Nonlinear filters are often very computationally expensive and usually not suitable for real-time applications. Real-time navigation algorithms are typically based on linear estimators, such as theâ€¦ (More)

The problem of estimating the state vector of a dynamical system from vector measurements, when it is known that the state vector satisfies norm equality constraints is considered. The case of aâ€¦ (More)

The well-known Wahba Problem [1] is a non-linear, weighted least-squares problem that seeks to obtain the optimal attitude matrix from a set of at least two independent vector measurements. The mostâ€¦ (More)

Non-convex and non-affine parameterizations of uncertainty are intrinsic within every attitude estimation problem given the fact that minimal and/or nonsingular representations of the attitude matrixâ€¦ (More)

A method to deal with uncertainties in initial orbit determination (IOD) is presented. This is based on the use of Taylor differential algebra (DA) to nonlinearly map the observation uncertaintiesâ€¦ (More)

Using direction vectors of unit length as measurements for attitude estimation in an extended Kalman filter inevitably results in a singular measurement covariance matrix. Singularity of theâ€¦ (More)

Introduction: The Perception Sensory Threshold (ST) for sinusoidal current stimuli at 5, 250, and 2,000 Hz is commonly used in the assessment of peripheral nerve fibers (C, AÎ´, and AÎ², respectively).â€¦ (More)

The Orbital Cygnus vehicle is being developed to perform autonomous rendezvous with International Space Station (ISS) and to provide cargo services to the faculty. Safety through fault management hasâ€¦ (More)

Many space applications involve rendezvous with a vehicle in circular orbit. A subset of these applications requires the visiting vehicle to approach with a constant direction as seen by the target.â€¦ (More)

Linear covariance analysis can serve as a viable technique in determining both navigation errors and trajectory dispersions for spacecraft rendezvous analysis and design. This work addresses issuesâ€¦ (More)