Inertial reference unit

About: Inertial reference unit is a research topic. Over the lifetime, 1306 publications have been published within this topic receiving 22068 citations. The topic is also known as: IRU.

Calibration apparatus, methods and applications

Abstract: An inertial sensor calibration method and inertial sensor calibration apparatus. One or more diffraction patterns are generated by one or more fixed and/or moveable gratings (inertial sensors) illuminated by an atomically stabilized source attached to a base and detected by an imager. The grating and/or inertial sensor has a designed parameter value and an actual respective parameter value, such as motion or distance that can be determined upon ultra-precise measurement. Such ultra-precise measurement can be used to calibrate the grating or inertial sensor.

Inertial sensing for gait analysis and the scope for sensor fusion

Abstract: Conventional gait analysis systems make use of cameras and are therefore bounded to a restricted area. In this work, we focus on developing a low-cost, wearable gait analysis system based on inertial sensors, as a suitable ambulatory alternative to be used in unconstrained locations. The developed system is tailored to study lower body motion in terms of gait parameters and joint kinematics. The main focus is in using the inertial sensors data, e.g. joint acceleration and quaternion rotation readings, for the reconstruction of visually appealing motion sequences from low-dimensional sensor input. This requires inertial sensor data to be mapped and fused with optical motion capture data. For this purpose, we propose to use a hierarchical skeleton model obtained from an optical motion capture database.

Attitude Control System of the Wilkinson Microwave Anisotropy Probe

Abstract: The Wilkinson Microwave Anisotropy Probe mission produces a map of the cosmic microwave background radiation over the entire celestial sphere by executing a fast spin and a slow precession of its spin axis about the sun line to obtain a highly interconnected set of measurements. The attitude control system implements this spin-scan observing strategy while minimizing thermal and magnetic fluctuations, especially those synchronous with the spin period. The spacecraft attitude is sensed and controlled using an inertial reference unit, 2 star trackers, a dual-head digital sun sensor, 12 coarse sun sensors, 3 reaction wheel assemblies, and a propulsion system. Sufficient attitude knowledge is provided to yield instrument pointing to a standard deviation (1σ) of 1.3 arc-min per axis. The attitude control system also maintains the spacecraft attitude during orbit maneuvers, controls the spacecraft angular momentum, and provides for safety in the event of an anomaly. An overview of the design of the attitude control system to carry out this mission is presented, as well as some early flight experience.

Spacecraft provided with a device for estimating its velocity vector with respect to an inertial frame and corresponding estimation method

Abstract: The spacecraft (1) has an estimation device (5) whose gyrometer (9) measures an instantaneous rotational velocity vector of the spacecraft relative to an inertial reference frame, and spatially spaced magnetometers (15) measure a vector of magnetic field produced by a celestial body. A computer (20) estimates a velocity vector of the spacecraft by solving an equation relating the instantaneous velocity vector to a time derivative and a spatial gradient of the field vector, a spacecraft position vector, and a rotational velocity vector of a reference frame with respect to the inertial frame. The celestial body is the Earth, and the magnetic field is terrestrial magnetic field. The reference frame is related to the celestial body and is a geocentric-equatorial reference frame. Independent claims are also included for the following: (1) a method for estimating a velocity vector relative to an inertial reference frame of a spacecraft (2) a method for determining a corrected velocity vector of a spacecraft.

Video and inertial sensors based estimation of kinematical parameters in swimming sport

Abstract: The purpose of this study was to investigate if tracking of kinematical parameters (longitudinal acceleration, velocity and pitch angle) in swimming sport is feasible using data acquired with inertial sensors: accelerometer and gyroscope. Video data analysis combined “video + inertial sensor” and “inertial sensors only” methods are presented for estimation of kinematical parameters. The equation for estimation of longitudinal acceleration from inertial sensors data is derived and complementary filter for estimation of pitch angle variation is proposed. The inertial sensor based kinematical parameters are compared with video data analysis and electromagnetic tracking system derived parameters.