VCT SIMULATION

VCT has a capability unique in the industry for predicting the aerodynamic and hydrodynamic coefficients of all types of airborne and undersea vehicles prior to scale-model testing. This capability is based on analytical, computational fluid dynamics (CFD) and semi-analytical predictive techniques developed over the past 30 years and applied successfully to more than 380 vehicles.

VCT utilizes a variety of codes for hydrodynamic and control system analysis. Linear design techniques allow a quick computational turn around, as well as the application of the wealth of linear system theory. These physics-based analyses couple with nonlinear six-degree-of-freedom (6-DoF) equations of motion, as well as models of the vehicle control hardware and software. These codes are implemented via a system of computer programs named VCT Tools™, which represents the state-of-the-art in vehicle modeling and simulation.

 

The complete fluid dynamic representation required by the equations of motion for the forces and moments is computed using proprietary VCT codes with individual contributions from the vehicle’s geometric components; the body, the various fins, protuberances (external transducers) and the propulsor. The VCT build-up approach isolates each component’s force and moment contributions and the interference effects between components.

Input parameters to HydroV™ consist of a three-view drawing, weight and balance information and operational conditions. The fluid dynamic model produced by HydroV™ includes lift, drag and moment in the geometry component’s local reference frame. Angular velocity, acceleration, cross-coupled and out-of-plane effects brought about by kinematic transformations are computed at each time step in SimV™.

VCT’s approach consists of theoretical formulations, computational fluid dynamic (CFD) techniques and data correlations of systematic databases, all implemented via VCT Tools™.

Transfer functions for all in-plane and out-of-plane state variables for various inputs (control and disturbance) are computed and displayed in the form of Bode plots and root locus diagrams. Stochastic processes, such as wind-driven surface waves or deep ocean internal waves, are analyzed using spectral techniques.

Nonlinear six-degree-of-freedom (6-DoF) trajectory simulations are conducted for both self-propelled and towed vehicles. Simulations incorporate a broad class of control systems logic. Arbitrary maneuvers are executed in either a zero-noise environment or under the severe environmental conditions encountered by sea and air vehicles.  Sensor noise and sensor accuracy can be varied in simulations.