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

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Presentation on theme: "Magellan Preliminary Design Review Charlie Reverte Zachary Omohundro Chris Baker Chin Keong Ling Aaron Morris 12/11/2002."— Presentation transcript:

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

2 Operational 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 Requirements

3 Concept Image

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

5 Electrical 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. Specifications

6 Sensing 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 Specifications

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

8 High Level Software 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 Specifications

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 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 Specifications

11 Chassis Layout 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 Major Subsystems DrivePump Battery Pack Air and Elec. Lines TankDrive Battery Pack

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

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

14 Chassis Pressure System 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 Major Subsystems Pump TANK

15 Inflatable Wheels Sphere and torus shaped internal pressure volume Enclosed in wheel sleeve –Stability/traction –Abrasion resistance Central pump drives independent wheel circuits Major Subsystems 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 Passive hook and catch mechanism –disengages when robot is level –engaged by driving catch into hook Major Subsystems

17 Docking Mechanism Major Subsystems

18 Docking Mechanism Major Subsystems

19 Docking Mechanism Major Subsystems

20 Base Station 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 Major Subsystems

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

22 Status and Control Electronics 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 Specifications

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

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

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

26 Performance Goals > 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 Operations

27 Deployment 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 Operations

28 Recovery 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 Operations

29 Failure Scenarios Operations Failure Mode Effect Failure ModeConsequenceResponse Wheel puncture/Loss of drive actuator Loss of mobility in that direction Deflate axle, use body as a reaction/steering tail Slow pressure lossRobot becoming unsafe, or wheel is deflating Open reservoir to maintain pressure level Rapid loss of main pressureRobot unsafeFull systems shutdown Computer LockupRobot shuts downReboot w/ watchdog Navigation Sensor FailureRobot effectively blindAttempt immediate return to base with sonar and internal map Proximity Sensor FailureRobot likely to hit obstaclesAttempt immediate return to base with navigation sensor and internal map Loss of steering actuatorReduced mobilityOnly actuate remaining functional steering piston Violation of room and pillar assumption Wall centering is no longer valid Follow a single wall to continue mapping


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