Potential Fields Navigation Using ARToolkit
Potential Fields is a concept that comes from the fundamentals of electricity and magnetism. A charge with high potential (positive) will repel the electric field away from it, while a charge with low potential (negative) will attract the electric field. With many of these attractive or repulsive points present in the electric field, a field of vectors is created representing all of the forces at each point in the field. This vector field can be navigated by following each vector at each present location, leading towards the point of lowest potential in the field (global minimum). This can be applied to robotics by creating a field where obstacles are repulsive points, and the target is an attractive point. If the robot is instructed to follow the velocities (vectors) of this field, it will be led to the target, while also navigating around the obstacles. In order to recognize the obstacles, ARToolkit is used because of its strengths in enclosed environments. This allows for the robot to update its information about the obstacles and target in real-time, giving the robot the ability to avoid mobile obstacles and targets. The NXT was used for this project due to its ease of use, and its Bluetooth communication capabilities. The velocities for each wheel (calculated based on the velocities from the vector field) are sent over a Bluetooth connection from the host PC to the NXT, allowing for real-time communication and navigation with the NXT. Here is a video demonstrating the program's abilities to avoid moving targets and obstacles. For more information on Potential Fields Navigation, visit our tutorial.