<ul><li>Institute for Personal Robots in Education </li></ul><ul><li>Kickoff Meeting, September 15, 2006 </li></ul><ul><li...
Off-the-shelf Candidates <ul><li>Lego Mindstorm NXT ($300) </li></ul><ul><li>Parallax Scribbler ($80) </li></ul><ul><li>Pa...
Some Details <ul><li>Lego Mindstorms NXT ($300) </li></ul><ul><ul><li>32-bit ARM7; 64Kb RAM; bluetooth; USB </li></ul></ul...
iRobot Roomba <ul><li>Roomba ($150-250) </li></ul><ul><ul><li>2 bump sensors </li></ul></ul><ul><ul><li>Odometery </li></u...
Scribbler <ul><li>Scribbler ($80) </li></ul><ul><ul><li>Sensors </li></ul></ul><ul><ul><ul><li>IR “ranger”; 2 receivers an...
Brain-less Bluetooth Robots? <ul><li>2 Windows XP SP2 dell laptops </li></ul><ul><li>2 Cellink Bluetooth 2.0 USB Dongles <...
Bluetooth Latency
Bluetooth Throughput
Scribbler Results <ul><li>Latency histogram </li></ul><ul><ul><li>(1 byte roundtrip) </li></ul></ul><ul><li>Limited by ser...
Locomotion <ul><li>Holonomic design  </li></ul><ul><ul><li>Arbitrary robot translation / rotation </li></ul></ul><ul><ul><...
Processor Options <ul><li>Philips 32bit ARM $7.58 </li></ul><ul><ul><li>60MHz 46 GPIO  </li></ul></ul><ul><ul><li>16 kB RA...
Wireless Options <ul><li>Custom protocol 400MHz  64 kbps  $5.04 </li></ul><ul><li>Zigbee 900MHz 250 kbps $7.14 </li></ul><...
Bluetooth Options <ul><li>Serial Port Module </li></ul><ul><ul><li>Expensive </li></ul></ul><ul><li>Chip </li></ul><ul><ul...
First Tier Sensors <ul><li>Lidar laser range finder / bar code reader </li></ul><ul><ul><li>One spinning mirror, laser and...
Second Tier Sensors <ul><li>Photoresistor, solar cell, phototransistor ambient light detector </li></ul><ul><li>Hall-effec...
Lidar Circuit <ul><li>-126 dB laser power return over 10m w/ 1” receiver lense </li></ul><ul><li>1mW laser -> 0.3 nA photo...
Lidar Spice Simulation <ul><li>Phase detector compares received signal with reference signal </li></ul><ul><ul><li>Robust ...
Motor Options – DC Gearhead <ul><li>DC Gearhead Pros </li></ul><ul><ul><li>Widely available </li></ul></ul><ul><ul><li>Sim...
Motor Options – Stepper Motor <ul><li>Stepper Motor Pros </li></ul><ul><ul><li>Naturally low speed, high torque – no gears...
Power Options – Alkaline, Tether <ul><li>Alkaline Pros </li></ul><ul><ul><li>Medium power density </li></ul></ul><ul><ul><...
Power Options – NiMH, NiCd, Lithium <ul><li>NiMH, NiCd Pros </li></ul><ul><ul><li>Cheapest rechargeable option </li></ul><...
Battery Options – Lead Acid <ul><li>Lead Acid Pros </li></ul><ul><ul><li>Highest power density </li></ul></ul><ul><ul><ul>...
Example Budget <ul><li>Processing:  $15.18 </li></ul><ul><li>Wireless:  $13.30 </li></ul><ul><li>3 Motors & motor drivers:...
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Tucker Balch's Hardware Slides - Institute for Personal Robots in ...

