Theory of operation
The following is a description of the systems operation from
start to finish.
- The OOPic processor has the search path the robot will
take programmed previous to the robot entering the maze.
On power-up of the robot, no programming is necessary.
- The algorithm running in the OOPic processor steers the
robot. Essentially it scans the wall sensing modules
looking for landmarks. Landmarks are the locations of
walls during the robot's journey through the maze. The
fire sensors do not effect direction control at this
time, however, they are monitored for the ambient
infrared light level.
- The OOPic scans the wall sensors by selecting which
output of the signal generator is active.
- The sensor module that is connected to the active signal
output will begin emitting a 38Khz infrared signal. The
infrared detector contained in the sensor module will
detect if the 38Khz infrared signal is reflected (from
the wall of the maze). Note that the range of the wall
sensors is 2 - 6 inches.
- The algorithm can tell where it is by observing which
wall sensors are detecting walls. The algorithm controls
the robot drive accordingly to keep the robot traveling
along the preprogrammed search path.
- The robot drive is controlled in two ways by the
algorithm. To do this, it uses the OOPic's two PWM
outputs and two motor direction outputs. The motor
directions are both set to forward to move the robot
forward. The motor directions are made opposite to rotate
the robot. A preset duty cycle for both PWM outputs
determines the average speed of the robot. Changing the
appropriate PWM duty cycle above or below the preset PWM
duty cycle makes minor course corrections.
- Since the path the robot will travel is preprogrammed, it
is possible for the robot to know when it is a room. When
the robot enters a room, the algorithm scans the fire
sensing modules. If the fire sensing modules indicate a
fire is in the room, the algorithm switches into a fire
following mode.
- In the fire following mode, the algorithm scans the fire
sensors. The fire sensors output two analog signals,
indicating the infrared intensity to the left and right
of the robot. The OOPic has the ability to sample the
analog waveforms. The algorithm uses the sampled data to
determine which direction to move the robot in order home
in on the fire.
- When the output of the fire sensors
reaches a certain level the algorithm determines that the
robot is close enough to the flame to extinguish it. The
OOPic then activates the extinguishing system.
- The algorithm having used it's
extinguishing system will then go into a wait mode where
the robot does not move.
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Last Modified: Feb 14, 2000
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