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.