Life in the Atacama, Design Review, December 19, 2003 Carnegie Mellon Rover Chassis Life in the...
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Transcript of Life in the Atacama, Design Review, December 19, 2003 Carnegie Mellon Rover Chassis Life in the...
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Rover Chassis
Life in the Atacama Design ReviewDecember 19, 2003
Stu Heys, Dimi Apostolopoulos
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Description and MotivationA new rover chassis for mobility and science is to replace Hyperion in the upcoming campaigns
That is motivated by the need to•Accommodate various science instruments•Improve mobility especially in inclined terrain•Optimize propulsion subsystem
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Key Requirements & Design Drivers• Provide unobstructed FOV and necessary actuated motions for science payloads
• Modify wheel design to improve terrainability• Increase wheel torque to improve slope climbing• Increase rover speed to decrease traverse times• Eliminate drivetrain hysteresis to improve control
• Minimize mechanical complexity. Maintain as much of Hyperion’s design as possible
• Design for 150 kg GVW
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Building on Hyperion’s CompetenciesHyperion New Rover4 driven wheels, brushless DC Same
Chain drive 5+ cm hysteresis in drive system
Coaxial drive zero hysteresis, fewer parts
1 degree of steer motion 3.5m turn radius
2 symmetrical degrees 2.5m turn radius
1 degree of roll freedom inconsistent performance over rough terrain chassis receives direct shocks from bumps
2 degrees of roll with averaged chassis chassis somewhat isolated from shocks each wheel performs identically in rough terrain
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
New Rover Configuration
Steer and roll articulation at front and rear
Pan and tilt unit base atop forward leaning mast
~2.3m2 solar array
Fluorescence imager location .85m range of motion
~.32m3 electronics enclosure roughly equal in volume to Hyperion
Drivetrain completely enclosed by axle structure
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Steering & Articulation
Chassis averages as front tire climbs 30cm obstacle
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Evaluation of Steering Geometries
Metrics -2 to 2 (0 for Hyperion) weightingexplicit front
double passive coupled notes
# actuators 2 -1 -2 0 0mech complexity fab 3 -2 -6 -1 -3
assbymaint
turning radius 1 1 1 2 2 schematicnav cam location 2 -1 -2 0 0req s/w mod nav stereo 3 -1 -3 0 0
controller 3 -1 -3 -1 -3stability 3 1 3 -1 -3 20 degree, 15 cm obstexpected mass 2 -1 -2 -1 -2 analysisexpected power 2 0 0 1 2payload accomodation ease of solar panel 2 0 0 0 0
e box 1 1 1 0 0science intergration 2 1 2 -1 -2 schematic
ease of dead rec 3 -1 -3 1 3agility 1 0 0 1 1failure modes 2 -2 -4 -1 -2heritage 1 -2 -2 -1 -1
weighted weightedtotal -8 -20 -2 -8
LITA 04 Configuration matrix - 10/16/03
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Linear table spans frame members, supports fluorescence imager
Sensor & Solar Panel ConfigurationSub panels slide out of frames with integrated electrical connections
Panels fold up for easy access to e-box and science instruments Science instruments
isolated from vehicle controls
Electronics box nestled between frame members
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Technical Approach•Prototype chassis roll mechanism•Tune-up controller to optimize mobility•Utilize test results to finalize detailed design of axles and pivots•Define volumetric and instrument functional requirements•Finalize sensor placement configuration•Detail design chassis for optimal accommodation of the solar panels,
electronics and science instruments•Design mechanism for fluorescence imager and pan/tilt unit•Integrate prototype instrument deployment mechanism on Hyperion
FEA results for axle
Carnegie MellonLife in the Atacama, Design Review, December 19, 2003
Design & Implementation IssuesComplex Integration•Science payloads (esp. fluorescence imager)
•2+ degree of freedom•Mast (in-house pan & tilt design)
•Design for 4+ cameras•Solar panels
•Optimized for cell size while avoiding wheel interferences
•Plow•Tricky deployment issues