  1. 1. <ul><li>Institute for Personal Robots in Education </li></ul><ul><li>Kickoff Meeting, September 15, 2006 </li></ul><ul><li>Hardware </li></ul><ul><li>Professor Tucker Balch </li></ul><ul><li>Keith O’Hara </li></ul><ul><li>Dan Walker </li></ul><ul><li>Ben Axelrod </li></ul><ul><li>Hai Dai </li></ul><ul><li>Can Envarli </li></ul>
  2. 2. Off-the-shelf Candidates <ul><li>Lego Mindstorm NXT ($300) </li></ul><ul><li>Parallax Scribbler ($80) </li></ul><ul><li>Parallax Boebot ($150) </li></ul><ul><li>Parallax Crawlers ($400-600) </li></ul><ul><li>Palm Pilot Robot Kit ($300) </li></ul><ul><li>Lego Mindstorm ($200) </li></ul><ul><li>Handyboard ($300-400) </li></ul><ul><li>Handyboard Cricket ($59-$100) </li></ul><ul><li>iRobot Roomba ($200-350) </li></ul><ul><li>Khepera ($2000) </li></ul><ul><li>TERK </li></ul><ul><li>Humanoids </li></ul><ul><li>AIBO </li></ul>
  3. 3. Some Details <ul><li>Lego Mindstorms NXT ($300) </li></ul><ul><ul><li>32-bit ARM7; 64Kb RAM; bluetooth; USB </li></ul></ul><ul><ul><li>3 servos (built in rotation sensors) </li></ul></ul><ul><ul><li>Ultrasonic, Sound, light and touch sensors (digital wire interface) </li></ul></ul><ul><ul><li>Microsoft robotics studio </li></ul></ul><ul><li>Palm Pilot Robot Kit (Acroname $300) </li></ul><ul><ul><li>(IR rangers, omni-directional wheels) </li></ul></ul><ul><li>Body-less Handyboard Cricket ($59) </li></ul><ul><ul><li>Two sensors, Two Motors, IR communication </li></ul></ul><ul><ul><li>Programmed in Logo (4k external memory) </li></ul></ul><ul><ul><li>Expansion ports for mores sensors and motors </li></ul></ul>
  4. 4. iRobot Roomba <ul><li>Roomba ($150-250) </li></ul><ul><ul><li>2 bump sensors </li></ul></ul><ul><ul><li>Odometery </li></ul></ul><ul><ul><li>IR wall sensor on right side </li></ul></ul><ul><ul><li>Cliff/pickup sensors </li></ul></ul><ul><ul><li>Virtual wall infrared sensor </li></ul></ul><ul><ul><li>Remote control infrared sensor </li></ul></ul><ul><ul><li>Vacuum and motor control </li></ul></ul><ul><ul><li>Serial interface </li></ul></ul><ul><li>Roombadevtools Bluetooth Interface ($100) </li></ul>
  5. 5. Scribbler <ul><li>Scribbler ($80) </li></ul><ul><ul><li>Sensors </li></ul></ul><ul><ul><ul><li>IR “ranger”; 2 receivers and emitter </li></ul></ul></ul><ul><ul><ul><li>Stall sensor </li></ul></ul></ul><ul><ul><ul><li>3 light </li></ul></ul></ul><ul><ul><ul><li>2 “line” (IR pairs) </li></ul></ul></ul><ul><ul><li>2 DC motors </li></ul></ul><ul><ul><li>Programmed in PBasic </li></ul></ul><ul><ul><li>Serial communication (up to 38400 baud) </li></ul></ul><ul><ul><li>SD202 Bluetooth adapter ($100) </li></ul></ul><ul><ul><ul><li>Serial emulation </li></ul></ul></ul><ul><ul><ul><li>Class 1 </li></ul></ul></ul>
  6. 6. Brain-less Bluetooth Robots? <ul><li>2 Windows XP SP2 dell laptops </li></ul><ul><li>2 Cellink Bluetooth 2.0 USB Dongles </li></ul><ul><li>Measure latency of varying size forward packets and 1 byte reply </li></ul><ul><li>3 different conditions </li></ul><ul><ul><li>5 ft. separation </li></ul></ul><ul><ul><li>30 ft. separation </li></ul></ul><ul><ul><li>Background 802.11b flood ping </li></ul></ul><ul><li>10,000 samples </li></ul>
  7. 7. Bluetooth Latency
  8. 8. Bluetooth Throughput
  9. 9. Scribbler Results <ul><li>Latency histogram </li></ul><ul><ul><li>(1 byte roundtrip) </li></ul></ul><ul><li>Limited by serial baud-rate and basic stamp not bluetooth </li></ul><ul><li>Interference and retransmissions could have effect </li></ul>
  10. 10. Locomotion <ul><li>Holonomic design </li></ul><ul><ul><li>Arbitrary robot translation / rotation </li></ul></ul><ul><ul><li>No caster needed </li></ul></ul><ul><ul><li>Three wheel drive is complex </li></ul></ul><ul><ul><li>Wheels are difficult to make </li></ul></ul><ul><li>Differential drive </li></ul><ul><ul><li>Point turn </li></ul></ul>
