P1 Exercise 4 - Events

Events are external processes, such as button presses, that cause the robot to react. So far our code has been written linearly, meaning that all functions, such as move and rotate, are called out in a known sequence. Events on the other hand happen … well … whenever they happen. You cannot tell exactly when someone walks into your room, when exactly it starts to rain, or when there is an obstacle in front of the robot that triggered a bumper sensor.

In a programming environment, a specific event is usually associated with a callback function, which is executed whenever the event happens. For example in figure 4 you can see two types of callback functions: robot.whenTouched which is called when you press a button on top of the robot, and robot.whenBumperPressed which is called when you hit the robot’s bumper.

Figure. 4: An example of event based robot control. iRobot project code 4NGY4