In this article a new concept of a smart satellite pushbroom imaging system with internal compensation of attitude instability effects is presented. The compensation is performed within the optical path by an active opto-mechatronic stabilization of the focal plane image motion in a closed loop system with visual feedback. The real-time image motion measurement is derived from an auxiliary matr...

This article considers a novel approach to using global positioning system (GPS) signal strength readings and estimated velocity vector for estimating the attitude of a small fixed-wing unmanned aerial vehicle (UAV). This approach has the benefit being able to estimate full position, velocity and attitude states of a UAV using only the data from a single GPS receiver and antenna. Two different ...

Due to their size, small rotorcraft are vulnerable to external flow disturbances that are challenging to flight stability and control. This paper describes preliminary results from using onboard flow measurements to augment inertial sensors for attitude control. We derive a dynamic model that captures the aerodynamic effects of wind on a single degree-of-freedom tandem-rotor test stand. A pair ...

ABSTRACT This paper will detail the navigation and dispersion design and analysis of the first Orion crewed mission. The optical navigation measurement model will be described. The vehicle noise includes the residual acceleration from attitude deadbanding, attitude maneuvers, CO2 venting, wastewater venting, ammonia sublimator venting and solar radiation pressure. The maneuver execution errors ...

In this work, we address the problem of global attitude control using direct inertial measurements. When using direct inertial measurement to observe the rigid body attitude, it is shown that due to a geometrical obstruction, it is impossible to achieve global asymptotic stability. In fact, for a particular initial condition the tracking error quaternion converges to a pure imaginary quaternion...

Robotic systems that operate in environments without access to global references like GNSS normally estimate their position by odometry. The incremental nature of this measurement is subject to drift that accumulates to large errors in the position estimate. We minimize this drift by exploiting scene knowledge in form of vanishing directions. These provide a scene referenced orientation measure...

Introduction: In the recent years different studies have been performed to determine attitude of different groups of the society towards psychiatric disorders , that their results could develop positive changes to improve the attitude of society with proper planning in this respect. Materials & Methods: This descriptive cross – sectional study has designed to determine the attitude of 600 high...

This study addresses the control problem of an unmanned quadrotor in an indoor environment where there is lack of absolute localisation data. Based on an attached inertia measurement unit, a sonar and an optic-flow sensor, the state vector is estimated using sensor fusion algorithms. A novel switching model predictive controller is designed in order to achieve precise trajectory control, under ...

This paper deals with the attitude estimation of a rigid body equipped with angular velocity sensors and reference vector sensors. A quaternion-based nonlinear observer is proposed in order to fuse all information sources and to obtain an accurate estimation of the attitude. It is shown that the observer error dynamics can be separated into two passive subsystems connected in "feedback". Then, ...

We present two results on attitude estimation using vector and rate gyro measurements, when both sets of measurements are biased. The first result concerns an observer for attitude and gyro bias that has previously been presented by Hamel and Mahony, and by Mahony, Hamel, and Pflimlin, with proven almost-global stability results when either (i) the reference vectors in the inertial frame are st...