Design and experimental validation of reorientation manoeuvres for a free falling robot inspired from the cat righting reflex

This paper presents two distinct manoeuvres allowing an articulated robot in free fall to change its orientation using closed paths in the joint space. It is shown through dynamics simulations that the magnitude of the net rotation is dependent upon the amplitude of the angular displacement of the joints. With realistic joint limitations, the robot, which includes rotary actuators only, can perform a 180-degree reorientation about its longitudinal axis, similar to the cat righting reflex. The second manoeuvre allows the robot to accomplish rotations of smaller magnitude about a different axis. A physical prototype and a VICON motion tracking system are used to experimentally validate the simulation results. Finally, it is shown that the two manoeuvres, which yield rotations about fixed axes, can be repeated and alternated to enable the robot to reach any arbitrary 3D orientation

Conception et validation expérimentale de manœuvres inspirées du réflexe de redressement du chat pour la réorientation d'un robot articulé en chute libre

Ce mémoire présente deux manoeuvres permettant de modifier l’orientation d’un robot articulé en apesanteur, en n’utilisant que ses mouvements internes, à l’instar du réflexe de redressement du chat. Celles-ci ont comme caractéristique principale d’opérer ce changement malgré le fait qu’elles se traduisent par des boucles fermées dans l’espace articulaire du robot. Les manoeuvres peuvent être executées séquentiellement, en variant leurs amplitudes, afin de rendre atteignable n’importe quelle orientation dans l’espace tridimensionnel. La dynamique des manoeuvres est explorée en simulation afin d’identifier des paramètres favorables. Des exemples de réorientation sont présentés en simulation avec un modèle de robot à quatre membrures et trois articulations rotoïdes. Enfin, un prototype physique est construit à partir de ce modèle et les résultats numériques sont validés expérimentalement à l’aide d’une tour d’apesanteur et d’un système de capture de mouvements.This Master’s thesis introduces two distinct manoeuvres allowing a free-floating robot to reorient itself using its internal movements only, like the cat-righting reflex. The principal interest of these manoeuvres lies in the fact that they achieve this reorientation even though they are represented by closed loops in the joint space of the robot. The manoeuvres can be executed in sequence, with varying amplitude, in order to reach any orientation in three-dimensional space. Their dynamics are explored through numerical simulation in order to find favourable parameters. Reorientation examples are presented in simulation with a robot model composed of four links and three rotary actuators. Finally, a practical prototype is built from this model and the simulation results are experimentally validated using a drop tower and a motion capture system

Middeck Active Control Experiment (MACE), phase A

A rationale to determine which structural experiments are sufficient to verify the design of structures employing Controlled Structures Technology was derived. A survey of proposed NASA missions was undertaken to identify candidate test articles for use in the Middeck Active Control Experiment (MACE). The survey revealed that potential test articles could be classified into one of three roles: development, demonstration, and qualification, depending on the maturity of the technology and the mission the structure must fulfill. A set of criteria was derived that allowed determination of which role a potential test article must fulfill. A review of the capabilities and limitations of the STS middeck was conducted. A reference design for the MACE test article was presented. Computing requirements for running typical closed-loop controllers was determined, and various computer configurations were studied. The various components required to manufacture the structure were identified. A management plan was established for the remainder of the program experiment development, flight and ground systems development, and integration to the carrier. Procedures for configuration control, fiscal control, and safety, reliabilty, and quality assurance were developed

