CS244-Introduction to Embedded Systems and Ubiquitous ComputingCS244 – Lecture 7Simplified Block DiagramSensors and ActuatorsSensorsExample: Acceleration SensorCharge-coupled devices (CCD)CMOS Image SensorsComparison CCD/CMOS sensorsExample: Biometric SensorsExample: Artificial eyesArtificial eyes (2)Other examples of sensorsSlide 14Slide 15ActuatorsStepper Motor ControllerMEMS ActuatorsSlide 19Slide 20Sample-and-Hold CircuitAliasingAnalog to Digital ConversionAnalog-to-Digital ConverterFlash A/D ConverterSignal ProcessingFrequency DomainSlide 28Digital-to-Analog (D/A) ConvertersCS244-Introduction to Embedded Systems and Ubiquitous ComputingInstructor: Eli BozorgzadehComputer Science DepartmentUC IrvineWinter 2010Winter 2010- CS 2442CS244 – Lecture 7Sensors, Actuators and Other hardware componentsICS212 WQ05 (Dutt) Hardware Components: Sensors, Actuators, ConvertersSimplified Block DiagramactuatorsactuatorsSensors and ActuatorsSensors:Capture physical stimulus (e.g., heat, light, sound, pressure, magnetism, or other mechanical motion)Typical generate a proportional electrical currentMay require analog interfaceActuatorsConvert a command to a physical stimulus (e.g., heat, light, sound, pressure, magnetism, or other mechanical motion)May require analog interfacesolenoidmiclaser diode/transistorspeakerdc motorcompassaccelerometerSensorsProcessing of physical data starts with capturing this data.Sensors can be designed for virtually every physical stimulus heat, light, sound, weight, velocity, acceleration, electrical current, voltage, pressure, ...Many physical effects used for constructing sensors. law of induction (generation of voltages in an electric field), light-electric effects.Example: Acceleration SensorCourtesy & ©: S. Bütgenbach, TU BraunschweigMEMS deviceSmall mass in centerWhen accelerated:Mass displaced from centerResistance of wires connected to mass changeDetect change in resistance and model accelerationCharge-coupled devices (CCD)Image Sensors: Based on charge transfer to next pixel cellImage Sensors: Based on charge transfer to next pixel cellCMOS Image Sensors Based on standard production process for CMOS chips, allows integration with other components.Comparison CCD/CMOS sensorsSource: B. Diericks: CMOS image sensor concepts. Photonics West 2000 Short course (Web)Example: Biometric SensorsExample: Fingerprint sensor (© Siemens, VDE):Example: Fingerprint sensor (© Siemens, VDE):Integrated into ID mouse.Example: Artificial eyes© Dobelle Institute(www.dobelle.com)Artificial eyes (2)He looks hale, hearty, and healthy — except for the wires. They run from the laptops into the signal processors, then out again and across the table and up into the air, flanking his face like curtains before disappearing into holes drilled through his skull. Since his hair is dark and the wires are black, it's hard to see the actual points of entry. From a distance the wires look like long ponytails.© Dobelle Institute(www.dobelle.com)Other examples of sensorsHeart monitoring sensors“Managing Care Through the Air”IEEE Spectrum Dec 2004Rain sensors for wiper controlHigh-end autosPressure sensorsTouch pads/screensProximity sensorsCollision avoidanceEngine control sensorsAudio sensors Motion sensorsThermal sensorsSARS detection (“high fever”)Simplified Block DiagramactuatorsactuatorsSensors and ActuatorsSensors:Capture physical stimulus (e.g., heat, light, sound, pressure, magnetism, or other mechanical motion)Typical generate a proportional electrical currentMay require analog interfaceActuatorsConvert a command to a physical stimulus (e.g., heat, light, sound, pressure, magnetism, or other mechanical motion)May require analog interfacesolenoidmiclaser diode/transistorspeakerdc motorcompassaccelerometerActuatorsOutput physical stimulus varies in range and modality Large (industrial) control actuatorsPneumatic systems: physical motionOptical outputIRThermal outputSmall motor controllers (stepper motors)MEMS devicesList goes on…..Stepper Motor ControllerStepper motor: rotates fixed number of degrees when given a “step” signalIn contrast, DC motor simply rotates when power applied, and coasts to stopRotation achieved by applying specific voltage sequence to coilsController greatly simplifies thisMEMS ActuatorsHuge variety of actuators and output devices.Microsystems motors as examples (© MCNC)(Dimensions in the order of several microns)(© MCNC)ActuatorsCourtesy and ©:E. Obermeier, MAT,TU BerlinSimplified Block DiagramactuatorsactuatorsSample-and-Hold CircuitSampling: how often the signal is converted.Quantization: how many bits used for sampling.Model: Vx = Ve when Clock = 1AliasingPotential Consequence of sampling, e.g.:Signal frequency: 5.6 HzSampling frequency: 9 HzAnalog to Digital ConversionSampling: how often is the signal converted?Twice as high as the highest frequency signal present in the inputQuantization: how many bits used to represent a sample?Sufficient to provide required dynamic range Under-loading: dynamic range not used properlyClipping: input signal beyond the dynamic rangeAliasing: erroneous signals, not present in analog domain, but present in digital domainUse anti-aliasing filtersSample at higher than necessary rateAnalog-to-Digital ConverterproportionalityVmax = 7.5V0V11111110000000100100011010001010110000010011010101111001101111010.5V1.0V1.5V2.0V2.5V3.0V3.5V4.0V4.5V5.0V5.5V6.0V6.5V7.0Vanalog to digital4321t1 t2 t3t40100 1000 0110 0101timeanalog input (V)Digital outputdigital to analog43210100 1000 0110 0101t1 t2 t3t4timeanalog output (V)Digital inputICS212 WQ05 (Dutt) Hardware Components: Sensors, Actuators, ConvertersFlash A/D Converter Parallel comparison with reference voltage Speed: O(1) HW complexity: O(n)n= # of distinguished voltage levelsICS212 WQ05 (Dutt) Hardware Components: Sensors, Actuators, ConvertersSignal ProcessingDigital signal S0, S1, S2 … Sn-1What can we do with it?Transpose: e.g., Zi = Si + KAmplify: e.g., Zi = Si  Compose: e.g., Zi = (S1i  1 + K1) + (S2i  2 + K2) Filter: e.g, Zi = (Si+ Si+1) / 2Compress: e.g., using Huffman codesArchive, match against database, etc.Or, process after converting to frequency domainSpectral analysisICS212 WQ05 (Dutt) Hardware