Magellan Preliminary Design Review Charlie Reverte Zachary Omohundro

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

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

Concept Image

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 Mechanical

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

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 Sensing

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

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

Specifications 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

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

Major Subsystems • • • 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 • • • 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

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

Major Subsystems Inflatable Wheels • 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

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

Major Subsystems Docking Mechanism

Major Subsystems Docking Mechanism

Major Subsystems Docking Mechanism

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

Specifications 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

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

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

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

Operations Performance Goals • > 1 k. Wh 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 • < $20 K • < 2 Person field team

Operations • • • Deployment Drill Borehole Deploy Ferret to examine 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 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

Failure Scenarios Operations Failure Wheel puncture/Loss of Mode drive actuator Failure Mode Consequence Effect Response Loss of mobility in that direction Deflate axle, use body as a reaction/steering tail Slow pressure loss Robot becoming unsafe, or wheel is deflating Open reservoir to maintain pressure level Rapid loss of main pressure Robot unsafe Full systems shutdown Computer Lockup Robot shuts down Reboot w/ watchdog Navigation Sensor Failure Robot effectively blind Attempt immediate return to base with sonar and internal map Proximity Sensor Failure Robot likely to hit obstacles Attempt immediate return to base with navigation sensor and internal map Loss of steering actuator Reduced mobility Only actuate remaining functional steering piston Violation of room and pillar assumption Wall centering is no longer valid Follow a single wall to continue mapping