole system. Charger for the battery is
also available in side the robot which automatically charges the battery
and indicates the power of the battery. Different regulated power supplies
are providing required voltages to the different circuits.
Remote
Control
Transmitter
10 frequencies are
generated in the computer using turbo C. Each of these frequencies is used
to operate different parts of robot i.e. Forward/reverse movement of robot,
Steering left/right of robot, Arm up/down, Arm forward/reverse movement
and hand open/clench movement. The bandwidth of these 10 channels (Frequencies)
is nearly 3000Hz.
 These
10 frequencies (only one frequency generated at a time) are taken out of
the P.C Speaker and are processed through matching network and then fed
into the transmitter of 49.890 MHz. Where These frequencies are modulated
with the carrier frequency of 49.890 MHz and transmitted, as such a high
frequency can travel with out any solid medium.
Receiver
 This
transmitted signal is received in the receiver section of the robot. The
signal received is processed by the receiver and audio signal is recovered
form carrier frequency. This recovered audio signal is actually the frequency
that was generated by the computer on the transmitter side. The audio signal
is now fed into an array of ten LM 567's. LM 567 is an eight pin DIL IC.
Which is a Phase Locked Loop (PLL). If the frequencies fed to LM 567 matches
the
internal frequency
(Adjustable) of the LM 567, Pin 8 of LM 567 is grounded. The pin 8 of each
LM 567 is used to operate ten relays, which in turn control motors that
drive the robot. Out of ten relays used, five are Single Pole Double
Throw (S.P.D.T) type used to switch on the control motors. The rest of
the five relays are Double Pole Double Throw (D.P.D.T) type which are used
to reverse the direction of the motors. Five motors are used to control
each movement of the robot i.e.
-
Forward/Reverse
Movement of the robot
-
Steering
right/left movement
-
Arm up/down
movement
-
Arm forward/reverse
movement
-
Hand open/clench
movement
Excepting forward/reverse movement
of robot all other movements are fitted with limit switches. These switches
do not allow each individual movement to go beyond specific limits. |
