Page 113 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

4.2.1 Enter the ROV simulator
In general, ROV simulators apply virtual reality and computer modeling technologies to generate realistic, scenario-based ROV simulations. Simulation (to a greater or lesser extent) models stan- dard components of a real-life ROV system (e.g., acoustic imaging, obstacle avoidance, unit track- ing, underwater cameras and lights, manipulator arms, and environmental factors such as currents, variable turbidity, and tether effects) in the context of a real-time interactive operation.
Most currently available commercial systems are capable of being implemented for particular ROVs, utilizing distributed processing that uses networked CPUs (central processing units) to oper- ate a range of modules. These relate to the simulation of systems supported by the ROV system. WCROV simulators involve the simulation of a larger number of subsystems and interfaced con- trols, while OCROV systems can vary greatly from minimal onboard systems to such complex mul- tiple systems that would make some WCROV manufacturers envious.
Since 1999, simulator designers have favored various modules that performed different elements of the simulation—each running on a dedicated CPU. Currently, CPUs and GPUs (graphics proces- sing units) will run multiple modules described in the following sections from a single desktop or laptop. Not all simulators will have the same numbers and types of modules but will consist of some combination thereof.
The instructor control module
The instructor control module (ICM) acts as the simulator’s “referee” computer and also as the control center for the simulator. The instructor can monitor the trainee’s progress while performing a mission in real time. He or she may then initiate various commands that change the operational status of the ROV and peripheral equipment, as well as modify undersea environmental parameters.
The ICM enables the instructor to have total control of the VROV’s subsystems and its environ- ment during each training session. It will normally feature a “God’s-Eye view” (Figure 4.6) of the entire scene including an external rendering of the ROV for the instructor’s viewing as it proceeds through a mission. It can also provide split screens that include access to the displays that the ROV pilot and navigator would have. The ICM capabilities vary by manufacturer but would normally include (but are not limited to) the following:
1. Selective degradation or disabling of vehicle components to simulate subsystem failures
2. Control over environmental parameters such as ambient lighting, current direction/velocity, and
water turbidity (muddy/murkiness)
3. Recording and playback training session
The console interface module
The console interface module (CIM) executes a serial communications program that interacts
with an OEM ROV operator console. The CIM’s data stream can mimic that of the ROV and essentially becomes the ROV during execution of ROV training simulations. Sometimes simulators use replicas of OEM console equipment where the Pilot Program and Interface are combined. Pilot screen overlays are either provided through the OEM console equipment (or graphical user inter- face) or can be replicated in the simulator software.
When used for prototype vehicle and control system development, the combination of precision dynamic configuration and complete control software integration provides the opportunity for veri- fication and fine tuning of vehicle design and control system functionality in a virtual environment.
4.2 Simulation 101