VCT’s best practices call for nine steps to successfully develop a G&C system for a vehicle. 

  1. Develop a high fidelity model and maneuvering simulation for the vehicle hydrodynamics and dynamic modes.
  2. Define vehicle requirements, including speed, depth, environmental disturbances, and payload steadiness limits.
  3. Develop system design parameters (e.g. feedback gains, logic, filters and limits for the G&C).
  4. Laboratory testing of the software using the VCT Software-in-the-loop simulator (SITL)
  5. Laboratory testing of the software plus a Single Board Computer (SBC) with the same processor used on the vehicle using the VCT Processor-in-the-Loop simulator (PITL)
  6. Laboratory testing of the software including the processor, vehicle management software, and actuators using the VCT Hardware-in-the-Loop simulator (HITL).
  7. Integration testing.
  8. Conduct focused full scale testing based on pre-test simulation results and near real time feedback during the testing.
  9. Validate and correlate the VCT simulation using the full scale test data from step-8.

The repeated application of this logical process continuously improves the underlying model and simulation and leads to better and better results in the future.  VCT’s track record with delivering G&C systems that work the first time in the water is proof that the high fidelity M&S based approach is the lowest risk and most cost productive path for developing G&C systems for undersea vehicles. 

VCT’s approach to autopilot development uses state-of-practice design techniques.  Extensive use is made of simulation testing during the development using correlated high fidelity models of the hydrodynamics and G&C components, including noise.  The design proceeds from linear state-space design and analysis to nonlinear time-domain simulation testing.  The state-of-practice in the feedback control portion of the autopilot design are Classical Control (linear time-invariant) methods.  These methods produce robust, predictable stability margins and excellent autopilot performance.  VCT uses its database of over 380 vehicles and its modeling and simulation program VCT Tools to develop the hydrodynamic models for the vehicle.  The vehicle hydrodynamic model, actuator model, autopilot and environmental conditions will be integrated into VCT Tools to simulate time domain non linear maneuvers.