Motion Planning for Relocatable Robots Performing On-Orbit Locomotion and Manipulation Tasks

In-space assembly is a key technology for the future development of large infrastructures in space, from space stations and telescopes, to solar power plants or planetary bases. Such structures are much larger than cargo areas in current launchers, therefore they must be sent in separate pieces that are assembled in situ, typically using relocatable robotic manipulators. The efficient exploitation of the locomotion and manipulation (loco-manipulation) abilities for such robotic systems requires suitable planning tools. In this paper, we present a motion planning approach for exploiting loco-manipulation abilities of self-relocatable space robots, assuming that they move over specific interconnects that provide the required mechanical, power and data connectivity. The proposed approach consists of three planning layers: a high-level planning for obtaining the contact sequence, a low-level planning for the joint trajectories, and a validation layer. The motion planner provides plans for single locomotion and manipulation tasks, as well as combined loco-manipulation tasks. The approach is illustrated with examples for two robotic systems: MOSAR-WM, a relocatable walking manipulator, and a multi-arm robot (MAR) equipped with two arms attached to a central tors

Design and Development of a Relocatable Robotic Arm for Servicing On-Orbit Modular Spacecraft

The raise of orbital robotics opens a new horizon of possibilities for upcoming space missions. In the context of a global space sustainability, this paper deals with the design, development and testing of a new generation of robotic manipulator for on-orbit maintenance and servicing. This device tackles especially modular missions related to assembly and reconfiguration of modular satellites, coupled with the paradigm of standardization of spacecraft featuring standard interconnects. This robotic system benefits from an innovative multidisciplinary design for performing manipulation and relocation tasks over compatible spacecraft structures. The proposed robotic manipulator is experimentally evaluated on a representative ground demonstrator in a laboratory environment

MOSAR : Modular spacecraft assembly and reconfiguration demonstrator

With rapid development of space systems in recent years and their limited lives, it is imperative that a sustainable space development approach is developed to support more affordable access to space for all stakeholders. The European Commission hence funded the MOSAR project which aims to create a new paradigm technology to address this increasing challenge. This paper provides an overview of this technology’s preliminary development to enable on-orbit servicing. Building on five successful projects which collectively created all required common building blocks for both planetary explorations and in-orbit missions, a novel architecture is proposed to create a walking manipulator to demonstrate its unique capability in both space system assembly and on-orbit servicing. Preliminary design concepts of a walking manipulator and spacecraft modules are shown. A dedicated simulator is also developed to evaluate the proposed novel architecture for these targeted applications

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

Contribution à la modélisation et à la commande de robots mobiles autonomes et adaptables en milieux naturels

This work is focused on the conceptualization, the modeling and the genericcontrol of mobile robots when moving in off-road contexts and facing slipperyterrains, especially for very accurate tracking and following applications. Thisthesis summarizes the proposed methods and the obtained results to addressthis research issue, first for path following applications (absolute localization)and then for edge and target tracking applications (relative localization). A finalsection of this thesis introduces an adaptive robotic concept and its associatedcontroller allowing the adaptation of the pose (position and orientation) of thechassis with respect to the environment topography.For each application, this thesis introduces a panel of innovative control algorithmsfor controlling skid-steering, two-wheel steering and four-wheel steeringmobile robots. Each algorithm of the panel is described, in this thesis, infour steps : modeling, estimation, control and experiments.The first main contribution of this thesis deals with the slippage estimation.The latter is adaptive and model-based. It also includes the extended kinematicmodeling only or together with the dynamic modeling of the mobile robot toensure a robust estimation of the slippage whatever the speed of the robot, encountereddynamic phenomena or even ground characteristics.The second main contribution deals with the design of a generic control approachfor mobile robots when path following and target tracking. The proposedstrategy is mostly based on a backstepping method and is illustrated inthis thesis via a panel of control laws. When combining this proposed controlapproach with the slippage estimation described above, significant improvedtracking and following performances are obtained (in term of stability, repeatability,accuracy and robustness) whatever the encountered context.All algorithms have been tested and validated through simulations and/orfull-scale experiments, indoor and off-road, with different mobile robots.Les problématiques de recherche abordées dans cette thèse concernent la conceptualisation, la modélisation et la commande générique des robots mobiles lors de leur évolution en milieux extérieurs et en présence de glissement pour des applications de suivi de précision. Ainsi, ce mémoire synthétise dans un premier temps les développements et résultats obtenus lors du suivi de trajectoire (localisation absolue), puis synthétise ensuite ceux obtenus lors de suivi de structure et de cible (localisation relative). Une dernière partie introduit un concept de plateforme robotique reconfigurable et sa commande associée pour adapter l’assiette et les dimensions du châssis en fonction de la topographie du terrain.Pour chaque application de suivi, ce mémoire présente un panel de lois de commande originales pour des robots différentiels, à un train et à deux trains directeurs. Chaque modalité de commande est présentée en quatre étapes : modélisation, estimation, commande et expérimentations. La première contribution majeure de la thèse concerne l’estimation du glissement. Cette dernière est adaptative et basée modèle. Elle intègre la modélisation cinématique étendue seule ou couplée à la modélisation dynamique du robot mobile pour assurer une estimation intègre quels que soient la vitesse, les phénomènes dynamiques rencontrés et la nature du sol. La seconde contribution majeure concerne le développement d’une stratégie de commande générique pour les robots mobiles. Cette stratégie est basée sur le principe de la commande en cascade (ou par backstepping) et est déclinée dans ce mémoire à travers un panel de lois de commande. Cette méthodologie de commande, lorsqu’elle est associée à l’observation du glissement précédent, permet d’obtenir des performances de suivi accrues quel que soit le contexte rencontré. L’ensemble des algorithmes ont été validés en simulation et/ou expérimentalement à l’aide de différentes plateformes robotiques en contextes réels

