S Ahmad Central Electronics Engineering Research Institute Pilani

S Ahmad Central Electronics Engineering Research Institute, Pilani Workshop on Embedded System in Automobile Industry Indian Institute of Technology, Mumbai 1 st December, 2003 BARC Presentations 24 April, 2003

Introduction n Automotive Industry Quest Passenger Car - Performance Improvement, Reduced Cost, Enhanced Reliability n n n Conventional Sensor - MEMS Replacement Newer Possible Applications Earliest Use - Manifold Absolute Pressure Sensor - MAP - 1979 Silicon Accelerometer - Airbag - 1990 s Warranty Period - 10 Years/ 150, 000 Miles BARC Presentations 24 April, 2003 2

Introduction n n Improved Fuel Efficiency, Emission and Safety - Federal Standards Higher Expectations - Performance, Comfort Greater Availability - Micro-controller, Memory, Display and Enhanced Diagnostics Very Harsh Under the Hood Environment High Temperature, Shock, Vibration, Humidity, Corrosive Media, EMC and RFI Military Grade at Lowest Consumer Price BARC Presentations 24 April, 2003 3

Automotive Sensor Global Market Growth BARC Presentations 24 April, 2003 4

Automotive Sensor Usage Early Estimate - 1997 BARC Presentations 24 April, 2003 5

Automotive Industry MEMS Sensors BARC Presentations 24 April, 2003 6

Product Evolution Time Schedule BARC Presentations 24 April, 2003 7

Top Ten MEMS Markets n n n n n Micro-fluidic Biochip Glucose Monitoring MEMS Sensor Tire Pressure Sensors Hard Disc Drive Heads Inkjet Print Head Medical Condition Detection Device Large Format Print Head Automotive Function Enabling Device ABS Accelerometer and Gyroscope Automobile Mass Airflow Sensor Venture Development Corporation BARC Presentations 24 April, 2003 8

Basic Auto MEMS Requirements n n n n n Crash Sensing - Air Bag Deployment Vehicle Dynamic Control Rollover Detection System Antitheft System Electronic Parking Brake System Vehicle Navigation System Seat Occupancy / Passenger Position Climate Control Digital Engine Control Road Conditions BARC Presentations 24 April, 2003 9

Major Growth Areas n n n Accelerometer – VDC and Airbags Pressure Sensor – Transmission, Brakes, Diesel Fuel Rails, Refrigeration, Tires, Fuel Evaporation, Yaw Rates, GPS Backup Position Sensor – Wheel Speed, Camshaft, Crankshaft, Pedal Positions Humidity Sensor – Cabin Comfort Distance Sensor – Collision Avoidance BARC Presentations 24 April, 2003 10

Airbag Deployment n n n n n Acceleration - Continuously Measured Acceleration Exceeds Some Threshold Measured Acceleration Curve Integrated Large Velocity Change - Airbag Fired Steering Wheel and Side Airbag Firing Earlier Sensors - Distributed g Switch Insufficient Information – On/Off Type More Expensive , Less Reliable MEMS Accelerometer - Far Better Gyroscope - ANALOG Devices - Introduced BARC Presentations 24 April, 2003 11

Vehicle Dynamic Control n n n n VDC - Vehicle Skid Control Contains : Gyroscope, Low g Accelerometer, Wheel Speed Sensor Yaw Rate Prediction - Speed Measurement Gyroscope Measurement - Compared Larger Difference - Single Wheel Brake or Torque Reduction Applied, Airbag Fired Shock / Vibration Tolerant Gyroscopes - Need ANALO Devices - i. MEMS Gyro Better Device BARC Presentations 24 April, 2003 12

Vehicle Rollover Detection n n n n More Appropriate - Vans, Trucks, Sport Vehicle Roll Angle and Rate Measurement - Tripping Gyroscope - Roll Rate, Integration - Angle Z - Axis Acceleration – Additional Accelerometer Sideways Sliding Cause Rollover - Curb/Object Dual Axes Low g Accelerometer – Ideal Solution Shock/Vibration Resistant Gyros - Necessary Fast Response Time Gyroscope - Essential BARC Presentations 24 April, 2003 13

