1. Sensors (v.1c)1 CENG4480_A1 Sensors Sensing the real world

2. Sensors (v.1c)2 Sensors §Motion (Orientation/inclination )sensors §Force/pressure/strain §Position §Temperature and humidity §Rotary position §Light and magnetic field sensors

3. Sensors (v.1c)3 Motion (Orientation/inclination sensors §Acceleration §Gyroscope §Compass §Tilt Sensor

4. Sensors (v.1c)4 Accelerometer http://en.wikipedia.org/wiki/Accelerometer §Functions: l measure acceleration in one or more directions, position can be deduced by integration. l Orientation sensing : tilt sensor l Vibration sensing §Methods: l Mass spring method ADXL78 ( from Analog Device ) l Air pocket method (MX2125)

5. Sensors (v.1c)5 ADXL78 (from Analog Device http://www.analog.com/UploadedFiles/Data_Sheets/ ADXL78.pdf ) http://www.analog.com/UploadedFiles/Data_Sheets/ ADXL78.pdf §Mass spring type (output acceleration in G) §Measure the capacitance to create output

6. Sensors (v.1c)6 ADXL330 accelerometer for three (X,Y,Z ) directions http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf §3D

7. Sensors (v.1c)7 2D translational accelerometer MX2125 (from www.parallax.com) §Gas pocket type §When the sensor moves, the temperatures of the 4 sensors are used to evaluate the 2D accelerations

8. Sensors (v.1c)8 Accelerometer demo: orientation sensing § http://www.youtube.com/watch?v=9NEiBDBXFEQ http://www.youtube.com/watch?v=VP4-wdMMLFo Self-balance Robot Sensor demo

9. Sensors (v.1c)9 Accelerometer demo : Tilt sensing demo § http://www.youtube.com/watch?v=C6uVrYz-j70 Tilt sensing demo

10. Sensors (v.1c)10 Gyroscopes http://en.wikipedia.org/wiki/Gyroscope §Gyroscope l Measure rotational angle §Rate Gyroscope l measure the rate of rotation along 3-axes of X (pitch), Y (roll), and Z (yaw). l Modern implementations are using Microelectromechanical systems (MEMS) technologies. Gyroscope

11. Sensors (v.1c)11 §FEATURES l Complete rate gyroscope on a single chip Microelectromechanical systems (MEMS) l Z-axis (yaw-rate) response §APPLICATIONS l GPS navigation systems l Image stabilization l Inertial measurement units l Platform stabilization Gyroscope to measure Rational acceleration ADXRS401 http://www.analog.com/UploadedFiles/Data_Sheets/ADXRS401.pdf

12. Sensors (v.1c)12 Compass-- the Philips KMZ51 magnetic field sensor §50/60Hz (high) operation, a jitter of around 1.5°

13. Sensors (v.1c)13 Rate gyroscope demo § http://www.youtube.com/watch?v=VP4-wdMMLFo Using Gyroscope compass for virtual reality application in an iphone

14. Sensors (v.1c)14 Application of motion sensors Self balancing robot §by Kelvin Ko §http://hk.youtube.com/watch?v=2u-EO2FDFG0http://hk.youtube.com/watch?v=2u-EO2FDFG0 20cm 35cm Motion sensors: gyroscope and accelerometer

15. Sensors (v.1c)15 Complementary filter §Since §Combine two sensors to find output 15 Gyroscope High frequency Acceleromete r Low frequency

16. Sensors (v.1c)16 Complementary filter θ=rotation angle,  =filter time constant, s=laplace operator http://en.wikipedia.org/wiki/Low-pass_filter http://en.wikipedia.org/wiki/High-pass_filter http://en.wikipedia.org/wiki/Low-pass_filter 16

17. Sensors (v.1c)17 Self Balanced robot using complementary filter 17

18. Sensors (v.1c)18 Tilt Sensor by OMRON http://rocky.digikey.com/WebLib/Omron%20Web%20Data/D6B.pdf §Detect tilting 35 ~ 65 degrees in right-and- left inclination

19. Sensors (v.1c)19 Force/pressure/strain §Force-sensitive resistor (FSR) §Strain gauge §Flexion §Air pressure

20. Sensors (v.1c)20 Force Sensing Resistors http://www.interlinkelectronics.com/library/media/papers/pdf/fsrguide.pdf §FSR402

