Environmental Challenges in Specific Infrared Communication 2002 Electrical Engineering Senior Project Presentations Andy Graham
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 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 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
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 Turns to match differences Gives priority to joystick input, allowing for override Threshold Values
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 More intelligent directions given by autonomous robot 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