  11. 11. Processor Options <ul><li>Philips 32bit ARM $7.58 </li></ul><ul><ul><li>60MHz 46 GPIO </li></ul></ul><ul><ul><li>16 kB RAM, 256 kB program memory (32x GNAT) </li></ul></ul><ul><li>Philips 32bit ARM $10.09 </li></ul><ul><ul><li>60MHz 81 GPIO </li></ul></ul><ul><ul><li>64 kB RAM, 1000 kB program memory (128x GNAT) </li></ul></ul><ul><ul><li>BGA package complicates routing </li></ul></ul><ul><li>Philips 32bit ARM $15.18 </li></ul><ul><ul><li>60MHz </li></ul></ul><ul><ul><li>512 kB RAM, 8000 kB program memory (1000x GNAT) </li></ul></ul><ul><ul><li>External memory (program flash, RAM) </li></ul></ul><ul><li>Sharp 32bit ARM $26.49 </li></ul><ul><ul><li>77MHz </li></ul></ul><ul><ul><li>8000 kB RAM, 8000 kB program memory (1000x GNAT) </li></ul></ul><ul><ul><li>External memory (program flash + SDRAM) </li></ul></ul><ul><ul><li>Includes Memory Management Unit (Fully linux capable) </li></ul></ul>
  12. 12. Wireless Options <ul><li>Custom protocol 400MHz 64 kbps $5.04 </li></ul><ul><li>Zigbee 900MHz 250 kbps $7.14 </li></ul><ul><li>Bluetooth module 2.4GHz 3Mbps $23.00 </li></ul><ul><li>Bluetooth chip 2.4GHz 3Mbps $5.52 </li></ul>
  13. 13. Bluetooth Options <ul><li>Serial Port Module </li></ul><ul><ul><li>Expensive </li></ul></ul><ul><li>Chip </li></ul><ul><ul><li>Cheaper </li></ul></ul><ul><ul><li>More flexible </li></ul></ul><ul><ul><ul><li>Not limited to serial port style </li></ul></ul></ul><ul><ul><ul><li>Use “headset” audio features </li></ul></ul></ul><ul><ul><li>CSR </li></ul></ul><ul><ul><ul><li>External flash memory allows custom programming </li></ul></ul></ul><ul><ul><ul><li>Onboard micro can run upper Bluetooth stack or our own applications </li></ul></ul></ul><ul><ul><ul><ul><li>Reduced datarate and total connections </li></ul></ul></ul></ul><ul><ul><ul><li>GaTech (Thad) already has purchased development kit </li></ul></ul></ul><ul><ul><ul><li>Interface: serial port profile (high level), RFCOMM, L2CAP (low level) </li></ul></ul></ul>
  14. 14. First Tier Sensors <ul><li>Lidar laser range finder / bar code reader </li></ul><ul><ul><li>One spinning mirror, laser and detector for both technologies </li></ul></ul><ul><li>640x480 color CMOS camera with lense (OV7649) </li></ul><ul><ul><li>Coprocessor for color segmentation, background subtraction </li></ul></ul><ul><ul><li>$18 </li></ul></ul><ul><li>Dual axis magnetometer (HMC1052) </li></ul><ul><ul><li>Non-line-of-sight bearing to magnetic beacon, compass </li></ul></ul><ul><ul><li>$5.50 </li></ul></ul><ul><li>Microphones for sound localization </li></ul><ul><ul><li>Are dual microphones worth cost & processing? </li></ul></ul><ul><li>Dual piezoelectric vibration detector </li></ul><ul><ul><li>$0.49 </li></ul></ul><ul><li>Temperature </li></ul>
  15. 15. Second Tier Sensors <ul><li>Photoresistor, solar cell, phototransistor ambient light detector </li></ul><ul><li>Hall-effect magnetic sensor </li></ul><ul><li>IR line detector, obstacle detector, Sharp rangers </li></ul><ul><li>IR reflective grid for localization </li></ul><ul><li>Bump switches </li></ul><ul><li>Accelerometer for motion detection, bump sense ($5.51) </li></ul><ul><li>Ultrasonic </li></ul><ul><li>Capacitive electric field sensing (touch, proximity) </li></ul><ul><li>Passive IR motion detector (burglar alarm) </li></ul><ul><li>Optical computer mouse sensor for odometry </li></ul><ul><li>Metal detector </li></ul><ul><li>Thermopile non-contact temperature sensing </li></ul>
  16. 16. Lidar Circuit <ul><li>-126 dB laser power return over 10m w/ 1” receiver lense </li></ul><ul><li>1mW laser -> 0.3 nA photocurrent </li></ul>
  17. 17. Lidar Spice Simulation <ul><li>Phase detector compares received signal with reference signal </li></ul><ul><ul><li>Robust to the presence of noise </li></ul></ul><ul><ul><li>Output is DC signal - sensor bandwidth determined by output filter </li></ul></ul><ul><ul><li>Output is logarithmically amplified to increase dynamic range </li></ul></ul>
