Environmental Challenges in Specific Infrared Communication Andy Graham 2002 Electrical Engineering Senior Project Presentations

Project Objectives Create a reliable, continuous system of communication, enabling the wheelchair to follow the smaller, completely autonomous robot Allow for standard operation of the wheelchair as well as a manual override Design a system that remained functional outdoors.

Project Objectives Artist’s Rendition

Project History A sensory system previously existed on the wheelchair, lacking movement Experience with photo detectors in the EE 350 course, as well as issue with sunlight Television Remote Controls

Approaches Columniation – sensors exposed only to a select range of vertical visibility Encoding the infrared light diodes in a certain frequency of emission.

The System: the Beacon Oscillating on/off at a rate of 90 Hz, using an LMC 555 CMOS timer Two 12 bulb arrays of LEDs, 24 volts Two 12 bulb arrays of LEDs, 24 volts Built into a pre-fab’d printed circuit board Mounted at Appropriate height

The System: the Sensors Two L/R sets of five 25° photo detectors Built indoor version first Built indoor version first over 180° visibility over 180° visibility

The System: the Sensors Outdoor version extracts modulating signal though A/C coupling, lower ambient light resistance Amplifies signal, single source LM358 op- amps, increasing resolution, gain of ~4 Amplifies signal, single source LM358 op- amps, increasing resolution, gain of ~4

The System: the Sensor Cover Attempt at columniation, protects sensors Minimal apparent effect

The System: the Program Inputs via A to D converters PIC 16F877 Retains High/ Low Value for each set of sensors Retains High/ Low Value for each set of sensors Turns to match differences Turns to match differences Gives priority to joystick input, allowing for override Gives priority to joystick input, allowing for override Threshold Values Threshold Values

The System: Flow Chart

The System: Demo & Results Consistent accuracy, 6” to 2’ stopping range Fluid, reliable motion, good detection distance Fully functional override

Future Considerations Removal / combination of indoor/outdoor versions Corners would be a significant challenge Corners would be a significant challenge More intelligent directions given by autonomous robot Some local sensing Some local sensing Removal of threshold values

The End Special thanks to Prof. Kuc, Ed Jackson for allowing me to join the project, as well as their continued assistance throughout To the rest of the guys on the team, good luck next year