1. IR Sensors

2. Two Types Diode-Phototransistor Pair Sharp Sensors

3. Sharp Sensor Pros ●Easy to use Cons ●Expensive ●Large ●Noisy readings

4. Diode-Phototransistor Pair Pros ●Cheap ●Small ●More accurate Cons ●Complex to manage

5. Example Parts Diode (Emitter): SFH-4545 Phototransistor (Receiver): TEFT4300 10SC010075 SC10 3/4 Nylon Screw Insulators I will try to get these in the lab Black Thermal Tubing Prevents IR leakage Use hot-air gun to shrink

6. Example Setup: Emitter MCU GND 5V 0.1 uF4.7 uF How to insulate: 1.Cut small piece of thermal tubing 2.Put tubing over emitter so only tip is exposed 3.Use hot-air gun to shrink tubing

7. Example Setup: Receiver 3.3V MCU GND How to insulate: 1.Cut a small piece of the Nylon Screw Insulator 2.Use a SMALL amount of glue to glue it over the TEFT4300 3.Cover with thermal tubing, same way as previous slide

8. Example Sensor Layout

9. Position Correction Wall-in-front correction http://micromouseusa.com/?p=398 Corrects angle and translational position Use twice at dead end to correct X and Y position Post detection http://micromouseusa.com/?p=828 Corrects translational position while on the move Must calibrate for each speed

10. Software Tips Only turn one on at a time Turn them on only long enough to get a good reading Charge period: ~100 us Discharge period: ~140 us Do post-detection and wall-in-front correction Subtract ambient noise from sensor reading

11. Maze Adjustments Since the Diode/phototransistor pair reads the intensity of the light, the material of the maze walls will significantly change the readings you get. For example, UCSD uses wooden walls, while UCLA uses plastic walls. The plastic walls will reflect a lot more light. If your mouse is very stable, you might be able to just multiply all your sensor values by a constant to account for the difference. However, in reality the relationship is not always linear, so it may be necessary to re-calibrate all your sensor values. It is probably a good idea to multiply all your sensor values by 100 or 1000 from the beginning, then you can adjust it up or down as needed when you run your mouse on a new maze. This makes it so you don't need to use floating point to make small adjustments.