1. CS 546: Intelligent Embedded Systems Gaurav S. Sukhatme Robotic Embedded Systems Lab Center for Robotics and Embedded Systems Computer Science Department University of Southern California gaurav@usc.edu http://robotics.usc.edu/~gaurav/CS546

2. Administrative The CS dept is working on a bigger room for the class The class cap has been raised to 45 Is there anyone here –who has not yet filled the questionnaire ? –who has filled the questionnaire and not got a response from me ? –who wants to be in the class, and is not on the class mailing list ?

3. Today Overview of the ENS box (Richard Pon and Jeff Tseng, Aevena) TinyOS tutorial Homework #2 –Karthik will give a brief explanation –Homework is online on the class website Sensing, sensor calibration, and actuation basics

4. Homework #2 Karthik just gave you details Due a week from today – no extensions

5. Last week Memory Processor InterfaceSensor and actuator suite Energy supply External communication Platform OS and SW architecture Tools User interface Application Figure adapted from [Pottie and Kaiser 2005]

6. Today Memory Processor InterfaceSensor and actuator suite Energy supply External communication Platform OS and SW architecture Tools User interface Application Figure adapted from [Pottie and Kaiser 2005] 1/24, 4/18: Cyclops 1/31: Networking 2/21: Energy management 4/18: Cyclops 2/7,14 and 28: Time synch, localization and data management 3/21,28 and 4/11: Environmental monitoring

7. Sensors Basic principles Noise and figures of merit Types of sensors Calibration

8. Sensing Architecture Feedback transducer network Signal channel Transducer Analog signal procesing Digital signal processing A/D conversion Physical signal at source Physical signal at transducer Output signal

9. Sources of Noise Feedback transducer network Signal channel Transducer Analog signal procesing Digital signal processing A/D conversion Physical signal at source Physical signal at transducer Output signal

10. Figures of Merit Responsivity: output signal/input signal Sensitivity: (output signal without input)/(responsivity) Drift: slow change in output due to low- frequency noise Cross talk

11. Types of Sensors Environmental –Pressure, gas phase composition, automotive exhaust gas oxygen, Motion and force –Accelerometers, rotation and rotation rate, piezoresistive strain, microphone, capacitative position Electromagnetic transducers –Antennas, magnetometers, digital cameras. laser rangefinders Chemical and biochemical –Oxygen, nitrate (amperometric)

12. Transduction Principles Pressure – capacitance change Gas – absorption changes conductivity Accelerometer and rate gyros – proof mass displacement changes Microphone – diaphragm displacement changes resistance Piezoelectric – force changes polarization charge Magetometer – motion wrt coil induces a current Camera – photodetectors and CCD arrays Nitrate – use microfluidics to reduce an electrode and measure current

13. Calibration Compare measurements to a reference Performed while manufacturing Tuning parameters (say a resistor) Need calibration methods in situ Usually non-linear interpolation

14. Next time Network and programming models