Perceptual disturbances in zero-g and 1-g differ. For example, the vestibular coriolis (or "cross-coupled") effect is weaker in zero-g. In 1-g, blindfolded subjects rotating on-axis experience perceptual disturbances upon head tilt, but the effects diminish in zero-g. Head tilts during centrifugation in zero-g and 1-g are investigated here by means of three-dimensional modeling, using a model t...

We demonstrate a new method for measuring the time constant of head-movement-contingent oscillopsia (HMCO) produced by vestibular Coriolis stimulation. Subjects briskly rotated their heads around pitch or roll axes whilst seated on a platform rotating at constant velocity. This induced a cross-coupled vestibular Coriolis illusion. Simultaneous with the head movement, a visual display consisting...

Many children with cerebral palsy walk with diminished knee extension during terminal swing, at speeds much slower than unimpaired children. Treatment of these gait abnormalities is challenging because the factors that extend the knee during normal walking, over a range of speeds, are not well understood. This study analyzed a series of three-dimensional, muscle-driven dynamic simulations to de...

When reaching movements are made during passive constant velocity body rotation, inertial Coriolis accelerations are generated that displace both movement paths and endpoints in their direction. These findings directly contradict equilibrium point theories of movement control. However, it has been argued that these movement errors relate to subjects sensing their body rotation through continuin...

ROBUST OBSERVERS AND CONTROLLERS FOR MARINE SURFACE VESSELSUNDERGOING MANEUVERING AND COURSE-KEEPING TASKS byNASSIM SAADDINE KHALEDAugust 2010Advisor: Prof. Nabil G. ChalhoubMajor: Mechanical EngineeringDegree: Doctor of Philosophy The dynamic behavior of marine surface vessels is highly nonlinear. Moreover, itis significantly influenced by environmental disturba...

Over the past 10 years, geodynamo simulations have grown rapidly in sophistication. However, it is still necessary to make certain approximations in order to maintain numerical stability. In addition, models are forced to make assumptions about poorly known parameters for the Earth’s core. Different magnetic Prandtl numbers have been used and different assumptions about the presence of radiogen...

The dynamic model of a mechanical system relates the time evolution of its configuration (position, velocity and acceleration) with the forces and torques acting upon it. The inverse dynamic model is important for system control while the direct model is used for system simulation. Serial structure manipulator dynamic modelling is a well established subject. So, recent developments have been or...

We are interested in using low degree-of-freedom robots to perform complex tasks by not grasping (nonprehensile manipulation). By not grasping, the robot can use gravitational, centrifugal, and Coriolis forces as virtual motors to control more degrees-of-freedom of the part. The extra motion freedoms of the part are exhibited as rolling, slipping, and free ight. This paper describes controllabi...

The aerodynamic performance of hovering insects is largely explained by the presence of a stably attached leading edge vortex (LEV) on top of their wings. Although LEVs have been visualized on real, physically modeled, and simulated insects, the physical mechanisms responsible for their stability are poorly understood. To gain fundamental insight into LEV stability on flapping fly wings we expr...

Originally introduced in connection with general relativistic Coriolis forces, the term frame-dragging is associated today a plethora of effects related to off-diagonal element metric tensor. It also frequently subject misconceptions leading incorrect predictions, even nonexistent effects. We show that there are three different levels corresponding distinct gravitomagnetic objects: potential 1-...