Heterogenous Hazard Avoidance Behavior in Autonomous, Mobile Robots Joseph D. Lawton & Jeffery A. Seeger Project Advisor: Jeffrey Horn Northern Evolutionary Robotics Laboratory (NERL) Department of Mathematics and Computer Science NMU Celebration of Student Research and Creative Works April 12, 2001

2 NMU Celecbration of Student Research and Creative Works Abstract Obstacle avoidance is considered a fundamental behavior in autonomous robotics. Avoiding multiple, diverse types of obstacles is especially difficult. We have developed and programmed a robot to avoid obstacles in its path, moving obstacles approaching it from any direction, overhead obstacles, and certain traps, such as holes in the ground, and sudden drop-offs. To avoid all of these obstacles simultaneously, using only a few sensors, requires sophisticated algorithms dealing with the dynamic environment around them

3 NMU Celecbration of Student Research and Creative Works Background Previously programmed rover behaviors: Obstacle Avoidance Edge Avoidance (“Stay-on Table”) Beacon Following Wall Following All of these are STIMULUS-RESPONSE strategies, Also known as REACTIVE PLANNING But each took up most of the processor resources (memory, speed), and so existed separately, on different rovers

4 NMU Celecbration of Student Research and Creative Works Goals of this project For the first time (at NMU!): Integrate two or more of the basic S-R behaviors Implement a rover able to avoid two or more DIFFERENT TYPES of hazards (hence, “heterogenous hazard avoidance” ) Our Approach: First upgrade rover with more powerful processor Use a single sensor (infrared detector) to scan the environment (using articulated sensor mount, or “neck”) Build up an internal model of the world Decide on course of action based on that model (I.e., a large look-up table of S-R rules) First go for integrated obstacle avoidance and edge avoidance

5 NMU Celecbration of Student Research and Creative Works Results Integrated Obstacle and Edge Avoidance More Robust Behavior than any Previous NMU Rover! –Able to avoid obstacles, holes, and stay on table simultaneously –Has difficulty detecting edges when approaching at shallow angle (thus it is MOST challenging to be able to “wal the plank”!) –Can fall off edge when backing up, thus table corners and other tight spots are problematic

6 NMU Celecbration of Student Research and Creative Works Future Enhancements Additional sensors! (IR, sonar rangers, contact sensors) Upgrade to an embedded PC, wirelessly connected to the NMU campus net (the internet) Integrate additional S-R behaviors: –goal seeking, such as wall following, edge following, beacon following) –Avoid Overhanging obstacles (ability to go under bridges, through holes, this means looking up!) –Play “keep away”, by avoiding moving objects approaching from any direction (this means motion detection, 360’ full circle scanning) Eventually, a very robust rover able to handle more complicated environments, such as navigating a ledge with obstacles on it while avoiding pursuing robots