McCloskey PhD thesis
Development of legged, wheeled, and hybrid rover mobility models to facilitate planetary surface exploration mission analysis

title={Development of legged, wheeled, and hybrid rover mobility models to facilitate planetary surface exploration mission analysis},
author={McCloskey, Scott Haddon},
school={Massachusetts Institute of Technology}

Covers attempts to simulate the entire mission profile.

Notes disadvantages with existing rocker-bogie systems (which ExoMars isn’t? using) in slopes and soft sand (p46, and graphs)

Wheels sink into soil, leading to high soil resistance, but well understood and simple to control.

Legs don’t sink, can step over stuff, can shift support base to retain stability over inclined terrain. Really complex to control, and will require more computational capability, probably. Also, energy is lost in moving the rover mass up and down.

Both is useful - combines the advantages of both: wheels are more efficient on the flat and smooth. But he says hybrids have to carry both systems (p51), but that’s not true with ExoMars.

Talks a lot about MoRETA


Besseron on HyLoS
G. Besseron, C. Grand, F. Ben Amar, F. Plumet, P. Bidaud, Stability of an Hybrid Wheeled-Legged Robot, 8th International Conference on Climbing and
Walking Robots (CLAWAR 2005), 2005.

Attempt to formulate a potential field system for keeping a robot stable. Interesting (and quite mathematical) but not directly relevant.

A. Coso, C. Tortora, eds., Modular Rover for Extreme Terrain Access Design
, 16.83x Space Systems Product Development, MIT, 2007

Describes the MoRETA rover in more detail, but the McCloskey thesis contains enough.

Townsend and Biesiadecki, Sliding Gait Algorithm for the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE)

Describes a “sliding gait” for ATHLETE, it seems to be using two wheels as anchors while “inching” the remaining wheels over the surface - rolling them while moving the legs.

title={Sliding Gait Algorithm for the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE)},
author={Townsend, Julie and Biesiadecki, Jeffrey},
booktitle={ASME 2012 5th Annual Dynamic Systems and Control Conference joint with the JSME 2012 11th Motion and Vibration Conference},
organization={American Society of Mechanical Engineers}

Inching Locomotion for Planetary Rover Mobility
Scott Moreland, Krzysztof Skonieczny, David Wettergreen

This one even has a little diagram of how inching works!

title={Inching locomotion for planetary rover mobility},
author={Moreland, Scott and Skonieczny, Krzysztof and Wettergreen, David and Asnani, Vivake and Creager, Colin and Oravec, Heather},
booktitle={Aerospace Conference, 2011 IEEE},

Benefit of “Push-pull” Locomotion for Planetary Rover Mobility

Paydirt, maybe! They do an interesting thing for measuring here - they use a widget to pull the rover, making it seem like it’s going up a slope. These are drawbar pull tests.

This is a paper by the same guys as above with the same robot.

They also use good metrics and detailed examination of how the soil moves around the wheels, which might be useful.

title={Benefit of” Push-Pull” Locomotion for Planetary Rover Mobility},
author={Creager, C and Moreland, S and Skonieczny, K and Johnson, K and Asnani, V and Gilligan, R},
journal={Earth and Space},

The Scarab roving vehicle(Wettergreen, 2010),developed at Carnegie Mellon university, is a four wheel drive robotic vehicle with the ability to inch. On each side, each wheel is attached to the end of an arm that extends out from the center
of the chassis at a shoulder joint. An actuator controls the angle between these arms,thus creating the ability to vary the wheel base (distance between the front and rear wheels). When inching, the rear wheels are held in place relative to the ground while the wheel base is increased and the front tires are driven forward.

Once the front wheels are in place, the back wheels are driven forward while the wheel base is reduced. During this cycle, two tires are always stationary relative to the ground acting as anchors from which the rest of the vehicle can push or pull itself in to position.

The ExoMars rover locomotion subsystem
Nildeep Patel et al.

title={The ExoMars rover locomotion subsystem},
author={Patel, Nildeep and Slade, Richard and Clemmet, Jim},
journal={Journal of Terramechanics},

Study and implementation of wheel walking for a Mars rover
Hu, Zhongliang

Mainly deals with Marsokhod but worth reading - there are a few details of other rovers there.

title={Study and implementation of wheel walking for a Mars rover},
author={Hu, Zhongliang},
publisher={Lule{\aa} tekniska universitet}