CARVEC Flight Control Systems

An on-board flight recorder module can record up to 12 hours of the full 61Hz telemetry data output. This can be replayed through the PC groundstation and the data logged/analysed as normal.

The total weight is under 6 ounces and is designed to run of the main 4.8v battery. It will operate from 4-12 volts and draws approx 0.1A (0.5W). It works with all current RC receivers (PCM recommended) and the receiver inputs are all fully optically-isolated.

During power-up, over 25 built-in tests are performed including closed-loop testing of all inertial sensors and checksums of all code/data regions. A single red LED indicates the result of all the tests to provide a master 'No-Go' indication which can be checked prior to flight.

All parameters are fully configurable using the interactive PC setup application - such as the pitch/roll angles corresponding to full cyclic stick deflection, all individual control-loop gain settings and many other parameters. The PC also has comprehensive displays of all the system telemetry data and logging functions allow graphs to be plotted in Excel for analysis. This data includes X/Y/Z vehicle rotation rates and accelerations to allow useful vibration analysis capabilities. The system supports all common swash-plate arrangements (Normal, 3 servo 120 degree CCPM, 3 or 4 servo 90 degree CCPM).

During flight, the cyclic stick becomes demanded aircraft attitude in pitch and roll. For example, if full right-stick has been configured as +45 degrees roll, the aircraft will follow the stick position from the hover attitude at mid-stick though to 45 degrees roll at full right deflection. When the stick returns to the mid-position, the aircraft automatically comes back level. A single switch on the transmitter selects between the 'auto' mode and the normal helicopter manual mode, allowing the pilot to turn the system completely off.

The autonomous control system also incorporates a 3-axis magnetic flux compass. The internal system yaw angle is stabilised to the actual magnetic heading. In addition, the actual aircraft heading is stabilised using magnetic heading to completely eliminate heading changes due to gyro drift.

See the Gallery page for demonstration videos of the GPS control in action.

The GPS position hold capability uses a 16-channel, SBAS (WAAS, EGNOS) compatible GPS receiver . The published accuracy is 2.5m CEP and has an aquisition time of approx 40 seconds.

When position-hold is engaged, the cyclic stick becomes a true velocity demand control. The values for full-stick movement are configurable using the groundstation. When the stick is released, the system will hold the current position.

This is a CARVEC lightweight electric aerial observation helicopter. It is equipped with the full autonomous hover capabilities. If the sticks are released in flight, the system will hold position and altitude indefinitely.

The altimeter/compass module and the GPS receiver can be seen mounted on the tailboom.

See the Products page for more details about this machine.

The position/altitude hold upgrade to the core attitude control system provides a true hands-off autonomous hover capability to the CARVEC system.

A barometric altimeter allows altitude control using either pressure or GPS altitude. The system allows a 'hold' function where the system maintains the current altitude. The upper and lower 25% of the collective stick movement cause the aircraft to climb or descend at a rate pre-configured using the groundstation. The mid 50% of the stick causes the system to switch into the hold mode and maintain the current height.

Another operating mode allows a specific height and climb-rate to be preset using the groundstation prior to flight. When the altitude hold mode is engaged, the aircraft will climb/dive to the required height at the required vertical speed.

The mount controller / stabilisation module is an add-on for the core attitude control system. It utilises the main system AHRS information in order to stabilise an on-board camera mount. This gives true earth-referenced stability control.The system has the capability to drive all 3 axis of a mount (pan/tilt/roll). It provides the following features:

3-axis precision controlled slew movement. This control can be either incremental (eg spring-loaded stick) or absolute (eg rotary dial).

Preset-position mode where all 3-axis are driven to a preset position.

Park-position mode where all 3 axis are driven to a separate 'park' position for transition flight.

Manual mode slewing (camera movement with no stabilisation).

Full 3-axis stabilised mode. Camera is attitude stabilised in all 3-axis. Operator slewing is still possible.

Maximum slew rate limiting for all axis to prevent sudden movements of heavy cameras.

All slew rates, max/min mount angles etc are fully configurable using interactive PC application.

Typical displays of the groundstation during a recorded flight replay and subsequent pitch/roll control analysis graphs

(click for larger image)

click here for detailed sensor specifications

This is the real-time video overlay system used to provide various system parameters to the pilot. These include:

Magnetic heading 'tape' display

Present Position (Lat/Long) + Satellites in use count

GPS course and speed

Altitude

Vertical Speed

Elapsed Flight Time

Main/Receiver/Auxiliary Battery Voltages

Rotor RPM

Temperatures (Ambient / External Sensor)

Warning messages from built-in-test results