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Magellan Preliminary Design Review
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  1. MagellanPreliminary Design Review Charlie Reverte Zachary Omohundro Chris Baker Chin Keong Ling Aaron Morris 12/11/2002

  2. Operational Requirements • Deployment and recovery through a 10” borehole • Un-tethered • Semi-autonomous • Rugged and waterproof • Drive on land and water • Traverse obstacles up to 8” • Carry mapping payload • Reasonable range • Purged and Pressurized • Expendable

  3. Concept Image

  4. Mechanical Specifications • 2 segment 4 wheeled rover • Solid drive axles • Steering via actuated center link • Inflatable wheels • Single purged and pressurized volume • Deployable sensor payload • Docking mechanism • Compact deployment configuration

  5. Electrical Specifications • Source: 24 volt Li-ion batteries • Target 1 KWh capacity • Locomotion and Actuation Motors (24VDC) • Front Drive • Rear Drive • Pneumatic Pump • Sensing • 24VDC Laser Scanner • Computing • PC/104+ form factor • Wireless Ethernet • Hard disk drive • Includes +5 conversion/regulation for secondary sensors.

  6. Sensing Specifications • Primary mapping payload • Laser rangefinder • Purged and pressurized • Linear potentiometer to sense laser orientation • Analog magnetic compass • Navigation sensors • Drive motor encoder counters • Intrinsically safe steering potentiometer • 3 axis accelerometers • Tilt sensor • Obstacle avoidance • Motor current sensors • Ultrasonic sensors • 3 front, 3 rear, 1 overhead • Primary mapping sensor tilt scan • Internal state sensors • Battery status • Chassis pressure monitor • Wheel pressure monitor • Thermal sensors on motors, pump and cylinders

  7. External Sensor Layout Major Subsystems • Rear 3 sonar configuration is identical

  8. High Level Software Specifications • Autonomy • Preprocessed topological graph of map from Voronoi • Node waypoint selection from graph search algorithm • Cost = D(edge) * batt/D + “interesting” + D(Origin) • Waypoint following once oriented • Track D(traveled) and battery consumption • Correct edge costs, use A* or D* to plot course to origin • Unexpected Voids – Enter Exploration Mode • Take Unknown Crosscuts until… • Exploration_Interest(Battery) < Battery Consumed • Dead End • Return To LPC, Relay, Await

  9. Navigation Specifications • Navigation • Node to Node Transition • Feature Identification: Corridor and Crosscut • Partial Carmen Construction for Reverse • Wall Centering and Obstacle Avoidance • Morphin algorithm

  10. On-board / Off-board Software Specifications • On-board • Voronoi Map and Feature ID (Bayes Classifier) • Logging: All Sensor Data – Time Stamped • Morphin • A* or D* path changes (shortest path home) • Carmen Map for reverse • Off-board • Preprocessing • Carmen Map Software • Sensor Realization for Teleoperation GUI

  11. Chassis Layout Major Subsystems Battery Pack • Front Segment • 2 Identical battery packs • Drive motor and pneumatic pump • PC/104 Stack • Sensor payload mounting • Rear Segment • 2 Identical Battery packs • Drive motor and pneumatic reservoir • Docking Mechanism Pump Drive Battery Pack Air and Elec. Lines Battery Pack Drive Tank Battery Pack

  12. Drive Layout Major Subsystems • Identical drives in both segments • Single drive shaft • O-Ring pressure seal • Bevel gear transmission • High gear ratio DC brushed motor

  13. Steering Mechanism Major Subsystems • Single central steering joint • Dual pneumatic cylinder actuation • Wire/Pneumatic tubing pass-throughs • ~ +/- 30o turn angle • Intrinsically-safe potentiometer for steering angle measurement

  14. Chassis Pressure System Major Subsystems • 1 Pump, 1 High pressure reservoir • 1 Valve per wheel • Solenoid valves to control pneumatic cylinders • 1 External valve/connector for initial pressurization & venting • High pressure venting prevents mine air intake • Redundant pressure monitoring with certified pressure monitoring system • Both segments and the mapping sensor (one pressure volume) purged and pressurized prior to deployment • Wheels, cylinders, never directly connected to internal pressure volume TANK Pump

