Automobile Rain Response System

1
Automobile Rain Response System

• Jason Perry
• Brian Russ
• Michael Echols
• Marcus Day
• May 6, 2005

2
Skye Surface Wetness Sensor

• Applications
• Primary use Leaf Wetness Sensor
• Automatically roll up windows when it starts to
  rain and they are left open
• Close sun roofs when it starts to rain
• Close convertible roof when it starts to rain.

3
Features

• Waterproof to prevent corrosion
• Epoxy Resin around sensor
• Plastic Packaging
• 5 year life expectancy
• Mounting to minimize
• vibration

4
Dimensions

• Size
• 57 mm Deep
• 82 mm Long
• 80 mm Wide
• Mounting Holes
• 4mm X 4mm dia
• 57 X 35 mm rectangle

5
Sensor Placement

• In the cowl panel of the car
• Provides flat surface for quick detection

6
Leaf Wetness Sensors

• Gold Plated Fingers
• Condensation lowers resistivity between fingers

Campbell Scientific model 237
7
Why Gold?

• Immune to effects of air, water and oxygen
• Will not tarnish, rust or corrode
• Among the most electrically conductive of all
  metals
• Most ductile of all metals can be drawn into
  tiny wires or threads without breaking
• Malleability is unparalleled can be shaped or
  extended into extraordinarily thin sheets

8
Controlling Resistivity of the Sensor

• Increasing Resistivity
• Small amount of silicone polish may be applied
• Layer of clean cloth
• Decreasing Resistivity
• Often coated with flat latex paint
• Paint absorbs moisture, lowers resistance between
  fingers making sensor more sensitive

9
Skye Surface Wetness Sensor Characteristics

• Operating Temperature
• -20 to 70C (-68 to 158F)
• Supply Voltage
• 5 15 volts at about 4mA
• Sensitivity Control
• Sets amount of water induced impedance change of
  the wetness grid
• Minimum, Medium, Maximum
• Output types
• Voltage
• Current

10
Output Voltage

• Analog output
• Dry (100 400mV)
• Rises steadily depending on the amount of water
• Maximum of 2.5 V
• Switching output
• Between -400mV and 400mV
• Remains negative until half wet 1.25 V

11
Output Current

• In the supply lead
• Dry (approximately 5mA)
• Rises abruptly to approximately 15mA when wet
• Transition at the same points as switching
  voltage outputs

12
Board Controls and Outputs

• Pin - function
• 1 Pos. 5 - 15V supply
• 2 Neg. 0V and Ground
• 3 Cable Sheath and Analog Ground
• 4 Pos./Neg. 400 mV Switching Output
• 5 0 - 400 mV Analog Output
• 6 0 - 2.5V Analog Output

13
Future Research and Development

• Analog output voltage vs. switching output
  voltage
• At what level of wetness does the voltage output
  reach 1.25 V?
• Is the switching output a better option than the
  analog output?

14
Future Research and Development

• Determine the analog voltage output vs. surface
  resistance

15
Sensor Benefits

• Convenience Feature
• Reduced Insurance Claims Due to Water Damage
• Can Be Added at the Factory or Installed as an
  Aftermarket Accessory to Older Vehicles

16
Existing Products

• No existing products dedicated to closure of
  automobile windows
• Smart buildings
• Automated Windshield Wipers

17
Costs and Profits

• Sensor price 250
• Manufacture 150
• 600 Retail
• If automobile companies offer as an option on new
  vehicles
• Profits are unlimited.