Magdalena Balazinska - Godfrey Tan RoboGuard Magdalena Balazinska - Godfrey Tan

Goals Guard a doorway or a hallway Detect doorway: position in the middle. Detect intruders and block their way. Move along a straight line

Subsumption Architecture IR Sensors Guard d s Stop Bump Sensors <Start> Bootstrap Collide d Motors Shaft Encoders Move Straight

Hardware and software components Handyboard: MC68HC11, 32K RAM, 9V Interactive C and Motorola assembly 2 DC motors (6.9V) 5 Sharp GP2D02 IR range sensors 5 bumper switches 2 shaft encoders Lego body

5 Sensors are positioned on a curve 3 Bumper switches 9V battery powering up the board and another 9V powering up the motors

Gear sets and motors

Sensors: the illusions and the reality GP2D02 is an infrared sensor; it transmits an IR signal and receives it back to detect The Specs say: 10cm to 80cm; an 8 bit number GP2D02: 10cm to 80cm

Sensors: the illusions and the reality Our experiments showed that the distance value given by the sensors were only reliable within a much shorter range (about half of the advertised range). Each sensor is with its own personality. Range: 4.5cm to 49.5cm Angle: 10.4º to 13.7º

Demo…

Summary Successes Limitations: Simple sensors and simple algorithms allow to achieve interesting behaviors Autonomous creature performs what seems like an “intelligent” task Limitations: Sensors ranges Batteries lifetime

Lessons learned Software eng. Robot eng. Reboot Change batteries. Check last piece of code modified. Check hardware connectors. Optimize algorithms.Test! Experiment! Don’t trust doc: read code. Don’t trust specs: experiment. You may be poor. Better be rich.