Contribution to the modelling and control of autonomous and adaptable mobile robots in natural environments

Les problématiques de recherche abordées dans cette thèse concernent la conceptualisation, la modélisation et la commande générique des robots mobiles lors de leur évolution en milieux extérieurs et en présence de glissement pour des applications de suivi de précision. Ainsi, ce mémoire synthétise dans un premier temps les développements et résultats obtenus lors du suivi de trajectoire (localisation absolue), puis synthétise ensuite ceux obtenus lors de suivi de structure et de cible (localisation relative). Une dernière partie introduit un concept de plateforme robotique reconfigurable et sa commande associée pour adapter l’assiette et les dimensions du châssis en fonction de la topographie du terrain.Pour chaque application de suivi, ce mémoire présente un panel de lois de commande originales pour des robots différentiels, à un train et à deux trains directeurs. Chaque modalité de commande est présentée en quatre étapes : modélisation, estimation, commande et expérimentations. La première contribution majeure de la thèse concerne l’estimation du glissement. Cette dernière est adaptative et basée modèle. Elle intègre la modélisation cinématique étendue seule ou couplée à la modélisation dynamique du robot mobile pour assurer une estimation intègre quels que soient la vitesse, les phénomènes dynamiques rencontrés et la nature du sol. La seconde contribution majeure concerne le développement d’une stratégie de commande générique pour les robots mobiles. Cette stratégie est basée sur le principe de la commande en cascade (ou par backstepping) et est déclinée dans ce mémoire à travers un panel de lois de commande. Cette méthodologie de commande, lorsqu’elle est associée à l’observation du glissement précédent, permet d’obtenir des performances de suivi accrues quel que soit le contexte rencontré. L’ensemble des algorithmes ont été validés en simulation et/ou expérimentalement à l’aide de différentes plateformes robotiques en contextes réels.This work is focused on the conceptualization, the modeling and the genericcontrol of mobile robots when moving in off-road contexts and facing slipperyterrains, especially for very accurate tracking and following applications. Thisthesis summarizes the proposed methods and the obtained results to addressthis research issue, first for path following applications (absolute localization)and then for edge and target tracking applications (relative localization). A finalsection of this thesis introduces an adaptive robotic concept and its associatedcontroller allowing the adaptation of the pose (position and orientation) of thechassis with respect to the environment topography.For each application, this thesis introduces a panel of innovative control algorithmsfor controlling skid-steering, two-wheel steering and four-wheel steeringmobile robots. Each algorithm of the panel is described, in this thesis, infour steps : modeling, estimation, control and experiments.The first main contribution of this thesis deals with the slippage estimation.The latter is adaptive and model-based. It also includes the extended kinematicmodeling only or together with the dynamic modeling of the mobile robot toensure a robust estimation of the slippage whatever the speed of the robot, encountereddynamic phenomena or even ground characteristics.The second main contribution deals with the design of a generic control approachfor mobile robots when path following and target tracking. The proposedstrategy is mostly based on a backstepping method and is illustrated inthis thesis via a panel of control laws. When combining this proposed controlapproach with the slippage estimation described above, significant improvedtracking and following performances are obtained (in term of stability, repeatability,accuracy and robustness) whatever the encountered context.All algorithms have been tested and validated through simulations and/orfull-scale experiments, indoor and off-road, with different mobile robots

Path Tracking of a Two-Wheel Steering Mobile Robot: An Accurate and Robust Multi-Model Off-Road Steering Strategy

International audienceIn this paper, the problem associated with accurate control of a two-wheel steering mobile robot following a path is addressed thanks to a backstepping control strategy. This approach involves an observer to estimate the grip conditions, based on previous work, and the proposed control algorithm for the front axle. Since the significant parameters of the grip conditions are available from the observer, namely the sideslip angles and the cornering stiffnesses, it is then suitable to include them into an algorithm to control mobile robots and obtain a more accurate path tracking. This is made possible by gathering into a single backstepping approach both kinematic and dynamic models. This new point of view permits to take account of both kinematic and dynamic behaviors and grip parameters in the control law. The proposed approach is experimentally evaluated at different speeds and compared with two other state-of-the-art path tracking algorithms and evaluated for several values of lateral deviations

Stiffness and damping real-time control algorithms for adjustable suspensions : A strategy to reduce dynamical effects on vehicles in off-road conditions

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Adaptive trajectory control of off-road mobile robots: A multi-model observer approach

International audienceIn this paper, the problems associated with accurate path tracking control in off-road conditions is addressed with model-based adaptive control. In particular, the estimation of grip conditions is investigated through the derivation of a new observer and by gathering kinematic and dynamic models into a single framework. This new reference point employs a unique observer regardless of the velocity of the robots. Previous approaches necessitated the switching of models depending upon the phenomena encountered as well as robot dynamics. The observer proposed here allows an accurate and reactive estimation of sliding. This permits to feed relevantly a control law based on an extended kinematic model, enabling accurate path tracking, even in harsh conditions and when facing significant dynamic effects such as spin around