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.

Simultaneous Calibrations of Voyager Celestial and Inertial Attitude Control Systems in Flight

Abstract: A mathematical description of the data reduction technique used to simultaneously calibrate the Voyager celestial and inertial attitude control subsystems is given. It is shown that knowledge of the spacecraft limit cycle motion, as measured by the celestial and the inertial sensors, is adequate to result in the estimates of a selected number of errors which adversely affect the spacecraft attitude knowledge.

An attitude heading and reference system: Basic concepts and prototype

Abstract: This article proposes a basic platform for inertial measurements. In order to control an autonomous vehicle, it is fundamentally important to know its attitude. For aerial vehicles, this information is critical to determining the control loop's feedback parameters. For manned aircraft, roll, pitch and yaw can be obtained through orientation by an inertial reference, usually the ground, or instruments such as an artificial horizon or a compass. Still all of them are dependent on pilot interaction. For unmanned platforms, it becomes necessary to use an electronic device capable of measuring physical quantities related to that goal. A device that aggregates these sensors is called IMU (Inertial Measurement Unit). An IMU contains inertial sensors that measure linear acceleration and angular rate, among other physical data. Through reading and fusing these data it is possible to obtain attitude information which, applied to flight history, can help to determine the position relative to an initial position, as well as feeding the control loop with the necessary data to control actuators, in a way that allows an aircraft to be stabilized or maneuvered to follow a predetermined trajectory, fulfilling the role of replacing a pilot. Our proposed platform is composed of sensors for inertial measurements, as well as a basic firmware capable of estimating the attitude of the platform, effectively creating an attitude heading reference system (AHRS).

A self-calibration method based on one-time electrification before launching for Inertial Navigation System

Abstract: The measuring error of Inertial Navigation System (INS) is the main fact that affects the hitting accuracy of inertial-guided missile. Error parameters compensation could get high-precision. First of all, this article builds an error model of gyro and accelerometer, and then in order to achieve these error parameters' value as closely as possible to their true value in application, a quick self-calibration method based on one-time electrification before launching for inertial platform is proposed. Via this method, INS rotates to 9 particular positions, outputs of inertial sensors are collected in drift state and each error parameter can be separated. The self-calibration method requires no additional devices, improving the maneuverability of the whole system. Finally, experiments are carried out using both the self-calibration method and unit calibration method, the two methods' results show that the largest compared accuracy is 9.40%, which demonstrates the practicability and validity of the suggested method.

Position-based gyroless control of spacecraft attitude

Abstract: A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i.e., attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.

Method for calibrating the positioning error of a radar and the ground velocity drift of an inertial system installed on board of an aircraft

Abstract: The radar and the central inertial system are used to simaltaneously to measure the ground speed and the estimated values are stored. The aircraft is then manoevred and the measurements retaken. The setting errors between the measurement systems and the drift in the ground speed measurement of the central inertial system are determined by solving a vector equation. The equation relates the estimated speed, Vc, of the inertial system with that, Vr, of the radar by means of a rotational matrix, R, defining the angular errors in yaw, , trim and list and the ground speed drift, B, of the central inertial system by Vc = Vr + B applied to each orientation of flight expressed by aircraft reference system.