Sensors. human sensing. basic sensory. advanced sensory. 5+N senses <link> tactile touchless (distant) virtual. e.g. camera, radar / lidar, MS Kinect

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2 Sensors human sensing 5+N senses <link> basic sensory tactile touchless (distant) virtual advanced sensory e.g. camera, radar / lidar, MS Kinect

3 Human senses Traditional sight smell taste touch hearing Other senses balance acceleration pain pressure/tension time temperature kinesthetic sense internal body senses

4 Sensors local x remote detection (contact x contactless) detection x measurement Is there an obstacle? How far is the obstacle? active x passive

5 Favourite sensors in (mobile) robotics tactile micro switches, end switches, bumpers electrical motor current consumption measurement, induced current sensing/measurement etc. directional acoustic, optical point measurement using detection of reflected beam obstacle detection, environment mapping line sensors directional measurement multiplexed in time cameras image processing MEMS use of microscopic phenomena to replace big mechanical sensors various sensor types (accelerometers / gyros, pressure, temperature, ) also as actuators (pumps, motors ) virtual indirect measurement, using action consequences to detect the action

6 Measurement using signal reflection TOF measuring time needed for the signal to return precise measurement needed phase-shift sending modulated signal, measuring phase shift of reflected signal 2 * π * f * TOF

7 Measurement using signal reflection ultrasonic, infrared, laser, radar intensity measurement possible in addition the signal must get reflected the measurement is active environment vulnerability interferences detectable signal

8 Measurement using signal interruption gate detection of signal reflection (or lack of) reflected signal intensity thresholding

9 Ultrasonic direct TOF measurement is possible measurement range ~ 1 cm 10m multiple reflection detection is possible

10 Ultrasonic Reality:

11 Infrared PSD beam spread exploitation up to single meters distance measurement illumination problems Example: Sharp GP2D12, GP2Y0A21

12 Infrared single narrow beam reflexive short range CNY-70, QRD1113/4, GP2S60

13 Laser 1D, 2D, 3D rangefinder, scanner 20 km possible

14 Some popular laser rangefinders SICK Hokuyo LMS 100 TIM 310 LMS 400 NAV

15 MEMS components in scale µm accelerometers gyros pressure sensors displays, pumps, engines

16 MEMS components in scale µm accelerometers gyros pressure sensors displays, pumps, engines

17 MEMS

18 Odometry measurement of distance travelled wheel revolution measurement motor revolutions measurement gearbox! sensing mechanical inductive, capacitive resolver, synchro optical Hall effect sensor

19 Hall effect V H = k I B

20 encoders absolute x relative rate quadrature binary Gray single-track Gray

21 Rate sensor detects change between black/white (or between nothing/reflection, nothing/signal) number of changes indicates rotation angle frequency of changes indicates speed

22 Rate

23 PostSript the Mighty /grc 0.5 def /noofarc 4 def /frc 360 noofarc div def /radius 30 def 0 2 noofarc { /pos exch def black 0 0 moveto 0 0 radius pos grc sub frc mul pos 1 grc sub add frc mul arc fill white 0 0 moveto 0 0 radius pos 1 grc sub add frc mul pos 2 add grc sub frc mul arc fill } for

24 Quadrature two sensors two tracks displaced by ½ step, sensors on a cord single track, two sensors displaced by ½ step angle

25 Quadrature clockwise counterclockwise phase A B phase A B

26 How to interpret the signal?

27 Binary more sensors in different tracks problem edges & sensor placement & noise

28 Gray code single change in each step recursive construction 0 + level n reversed level n

29 Binary vs Gray code

30 Single-track Gray code Precision problem At least 9 tracks needed for 1 Gray code precision 1994 N.B.Spedding 2001 Hiltgen, Paterson single-track for 9 sensors, 360 positions

31 Some real encoders Old style computer mouse

32 Some real encoders US Digital E4 E4 Miniature Optical Kit Encoder CPR ( PPR) 2 channel quadrature TTL squarewave out

33 Some real encoders Austria Microsystems AS5035 AS5035 Magnetic Rotary Position Sensor 2 quadrature A/B outputs 64 pulses per channel / 256 edges per rev. / 1.4 per step Index output (one pulse per revolution) user-programmable zero position 3.3V / 5V power

34 DIY Encoder sensors CNY70, QRD encoder wheel