programming question

VEX V5 Technical Support UNOFFICIAL Tech Support
#1

Hey, im extremely new to vex. I learned some simple programming through the 2005 inventors guide. One challenge is to make a robot hit a wall three times and then stop. THe guide indicates the solution code is on this site somewhere, but i can not find it anywhere. Does anyone know where to find it or can they share the solution with me?

Aaron Mosher

#2

First off let me ask which programming language are you trying to use? EasyC? ROBOTC?

The concept is very simple:

int Bumps = 0; //Create a variable for the number of times the robot hits the wall. (also set it to 0, as the robot has not hit the wall yet)

while(Bumps < 3) //Repeat the following code until the robot has hit the wall 3 times.
{
if(SensorValue[Touch] = 1) //If the touch sensor has been pressed, i.e. if the robot has hit the wall.
{
Bumps = Bumps + 1; //Record that bump by adding 1 to the variable Bumps.
//Also run the drive motors in reverse away from the wall.
}

else //Otherwise assume that the touch sensor has not been pressed, i.e. assume that the robot is not touching the wall yet.
{
//Run the drive motors forward towards the wall.
}
}

//After Bumps has reached 3, turn off the drive motors.

Hopefully I explained that well enough.

~Jordan

#3

Thanks for the response, i will try to program this. I am using Easy C programming.

#4

You’ll need to add at least a 100ms time delay after setting robot to backup from the wall, otherwise the bump counter will keep counting before the robot can even stop.

The typical while(1) {} event loop in EasyC takes 1-5ms per loop.
The motor PWM signal only updates once per 20ms.
The robot takes even longer than that to react as well.
So without a time delay, this program will count 3 bumps before the motors can even reverse from the first bump.

#5

Whoops – I knew I was missing something. I completely forgot to write that the backup should be for an amount of time. Here:

int Bumps = 0; //Create a variable for the number of times the robot hits the wall. (also set it to 0, as the robot has not hit the wall yet)

while(Bumps < 3) //Repeat the following code until the robot has hit the wall 3 times.
{
if(SensorValue[Touch] = 1) //If the touch sensor has been pressed, i.e. if the robot has hit the wall.
{
Bumps = Bumps + 1; //Record that bump by adding 1 to the variable Bumps.
//Also run the drive motors in reverse away from the wall for 3 seconds. (or a different amount of time -- your decision)
}

else //Otherwise assume that the touch sensor has not been pressed, i.e. assume that the robot is not touching the wall yet.
{
//Start running the drive motors forward towards the wall.
}
}

//After Bumps has reached 3, turn off the drive motors.

~Jordan

#6

Thanks everyone for your replies, i was able to successfully get the robot to work.

#7