21. Sensors (v.1c)21 Force Sensing Resistor Demo § http://www.youtube.com/watch?v=LQ21lXr6egs

22. Sensors (v.1c)22 Application for a walking robot §Walking robot

23. Sensors (v.1c)23 Application of force sensing resistance sensors to balance a walking robot §Balancing Floor tilled right upper leg bend left Floor tilled left upper leg bend right Neutral position Four sensors under the foot

24. Sensors (v.1c)24 Four Force sensors under the foot §D§D

25. Sensors (v.1c)25 The Nao robot uses force feedback at its feet http://en.wikipedia.org/wiki/Nao_(robot) § http://www.robotshop.com/Images/xbig/fr/robot-humanoide-nao-edition-academique-v3plus-aldebaran.jpg http://www.youtube.com/watch?v=2STTNYNF4lk

26. Sensors (v.1c)26 Strain Gauge : Force sensors http://www.meas-spec.com/myMeas/default/index.asp §Piezoelectric crystal: produces a voltage that is proportional to force applied §Strain gauge: cemented on a rod. One end of the rod is fixed, force is applied to the other end. The resistance of the gauge will change with the force.

27. Sensors (v.1c)27 Single element strain gauge §sensitive to temperature change. VbVb R R R Gauge=R+  R gauge load rod V0V0

28. Sensors (v.1c)28 Four-element (Wheatstone bridge) strain gauge sensor, §Four times more sensitive than single gauge system; not sensitive to temperature change. §All gauges have unstrained resistance R. b1=R-  R t2=R+  R b2=R-  R t1=R+  R VbVb t1 t2 b1 b2 rod load V0V0

29. Sensors (v.1c)29 Flexion (bend) sensors §resistance: §10 KΩ (0°); §30-40 KΩ (90°) http://www.flexpoint.com/ http://www.jameco.com/wcsstore/Jameco/Products/ProdDS/150551.PDF

30. Sensors (v.1c)30 Felixon resistance Demo § http://www.youtube.com/watch?v=m4E5SP7HCnk&feature=related

31. Sensors (v.1c)31 Air pressure sensor §Measure up to 150 psi (pressure per square inch ).

32. Sensors (v.1c)32 Position sensors §Infra-red range sensor §Linear and Rotary position sensors

33. Sensors (v.1c)33 Infra-red Range detectors by SHARP (4 to 30cm) http://www.acroname.com/robotics/info/articles/sharp/sharp.html §An emitter sends out light pulses. A small linear CCD array receives reflected light. §The distance corresponds to the triangle formed.

34. Sensors (v.1c)34 IR radar using the Sharp range detector § http://www.youtube.com/watch?v=tStBLAiQaC8&feature=related

35. Sensors (v.1c)35 Position sensors, from[1] §RotaryLinear §Optical shaft encoder

36. Sensors (v.1c)36 Magnetic rotary encoder (http://www.renishaw.com/UserFiles/acrobat/UKEnglish/L-9517-9147.pdf) §non touch sensing

37. Sensors (v.1c)37 Optical rotary encoder (http://en.wikipedia.org/wiki/Rotary_encoder) §The light received (on or off) will tell the rotation angle) 3 light emitters 3 light receivers Rotation shaft Light paths http://www.youtube.com/watch?v=RuIislTGOwA Crank shaft sensor

38. Sensors (v.1c)38 Temperature and humidity §Temperature §humidity

39. Sensors (v.1c)39 Temperature sensors LM135/235/335 features(from NS) http://www.national.com/pf/LM/LM135.html § Directly calibrated in °Kelvin § 1°C initial accuracy available § Operates from 400 µA to 5 mA § Less than 1 Ohm dynamic impedance § Easily calibrated § Wide operating temperature range § 200°C over range § Low cost

40. Sensors (v.1c)40 Application note (connecting to an ADC e.g. ADC0820 or ADC0801) §

41. Sensors (v.1c)41 Capacitive Atmospheric Humidity Sensor http://rocky.digikey.com/WebLib/BC%20Components/Web%20Data/2322%20691%2090001.pdf §BCcomponents 2322 691 90001 10-90%RH Dc

42. Sensors (v.1c)42 Leaf Sensor Alerts When Plants Are Thirsty § http://www.youtube.com/watch?v=VM4X_fqPPco

43. Sensors (v.1c)43 TSL250, TSL251, TSL252 LIGHT-TO-VOLTAGE OPTICAL SENSORS http://focus.ti.com/general/docs/scproducts.jsp §Light-to-voltage optical sensors, each combining a photodiode and an amplifier (feedback resistor = 16 MW, 8 MW, and 2 MW respectively). §The output voltage is directly proportional to the light intensity on the photodiode.

