The Experts below are selected from a list of 27483 Experts worldwide ranked by ideXlab platform
Alexander Oliva - One of the best experts on this subject based on the ideXlab platform.
-
cooperative visual Inertial Sensor fusion fundamental equations and state determination in closed form
Autonomous Robots, 2020Co-Authors: Agostino Martinelli, Alessandro Renzaglia, Alexander OlivaAbstract:This paper investigates the visual and Inertial Sensor fusion problem in the cooperative case and provides new theoretical and basic results.Specifically, the case of two agents is investigated. Each agent is equipped with Inertial Sensors (accelerometer and gyroscope) and with a monocular camera. By using the monocular camera, each agent can observe the other agent. No additional camera observations (e.g., of external point features in the environment) are considered.First, the entire observable state is analytically derived. This state contains the relative position between the two agents (which includes the absolute scale), the relative velocity, the three Euler angles that express the rotation between the two local frames and all the accelerometer and gyroscope biases.Then, the basic equations that describe this system are analytically obtained. %In other words, both the dynamics of the observable state and all the camera observations are expressed only in terms of the components of the observable state and in terms of the Inertial measurements. These are the fundamental equations that fully characterize the problem of fusing visual and Inertial data in the cooperative case. The last part of the paper describes the use of these equations to obtain a closed-form solution that provides the observable state in terms of the visual and Inertial measurements provided in a short time interval. The impact of the presence of the bias on the performance of this closed-form solution is also investigated and a simple and effective method to obtain the gyroscope bias is proposed.Extensive simulations clearly show that the proposed method is successful. It is worth noting that it is possible to automatically retrieve the absolute scale and simultaneously calibrate the gyroscopes not only without any prior knowledge, but also without external point features in the environment.
-
Cooperative Visual-Inertial Sensor Fusion: The Analytic Solution
IEEE Robotics and Automation Letters, 2019Co-Authors: Agostino Martinelli, Alexander Oliva, Bernard MourrainAbstract:This letter analyzes the visual–Inertial Sensor fusion problem in the cooperative case of two agents, and proves that this Sensor fusion problem is equivalent to a simple polynomial equations system that consists of several linear equations and three polynomial equations of second degree. The analytic solution of this polynomial equations system is easily obtained by using an algebraic method. In other words, this letter provides the analytic solution to the visual–Inertial Sensor fusion problem in the case of two agents. The power of the analytic solution is twofold. From one side, it allows us to determine the relative state between the agents (i.e., relative position, speed, and orientation) without the need of an initialization. From another side, it provides fundamental insights into all the theoretical aspects of the problem. This letter mainly focuses on the first issue. However, the analytic solution is also exploited to obtain basic structural properties of the problem that characterize the observability of the absolute scale and the relative orientation. Extensive simulations and real experiments show that the solution is successful in terms of precision and robustness.
Agostino Martinelli - One of the best experts on this subject based on the ideXlab platform.
-
cooperative visual Inertial Sensor fusion fundamental equations and state determination in closed form
Autonomous Robots, 2020Co-Authors: Agostino Martinelli, Alessandro Renzaglia, Alexander OlivaAbstract:This paper investigates the visual and Inertial Sensor fusion problem in the cooperative case and provides new theoretical and basic results.Specifically, the case of two agents is investigated. Each agent is equipped with Inertial Sensors (accelerometer and gyroscope) and with a monocular camera. By using the monocular camera, each agent can observe the other agent. No additional camera observations (e.g., of external point features in the environment) are considered.First, the entire observable state is analytically derived. This state contains the relative position between the two agents (which includes the absolute scale), the relative velocity, the three Euler angles that express the rotation between the two local frames and all the accelerometer and gyroscope biases.Then, the basic equations that describe this system are analytically obtained. %In other words, both the dynamics of the observable state and all the camera observations are expressed only in terms of the components of the observable state and in terms of the Inertial measurements. These are the fundamental equations that fully characterize the problem of fusing visual and Inertial data in the cooperative case. The last part of the paper describes the use of these equations to obtain a closed-form solution that provides the observable state in terms of the visual and Inertial measurements provided in a short time interval. The impact of the presence of the bias on the performance of this closed-form solution is also investigated and a simple and effective method to obtain the gyroscope bias is proposed.Extensive simulations clearly show that the proposed method is successful. It is worth noting that it is possible to automatically retrieve the absolute scale and simultaneously calibrate the gyroscopes not only without any prior knowledge, but also without external point features in the environment.
