a single-wheel test rig for ocean world rover
TRANSCRIPT
Other Test Rigs
Existing Single Wheel Test Rigs
A Single-Wheel Test Rig for Ocean World RoverYe Lu1*, Madhura Rajapakshe2, Rachana Agrawal1*, Athul Pradeepkumar1*, and Sarag J. Saikia1†
1School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN 47907, USA2Ravenna Lab, Smithers Rapra Inc., Ravenna, OH 44266, USA
*Graduate Student, †Research Assistant Professor
JPL Variable Terrain
Tilt Platform
4.88m x 4.88 m Platform
Up to 25-deg tilt
CMU Inflatable Robotic Rover Testbed
Year: 2003
Size: 1 m in width
Wheel Diameter: ~1.4 m
Track Length: ~8 m
Projects: JPL Inflatable
Rover
ESA RCET Single Wheel
Terramechanics measurement
system
JPL Rover Single Wheel
Test TrackCMU Single Wheel Soil Imaging Testbed
Year: 2012
Wheel Diameter: 23cm and 41cm (tested)
Unique: Shear Interface Imaging Analysis
MIT Robotic Mobility Group
Year: 2013
Size (L×W×H): 2.7×1×1 m
Wheel Diameter: 0.5 m
Horizontal Speed: 10 cm/s
Related: MSL, MIT Artemis
terramechanics model
Test bed at Tohoku university, Japan
Year: 2013
Size (L×W×H): 1×0.8×0.6 m
Wheel Diameter: 0.18 m
Vertical Load: 65 N
Soil Depth: 0.12 m
Horizontal Speed: 3 cm/s
Slip Angle: 5–30 deg
Italy AMALIA Rover Wheel Testing
Year: 2016
Dimension (L×W×H): 2.7×1×1 m
Max Wheel Diameter: 0.6 m
Max Vertical Load: 800 N
Soil Depth: 0.2 m
Body Surface Gravity Load for 200 kg
Earth 1 g 1960 N
Mars 0.378 g 742 N
Europa/Titan 0.134 g 263 N
Enceladus 0.011 g 22 N
Ganymede 0.146 g 286 N
Current DesignAdditional features
Dynamic Slip/Camber
Low Gravity
Surface Feature
Durability
Full Vehicle dynamic
Testin
g C
ap
ab
ilities
Presented at NASA Outer Planet Assessment Group Meeting, February 21-23, 2018, Hampton, VA
JPL Mars Yard
Suncups
Penitentes
Single Wheel
Static Testing
Dynamic Testing
Drawbar-Pull
Wheel Sinkage
Wheel Slippage
Unidirectional
Rover System Testing Facilities
Glenn Tire Life Test
CMU Single Wheel Testbed
Challenge 1: Low gravity
Shinshu University, Japan
Single Wheel Test Bed
Challenge 2:Surface Simulant
The exact surface conditions on Ocean
Worlds are yet to be determined due to the
lack of high-resolution images and lack of in-
situ measurement. Some studies have
investigated Earth analogs, and the surface
may present unique features. The test rig
should accommodate a variety of features
including
• Sharp edges (tire puncture resistance)
• Rugged terrains
• Rigid surfaces cover in fine-grained
particles
Hardware Selection and
Quote
Test Rig Design
Test Rig Assembly
and Fabrication
Test Rig Testing
and Validation
Testing Method Development
Tire Testing and
Evaluation
2018 Q1 2018 Q2 2018 Q3 2018 Q4 2019 Q1 2019 Q2 2019 Q3
Project Timeline
This work is being supported by the NASA COLDTech program.
The author thanks the OPAG organizing committee for travel support!
Acknowledgements
Image Credits: ESA, NASA, JPL, GRC, CMU
[1] Dimitrios Apostolopoulos, Michael D. Wagner, Stuart Heys, and James Teza, “Results of the Inflatble Robotic Rover
Testbed”, CMU-RI-TR-03-18, 2003 [2] Gregory D. Puszko, “Terramechanical Analysis of Rover Wheel Mobility over
Simulated Martian Terrain at Various Slip Conditions and Vertical Loads”, MIT, 2013 [3] Karl Iagnemma, “A Laboratory
Single Wheel Testbed for Studying Planetary Rover Wheel-terrain Interaction” MIT Technical Report 01-05-05, 2005 [4]
Flippo, University of Oklahoma [5] Giancarlo Genta and Cristiano Pizzamiglio, “Testing of planetary rover wheels:
Design and setup of a testing machine”, 2016 IEEE Metrology for Aerospace, 2016 [6] Ishigami et al. “Terramechanics-
based model for steering maneuver of planetary exploration rovers on loose soil”, Journal of Field Robotics, No. 24,
Issues, 3 2007 [7] Lizuka and Kubota, “Study on Effect of Grousers Mounted Flexible Wheel for Mobile Rovers”,
Journal of Asian Electric Vehicles, No. 10, 2012
References
Camber Angle
Surface
Slip Angle
Direction
of Travel
Challenge 3: Dynamic Slip/Camber Testing
Slip and camber angles affect the vehicle dynamics. Understanding
the behavior of the tires under various slip angle and camber angle
conditions will improve the model of the rover dynamics.
The current phase of the project focuses on the design and fabrication of the single wheel test rig. The proposed
single wheel test rig fills the gap in rover wheel testing for ocean worlds. The design assimilates the features
available in the existing test rigs for planetary rovers, and take into account the additional requirements for testing
rover wheels in conditions present on ocean worlds. The test rig will be versatile to allow simulating various terrain
and surface conditions and low gravity.
Overview
Simulating low gravity condition on Ocean Worlds complicates the
design of the test rig. The weight of only one sensor (5 kg) exerts a
load of 50 N on the wheel which is higher than 22 N. Including the
test rig structure and other hardware; the extra load needs to be
compensated by a constant force actuator.
The current test rig builds upon the features found on previous test
rigs and will also address the following challenges.