Space Exploration Robotic Systems - Orbital Manipulation Mechanisms

In the future, orbital space robots will assist humans in space by constructing and maintaining space modules and structures. Robotic manipulators will play essential roles in orbital operations. This work is devoted to the implemented designs of two different orbital manipulation mechanical grippers developed in collaboration with Thales Alenia Space Italy and NASA Jet Propulsion Laboratory – California Institute of Technology. The consensus to a study phase for an IXV (Intermediate eXperimental Vehicle) successor, a preoperational vehicle called SPACE RIDER (Space Rider Reusable Integrated Demonstrator for European Return), has been recently enlarged, as approved during last EU Ministerial Council. One of the main project task consists in developing SPACE RIDER to conduct on orbit servicing activity with no docking. SPACE RIDER would be provided with a robotic manipulator system (arm and gripper) able to transfer cargos, such as scientific payloads, from low Earth orbiting platforms to SPACE RIDER cargo bay. The platform is a part of a space tug designed to move small satellites and other payloads from Low Earth Orbit (LEO) to Geosynchronous Equatorial Orbit (GEO) and viceversa. The assumed housing cargo bay requirements in terms of volume (<100l) and mass (<50kg) combined with the required overall arm dimensions (4m length), and mass of the cargo (5-30kg) force to developing an innovative robotic manipulator with the task-oriented end effector. It results in a seven degree-of-freedom arm to ensure a high degree of dexterity and a dedicate end-effector designed to grasp the cargo interface. The gripper concept developed consists in a multi-finger hand able to lock both translational and rotational cargo degrees of freedom through an innovative underactuation strategy to limit its mass and volume. A configuration study on the cargo handle interface was performed together with some computer aided design models and multibody analysis of the whole system to prove its feasibility. Finally, the concept of system control architecture, the test report and the gripper structural analysis were defined. In order to be able to accurately analyze a sample of Martian soil and to determine if life was present on the red planet, a lot of mission concepts have been formulating to reach Mars and to bring back a terrain sample. NASA JPL has been studying such mission concepts for many years. This concept is made up of three intermediate mission accomplishments. Mars 2020 is the first mission envisioned to collect the terrain sample and to seal it in sample tubes. These sealed sample tubes could be inserted in a spherical envelope named Orbiting Sample (OS). A Mars Ascent Vehicle (MAV) is the notional rocket designed to bring this sample off Mars, and a Rendezvous Orbiting Capture System (ROCS) is the mission conceived to bring this sample back to Earth through the Earth Entry Vehicle (EEV). MOSTT is the technical work study to create new concepts able to capture and reorient an OS. This maneuver is particularly important because we do not know an OS incoming orientation and we need to be able to capture, to reorient it (2 rotational degrees of freedom), and to retain an OS (3 translational degrees of freedom and 2 rotational ones). Planetary protection requirements generate a need to enclose an OS in two shells and to seal it through a process called Break-The-Chain (BTC). Considering the EEV would return back to Earth, the tubes orientation and position have to be known in detail to prevent any possible damage during the Earth hard landing (acceleration of ∼1300g). Tests and analysis report that in order for the hermetic seals of the sample tubes to survive the impact, they should be located above an OS equator. Due to other system uncertainties an OS presents the potential requirement to be properly reoriented before being inserted inside the EEV. Planetary protection issues and landing safety are critical mission points and provide potential strict requirements to MOSTT system configuration. This task deals with the concept, design, and testbed realization of an innovative electro-mechanical system to reorient an OS consistent with all the necessary potential requirements. One of these electro-mechanical systems consists of a controlled-motorized wiper that explores all an OS surface until it engages with a pin on an OS surface and brings it to the final home location reorienting an OS. This mechanism is expected to be robust to the incoming OS orientation and to reorient it to the desired position using only one degree of freedom rotational actuator

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 344)

This bibliography lists 125 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during January, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Unified Dynamics and Control of a Robot Manipulator Mounted on a VTOL Aircraft Platform