-
Cooperative Visual-Inertial Sensor Fusion: The Analytic Solution
IEEE Robotics and Automation Letters, 2019Co-Authors: Agostino Martinelli, Alexander Oliva, Bernard MourrainAbstract:This letter analyzes the visual–Inertial Sensor fusion problem in the cooperative case of two agents, and proves that this Sensor fusion problem is equivalent to a simple polynomial equations system that consists of several linear equations and three polynomial equations of second degree. The analytic solution of this polynomial equations system is easily obtained by using an algebraic method. In other words, this letter provides the analytic solution to the visual–Inertial Sensor fusion problem in the case of two agents. The power of the analytic solution is twofold. From one side, it allows us to determine the relative state between the agents (i.e., relative position, speed, and orientation) without the need of an initialization. From another side, it provides fundamental insights into all the theoretical aspects of the problem. This letter mainly focuses on the first issue. However, the analytic solution is also exploited to obtain basic structural properties of the problem that characterize the observability of the absolute scale and the relative orientation. Extensive simulations and real experiments show that the solution is successful in terms of precision and robustness.
Bernard Mourrain - One of the best experts on this subject based on the ideXlab platform.
-
Cooperative Visual-Inertial Sensor Fusion: The Analytic Solution
IEEE Robotics and Automation Letters, 2019Co-Authors: Agostino Martinelli, Alexander Oliva, Bernard MourrainAbstract:This letter analyzes the visual–Inertial Sensor fusion problem in the cooperative case of two agents, and proves that this Sensor fusion problem is equivalent to a simple polynomial equations system that consists of several linear equations and three polynomial equations of second degree. The analytic solution of this polynomial equations system is easily obtained by using an algebraic method. In other words, this letter provides the analytic solution to the visual–Inertial Sensor fusion problem in the case of two agents. The power of the analytic solution is twofold. From one side, it allows us to determine the relative state between the agents (i.e., relative position, speed, and orientation) without the need of an initialization. From another side, it provides fundamental insights into all the theoretical aspects of the problem. This letter mainly focuses on the first issue. However, the analytic solution is also exploited to obtain basic structural properties of the problem that characterize the observability of the absolute scale and the relative orientation. Extensive simulations and real experiments show that the solution is successful in terms of precision and robustness.
Arnaud Landragin - One of the best experts on this subject based on the ideXlab platform.
-
a transportable cold atom Inertial Sensor for space applications
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 2017Co-Authors: Vincent Menoret, Arnaud Landragin, Remi Geiger, Guillaume Stern, Patrick Cheinet, B Battelier, N Zahzam, Pereira Dos F Santos, Alexandre Bresson, Philippe BouyerAbstract:Atom interferometry has hugely benefitted from advances made in cold atom physics over the past twenty years, and ultra-precise quantum Sensors are now available for a wide range of applications [1]. In particular, cold atom interferometers have shown excellent performances in the field of acceleration and rotation measurements [2,3], and are foreseen as promising candidates for navigation, geophysics, geo-prospecting and tests of fundamental physics such as the Universality of Free Fall (UFF). In order to carry out a test of the UFF with atoms as test masses, one needs to compare precisely the accelerations of two atoms with different masses as they fall in the Earth’s gravitational field. The sensitivity of atom interferometers scales like the square of the time during which the atoms are in free fall, and on ground this interrogation time is limited by the size of the experimental setup to a fraction of a second. Sending an atom interferometer in space would allow for several seconds of excellent free-fall conditions, and tests of the UFF could be carried out with precisions as low as 10-15 [4]. However, cold atoms experiments rely on complex laser systems, which are needed to cool down and manipulate the atoms, and these systems are usually very sensitive to temperature fluctuations and vibrations. In addition, when operating an Inertial Sensor, vibrations are a major issue, as they deteriorate the performances of the instrument. This is why cold atom interferometers are usually used in ground based facilities, which provide stable enough environments. In order to carry out airborne or space-borne measurements, one has to design an instrument which is both compact and stable, and such that vibrations induced by the platform will not deteriorate the sensitivity of the Sensor. We report on the operation of an atom interferometer on board a plane carrying out parabolic flights (Airbus A300 Zero-G, operated by Novespace). We have constructed a compact and stable laser setup, which is well suited for onboard applications. Our goal is to implement a dual-species Rb-K atom interferometer in order to carry out a test of the UFF in the plane. In this perspective, we are designing a dual-wavelength laser source, which will enable us to cool down and coherently manipulate the quantum states of both atoms. We have successfully tested a preliminary version of the source and obtained a double species magneto-optical trap (MOT).
