mobile payload element (mpe)
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Kayser-Threde GmbHKayser-Threde GmbH Mobile Payload Element (MPE)Concept Study of a small autonomous, and innovative Sample Fetching RoverR. Haarmann1, Q. Mühlbauer1, L. Richter1, S. Klinkner2, C. Lee2, C. Wagner2,R. Jaumann3, A. Koncz3, H. Michaelis3, J. Schwendner4, H. Hirschmüller5, A. Wedler5
(1) Kayser-Threde GmbH, Wolfratshauser Strasse 48, 81379 Munich, Germany,E-Mail: richard.haarmann@kayser-threde.com, Telefon: +49 89 724 95-347, Fax: +49 89 724 95-291(2) von Hoerner & Sulger GmbH, (3) DLR Institute of Planetary Research, (4) German Research Center for Artificial Intelligence DFKI, (5) DLR Institute of Robotics and Mechatronics
Space
Industrial Applications
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Introduction
Image courtesy to ESA
Mobile Payload Element (MPE) Small, autonomous, innovative vehicle of roughly ~15 kg Operating in the challenging environment of the
lunar south pole acquires samples of lunar soil ~100m around its lander brings them back to the spacecraft for further analysis
German national contribution to the ESA Lunar Lander Mission cancelled in fall 2012
Alternative: contribution to a Moon Exploration Program under Cooperation of ESA & ROSKOSMOS (under discussion)
Phase 0/A: April 2011 – March 2012concluded with successful PRR
Ongoing Activites Delta Phase A: October 2012 – October 2013 Locomotion Subsystem Avionics Close-up Imager Sample Transfer Mechanism Autonomy Payload Experiment & Illumination Prediction Image courtesy to Roskosmos
Reference Scenario & Model Payload
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Reference Scenario Realistic background for
subsystem trade-offs Environmental conditions Operation Communication Power,…
MPE Model Payload and Sampling Acquisition of regolith samples illuminated and locally shaded terrain surface, subsurface underneath large boulders
Documentation of the samples In-situ characterization of the sample
material A Camera Payload: Stereo camera with LED-illumination
A Scientific Payload: Mole sampler Close-Up Imager Philae ROLIS Close-Up Imager
MOLE Sampling Device
Stereo Camera
4
MPE OverviewActive Chassis adaption of each wheel to the surface alignment of solar generators
and instrumentsPower Supply System Solar generators: 25W Secondary battery: 160Wh
Active Thermal Control System Operation in shaded regions: >2h Survivable darkness periods: >13h
Communication UHF-band (up/down): 9.6 kbit/s S-band (down): 512 kbit/s
Onboard Computer LEON3FT GR712RC
Sensor Package Stereo Camera LED flash lighting 2 axes inclinometer Wheel and body encoders
Operational Modes Tele-operated mode Autonomous mode
Mass Budget SummaryMPE Concept Phase A
Total Massincl. Margin [kg]
MPE (Rover + Payloads) 15,777
Rover (w/o Payload) 13,525
Camera Payload 0,305
Scientific Payload 1,948
MPE Overview
5
900m
m
990mm
823m
m
740m
m
700mm660mm
541mm
493mm
493mm
303mmMole Sampler
Close-upImager
Compatibility to the Russian Moon Exploration Programm
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Current Situation ESA Lunar Lander Mission Stopped in fall 2012
Lunar Resource/Chandrayaan-2 Terminated in January 2013
ESA and Roscosmos currently discuss acorporate lunar exploration program
A future program will probably comprisea rover mission, similar to Lunar Landeror Lunar Resource
Both missions were very similar: Operation on lunar south pole area in highly illuminated areas Collection of soil samples Rover weight: ~10kg - ~15 kg Mission duration: 6-9 months - 12 monthsConclusion: MPE it is highly suitable for an upcoming ESA/Russian Mission If usage of RTG‘s and RHU‘s are possible (like Lunar Resource) Survival capabilities of darkness periods could be increased Image courtesy
to Roskosmos
Image courtesy to Roskosmos
Actuator Design
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ILM 38 Motor Units Actuator design is based on permanent magnet
synchronous motors, developed at DLR RMC Combined with low backlash Harmonic Drive gears Derived from ROCKVISS actuation unit Same technology was further developed for
DexHand and MASCOT
Advantages of those ILM actuators Well suited for high dynamic tasks High efficiency High torque capacity Low number of mechanical components
Trade-Offs led to Incorporation of PTFE sealing combined with
labyrinth Potentiometer as absolute position sensor
(position controlled actuators only)
Combined with low backlash Harmonic Drive gears
Same technology was further developed for
Wheel Design
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Requirements Provide ground interaction Withstand static & dynamic loads Withstand temperature cyclesParameters MPE nominal velocity: 5.4 mm/s (tele-ops.) Terrain: lunar Regolith with varying degree of
compactness Minimum diameter: 250mm accommodation of driving and steering actuator within the wheel
Approach Several concepts were established and
evaluated 3 wheel-options were designed and traded Wheel properties and strength were
determinedWheel Design Diameter: 250mm Width: 60mm
can be reduced down to 40mm 25 Grousers
Mass:Al-Version: 267gTi-Version: 160g
Integrated Avionic Design
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Design Drivers Minimal volume and mass. Efficient use of solar & battery power minimal energy wastage on unused functions.