Security - Antitheft n n n Vehicle Towing - Popular Type Theft Tilt Detection System - Effective Sensor Pan European Specification - 30 Tilt over 3 minute period - i. e. 0. 016 o tilt per second Fluid Tilt Sensor - Possible Use - Limited Tilt Range, Parked Car @ Large Tilt Angle - Sensor Ineffective Harsh Environment - Temperature Change, Sensor Performance Heavily Impaired Low g Accelerometers – Ideal Tilt Sensor BARC Presentations 24 April, 2003 14

Parking Brake System n n n Manual Parking Brake Activation Robust Push or Pull Type Operation Braking Force Magnitude - No Concern Electronic Parking Brake - Button Activation Sensor Measures Vehicle Inclination Braking Force Requirement Determined Brake Applied - Easy Operation Low g Accelerometers - Ideal Tilt Detection Sensor Sometimes – Single Sensor Used Both Antitheft and Parking Brake Systems BARC Presentations 24 April, 2003 15

Vehicle Navigation System n n n Standard Feature – Luxury Cars Global Positioning System– Fundamental Part GPS - Position and Altitude but No Direction Magnetometer – Early Direction Sensor Large Ferrous Metal Object - Confused Magnetometer Performance - Not Reliable Compass and GPS – Initial Start Travel Direction Match - Map Data - Direction Gyroscope - When and How Much Car Turned, Directional Data Match - Map Data Gyroscope - Heading Information, Low g Accelerometer – Position Data , Integration BARC Presentations 24 April, 2003 16

Electronic Engine Control n n n n Intake Manifold Pressure - Air to Fuel Ratio Mass Air Flow Devices - MEMS Version Barometric Pressure - Altitude Information Rich to Lean Fuel to Air Mixture Decision Cylinder Pressure Measurement - Performance Optimization - Piezoelectric/ Fiber Optic Sensor Exhaust Gas Re-circulation - Capacitive Pressure Sensor – Better Solution Hydraulic Fluid Pressure - Isolated Diaphragm Type Configuration, Sensor – ASIC Integration Fuel Injection - Silicon Fuel Injection Nozzle BARC Presentations 24 April, 2003 17

Sensor Cluster System n n n Same Sensor Family - Variety of Measurements Accelerometer/Gyros - Sometimes 15 Sensors Difficult Integration, Unsafe Operation Fear Inertial Measurement Unit - Six Axes Inertial Measurements, Proper location Signal Routing Additional Stand Alone Sensors - Still Required Sensor Cluster Configuration - More Economical Solution, Better Micro-controller Utilization BARC Presentations 24 April, 2003 18

Commercial Off-the-Shelf MEMS Pressure Sensor BARC Presentations 24 April, 2003 19

6 H-Si. C High g Piezo-resistive Accelerometer BARC Presentations 24 April, 2003 20

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ARIES Airbag Deployment Test System BARC Presentations 24 April, 2003 22

Three Axes MEMS Accelerometer Sandia Laboratories BARC Presentations 24 April, 2003 23

Delphi Automotive System Air Bag BARC Presentations 24 April, 2003 24

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Piezo-resistive Pressure Sensor - CEERI BARC Presentations 24 April, 2003 26

Zn. O Piezoelectric Acoustic Sensor - CEERI BARC Presentations 24 April, 2003 27

Polysilicon Load Cell - CEERI BARC Presentations 24 April, 2003 28

Three Axes Bulk Micro-machined Accelerometer Test Structure - CEERI BARC Presentations 24 April, 2003 29

Sensor Interface ASIC - Schematic BARC Presentations 24 April, 2003 30

Sensor Output – Without Conditioning BARC Presentations 24 April, 2003 31

Corrected Sensor Output BARC Presentations 24 April, 2003 32

Universal Signal Conditioner – Resistive Bridge BARC Presentations 24 April, 2003 33

Intelligent Pressure Sensor Chip BARC Presentations 24 April, 2003 34

Capacitive Sensor Interface ASIC BARC Presentations 24 April, 2003 35

Conclusions n n n n Automobile MEMS Sensor - Fast Growing Multi Billion Dollar Industry Growth Intelligent Sensor Development - Needed Interface and Signal Conditioning - Essential Hybrid Approach - Initial Stage ASICs Use - Commercial ASICS Available Sensor Cluster Approach – Better Solution Already Late Start – Sooner Starting Better BARC Presentations 24 April, 2003 36

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