-
continuous cold atom Inertial Sensor with 1 nrad sec rotation stability
Physical Review Letters, 2016Co-Authors: Indranil Dutta, B. Venon, D Savoie, Carlos L. Garrido Alzar, B Fang, Remi Geiger, Arnaud LandraginAbstract:We report the operation of a cold-atom Inertial Sensor which continuously captures the rotation signal. Using a joint interrogation scheme, where we simultaneously prepare a cold-atom source and operate an atom interferometer (AI), enables us to eliminate the dead times. We show that such continuous operation improves the short-term sensitivity of AIs, and demonstrate a rotation sensitivity of $100\text{ }\text{ }\mathrm{nrad}/\mathrm{sec}/\sqrt{\mathrm{Hz}}$ in a cold-atom gyroscope of $11\text{ }\text{ }{\mathrm{cm}}^{2}$ Sagnac area. We also demonstrate a rotation stability of $1\text{ }\text{ }\mathrm{nrad}/\mathrm{sec}$ at ${10}^{4}\text{ }\text{ }\mathrm{sec}$ of integration time, which represents the state of the art for atomic gyroscopes. The continuous operation of cold-atom Inertial Sensors will lead to large area AIs at their full sensitivity potential, determined by the quantum noise limit.
Henggao Ding - One of the best experts on this subject based on the ideXlab platform.
-
a micromachined gas Inertial Sensor based on thermal expansion
Sensors and Actuators A-physical, 2014Co-Authors: Rong Zhu, Song Lin Cai, Henggao Ding, Yong Jun YangAbstract:Abstract Thermal expansion in volume is a natural phenomenon as a result of change in temperature. However, it is used rarely as an actuating source of movement in macrocosm due to its weak motion. In this paper we propose to utilize a gas thermal expansion in microcosm to generate seismic gaseous mass for sensing Inertial quantities including angular rate and acceleration. The expansion-based Inertial Sensor possesses the advantages of simple structure, low fabrication cost, high shock resistance, large-range rotation gauge, and low coupling between rotation and acceleration. We present the theory principle for applying thermal expansion to Inertial Sensor, and conduct the validation of simulations and experiments on the new Sensor. The results indicate that the Sensor with a tailor-made read-out circuit is effective to simultaneously detect both of the Z-axis rotation and the Y-axis acceleration, and exhibits a good linearity of angular rate output with respect to a large-range rotation of ±3000°/s.
-
micromachined gas Inertial Sensor based on convection heat transfer
Sensors and Actuators A-physical, 2006Co-Authors: Henggao Ding, Yan Su, Zhaoying ZhouAbstract:A micromachined gas Inertial Sensor based on the principle of convection heat transfer is presented in the paper. The configuration of the Sensor consists of a small silicon etched cavity, a suspended central heater and four suspended thermistor wires, all of which are assembled and packaged in a hermetic chamber. The Sensor has similar configuration with known thermal accelerometers, but is different and novel because it is not only as a dual-axis accelerometer but also as a single-axis gyroscope. Numerical simulations and primary experiments are performed to validate the effectiveness of the Sensor.