  18. 18. Motor Options – DC Gearhead <ul><li>DC Gearhead Pros </li></ul><ul><ul><li>Widely available </li></ul></ul><ul><ul><li>Simple driver electronics </li></ul></ul><ul><ul><li>Medium efficiency </li></ul></ul><ul><ul><li>Brushes automatically adjust speed and current draw to match requested torque </li></ul></ul><ul><ul><li>Current draw is a good indicator of requested torque – “stall sensor” </li></ul></ul><ul><li>DC Gearhead Cons </li></ul><ul><ul><li>The gears are more expensive than the motor </li></ul></ul><ul><ul><li>Poor reliability in our price range – plastic parts, brushes, bad bearings, etc </li></ul></ul><ul><ul><li>No encoder and expensive to add encoder </li></ul></ul><ul><ul><li>Brushes cause high electromagnetic noise levels which interfere with other electronics, especially sensors </li></ul></ul><ul><ul><li>Acoustically noisy </li></ul></ul>
  19. 19. Motor Options – Stepper Motor <ul><li>Stepper Motor Pros </li></ul><ul><ul><li>Naturally low speed, high torque – no gears necessary </li></ul></ul><ul><ul><li>Controllable in precise rotational increments – no encoder necessary </li></ul></ul><ul><ul><li>High reliability – metal construction, ball bearings, no brushes to wear out </li></ul></ul><ul><ul><li>Motor bearing can be wheel bearing </li></ul></ul><ul><ul><li>No brushes means low electromagnetic noise </li></ul></ul><ul><ul><li>Higher power (RPM or torque) than DC gearhead </li></ul></ul><ul><li>Stepper Motor Cons </li></ul><ul><ul><li>Low efficiency </li></ul></ul><ul><ul><li>Heavy </li></ul></ul><ul><ul><li>More complex electronics </li></ul></ul><ul><ul><li>Electrically commutated – software must do the job of brushes in the DC gearhead </li></ul></ul><ul><ul><ul><li>Motor cannot deliver high torque at high RPM so software must slow motor if high torque is required </li></ul></ul></ul><ul><ul><ul><li>Hard to predict torque </li></ul></ul></ul>
  20. 20. Power Options – Alkaline, Tether <ul><li>Alkaline Pros </li></ul><ul><ul><li>Medium power density </li></ul></ul><ul><ul><li>Medium energy density </li></ul></ul><ul><ul><li>Student purchasable </li></ul></ul><ul><ul><li>Not including rechargable batteries reduces price of robot for us </li></ul></ul><ul><li>Alkaline Cons </li></ul><ul><ul><li>Not rechargable </li></ul></ul><ul><ul><ul><li>~ 10K batteries landfilled per year </li></ul></ul></ul><ul><ul><li>Only available in common form factors (AA, AAA, etc) </li></ul></ul><ul><li>Tethered Pros </li></ul><ul><ul><li>Medium power density </li></ul></ul><ul><ul><li>Infinite energy density </li></ul></ul><ul><ul><li>Cheapest solution </li></ul></ul><ul><ul><li>Most reliable communications </li></ul></ul><ul><li>Tethered Cons </li></ul><ul><ul><li>Tether interferes with robot operation </li></ul></ul><ul><ul><li>Tether annoyance increases with number of robots deployed </li></ul></ul>
  21. 21. Power Options – NiMH, NiCd, Lithium <ul><li>NiMH, NiCd Pros </li></ul><ul><ul><li>Cheapest rechargeable option </li></ul></ul><ul><li>NiMH, NiCd Cons </li></ul><ul><ul><li>Low power density </li></ul></ul><ul><ul><li>Low energy density </li></ul></ul><ul><li>Lithium Pros </li></ul><ul><ul><li>High energy density </li></ul></ul><ul><ul><li>Least weight </li></ul></ul><ul><li>Lithium Cons </li></ul><ul><ul><li>Expensive </li></ul></ul><ul><ul><li>Low power density </li></ul></ul><ul><ul><li>Complicated charging </li></ul></ul>
  22. 22. Battery Options – Lead Acid <ul><li>Lead Acid Pros </li></ul><ul><ul><li>Highest power density </li></ul></ul><ul><ul><ul><li>Low internal resistance means less motor generated electromagnetic interference </li></ul></ul></ul><ul><ul><li>High energy density </li></ul></ul><ul><li>Lead Acid Cons </li></ul><ul><ul><li>Heavy </li></ul></ul><ul><ul><li>Must not be allowed to completely discharge or battery capacity will suffer </li></ul></ul><ul><ul><ul><li>Will retain charge for 2 years </li></ul></ul></ul>
  23. 23. Example Budget <ul><li>Processing: $15.18 </li></ul><ul><li>Wireless: $13.30 </li></ul><ul><li>3 Motors & motor drivers: $33.35 </li></ul><ul><li>Lidar: $20.68 </li></ul><ul><li>Camera: $9.43 </li></ul><ul><li>Additional sensors: $8.94 </li></ul><ul><li>Battery: $14.01 </li></ul><ul><li>Manufacturing: $20.00 </li></ul><ul><li>Total: $134.89 </li></ul>

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