An innovative type of mobile manipulator, designated Manipulator on VTOL (Vertical Take-Off and Landing) Aircraft (MOVA), is proposed as a potential candidate for autonomous execution of field work in less-structured indoor and outdoor environments. Practical use of the MOVA system requires a unified controller that addresses the coupled and complex dynamics of the composite system; especially the interaction of the robotic manipulator with the aircraft airframe. Model-based controller design methods require explicit dynamics models of the MOVA system. Preliminary investigation of a two-dimensional MOVA system toward a dynamics model and controller design is presented in preparation for developing the controller of the more complex MOVA system in 3D space. Dynamics of the planar MOVA system are derived using the Lagrangian approach and then transforming the result into a form that facilitates controller design using the concept of a virtual manipulator. A MOVA end-effector trajectory tracking controller was designed with the transformed dynamics equation using the integrator back-stepping control design framework. Validity of the controller is shown via stability analysis, simulation results, and results from a physical test-bed. A systematic approach is illustrated for the derivation of the 3D MOVA system dynamics equations. The resulting dynamics equations are represented abstractly in the standard robot dynamics form and proven to have the skew-symmetric property, which is a useful property for control derivation. An open source Mathematica program was developed to achieve automatic symbolic derivation of the MOVA system dynamics. Accessory tools were also designed to create a tool-chain that starts with an Autodesk Inventor CAD drawing, generates input to the Mathematica program, and then formats the output for direct use in MATLAB and Simulink. A unified nonlinear control algorithm that controls the 3D MOVA system, including both the aircraft and the onboard manipulator, as a single entity was developed to achieve trajectory tracking of the MOVA end-effector position and attitude based on the explicit dynamics equation. Globally Uniformly Ultimately Bounded (GUUB) stability is proven for the controller using Lyapunov-type stability analysis. Physical testing was constructed in order to to demonstrate the performance of the proposed controller on a MOVA system with a two-link onboard manipulator

Planification et réalisation de manœuvres de réorientation de robots en chute libre

Ce mémoire présente des manœuvres de réorientation appliquées à un robot articulé et à un robot mobile en chute libre. Ces manœuvres, initialement inspirées du phénomène du chat qui atterrit toujours sur ses pattes, sont aussi attribuées à d'autres animaux, tels que certains reptiles et même les humains dans le contexte de certains sports. Les manœuvres de réorientation ont aussi des applications dans le domaine de la robotique. En effet, de tels manœuvres s'avèrent utiles pour le contrôle de pose d'atterrissage pour des robots susceptibles aux chutes, comme les robots sauteurs ou les robots de secours qui doivent être déployés dans des environnements dangereux et difficiles à parcourir. Dans cette optique, le travail présenté dans ce mémoire vise à développer et démontrer des manœuvres de réorientation permettant une réorientation rapide (redressement de 180 degrés -- le pire cas possible -- dans le temps d'une chute d'un mètre) et multiaxe. Tout d'abord, une architecture articulée ainsi que deux manœuvres de réorientation sont conçues afin d'atteindre les capacités de réorientation visées et les performances de cette architecture sont testées en simulation. Les résultats obtenus démontrent que l'architecture proposée est capable de se réorienter selon plusieurs axes, mais n'atteint pas les performances visées en termes de vitesse de réorientation. Par la suite, une architecture mobile omnidirectionnelle et compacte est conçue afin d'adresser les limitations de la première architecture. Un prototype de cette architecture est développé et permet d'effectuer une réorientation de 179 degrés selon son axe de tangage en 0.44 secondes tout en conservant sa capacité de se redresser selon plusieurs axes. Les performances de réorientation visées sont alors atteintes avec ce deuxième prototype. Enfin, une méthode de fusion de données par filtre de Kalman étendu servant à estimer l'orientation d'une plateforme en apesanteur est explicitée et est validée dans des conditions contrôlées. Ces résultats démontrent l'utilité de telles méthodes de fusion de données pour implémenter la planification automatique des manœuvres de réorientation dans les itérations futures du prototype développé.This thesis explores the application of reorientation manoeuvres to an articulated and a mobile robot architecture. These manoeuvres are often attributed to cats that are said to always land on their feet, but have also been observed in other animals and used by humans in certain sports. However, these manoeuvres are more than just a curiosity and have seen some use in the field of robotics. Indeed, reorientation manoeuvres are used for orientation control in falling robots, such as rescue robots deployed in dangerous environments, and in jumping robots. With such applications in mind, this thesis aims to develop and demonstrate fast (180-degree reorientation about one axis -- the worst-case scenario -- within the time of a one-metre fall), multi-axis reorientation manoeuvres. Firstly, an articulated architecture, along with two different manoeuvres, are designed in order to attain the desired reorientation capabilities and are tested in simulated conditions. The results obtained show that, although multi-axis reorientation is achieved, the required motor torques to reach the desired reorientation speeds are not feasible for the proposed architecture. Secondly, an omnidirectional mobile robot architecture is designed to address the limitations of the first architecture. A prototype of this mobile architecture is developed and is used to demonstrate a reorientation of 179 degrees about the pitch axis in 0.44 seconds as well as a reorientation about multiple axes. Therefore, with this prototype, the desired reorientation capabilities are achieved. Finally, the use of sensor fusion methods based on extended Kalman filtering in the context of estimation of the orientation of a free-floating platform is studied. The results obtained from this study support the viability of using such methods for on-board trajectory planning in future iterations of the developed prototype

