The AscTec AutoPilot is a precise and multifunctional research tool mounted on all AscTec UAVs. This flight control unit contains all necessary sensors to function as an IMU, it also has two onboard ARM7 microprocessors and various communication interfaces.
There are several strategies on how the AscTec AutoPilot can be utilized for your research projects. It can directly interpret the R/C data sent by the pilot and the serial data sent from the ground PC. For automatic missions, you can program and upload your own control algorithms directly onto the High Level processor of the UAV.
If more processing power is required or additional sensors, like cameras or laser scanners need to be connected, an additional onboard processor is installed. Its high performance and fast communication enable you to handle large amounts of data onboard. An optional WLAN module can be integrated to exchange this data between the additional processor and a ground PC. All gathered data can be used for your control algorithms and the calculated commands can then be sent to the AscTec AutoPilot.
Low Level processor
The Low Level (LL) processor handles sensor data processing, data fusion as well as our fast and stable attitude control algorithm with an update rate of 1000 Hz. It also processes the position control algorithm, using the onboard magnetometer and GPS module as additional sensor inputs. All AscTec UAVs can be operated by the pilot via a remote control in three different flight modes:
- GPS Mode (attitude-, height- and positioncontrol activated)
- Height Mode (attitude- and height-control activated)
- Manual Mode (attitude-control activated)
All AscTec UAVs have an emergency mode which is automatically activated if the data link between the UAV and the R/C of the safety pilot is lost (range > 1 km). You can choose between several emergency options depending on our mission.
Sensor data can be retrieved from the LL processor via a serial interface using a predefined serial protocol. Furthermore, the serial interface can be used to send attitude commands (pitch angle, roll angle, yaw rate and thrust) or even waypoint commands to the vehicle depending on the flight mode. Due to the size of the data structures, update rates of up to 15 Hz can be accomplished via a wireless serial link (XBee, range > 1 km). Higher update rates of up to 100 Hz can be achieved using a serial cable connection.
High Level processor
The basic concept of the AscTec AutoPilot is to offer easy programmability, and to provide a safety net while testing your own control algorithms. Therefore you can flash the High Level (HL) processor with your own algorithm and let it control the flight system. To recover from critical flight situations during your test flights, the pilot can always switch back to the well proven control algorithms on the LL processor as a safety backup.
The two microprocessors communicate with an extremely fast rate of 1000 Hz, hence all sensor data is available to the HL processoras well. Control commands can be sent back to the LL processor at the same frequency, for example the: rotational speed commands for each individual motor, pitch/roll/yaw/thrust commands, attitude commands or waypoint commands.
The HL processor offers UART, SPI and I2C interfaces as well as simple port I/Os to connect your own devices like additional sensors, servo motors or extension boards. Also custom payloads, like wireless cameras, can be powered by a 5 V or 12 V supply of the AscTec AutoPilot.