1 In Order of Presentation: Ishaan Sandhu Danny Kang Arslan Qaiser Eric Otte Anuar Tazabekov Capacitive Rain Sensor for Automatic Wiper Control

2 Introduction Design Requirements Proposed Design Solution Testing Results Budget Demonstration Conclusions

3 Automotive Safety and Convenience Automatic Headlights Hands-Free Calling Automatic Braking Automatic Windshield Wipers – Currently Optical (Expensive, Inaccurate) – DT6 Proposes Using a Capacitive Based Sensor

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5 Functionality Detect rain through 6 mm of glass Output control signals to wipers Accuracy Differentiate multiple levels of rain Ignore false stimuli on windshield, i.e. hands and dirt Compatibility Fit in existing housing area (1250 mm 2 ) Mount via adhesive to windshield Cost Production cost < $16 per unit

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7 Control Unit

8 COMSOL 3D Modeling Software Visual User Interface Calculates the base capacitance Can model dielectrics – Top layer – Bottom Layer Simulates electric field lines – Sensitivity

9 Analog Devices AD7745 Industry-leading accuracy down to 4 fF change in capacitance Interfaces with sensor traces to monitor capacitance (+/- 4 pF) Converts changing capacitance to 24-bit digital output signal Output routed to PIC using the I 2 C communication system Make text larger

10 Microchip PIC16F bit microcontroller, programmable in C code Initializes and configures AD7745 for operation Streams data from AD7745 and compares to known data ranges Data falling in range will activate appropriate wiper control signals Make text larger

11 COMPONENTCOST PIC16F1826 Microcontroller$0.90 AD7745 CDC$4.50 ADP Voltage Regulator$1.40 Surface-mount Passive Components$0.10 Two-layer PCB Production and Assembly$4.00 (est) Plastic Enclosure$0.50 (est) Total$11.40 (est)

12 Design Team 6Supplier (TRW)Change Technology CapacitiveOptical Cost per Unit $11.40$ % ↓ Physical Size 1,750 mm 2 3,850 mm 2 46% ↓ Detection Area 960 mm mm 2 72% ↑ Clear line of site No needRequired

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15 Successful completion of the project Exceeds all design requirements Higher accuracy Larger sensing area Smaller enclosure Significant savings

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