Intelligent Machines Design LaboratorySensor Presentation (4/18/06)

Alarm-o-bot

Andrew JosephTAs: Adam Barnett

Sara KeenInstructor: A. Arroyo

Problem

• Have you ever had trouble waking up in the morning?

• Do you hit the snooze button in a daze and just kept right on sleeping.

• Does this cause you to miss tests, classes, or assignment turnin days?

Solution – Alarm-o-Bot

• Hides itself based on low light intensity and distance parameters.

• Avoids obstacles in the way.

• The snooze button must be hit on the Alarm-o-bot to stop alarm.

• Alarm-o-bot continues to hide itself after each successive snooze.

Sensors Types

• Bump switch – act as snooze button for users to hit

• CDS sensor – detect light variance (find darkest place in room)

• IR sensor – obstacle avoidance

• RF TX/RX pair – communicate between clock and moving robot

IR SensorsIR Sensor Characterization

0

0.5

1

1.5

2

2.5

3

0 1 4 9 10 11 11 12 14 15 20 27 30 34 40 47 58 74

Distance (cm)

Volta

ge (V

)

IR Sensor 1

IR Sensor 2

• ADC values range from 500 (about 2.4V - close) to about 50 (about 0.4V - far).

• Distance measurements viable from 10cm to 80cm

CDS Sensors

CDS Sensors

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 1 2 3 4 5 6 7 8

Light Intensity

Volta

ge

CDS 1

CDS 2

CDS3

• Low resistance in high light, high resistance in low light

• Voltage divider with 10k resistor provides voltage range from 0V to 5V

• Sensor with highest voltage points to darkest area in room

RF Transmitter/Receiver

RF Transmitter/Receiver

• 2400 bps baud rate

• Operates at 315Mhz

• -103dbm sensitivity that pulls 3.5mA for 5V operation

• 10cm wire antenna used for receiver

• Encoding scheme for transmission through noisy environment

Conclusion

Questions?