Prevention of fault propagation in-built fault tolerance whenever possible
Extreme non-operational cold environmentSystem Layout Power subsystem Rover subsystem
Communications Onboard computer
Actuator subsytem Payload Subsystem
Payload power control Interfaces
Backplane Ground bar Starpoint
Autonomy Payload Experiment
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Optional payload on MPE Additional pan/tilt unit (see A. Wedler, ASTRA 2013, Paper# 2811409 )
Additional FPGA(Virtex 4QV (XQR4VFX60) or Virtex 5)
Flash module with the bitstream toprogram the FPGA
RAM module with storage size of 128 MB Power and communication driver electronic
Can be completely switched on/off Enhances the MPEs autonomy functions Advanced dense stereo matching methods can be
implemented (e.g. SGM) Allows stereo rectification Further image compression allows 1.5 Hz image
stream down to Earth Allows full autonomous driving Increases accuracy & robustness Increases the MPE speed
Illumination Prediction
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Challenging Illumination Conditions Max. Sun inclination:
3° over the horizon Complex and dynamic illumination
situation at ground level Illumination condition is highly
dependent on the local shape of the terrain
ConceptCombination of DEM and horizon models DEM centered at the lander location Generated by LRO Data before landing Generated by lander after landing Updated by stereo images of MPE
DEM has size of MPE operational area Horizon rings provide max. terrain elevation for
angular subsection Angular resolution independent from distance Multiple rings to compensate for parallax errors
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Sample TransferEndeffector on lander‘s robotic arm Completely passive device, actuated via arm force
Opening by pressing it on ground Closing via springs
Protects sample from direct solar illumination Ability to take surface samples Ability to receive samples from mole Ability to transfer mole/surface samples to
instrument ports Protection against clogged material / cross
contamination (via Piezo) Further concepts will be assessedand detailed
Completely passive device, actuated via arm force
Mole
Close-up Imager
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Rear CameraClose-UpImager
Mirror Narrow Angle Optics
Detector
Contradictory requirements lead to a two-lens/two detector design approach
Narrow-angle multispectral Close-up Imager (CUI) Sample characterization Focusing towards the mole LED Illumination FoV: 17,85° Focal length: ~45mm High resolution: 33μm/pixel
(1920x1080 CMOS)Wide-angle Rear Camera Tele-operated backward driving Wide-Angel rear view FoV: 89° Low resolution: ~512x 512 pixel
(to keep data rate low)
Total CUI mass: 0.73kg (incl. margin)Power: 5W (multispectral imaging)
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Summary & Outlook
MPE is the first sample fetching rover worldwide in the 15kg-class: dedicated mobile sampling device
Provides access to uncontaminated scientific interesting objects in an area ~100m around the Lunar Lander Controlled sample volume Regolith samples from surface and subsurface Regolith samples from illuminated and locally
shadowed terrain as well as from below boulders and blocks
MPE is versatile and can be incorporated in several missions
Innovative rover for technology demonstration as well as for the A&R community
MPE has a high public outreach potential
The Mars Pathfinder microrover Sojourner observed by its lander
Image courtesy to NASA
The Mobile Payload Element observed by its lander
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MPE Summary & Outlook
The MPE study had a successful PRR Review and Final Presentation at DLR Space Management in March 2012
The current MPE Delta Phase A started in October 2012 with focus on critical technologies and breadboard preparation
The MPE Team envisages to continue with a breadboard and testing phase, beginning in late 2013
The Mobile Payload Element is an excellent opportunity for the demonstration of European competences in space robotics
Thank You
Richard HaarmannRichard.Haarmann@Kayser-Threde.com
Aknowledgements:The MPE study was funded under DLR contracts 50JR1006 and 50JR1212
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