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CS 141: Introduction to ProgrammingLecture 19
Dr. Susan Bergin
Email: [email protected]
Room 2.108, Callan Building,
Department of Computer Science, NUI Maynooth
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Robots Revisited
! What do you need to know about the
RoboCar class?
" You need to know how to create an instance of
a RoboCar
" You need to know how to use the methods
covered in lectures and in labs
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Moving on to the sensors
! The NXT comes with a number of sensors andwere going to use
the touch sensor.
! The touch sensor should be plugged into Port 1 of
the NXT brick (see RoboCar API).! The method to check if the
sensor has been
pressed is the following:
robot.touchSensorIsPressed();
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Using the touch sensor - example
if(touch sensor is pressed)
{
// Do something e.g. reverse the robot
}
else
{
// Do something different e.g. go Forward
}
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Touch sensor in action..
publicclassTouchRobot {publicstaticvoidmain(String[] args) {
RoboCar robot = newRoboCar();
robot.setMotorSpeed(360);
if(robot.touchSensorIsPressed())
{
robot.moveBackward(1000);
}
else
{
robot.moveForward(1000);
}
}
}! But how do you get the program to continually check the
selection statment?
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Fixing this with a loop
while(true)// creates an infinite loop
{
if(robot.touchSensorIsPressed())
{
robot.moveBackward(1000);
}
else
{
robot.moveForward(1000);
}
}
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Putting It Together
publicclassTouchRobotLoop1{
publicstaticvoidmain(String[] args) {
RoboCar robot = newRoboCar();
robot.setMotorSpeed(360);
while(true)
{
if ( robot.touchSensorIsPressed() ){
robot.moveBackward(1000);
}
else
{
robot.moveForward(1000);
}
}
}
}
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More methods
! moveForwardForDistance(float distance)
" Method to move RoboCar forward the specified
distance (approximately).
! moveBackwardForDistance(float distance
" Method to move RoboCar backward the
specified distance (approximately).
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Something to think about..
!How would you solve this problem?The robot needs to drive
forwardfor an unknown distance until ithits an obstacle. It then
needs tonavigate around the obstacle(distances specified) and
continueagain until it hits the red wall. Trysolving this on paper
now!
!What if you dont know in advancehow many obstacles there
arebefore the red wall but you knowthat all the obstacles are all
thesame size and the red wall ismuch longer. Try solving this
on
paper now!
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Preparing for your January exam
! Lets begin to work through an exam paper
together
