163 research outputs found
Efficient Autonomous Navigation for Planetary Rovers with Limited Resources
Rovers operating on Mars are in need of more and more autonomous features to ful ll their
challenging mission requirements. However, the inherent constraints of space systems make
the implementation of complex algorithms an expensive and difficult task. In this paper
we propose a control architecture for autonomous navigation. Efficient implementations of
autonomous features are built on top of the current ExoMars navigation method, enhancing
the safety and traversing capabilities of the rover. These features allow the rover to detect
and avoid hazards and perform long traverses by following a roughly safe path planned by
operators on ground. The control architecture implementing the proposed navigation mode
has been tested during a field test campaign on a planetary analogue terrain. The experiments
evaluated the proposed approach, autonomously completing two long traverses while
avoiding hazards. The approach only relies on the optical Localization Cameras stereobench,
a sensor that is found in all rovers launched so far, and potentially allows for computationally
inexpensive long-range autonomous navigation in terrains of medium difficulty
Hardware-accelerated Mars Sample Localization via deep transfer learning from photorealistic simulations
The goal of the Mars Sample Return campaign is to collect soil samples from
the surface of Mars and return them to Earth for further study. The samples
will be acquired and stored in metal tubes by the Perseverance rover and
deposited on the Martian surface. As part of this campaign, it is expected that
the Sample Fetch Rover will be in charge of localizing and gathering up to 35
sample tubes over 150 Martian sols. Autonomous capabilities are critical for
the success of the overall campaign and for the Sample Fetch Rover in
particular. This work proposes a novel system architecture for the autonomous
detection and pose estimation of the sample tubes. For the detection stage, a
Deep Neural Network and transfer learning from a synthetic dataset are
proposed. The dataset is created from photorealistic 3D simulations of Martian
scenarios. Additionally, the sample tubes poses are estimated using Computer
Vision techniques such as contour detection and line fitting on the detected
area. Finally, laboratory tests of the Sample Localization procedure are
performed using the ExoMars Testing Rover on a Mars-like testbed. These tests
validate the proposed approach in different hardware architectures, providing
promising results related to the sample detection and pose estimation.Comment: Preprint version only. Final version at IEEE Xplore. Accepted for
IEEE Robotics and Automation Letter
Dynamic path planning for reconfigurable rovers using a multi-layered grid
Autonomy on rovers is desirable in order to extend the traversed distance, and therefore, maximize the number
of places visited during the mission. It depends heavily on the information that is available for the traversed
surface on other planet. This information may come from the vehicle’s sensors as well as from orbital images.
Besides, future exploration missions may consider the use of reconfigurable rovers, which are able to execute
multiple locomotion modes to better adapt to different terrains. With these considerations, a path planning
algorithm based on the Fast Marching Method is proposed. Environment information coming from different
sources is used on a grid formed by two layers. First, the Global Layer with a low resolution, but high extension
is used to compute the overall path connecting the rover and the desired goal, using a cost function that takes
advantage of the rover locomotion modes. Second, the Local Layer with higher resolution but limited distance
is used where the path is dynamically repaired because of obstacle presence. Finally, we show simulation and
field test results based on several reconfigurable and non-reconfigurable rover prototypes and a experimental
terrain
SLIM Robotics: Robotics in a Small Team With Space Requirements
In this paper, we present the rationale behind our development philosophy and explain which elements we adopted from general software engineering practices of industry, the open source community, embedded, and cloud technologies. We identify aspects of development practices and consider the transition from prototype to product and the difficulties the use of frameworks entails. Along with the explanations, examples, and use cases given, we will relate directly to a payload development for the International Space Station (ISS) with all the intricacies of qualification such as external requirements, and constraints. We hope to add to the scope of roboticists and software/framework developers alike by showing how we developed and improved robotics systems software from early prototypes to production grade-maturity
Concept, Development and Testing of Mars Rover Prototypes for ESA Planetary Exploration
This paper presents the system architecture and design of two planetary rover laboratory prototypes developed at the European Space Agency (ESA). These research platforms have been developed to provide early prototypes for validation of designs and serve ESA’s Automation & Robotics Lab infrastructure as testbeds for continuous research and testing. Both rovers have been built considering the constraints of Space Systems with the sufficient level of representativeness to allow rapid prototyping. They avoid strictly space-qualified components and designs that present a major cost burden and frequently lack the flexibility or modularity that the lab environment requires for its investigations. This design approach is followed for all the mechanical, electrical, and software aspects of the system. In this paper, two ExoMars mission-representative rovers, the ExoMars Testing Rover (ExoTeR) and the Martian Rover Testbed for Autonomy (MaRTA), are thoroughly described. The lessons learnt and experience gained while running several research activities and test campaigns are also presented. Finally, the paper aims to
provide some insight on how to reduce the gap between lab R&D and flight implementation by anticipating system constraints
when building and testing these platforms
A Newcomer's Guide to the Challenges of a Complex Space-to-Ground Experiment, With Lessons from Analog-1
An astronaut controlling a complex robot on the surface of earth from the ISS. This is exactly what we have done in ANALOG-1. Luca Parmitano teleoperated a rover in a moon-analogue geological mission scenario. On first sight the primary technical challenges seem to be the design of the robotic systems for space and ground. On a second look - with the perspective of using the system with an astronaut on the ISS in loop with an operations team in different ground centers - the scope and challenges drastically increase.