Advances in Spacecraft Attitude Control

Spacecraft attitude maneuvers comply with Euler's moment equations, a set of three nonlinear, coupled differential equations. Nonlinearities complicate the mathematical treatment of the seemingly simple action of rotating, and these complications lead to a robust lineage of research. This book is meant for basic scientifically inclined readers, and commences with a chapter on the basics of spaceflight and leverages this remediation to reveal very advanced topics to new spaceflight enthusiasts. The topics learned from reading this text will prepare students and faculties to investigate interesting spaceflight problems in an era where cube satellites have made such investigations attainable by even small universities. It is the fondest hope of the editor and authors that readers enjoy this book

Development of a Robotic Positioning and Tracking System for a Research Laboratory

Measurement of residual stress using neutron or synchrotron diffraction relies on the accurate alignment of the sample in relation to the gauge volume of the instrument. Automatic sample alignment can be achieved using kinematic models of the positioning system provided the relevant kinematic parameters are known, or can be determined, to a suitable accuracy. The main problem addressed in this thesis is improving the repeatability and accuracy of the sample positioning for the strain scanning, through the use of techniques from robotic calibration theory to generate kinematic models of both off-the-shelf and custom-built positioning systems. The approach is illustrated using a positioning system in use on the ENGIN-X instrument at the UK’s ISIS pulsed neutron source comprising a traditional XYZΩ table augmented with a triple axis manipulator. Accuracies better than 100microns were achieved for this compound system. Although discussed here in terms of sample positioning systems these methods are entirely applicable to other moving instrument components such as beam shaping jaws and detectors. Several factors could lead to inaccurate positioning on a neutron or synchrotron diffractometer. It is therefore essential to validate the accuracy of positioning especially during experiments which require a high level of accuracy. In this thesis, a stereo camera system is developed to monitor the sample and other moving parts of the diffractometer. The camera metrology system is designed to measure the positions of retroreflective markers attached to any object that is being monitored. A fully automated camera calibration procedure is developed with an emphasis on accuracy. The potential accuracy of this system is demonstrated and problems that limit accuracy are discussed. It is anticipated that the camera system would be used to correct the positioning system when the error is minimal or notify the user of the error when it is significant

Advances in Spacecraft Attitude Control

Spacecraft attitude maneuvers comply with Euler's moment equations, a set of three nonlinear, coupled differential equations. Nonlinearities complicate the mathematical treatment of the seemingly simple action of rotating, and these complications lead to a robust lineage of research. This book is meant for basic scientifically inclined readers, and commences with a chapter on the basics of spaceflight and leverages this remediation to reveal very advanced topics to new spaceflight enthusiasts. The topics learned from reading this text will prepare students and faculties to investigate interesting spaceflight problems in an era where cube satellites have made such investigations attainable by even small universities. It is the fondest hope of the editor and authors that readers enjoy this book