Review of Anthropomorphic Head Stabilisation and Verticality Estimation in Robots

International audienceIn many walking, running, flying, and swimming animals, including mammals, reptiles, and birds, the vestibular system plays a central role for verticality estimation and is often associated with a head sta-bilisation (in rotation) behaviour. Head stabilisation, in turn, subserves gaze stabilisation, postural control, visual-vestibular information fusion and spatial awareness via the active establishment of a quasi-inertial frame of reference. Head stabilisation helps animals to cope with the computational consequences of angular movements that complicate the reliable estimation of the vertical direction. We suggest that this strategy could also benefit free-moving robotic systems, such as locomoting humanoid robots, which are typically equipped with inertial measurements units. Free-moving robotic systems could gain the full benefits of inertial measurements if the measurement units are placed on independently orientable platforms, such as a human-like heads. We illustrate these benefits by analysing recent humanoid robots design and control approaches

Gradient-like observer design on the Special Euclidean group SE(3) with system outputs on the real projective space

A nonlinear observer on the Special Euclidean group $\mathrm{SE(3)}$ for full pose estimation, that takes the system outputs on the real projective space directly as inputs, is proposed. The observer derivation is based on a recent advanced theory on nonlinear observer design. A key advantage with respect to existing pose observers on $\mathrm{SE(3)}$ is that we can now incorporate in a unique observer different types of measurements such as vectorial measurements of known inertial vectors and position measurements of known feature points. The proposed observer is extended allowing for the compensation of unknown constant bias present in the velocity measurements. Rigorous stability analyses are equally provided. Excellent performance of the proposed observers are shown by means of simulations

Flight-Time Identification of a UH-60A Helicopter and Slung Load

This paper describes a flight test demonstration of a system for identification of the stability and handling qualities parameters of a helicopter-slung load configuration simultaneously with flight testing, and the results obtained.Tests were conducted with a UH-60A Black Hawk at speeds from hover to 80 kts. The principal test load was an instrumented 8 x 6 x 6 ft cargo container. The identification used frequency domain analysis in the frequency range to 2 Hz, and focussed on the longitudinal and lateral control axes since these are the axes most affected by the load pendulum modes in the frequency range of interest for handling qualities. Results were computed for stability margins, handling qualities parameters and load pendulum stability. The computations took an average of 4 minutes before clearing the aircraft to the next test point. Important reductions in handling qualities were computed in some cases, depending, on control axis and load-slung combination. A database, including load dynamics measurements, was accumulated for subsequent simulation development and validation

Robust longitudinal rate gyro bias estimation for reliable pitch attitude observation through utilization of a displaced accelerometer array

In this thesis, a novel attitude estimation device is proposed utilizing cost-effective measurement sensors. The device fuses a rate gyroscope with an accelerometer array to estimate and eliminate the rate gyro bias online yielding accurate real time aircraft attitude tracking. Attitude determination algorithms are dependent on instantaneous and accurate measurements of translational and rotational body rates for precise estimation of vehicle orientation in three-dimensional space. Measurement error of instantaneous rate sensors, gyroscopes, is introduced via inherent biases and signal noise resulting in gyro drift. Integration of the rate signal for calculation of a net displacement amplifies these minute measurement errors leading to inaccurate and unreliable attitude observation. The proposed device is a departure from typical attitude observers and bias estimators due to its reliance on accelerometers measuring the local gravitational vector in lieu of additional magnetic field sensors or GPS. The end result of this work is a longitudinal attitude estimation device able to compute a rate gyro bias in real-time producing accurate pitch angle tracking while subjected to simulated aircraft flight conditions. The effectiveness of the newly constructed attitude estimation algorithm is demonstrated by comparison of attitude and rate gyro bias estimates produced from noise corrupted and biased sensors with the actual attitude of a nonlinear aircraft model and true rate gyro bias

Attitude Measurement

In many practical situations, it is important to determine and measure the attitude of a particular vehicle, such as a ship, an airplane, a piece of mechanical equipment such as a, crane lifter, or a spacecraft. For this reason, many attitude sensors have been developed with advanced computer and semiconductor technologies. This section first introduces the various attitude sensors with an explanation of their operating principles and then presents several methodologies for attitude measurement and determination, including ships and crane lifters, aircraft, and spacecraft applications