  15. Inflatable Wheels Major Subsystems • Sphere and torus shaped internal pressure volume • Enclosed in wheel sleeve • Stability/traction • Abrasion resistance • Central pump drives independent wheel circuits • Wheels inflated in mine • Air supplied by base station via detachable snorkel • Wheels are vacuum deflated for recovery • Extra air is vented to mine

  16. Docking Mechanism Major Subsystems • Passive hook and catch mechanism • disengages when robot is level • engaged by driving catch into hook

  17. Docking Mechanism Major Subsystems

  18. Docking Mechanism Major Subsystems

  19. Docking Mechanism Major Subsystems

  20. Base Station Major Subsystems • Purged and pressurized • For deployment in gas filled mines • Video • Low light panospheric camera • Downward facing camera • Assists docking maneuvers • Light • LED rings around camera lenses • Tether to surface • Winch cable (pass through to robot) • Ethernet (fiber) • 2 video cables • Snorkel (pass through to robot) • Base station power • Borehole anchoring mechanism • Can anchor on sides of borehole like Ferret for stability during docking • Compass • Gives orientation of base station to assist docking • Wireless Ethernet • Detachable Snorkel

  21. Front Drive Rear Drive Power Configuration Major Subsystems Rear Segment Front Segment +5 Regulated Additional Sensors CPU Batt 3 Batt 1 Laser Batt 2 Batt 4 Air Pump

  22. Status and Control Electronics Specifications • Battery health monitor • One in each segment • Locomotion and actuation control • Front/Rear drive • RS-485 motor controller • Steering • Direct CPU control • Plain motor amplifier • Pneumatic pump • Pneumatic manifold control • Relay amplifier

  23. Front Drv Controller PID Amp Status and Control Electronics Major Subsystems Rear Segment Front Segment Steering Control Pneumatic Control CPU Pot Pump Digital Out Valves Valves Rear Battery Monitor Voltage A/D Current Rear Drv Controller Front Battery Monitor Voltage PID A/D RS-485 RS-485 Current Amp

  24. Sensor Layout Major Subsystems Front Segment Rear Segment Rear-Left Wheel Pressure Front-Left Wheel Pressure CPU A/D A/D Serial Inertial Sensing 3 + 1 Ultrasonic Sensors I/O Card RS-485 3 Ultrasonic Sensors RS-485 A/D 3-axis accel A/D Steering Angle Pot Laser Angle Pot Battery Voltage & Current A/D Drive Encoder DIO Laser RS-422 Gravimetric Sensing Battery Voltage & Current Drive Encoder DIO Electromagnetic Sensing A/D 2-axis tilt A/D Rear Segment Pressure Front Segment Pressure Analog Compass RS-485 RS-485 A/D Current & Thermal Sensing A/D Rear-Right Wheel Pressure Front-Right Wheel Pressure Current & Thermal Sensing A/D A/D

  25. Primary Sensor Deployment Major Subsystems • Primary mapping sensor deployed pneumatically • Dual redundant pneumatic actuators • Deployment device also serves as tilt module

  26. Performance Goals Operations • > 1 kWh battery life • Li-ion 142 Wh/kg, 357 Wh/L  7 kg, 2.8 L • < 70 lbs final mass • > 1 mph top speed • < 200 W average power consumption • 2.5 mile maximum straight line travel • 2 mile maximum safe straight line travel • .5 mile radius maximum circular traverse • > 50 deployments MTBF • < $20K • < 2 Person field team

  27. Deployment Operations • Drill Borehole • Deploy Ferret to examine mine conditions • Power on computer and systems • Purge and pressurize cylinders and laser • Lower robot and base station • Inflate front wheels when front segment clears ceiling • Deploy primary mapping sensor • Lower front wheels onto floor and drive forward • Inflate rear wheels • Disengage docking mechanism and detach snorkel • Begin mine exploration

  28. Recovery Operations • Teleoperate robot to engage docking mechanism • Raise base station and robot • Deflate wheels in mid air • Stow primary mapping sensor • Raise robot • Retrieve data for post processing • Inspect robot and recharge air and power

  29. Failure Scenarios Operations