A Modelica Library to Add Contact Dynamics and Terramechanics to Multi-Body Mechanics

The Contact Dynamics library extends the multi-body Modelica Standard Library with contact calculation to the environment, namely soft soil and hard obstacles. A focus is on terramechanics, i. e. wheels driving on soft and dry soil, and a handful of models are implemented. Additionally, a Hertz contact model for hard and elastic contact, between bodies themselves or to obstacles in the environment (e. g. rocks in the soft soil), is available as well. The capabilities of the library have been key in the development of rovers for planetary exploration such as the upcoming MMX mission to the Martian moon Phobos

Conquering the Cold: Thermal Testing of MMX Rover IDEFIX's Locomotion Subsystem for the Exploration on Phobos

The Martian Moon eXploration (MMX) mission, led by the Japan Aerospace Exploration Agency (JAXA), is scheduled for launch in 2024 with the objective of sample-return from the Martian Moon Phobos and additional scientific observations of Deimos. As part of this mission, the MMX rover 'IDEFIX', developed collaboratively by the French Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), will serve as a mobile scout on the surface of Phobos. With its four-wheeled design and a weight of 25 kg, the rover will operate in microgravity and conducting in-situ measurements in areas of scientific interest. The locomotion subsystem (LSS) of the MMX rover, developed, build and qualified by DLR's Robotics and Mechatronics Center, plays a key role in fulfilling the mission objectives. The LSS is designed to accomplish various high-level requirements, including the correct reorientation (so-called uprighting) of the rover after ballistic landing, precise alignment of the solar cells for optimal power generation, and the provision of different driving modes to explore Phobos and interact with its surface. Additionally, the LSS allows for adjusting the rover's ground distance to allow measurements with the Raman spectrometer. To ensure the LSS can withstand the challenging conditions of the MMX mission, particularly the harsh environment during the cruise phase and the expected extremely low temperatures on Phobos, a comprehensive thermal design was developed. The LSS was subsequently subjected to rigorous testing throughout the development phases. The testing involved evaluating the mechanical, electrical and thermal aspects of various subunits, including the complex hold-down and release mechanism (HDRM), as well as conducting full functionality tests of the flight representative LSS during the qualification and acceptance stages. This presentation provides an overview of DLR's approach to thermal testing activities for the LSS during the development phase of the MMX rover. It offers insights into the MMX mission as a whole and presents a detailed examination of the qualification and acceptance thermal tests conducted for the LSS, emphasizing the significance of these tests in ensuring the successful operation of the rover during the mission

Driving in Milli-G: The Flight Model of the MMX Rover Locomotion Subsystem and its Integration & Testing in the Rover

IDEFIX is a 25 kg four-wheeled rover that will explore the surface of the Martian Moon Phobos in 2027. The rover is jointly developed by the German Aerospace Center (DLR) and the Centre National d'Etudes Spatiales (CNES) and will be brought to Phobos within the Japan Aerospace Exploration Agency's (JAXA) Martian Moon eXploration (MMX) mission. Being the world's first wheeled system to drive in milli-gravity, IDEFIX's locomotion deserves special attention. This paper gives an overview of the locomotion subsystem (LSS) of the rover, which is entirely developed and built by the Robotics and Mechatronics Center of DLR (DLR-RMC). A representative LSS, mounted on an IDEFIX prototype, is shown in Figure 1. The LSS is tailored to the needs for the IDEFIX rover and the most important, sizing challenges and functional requirements are summarized. It is then shown how the final flight model (FM) design answers to these requirements. The assembly, integration and testing (AIT) with respect to the LSS consists of several steps of integration and testing at different facilities as well as a comprehensive test sequence once the rover is mostly integrated. Since the LSS is an important, interconnected and the functionally most complex subsystem of the rover, some functionalities could only be tested once the LSS was integrated into IDEFIX. These AIT aspects are therefore summarized in this paper as well

Fault Detection, Isolation and Recovery in the MMX Rover Locomotion Subsystem

In any mechatronic system, faults can occur. Likewise also in the MMX rover, which is a wheeled rover mutually developed by CNES (Centre national d'études spatiales) and DLR (German Aerospace Center), intended to land on Phobos. An essential part of the MMX rover is the locomotion subsystem which includes several sensors and eight motors actuating the four legs and the four wheels. In each of these components and their interfaces, there is a possibility that faults arise and lead to subsystem failures, which would mean that the rover cannot move anymore. To reduce this risk, the possible faults of the MMX locomotion subsystem were identified in a FMECA study and their criticality was classified, which is presented in here. During this examination, the criticality was graded depending on different mission phases. With the help of this study, the hardware, firmware and software design were enhanced. Fur- ther, certain fault detection, isolation and recovery strategies were implemented in the locomotion firmware and software as well as in the full rover software

SYSTOMONAS — an integrated database for systems biology analysis of Pseudomonas

To provide an integrated bioinformatics platform for a systems biology approach to the biology of pseudomonads in infection and biotechnology the database SYSTOMONAS (SYSTems biology of pseudOMONAS) was established. Besides our own experimental metabolome, proteome and transcriptome data, various additional predictions of cellular processes, such as gene-regulatory networks were stored. Reconstruction of metabolic networks in SYSTOMONAS was achieved via comparative genomics. Broad data integration is realized using SOAP interfaces for the well established databases BRENDA, KEGG and PRODORIC. Several tools for the analysis of stored data and for the visualization of the corresponding results are provided, enabling a quick understanding of metabolic pathways, genomic arrangements or promoter structures of interest. The focus of SYSTOMONAS is on pseudomonads and in particular Pseudomonas aeruginosa, an opportunistic human pathogen. With this database we would like to encourage the Pseudomonas community to elucidate cellular processes of interest using an integrated systems biology strategy. The database is accessible at