Rigid Body Attitude Estimation: An Overview and Comparative Study

The attitude estimation of rigid body systems has attracted the attention of many researchers over the years. The development of efficient estimation algorithms that can accurately estimate the orientation of a rigid body is a crucial step towards a reliable implementation of control schemes for underwater and flying vehicles. The primary focus of this thesis consists in investigating various attitude estimation techniques and their applications. Two major classes are discussed. The first class consists of the earliest static attitude determination techniques relying solely on a set of body vector measurements of known vectors in the inertial frame. The second class consists of dynamic attitude estimation and filtering techniques, relying on body vector measurements as well other measurements, and using the dynamical equations of the system under consideration. Various attitude estimation algorithms, including the latest nonlinear attitude observers, are presented and discussed, providing a survey that covers the evolution and structural differences of these estimation methods. Simulation results have been carried out for a selected number of such attitude estimators. Their performance in the presence of noisy measurements, as well as their advantages and disadvantages are discussed

Cyber-Physical Systems Enabled By Unmanned Aerial System-Based Personal Remote Sensing: Data Mission Quality-Centric Design Architectures

In the coming 20 years, unmanned aerial data collection will be of great importance to many sectors of civilian life. Of these systems, Personal Remote Sensing (PRS) Small Unmanned Aerial Systems (sUASs), which are designed for scientic data collection, will need special attention due to their low cost and high value for farming, scientic, and search-andrescue uses, among countless others. Cyber-Physical Systems (CPSs: large-scale, pervasive automated systems that tightly couple sensing and actuation through technology and the environment) can use sUASs as sensors and actuators, leading to even greater possibilities for benet from sUASs. However, this nascent robotic technology presents as many problems as possibilities due to the challenges surrounding the abilities of these systems to perform safely and eectively for personal, academic, and business use. For these systems, whose missions are dened by the data they are sent to collect, safe and reliable mission quality is of highest importance. Much like the dawning of civil manned aviation, civilian sUAS ights demand privacy, accountability, and other ethical factors for societal integration, while safety of the civilian National Airspace (NAS) is always of utmost importance. While the growing popularity of this technology will drive a great effort to integrate sUASs into the NAS, the only long-term solution to this integration problem is one of proper architecture. In this research, a set of architectural requirements for this integration is presented: the Architecture for Ethical Aerial Information Sensing or AERIS. AERIS provides a cohesive set of requirements for any architecture or set of architectures designed for safe, ethical, accurate aerial data collection. In addition to an overview and showcase of possibilities for sUAS-enabled CPSs, specific examples of AERIS-compatible sUAS architectures using various aerospace design methods are shown. Technical contributions include specic improvements to sUAS payload architecture and control software, inertial navigation and complementary lters, and online energy and health state estimation for lithium-polymer batteries in sUAS missions. Several existing sUASs are proled for their ability to comply with AERIS, and the possibilities of AERIS data-driven missions overall is addressed

A novel wireless low-cost inclinometer made from combining the measurements of multiple MEMS gyroscopes and accelerometers

Structural damage detection using inclinometers is getting wide attention from researchers. However, the high price of inclinometers limits this system to unique structures with a relatively high structural health monitoring (SHM) budget. This paper presents a novel low-cost inclinometer, the low-cost adaptable reliable angle-meter (LARA), which combines five gyroscopes and five accelerometers to measure inclination. LARA incorporates Internet of Things (IoT)-based microcontroller technology enabling wireless data streaming and free commercial software for data acquisition. This paper investigates the accuracy, resolution, Allan variance and standard deviation of LARA produced with a different number of combined circuits, including an accelerometer and a gyroscope. To validate the accuracy and resolution of the developed device, its results are compared with those obtained by numerical slope calculations and a commercial inclinometer (HI-INC) in laboratory conditions. The results of a load test experiment on a simple beam model show the high accuracy of LARA (0.003 degrees). The affordability and high accuracy of LARA make it applicable for structural damage detection on bridges using inclinometers.The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R. All these projects are funded with FEDER funds. The authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya, Catalunya, Spain for the funding provided through Agaur (2017 SGR 1482). It is also to be noted that funding for this research has been provided for Seyedmilad Komarizadehasl by Spanish Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).Peer ReviewedPostprint (published version

Estimating the orientation of a game controller from inertial and magnetic measurements

