Real-time Intelligent Labyrinth Pathfinder Autonomous Robot (RILPAR)

 
Department of Electrical and Computer Engineering
Azad University of Arak

Introduction:

RILPAR is an autonomous mobile robot designed in year 2000 after one year of dedicated research and development efforts. The robot is designed to explore and find the unknown path in complex physical/ realistic maze matrices (Labyrinth platforms). The robot operational environment is a 4m by 4m maze matrix with random choices of corridors. The robot is able to explore and find the shortest or fastest way from the start point to the exit point. The approximate time for a complete operation is about 14 minutes. The RILPAR operation is fully automated with no human contact.

System Description:

RILPAR is controlled based on an improved artificial intelligent algorithm very similar to A*. RILPAR is connected to a computer system via standard parallel data communication port. The communication is based on bi-directional data transformation so it can implement the feedback and command control techniques simultaneously. The robot is equipped with sensitive IR sensors at all four sides of the robot chassis to detect the labyrinth corridor walls. The robot's trajectory path discovery  from the start point to the end is based on building a history pattern of the path which was discovered during the maze matrix exploration. So the chance of repeating the same trajectory is very rare. A graphical interface shows the real-time operation of the robot on the screen. The customized C++ program acquires the transmitted data from the IR sensors at every single moment while the robot is operating. The system makes decision about the next possible movement (forward, right, left and backward) and based on that the computer system sends the specific code to the receiver circuit on the robot.

Stepper motor based mobile system:

Two stepper motors are involved in RILPAR mobility. There is no traditional steering system on this robot. The steering mechanism is similar to military tanks steering system. This feature makes the RILPAR so nimble for accurate maneuvers. The stepper motors get their power from an external source of power.

Obstacle detection system based on IR Sensors:

There are 3 reflection based IR sensors around the robot chassis. the sensors are able to detect any obstacle within 20cm of distance. In the labyrinth case the only obstacles are the walls. So when the robot goes to a new position of the labyrinth it collects the information from the sensors and sends them to the computer system. An electronic board on the robot makes a  unique code after the robot detects the wall(s). 

Stepper motors driver system:

The actual stepper motors driver commands are generated on the computer system and the computer sends them to the switching board on the robot. Even though it is not an appropriate way to drive the stepper motors but it gives us the ability to have speed and power control on the robot movements. 

Data communication system:

A bi-directional parallel data communication is implemented between the robot and the computer system. The robot sends the information collected from the obstacle detector sensors to the customized intelligent real-time program running on the computer system. The real-time data bus contains the stepper motors control bytes and obstacle detector sensors codes.