Remotely Augmented Vehicles & Remotely Piloted Vehicles
AFRC has used remotely augmented vehicles (RAVs) for a variety of flight test purposes for many years, and continues to support most of the ongoing AFRC research aircraft. The RAV capability uses ground-based computers to supplement or replace the onboard control and display systems.
Special cases of the RAV application include:
- Remotely computed displays (RCDs) in which ground-based computers assist the pilot in flying a precise maneuver by computing guidance parameters on the ground which are uplinked to drive displays on-board the aircraft.
- Remotely Augmented Vehicles (RAVs) which augment or replace on-board control systems with ground-based control laws or uplink commands to remotely drive aircraft control surfaces.
- Remotely piloted vehicles (RPVs) in which the research aircraft flown from a ground-based cockpit.
- Remotely Controlled Devices in which a ground station commands remote devices in a hazardous environment.
The RAV facility can be used for flight support or ground test. For vehicle-in-the-loop ground testing or simulation, coaxial cables connect the aircraft to the RAV computers. For stand-alone or hardware-in-the-loop simulation, uplink and downlink information is exchanged with the simulation host via shared memory. The RAV facility contains its own PCM computer responsible for monitoring the downlink signal, rate-limiting the incoming variables, converting the values into engineering units, monitoring the incoming radar data, and communicating uplink commands to the uplink encoder via a serial or parallel data bus. It also drives 16 stripchart channels for monitoring in real-time. Frame rates may range up to 500 Hz. The RAV control law computer is dedicated to generating uplink commands using incoming data from the PCM computer and algorithms appropriate for the application involved. It typically operates at 50 to 100 Hz. Duplicate control law computer systems are available in each simulation control room to provide software development and verification and validation. For RPV operations, there is a completely redundant system available to provide flight control.
The software structure of the tasks within each computer is identical to that used in the simulation computers. It consists of a background task to perform initialization and control displays, and a real-time task to execute the algorithms that generate uplink data or commands for the aircraft. The tasks communicate with one another by storing data in shared memory. Applications are coded in FORTRAN and C programming languages.
There is additional equipment supporting the RAV function. This equipment includes two-way radio communication with all other research stations during RAV operation, video monitors to display the test in progress, and data encryption and decryption capabilities. A real-time data recording capability is used to capture uplink, downlink, and radar data entering or leaving the facility. These data are used for project archival and post-mission playback. A reconfigurable ground station cockpit and display system is available for RPV requirements.