44. Sensors (v.1c)44 Cadmium Sulfoselenide (CdS) Photoconductive Photocells http://faculty.uml.edu/aelbirt/16.480/pdvp5001.pdf §Light sensing using CdS

45. Sensors (v.1c)45 Hall effect Sensors for sensing magnetic flux“B field”, see: http://doc.semicon.toshiba.co.jp/noseek/us/td/td2frame.htm §

46. Sensors (v.1c)46 Application on Magnetic levitation 磁懸浮 http://myweb.msoe.edu/~muthuswamy/pubs/DesignOfMagneticLevitationControllersUsingJacobiLinearizationFeedbackLinearizationAndSlidingMode.pdf § http://www.youtube.com/watch?v=XjjBqzilkIc Magnetic levitation Train Model 磁懸浮火車 http://www.youtube.com/watch?v=TeS_U9qFg7Y frog levitation http://www.youtube.com/watch?v=A1vyB-O5i6E

47. Sensors (v.1c)47 Hall effect sensors and brushless DC motors §Brushless DC motor http://dev.emcelettronica.com/files/u4/Brushless_DC_Motors_bldc_motor.jpg §Is it using Hall effect sensor? Don't known. http://www.youtube.com/watch?v=JmRkxZT4XhY http://www.youtube.com/watch?v=cm0h2Qf3upQ

48. Sensors (v.1c)48 Novel sensors §Kinect http://www.youtube.com/watch?v=nvvQJxgykcU http://www.youtube.com/watch?v=Mf44bWQr3jc http://www.ladyada.net/learn/diykinect/

49. Sensors (v.1c)49 Many KINECT DIY projects § http://www.youtube.com/watch?v=Brpu30vjCa4&feature=related http://www.youtube.com/watch?v=3V-TGXFZbbA&feature=related

50. Sensors (v.1c)50 Control systems Example: A temperature control system

51. Sensors (v.1c)51 Control example: Temperature control system § Temp. Sensor A/D CPU D/A Pulse Width modulation & solid state relay Heater Timer Sample & Hold Digital control circuit Instrum. amp. Water tank computer

52. Sensors (v.1c)52 Temperature control method 1: ON-Off (bang-bang) control (poor) §Easy to implement, bad control result -- contains overshoot undershot. Algorithm for on-off-control: §Loop forever: If (T from_sensor > T req required temperature) §then (heater off ) §else (heater on). T req Undershoot Overshoot Time Temp On-off control result Steady state error

53. Sensors (v.1c)53 Temperature control method 2 : Proportional-integral- differential (PID) temperature control (good) §Init. (set required temperature T req ) §Loop forever{ l get temperature T from sensor, l e=T - T req l then T w =e*G*{Kp+Kd*[d(e)/dt] +Ki*  e dt } l else §} //G,Kp,Kd,Ki can be adjusted by user Tw Proportional, differential, integral

54. Sensors (v.1c)54 PID block diagram §http://www.controlviews.com/question12- 12-03.html Figure 1 - Parallel PID block diagram Kd Ki Kp

55. Sensors (v.1c)55 PID control using pulse width modulation PWM § Fixed period and fixed number of pulses T w (depends on e ) T req PID control result of method 2 On-off control: oscillates and unstable Time Temperature Time

56. Sensors (v.1c)56 Summary §Studied the characteristics of various sensors §and their applications

57. Sensors (v.1c)57 References §[1] S.E. Derenzo, Interfacing -- A laboratory approach using the microcomputer for instrumentation, data analysis and control prentice hall. §[2] D.A. Protopapas, Microcomputer hardware design, Prentice hall §[3] CUHK_FYP report HML0602, KHW0703 §[4] http://www.engin.umich.edu/group/ctm §[5] http://en.wikipedia.org/wiki/PID_controller