UAV GROUND CONTROL UNIT. DESIGN AND IMPLEMENTATION
Peter V. Sharshavin
This paper describes an approach for universal civil UAV ground control unit design. The possible scenarios of civil aviation application are considered. GCU design approach based on versatility is justified. The construction and prototype are presented. GCU has portable construction, convenient user interface and hard environment tolerance.
The ground control unit (GCU) is used for unmanned aerial vehicle (UAV) control, telemetry data collection, UAV payload control, data reception and storage. Depending on task, GCU should have the features corresponding that. The design of universal GCU is not trivial. It demands all scenarios of civil unmanned aviation application to be taken into account.
Possible scenarios of civil unmanned aviation application are illustrated on fig. 1.
- UAV application for ground remote sensing (UAV1 on fig. 1). UAV is equipped by sensors for different wavelengths (optical, infrared, radio), radars etc. as a payload. This equipment demands wideband communication channel for real-time data transmission. Therefore, payload communication channel should be wideband and separated from command and telemetry channel .
- Group flight of a number of UAVs (UAV1, UAV2 on fig. 1) demands the network infrastructure to separate the channels.
- The flight on long distances (UAV3 connecting with GCU directly) induces large propagation losses on the communication channel. For small UAV increasing of transmission power to solve this problem is not acceptable because of size, weight and power consumption limits . The solution could be equipment the GCU by high gain antennas on turntable.
- The flight on very long distances (UAV3 connecting with GCU via UAV2) needs relay channel and hence the network protocol stack.
- UAV application for mineral exploration (UAV3) requires positioning with very high absolute accuracy. GNSS in combination with inertial navigation system doesn’t meet this requirement. One of solutions could be use GNSS augmentation. Therefore, the GCU should be augmentation station.
Also ground control unit should have convinient user interface with operator mistake protection and maximized process automation. The performance demands include high operating temperature range, hard environment and mechanical stress stability, high screen brightness and portable construction.
In according with listed demands the ground control unit block diagram has been designed (fig. 2). The main block of the GCU is computing unit. Computing unit performs UAV and payload data processing and storage, command sending, input-output and interaction with user. The designed PCB of computing unit is shown on fig. 3 .
GCU construction with modules placement is shown on fig. 7. The case is designed for operating on hands as well as stationary. The stand-alone operation is provided by internal lithium polymer battery.
User input-output implemented through high brightness liquid crystal screen, the keyboard on screen edges and the projected capacitive touchscreen. User interface has been organized with programmed keys on screen edges. The current function of keys is displayed on respective screen edge.
GCU has been equipped by a lot of various interfaces: from industrial CAN, RS-422, RS-485 to general purpose RS-232 and USB. The interfaces and power source have been galvanic isolated from other digital part. The presence of Ethernet interface allows connecting CGU to local network and remote operating. Also HDMI interfacefor external display connection is available.
At present time there is the CGU prototype  shown on fig. 8. This prototype is operating with “Delta”  and “Gamma”  UAVs which were created in Siberian Federal University. The operating experience has shown the propriety of selected GCU design approach.
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