nauka: Sagnac effect

Evidence: 100 • authority: 72

The Sagnac effect, also called Sagnac interference, named after French physicist Georges Sagnac, is a phenomenon encountered in interferometry that is elicited by rotation. The Sagnac effect manifests itself in a setup called a ring interferometer or Sagnac interferometer. A beam of light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus. In other words, when the interferometer is at rest wi…

Evidence: 61 • authority: 72

A gyroscope (from Ancient Greek γῦρος gŷros 'round' and σκοπέω skopéō 'to look') is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation (spin axis) is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, due to the conservation of angular momentum. Gyroscopes based on other operating principles also exist, such as the microchip-packaged MEMS gyroscopes found in electronic devices (sometimes called gyrometers), solid-state ring lasers, fibre optic gyroscopes, and the extremely sensitive quantum gyroscope. Applications of…

Evidence: 48 • authority: 80

Effect of Non-orthogonality in Dual-axis Gimbal on Rotational Inertial Navigation System

Evidence: 48 • authority: 88

Study of the Effects of Rotor Bearing Clearance on the Whirling of a Gimbal-Mounted Gyroscope. It has been observed that under certain conditions a gimbal-mounted gyroscope will assume a whirl of increasing amplitude upon the application of an impulsive force, the rate of increase of amplitude depending upon the gimbal inertia and the type and condition of the rotor bearings. This paper describes experimental and theoretical work carried out to investigate the effects of varying the gimbal inertia and bearing clearance upon the motion of the rotor shaft within its bearings during whirling, and upon the stability of the system. The investigation has been limited to systems in which the rotor…

Evidence: 48 • authority: 72

An inertial navigation system (INS; also inertial guidance system, inertial instrument) is a navigation device that uses motion sensors (accelerometers), rotation sensors (gyroscopes) and a computer to continuously calculate by dead reckoning the position, the orientation, and the velocity (direction and speed of movement) of a moving object without the need for external references. Often the inertial sensors are supplemented by a barometric altimeter and sometimes by magnetic sensors (magnetometers) and/or speed measuring devices. INSs are used on mobile robots and on vehicles such as ships, aircraft, submarines, guided missiles, and spacecraft. Older INS systems generally used an inertial…

Evidence: 42 • authority: 80

Mechanical model of a MEMS inertial rotational gyroscope

Evidence: 42 • authority: 80

Mechanical model of a MEMS inertial rotational gyroscope

Evidence: 36 • authority: 88

On the Stability of a Gimbal Mounted Gyroscope. The combination of large gimbal frame inertia with slackness in the main rotor bearings can result in a gyroscope executing self-excited oscillations. Such a gyroscope can be simulated by a model which reproduces the main features of this instability. As a first step towards a full analysis of this behaviour the paper establishes the stability criteria for the model.

Evidence: — • authority: 92

Risk-Aware Fault-Tolerant Multisensor Fusion for Human-Machine Decision Support in Autonomous Navigation and Mooring in Confined Waters.. Autonomous navigation and mooring in confined waters require a navigation solution that remains reliable when individual sensing channels are delayed, unavailable, or environmentally degraded. A risk- and integrity-aware architecture was developed for joint processing of RTK-GNSS, inertial and heading measurements, short-range radar, LiDAR, camera, AIS, ultrasonic ranging, propulsion feedback, environmental, and mooring-line tension data. Asynchronous time alignment is combined with sensor-quality assessment, innovation-based fault detection and isolation…

Evidence: — • authority: 92

Precision and Error Propagation in Static MEMS-IMU Inertial Navigation: A Stochastic Time-Series Analysis.. This paper investigates the precision and stochastic error propagation of navigation solutions obtained from a low-cost microelectromechanical system inertial measurement unit (MEMS-IMU) under static conditions. A modern smartphone equipped with an MEMS-IMU was rigidly mounted at a calibrated fixed location to establish a zero-reference scenario, and inertial measurements were collected while the device remained stationary. The dataset was divided into 75 non-overlapping segments, each comprising 30 s of data sampled at 10 Hz, to enable statistically robust analysis. For each segment,…

Evidence: — • authority: 92

Probability-Driven Adaptive Foot-Mounted Inertial Navigation with Local Straight-Heading and Stair-Height Constraints.. Foot-mounted inertial pedestrian navigation is an attractive infrastructure-free solution for pedestrian positioning in environments where Global Navigation Satellite System (GNSS) signals are unavailable, degraded, or intentionally excluded. However, mixed-gait and multi-level motion expose two persistent failure modes: unreliable zero-velocity detection during high-dynamic motion and weak yaw observability after standard zero-velocity-aided filtering. This paper presents a probability-driven adaptive foot-mounted inertial navigation framework that couples a lightweight m…

Evidence: — • authority: 92

Development of Non Expensive Technologies for Precise Maneuvering of Completely Autonomous Unmanned Aerial Vehicles.. In this paper, solutions for precise maneuvering of an autonomous small (e.g., 350-class) Unmanned Aerial Vehicles (UAVs) are designed and implemented from smart modifications of non expensive mass market technologies. The considered class of vehicles suffers from light load, and, therefore, only a limited amount of sensors and computing devices can be installed on-board. Then, to make the prototype capable of moving autonomously along a fixed trajectory, a "cyber-pilot", able on demand to replace the human operator, has been implemented on an embedded control board. This cy…