MMX - Development of a Rover Locomotion System for Phobos

Sedlmayr, Hans-Juergen; Barthelmes, Stefan; Bayer, Ralph; Bertleff, Wieland; Bihler, Markus; Buse, Fabian; Chalon, Maxime; Franke, Dennis; Ginner, Florian; Langofer, Viktor; Lichtenheldt, Roy; Obermeier, Thomas; Pignede, Antoine; Reill, Josef; Skibbe, Juliane; Tardivel, Simon

doi:10.1109/aero47225.2020.9172659

Cited by 18 publications

(17 citation statements)

References 5 publications

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“…It has seven grousers of 6 cm height, a rim curvature radius of −3 cm and a chevron angle of one degree. It performs 8 % better than the intermediate design and 64 % better than the previous prototype [22]. This large performance increase was enabled by the ability to efficiently run simulations on GPUs in parallel.…”

Section: Wheel Optimization Campaignmentioning

confidence: 99%

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Large Scale Discrete Element Simulation Campaigns – Simulating Extraterrestrial Soils in Partsival

Lichtenheldt¹,

Ono²,

Stubbig³

2021

14th WCCM-ECCOMAS Congress

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In planetary exploration, testing under the actual mission conditions is inherently not possible. Hence, simulation campaigns complement ground test campaigns. This specially applies to surface missions that include the complex behaviour of soils under non-terrestrial gravitation. Increasingly ambitious mission goals made large simulation campaigns with very precise particle models necessary for the simulation of soil interaction. Thus, to limit the amount of time and the computation hardware needed, DLR developed the particle simulation tool "Sir partsival". This tool does not only speed up simulations by usage of GPU computing, but also integrates the institute's experience in modelling of soil on Earth and beyond. Using partsival it was possible to speed up simulations by more than a factor of ten and thus conduct large simulation campaigns. Two examples are shown: a large, on-going validation campaign of DEM for wheel simulations, and the completed traction optimization for the MMX rover wheel.

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Section: Wheel Optimization Campaignmentioning

confidence: 99%

“…A recent application where partsival was successfully applied is the wheel design for the Martian Moon Exploration (MMX) rover [22]. Its mission goals are the demonstration of wheeled locomotion in lowgravity, in-situ science with dedicated instruments and scouting, i.e.…”

Section: Wheel Optimization Campaignmentioning

confidence: 99%

Large Scale Discrete Element Simulation Campaigns – Simulating Extraterrestrial Soils in Partsival

Lichtenheldt¹,

Ono²,

Stubbig³

2021

14th WCCM-ECCOMAS Congress

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“…Refer to [9] and [10] for an overview of the rover system and the scientific instruments carried by it. To obtain more details on the ongoing development of the MMX Rover, especially on the locomotion subsystem, refer to [18].…”

Section: Hardware Specificationmentioning

confidence: 99%

The MMX Rover on Phobos: The Preliminary Design of the DLR Autonomous Navigation Experiment

Vayugundla

Bodenmüller

Schuster

et al. 2021

2021 IEEE Aerospace Conference (50100)

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This paper summarizes the challenges of deep space planetary robotic-exploration missions, using the example of the DLR Autonomous Navigation Experiment within the MMX Rover project, and presents a preliminary design of the proposed solution to safe navigation of the MMX Rover on Phobos. The MMX Rover, a joint contribution of the German Aerospace Center (DLR) and the Centre National d'Etudes Spatiales (CNES) is part of the Martian Moons eXploration (MMX) Mission by the Japan Aerospace Exploration Agency (JAXA), whose mission objective is to understand the origin of the two Martian moons. The mission involves scientific data collection and a sample return from Phobos, the bigger of the two Martian moons. The mission is scheduled to launch in the third quarter of 2024. The MMX Rover will fly as a payload and will be jettisoned onto Phobos from a low altitude of about 40 metres. The rover has multiple objectives: terrain assessment to mitigate the risk for the sample-return approach of the spacecraft, exploration of the surface of Phobos and act as a scientific and technology demonstration platform. In this context, the Robotics and Mechatronics Institute, DLR, is preparing to perform an Autonomous Navigation Experiment as a technology demonstration to showcase the advantages of robot autonomy for exploring distant celestial bodies. If successful, the MMX Rover will be the first man-made object to land on and explore Phobos.

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“…The calculated motor rate is a maximum motor rate to which the actual motor rate is ramped up within the motor controller. The motor control is implemented on a FPGA on the locomotion electronic boards and is not discussed further in here, see [2] for more details. The communication between locomotion control and the locomotion boards runs with a frequency of 10Hz.…”

Section: Locomotion Control Algorithmmentioning

confidence: 99%

“…More specifically, it has four wheels, each of them mounted on a rotatable leg to allow for a folded position in the spacecraft and a deployment, also called uprighting, once the rover has landed on Phobos. These eight rotational degrees of freedom are driven individually by a custom-made and highly integrated drive train, see [2] for details on the mechatronic design of this locomotion subsystem.…”

Section: Introductionmentioning

confidence: 99%

Locomotion Control Functions for the Active Chassis of the MMX Rover

Skibbe

Barthelmes

Buse

2021

2021 IEEE Aerospace Conference (50100)

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This is the author's copy of the publication as archived with the DLR's electronic library at http://elib.dlr.de . Please consult the original publication for citation, see e.g. https://ieeexplore.ieee.org/document/9438423 Locomotion Control Functions for the Active Chassis of the MMX Rover J. Skibbe and S. Barthelmes and F. Buse JAXA's Martian Moons eXploration Mission (MMX) includes the delivery of an exploration rover to the Mars moon Phobos in 2026, engineered by the Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR). On Phobos, the gravity is about two thousand times lower than on Earth, which is why it is also called a milli-g environment. While the actual surface of Phobos is largely unknown, it is agreed within mission team that areas covered with regolith are to be expected. The design of the rover includes four actuated legs, with one rotational degree of freedom (DOF) each, and four individually driven, non-steerable wheels. The first task of the rover after landing on the surface of Phobos will be to deploy itself from its cruise configuration and to stand up on its wheels. Due to the rover dimensions, a full rotation of the legs and a wheel slip compensation are essential for this task. During operations, the locomotion system needs to provide drive and steer, as well as point turn abilities. Furthermore, the solar panel sun pointing, as well as the adjustment of scientific instruments, require that the rover aligns its body orientation and alters its body-to-ground distance. To satisfy all these requirements to the locomotion system of the MMX rover, appropriate locomotion control functions were developed. For driving curves and performing point turns, the skid steering method is applied and an "inching" locomotion mode for especially soft and steep terrain is adapted. In this inching locomotion, the front and rear wheel pair move alternately while the rover body moves up and down, which leads to enhanced traction performance compared to conventional driving in soft sand. This implies lower wheel slippage and sinkage resulting in a higher safety of the full rover system. The body orientation function, which is based on a kinematic control as well, provides a well coordinated movement and zero longitudinal slippage of the wheels during its execution. In this paper, a detailed description of the control algorithms is given and results from lab tests are presented and discussed. In a successful mission, these locomotion control functions will be the first ones actuating a wheeled mobile robot in milli-g environment.

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MMX - Development of a Rover Locomotion System for Phobos

Cited by 18 publications

References 5 publications

Large Scale Discrete Element Simulation Campaigns – Simulating Extraterrestrial Soils in Partsival

Large Scale Discrete Element Simulation Campaigns – Simulating Extraterrestrial Soils in Partsival

The MMX Rover on Phobos: The Preliminary Design of the DLR Autonomous Navigation Experiment

Locomotion Control Functions for the Active Chassis of the MMX Rover

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