In this paper we take a look behind the scenes, and gives insights which could guide future payload developers going on a similar endeavour. This paper outlines the Analog-1 experiment, itself, what it aimed to achieve, and how it was done, and uses it as a case study to outline the challenges and solutions a project team and particularly the payload developer - will have to overcome when designing an ISS experiment. This article may be especially insightful and a good starting point for those from a small research team at a university or other research institution with budget and time pressure. We will present it from the payload developers perspective and on concrete examples of the payloads we flown
Design and Integration of a Multi-arm Installation Robot Demonstrator for orbital large Assembly
Space facilities for orbital exploitation and exploration missions are increasingly requiring larger structure to extend their capabilities. Dimensions of future scientific outposts, solar stations and telescopes undoubtedly matter to expand our horizons, power our planet or explore the universe. Due to the foreseen large structures for such applications, a single self-deploying piece contained in standard launcher fairings might become inadequate. Another approach is that large structures could be broken down into standard modules that will be built in-orbit. Assembling
large structure in space is particularly challenging but the raise of key enablers as standard interconnects and advanced robotics opens a new horizon for such applications. It is assumed here that the large spacecraft structure and modules are equipped with standard interconnects (SI) that allow them to be mated to each other and to the robot
system for manipulation/transport/installation, or to allow the robot system to move across them.
This paper introduces the concept of a novel Multi-Arm Robot (MAR) dedicated to on-orbit large telescope assembly, its ground equivalent laboratory demonstrator design and preliminary hardware integration.
The MAR is a modular robot composed of three robotic subsystems - a torso and two symmetrical 7-degree of freedom (DOF) anthropomorphic arms with non-spherical wrists - that are functionally independent and can be connected by the means of Standard Interconnects. The modular approach of the MAR reduces the complexity of the different robotic appendages and offers a set of robotic configuration that extends the range of possible operations and provides an intrinsic system redundancy that reduces the overall mission risk.
To assess the MAR concept, a Technology Readiness Level (TRL) 4 ground demonstrator, has been designed to provide a framework that allows the multi-arm robot to execute its overall scope of operations in a ground laboratory environment. It comprises a testbed (dummy spacecraft structure, home base, storage area and mobile payloads) offering a space representative environment, a mission control center (computer, simulator and electrical/data support equipment) supervising the MAR's tasks, and a gravity compensation system (gantry crane and offloading system) for supporting the robot under 1-g
Demonstrator Design of a Modular Multi-arm Robot for On-orbit Large Telescope Assembly
The development of building blocks, and standard interconnects in particular, enables promising perspectives for the assembly of large structures on-orbit. By coupling these standard interconnects with
dexterous arms, it is now possible to imagine orbital robots assembling, in-situ, modular structures to emancipate from launcher constraints.
Such a mission scenario and related concept of operations are proposed within the ESA MIRROR project. It involves a modular multi-arm installation
robot to address this challenge. This paper deals with the design of a fully representative breadboard for this innovative robot in order to prove its concept and abilities. This demonstrator features a ground
equivalent robotic system, a testbed and necessary ground support equipments
VapC Toxins from Mycobacterium tuberculosis Are Ribonucleases that Differentially Inhibit Growth and Are Neutralized by Cognate VapB Antitoxins
The chromosome of Mycobacterium tuberculosis (Mtb) encodes forty seven toxin-antitoxin modules belonging to the VapBC family. The role of these modules in the physiology of Mtb and the function(s) served by their expansion are unknown. We investigated ten vapBC modules from Mtb and the single vapBC from M. smegmatis. Of the Mtb vapCs assessed, only Rv0549c, Rv0595c, Rv2549c and Rv2829c were toxic when expressed from a tetracycline-regulated promoter in M. smegmatis. The same genes displayed toxicity when conditionally expressed in Mtb. Toxicity of Rv2549c in M. smegmatis correlated with the level of protein expressed, suggesting that the VapC level must exceed a threshold for toxicity to be observed. In addition, the level of Rv2456 protein induced in M. smegmatis was markedly lower than Rv2549c, which may account for the lack of toxicity of this and other VapCs scored as ‘non-toxic’. The growth inhibitory effects of toxic VapCs were neutralized by expression of the cognate VapB as part of a vapBC operon or from a different chromosomal locus, while that of non-cognate antitoxins did not. These results demonstrated a specificity of interaction between VapCs and their cognate VapBs, a finding corroborated by yeast two-hybrid analyses. Deletion of selected vapC or vapBC genes did not affect mycobacterial growth in vitro, but rendered the organisms more susceptible to growth inhibition following toxic VapC expression. However, toxicity of ‘non-toxic’ VapCs was not unveiled in deletion mutant strains, even when the mutation eliminated the corresponding cognate VapB, presumably due to insufficient levels of VapC protein. Together with the ribonuclease (RNase) activity demonstrated for Rv0065 and Rv0617 – VapC proteins with similarity to Rv0549c and Rv3320c, respectively – these results suggest that the VapBC family potentially provides an abundant source of RNase activity in Mtb, which may profoundly impact the physiology of the organism
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