Localisation

The localisation of the robots is a very important part of the project. With localisation, the robot is able to keep track of its own position and direction. This is of high importance when a robot encounters a heavy object, because now it can find out which robot is the nearest to him and ask this specific robot for help. Besides the localisation, also a bluetooth-communication script is necessary to accomplish this. The way this communication is drafted and scripted is written in Bluetooth Communication.

Programming the Localisation

To begin, first the following information should be a given for the robot:

• Its beginposition (x- and y-coordinate)
• Its begindirection (angle of its direction with respect to the x-axis)

From this point on the rotation sensor inside of the actuators used for the NXT Robots are used to keep track of the robot's position. When the wheels of the robot are rotating, the robot is either going forward, going backwards or turning. This has to be taken into account when converting the steps of the motor to either angle or distance.

When the robot is going forward, the rotation sensor counts the steps that the actuator makes. These steps are then converted to a distance in the java script. To calculate this convergence factor, the robot was programmed to drive forward and continuously print the steps of the actuators on its display until the pressure sensors gave a value above zero. Next, the robot was placed at an exact distance of 1 meter from a heavy object. After hitting the heavy object the values of step was read and the convergence was calculated by dividing the amount of steps by 100. This gave us the amount of steps per centimeter. This was done 3 times and the average value was exactly 35 steps. So in conclusion, from here we were able to make the robots go a given straight distance.

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