Mobility on the Surface of Phobos for the MMX Rover - Simulation-aided Movement planning

The MMX Rover, recently named IDEFIX, will be the first wheeled robotic system to be operated in a milli-g environment. The mobility in this environment, particularly in combination with the interrupted communication schedule and the activation of on-board autonomous functions such as attitude control requires efficient planning. The Mobility Group within the MMX Rovers Team is tasked with proposing optimal solutions to move the rover safely and efficiently to its destination so that it may achieve its scientific goals. These movements combine various commands to the locomotion system and to the navigation systems developed by both institutions. In the mission's early phase, these actions will rely heavily on manual driving commands to the locomotion system until the rover behavior and environment assumptions are confirmed. Planning safe and efficient rover movements is a multi-step process. This paper focuses on the challenges and limitations in sequencing movements for a Rover on Phobos in the context of the MMX Mission. The context in which this process takes place is described in terms of available data and operational constraints

MMX - development of a rover locomotion system for Phobos

The MMX mission (Martian Moons eXploration) is a robotic sample return mission of the JAXA (Japan Aerospace Exploration Agency), CNES (Centre National d'Etudes Spatiales ) and DLR (German Aerospace Center) for launch in 2024. The mission aims to answer the question on the origin of Phobos and Deimos which will also help to understand the material transport in the earliest period of our solar system and the most important question how was the water brought on Earth. Besides the MMX mothership (JAXA) which is responsible for sampling and sample return to Earth a small rover which is built by CNES and DLR shall land on Phobos for in-situ measurements similar to MASCOT (Mobile Asteroid Surface Scout) on Ryugu. The MMX rover is a four wheel driven autonomous system with a size of 41 cm x 37 cm x 30 cm and a weight of approx. 25 kg. Multiple science instruments and cameras are integrated in the rover body. The rover body is basically a rectangular box, attached at the sides are four legs with one wheel per leg. When the rover is detached from the mothership, the legs are folded together at the side of the rover body. When the rover has landed passively (no parachute, braking rockets) on Phobos, the legs are autonomously controlled to bring the rover in an upright orientation. One Phobos day lasts 7 earth hours, which gives for the total mission time of 3 earth months, the number of about 300 extreme temperature cycles. These cycles and the wide span of surface temperature between day and night are main design drivers for the rover. This paper gives a short overview on the MMX mission, the MMX rover and a detailed view on the development of the MMX rover locomotion subsystem

MMX Rover Locomotion Subsystem - Development and Testing towards the Flight Model

Wheeled rovers have been successfully used as mobile landers on Mars and Moon and more such missions are in the planning. For the Martian Moon eXploration (MMX) mission of the Japan Aerospace Exploration Agency (JAXA), such a wheeled rover will be used on the Marsian Moon Phobos. This is the first rover that will be used under such low gravity, called milli-g, which imposes many challenges to the design of the locomotion subsystem (LSS). The LSS is used for unfolding, standing up, driving, aligning and lowering the rover on Phobos. It is a entirely new developed highly-integrated mechatronic system that is specifically designed for Phobos. Since the Phase A concept of the LSS, which was presented two years ago [1], a lot of testing, optimization and design improvements have been done. Following the tight mission schedule, the LSS qualification and flight models (QM and FM) assembly has started in Summer 2021. In this work, the final FM design is presented together with selected test and optimization results that led to the final state. More specifically, advances in the mechanics, electronics, thermal, sensor, firmware and software design are presented. The LSS QM and FM will undergo a comprehensive qualification and acceptance testing campaign, respectively, in the first half of 2022 before the FM will be integrated into the rove

Regolith science with the cameras on the MMX Rover

The JAXA Martian Moons Exploration (MMX) mission [1] has a primary objective to study the formation and origins of Phobos and Deimos. The MMX spacecraft will also deploy a CNES/DLR rover to the surface of Phobos [2,3]. This rover will be the first of its kind to attempt wheeled-locomotion on a low gravity surface. As such, this rover provides a unique opportunity to study not only the surface properties of Phobos, but also regolith dynamics on small-bodies. This information is valuable for understanding the surface processes and geological history of Phobos in addition to being of high importance to the landing (and sampling) operations of the main MMX spacecraft [1]

Cys-Ph-TAHA: a lanthanide binding tag for RDC and PCS enhanced protein NMR

Here we present Cys-Ph-TAHA, a new nonadentate lanthanide tag for the paramagnetic labelling of proteins. The tag can be easily synthesized and is stereochemically homogenous over a wide range of temperatures, yielding NMR spectra with a single set of peaks. Bound to ubiquitin, it induced large residual dipolar couplings and pseudocontact shifts that could be measured easily and agreed very well with the protein structure. We show that Cys-Ph-TAHA can be used to label large proteins that are biochemically challenging such as the Lac repressor in a 90 kDa ternary complex with DNA and inducer