L’estimation de l’orientation d’un corps rigide en mouvement dans l’espace joue un rôle indispensable dans les technologies de navigation, par exemple, les systèmes militaires de missiles, les avions civils, les systèmes de navigation chirurgicale, la cartographie faite par des robots, les véhicules autonomes et les contrôleurs de jeux. Cette technique est maintenant utilisée dans certaines applications qui nous touchent directement, notamment dans les contrôleurs de jeux tels que la Wii-mote. Dans cette veine, la recherche présentée ici porte sur l’estimation de l’orientation d’un corps rigide à partir des mesures de capteurs inertiels et magnétiques peu coûteux. Comme les capteurs inertiels permettent de mesurer les dérivées temporelles de l’orientation, il est naturel de commencer par l’estimation de la vitesse angulaire. Par conséquent, nous présentons d’abord une nouvelle façon de déterminer la vitesse angulaire d’un corps rigide à partir d’accéléromètres. Ensuite, afin d’estimer l’orientation, nous proposons une nouvelle méthode d’estimation de l’orientation d’un corps rigide dans le plan vertical à partir des mesures d’accéléromètres, en discernant ses composantes inertielle et gravitationnelle. Mais, ce n’est sûrement pas suffisant d’estimer l’orientation dans le plan vertical, parce que la plupart des applications se produisent dans l’espace tridimensionnel. Pour estimer les rotations dans l’espace, nous présentons d’abord la conception d’un contrôleur de jeu, dans lequel tous les capteurs nécessaires sont installés. Ensuite, ces capteurs sont étalonnés pour déterminer leurs facteurs d’échelle et leurs zéros, de manière à améliorer leurs exactitudes. Ensuite, nous développons une nouvelle méthode d’estimation de l’orientation d’un corps rigide se déplaçant dans l’espace, encore en discernant les composantes gravitationnelle et inertielle des accélérations. Finalement, pour imiter le contrôleur de jeu Wii, nous créons une interface usager simple de sorte qu’une représentation virtuelle du contrôleur de jeu puisse suivre chaque mouvement du contrôleur de jeu conçu (réalité virtuelle). L’interface usager conçue montre que l’algorithme proposé est suffisamment précis pour donner à l’usager un contrôle fidèle de l’orientation du contrôleur de jeu virtuel.Estimating the orientation of a rigid-body moving in space is an indispensable component of navigation technology, e.g., military missile systems, civil aircrafts, surgical navigation systems, robot mapping, autonomous vehicles and game controllers. It has now come directly into some aspects of our lives, notoriously in game controllers, such as the Wiimote. In this vein, this research focuses on the development of new algorithms to estimate the rigid-body orientation from common inexpensive inertial and magnetic sensors. As inertial sensors measure the time derivatives of the orientation, it is natural to start with the estimation of the angular velocity. More precisely, we present a novel way of determining the angular velocity of a rigid body from accelerometer measurements. This method finds application in crashworthiness and motion analysis in sports, for example, where impacts forbid the use of mechanical gyroscopes. Secondly, in an attempt to estimate the orientation in a simplified setting, we propose a novel method of estimating the orientation of a rigid body in the vertical plane from point-acceleration measurements, by discerning its gravitational and inertial components. Thirdly, it is surely not enough to estimate the orientation in the vertical plane, because most applications take place in three dimensions. For estimating rotations in space, we first present the game controller design, in which all necessary sensors are installed. Then, these sensors are calibrated to determine their scale factors and offsets so as to improve their performances. Thence, we develop a novel method of estimating the orientation of a rigid body moving in space from inertial sensors, also by discerning the gravitational and inertial components of the acceleration. Finally, in order to imitate the game controller Wii, we create a simple user interface in which a virtual representative of the game controller follows every orientation of the true game controller (virtual reality). The user interface shows that the proposed algorithm is sufficiently accurate to give the user a transparent control of the orientation of the virtual game controller

The assessment of a rotorcraft simulation model in autorotation by means of flight testing a light gyroplane

The simulation and flight testing of a light gyroplane aircraft is performed obtaining results regarding the flight dynamics attributes of the vehicle. The main aim of the work was to assess the ability of a mathematical model to simulate rotorcraft in the autorotative flight state. Additionally, the results acquired were to enhance the understanding of an aircraft class for which the existing database of knowledge is limited, particularly with regards to its flight mechanics characteristics. An appropriate aircraft configuration file was obtained enabling a platform of simulation results to be generated. Parametric studies were performed primarily focusing on the influence of the vertical centre of gravity position and rotor speed degree of freedom on gyroplane longitudinal stability. A data acquisition system unique in its sophistication for this class of aircraft was developed and installed on board. The software required to drive the system was designed, and rigorous tests verifying the instrumentation functionality were conducted both on ground and in real flight. A flight test programme capable of fulfilling the experimental aims was devised and realised, yielding results both on the steady state flight characteristics of the aircraft and its dynamic response to pilot inputs. Certain trends were established on the properties of gyroplanes by interpreting the results in terms of basic aerodynamic theory, and by comparing them to previous research findings. A comparison of the experimental data to that obtained from the simulation runs, served to fulfil the model validation aim of the work presented. The effect of model and flight discrepancies on the ability of the mathematical model to realistically emulate flight dynamics in autorotation was discussed, and possible suggestions for the reasons of mismatch were presented