Student Projects
Contact Information
University: Konkuk University, South Korea
Team Member(s): Byoung-Jin_Lee, Seung-Jun_Lee
Faculty Advisors: Prof. Sangkyung Sung
Email Address: schumir_@hotmail.com, hopengman@naver.com
Description:
Our platform is the Rotary Unmanned Aerial Vehicle (RUAV). For this automatic system, this is consisted with GPS (Global Positioning System), IMU (Inertial Measurement Unit), photo sensor for getting main rotor RPM data and NI-sbRIO. This rotary vehicle (helicopter) weights 4.1kg within 12cell Li-Po battery (5000mAh) and is 1.5m overall length.
Rotary UAV platform on ground
Products:
NI sbRIO-9602
NI 9870
LabVIEW 8.5
NI-RIO 2.4.1
The Challenge:
Automatic system in UAV is very complex. And aerial vehicle is high accidental platform. So UAV is very difficult and dangerous system. For solving those problems, we arranged what we need to do at first.
We need:
1. the high performance embedded system that is easy to develop.
2. the real time monitoring system to prevent the accidents.
3. to acquire the high rate sensor data for the high dynamic RUVA control.
4. the light hardware. If it is heavy, aircraft can’t fly!
Manual Flight Control
The Solution:
1. DSP or ARM processor based by C language is very famous in embedded system. But the composition of their development environment is not simple. The development tool is difficult to the beginner. And the library is rare. So to solve this problem, we choose NI-sbRIO.
sbRIO can be developed in LabVIEW environment. It is easy to develop the algorithm and use H/W, S/W library. We know that this embedded system is more expensive than other and LabVIEW is heavier than other development tools. But using this system, we save more time and reduce people in embedded part. So remain people can be putted in other part.
NI-sbRIO 9602
2. For operating UAV, GCS (Ground Control System) is also needed. GCS controls aerial vehicles paths, commands operations and notices the situation of UAV to developer or commander.
So GCS is very important part as flight system. In LabVIEW environment, using the LabVIEW front panel we can consist GCS. The front panel shows all of the flight data and changes the values. Its response is very fast, so we use those function of the front panel for the gain tuning of PID controller. It is very simple and easy. So we can also save more time.
Front panel of GCS
3. Though sbRIO has fast main processor (400MHz), many sensor data could make some problems. For control the high dynamic system, we need high update rate sensor data.
In our flight system, IMU (Inertial Measurement Unit) is consisted. The IMU outputs the packet in high rate (100Hz), and each packet has about 100byte data. It is very high rate and big packet. It takes many resources in sbRIO main processor. Therefore we reduce the calculations for sensor data in main processor for the guidance, navigation and control calculations.
sbRIO has also FPGA. FPGA operates the high fast logic gate calculations. So using FPGA, we can divide the sensor data calculations in main processor.
To use sensor data, several calculations are needed. Most of the calculations are bit or single byte calculations so these calculations can be operated in FPGA. Using this method, RTOS in main processor only converts rearranged bit data to useable data. It reduces the total calculations in the main process.
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Sensor Data Flow from FPGS to RTOS in Main Processor
4. Weight is one of the most important parameter in aerial vehicles. But sbRIO is heavier than other embedded system. So we should reduce the weight of other devices.
Case material is wood. Wood is light but not so strong material. But it is easy to cut and cheaper than other material. And we cut all of cable in this case shorter. Only needed devices to automatic flight are putted in to this case. For low power consumption, all decoration parts (LED, beep…) are removed.
This flight system needs 20W. So we designed the power supply to convert battery voltage (22.2V) to 12V, 5V and 3.3V. To make only needed voltage and ampere, our designed power supply is save the wasted power consumption. It means that FCS (Flight Control System) could use smaller battery.
Total Hardware Configuration
sbRIO is installed in bottom layer. In top layer, NI-9870, WLAN AP (Access Point), and power supply are installed. NI-9870 is able to communicate with sensors via RS-232. WLAN AP is used to connection to GCS. And Auto/Manual Switch converts the actuator signals between Auto/Manual signals. If RUAV is in dangerous situations during Auto-Pilot mode, pilot can control the vehicle using the Auto/Manual Switch.
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Data Flow of FCS
sbRIO 9602 don’t have the analog to digital converter. So we add Amtel AVR to sensing the battery analog voltage. sbRIO 9612 have this function but it is 70g heavier and more power consumption than 9602. The rearranged data in FPGA are sent to RTOS in main processor. The Controller in RTOS is operated getting the sensor data and output the control values. Those values are sent to FPGA to generate digital signal for actuator. Those digital signals are PWM signal. PWM signals input to main rotor motor or servo motors. And we observe these information via GCS
Flight Test Conclusion
Landing and take-off are dangerous operation to all of flight vehicles. For the fallow flight test, Human pilot controlled the RUAV in landing and take-off operations. Except two operations, all movements are controlled by Auto-Pilot. For the analyzations of the flight, sensor data is saved in flash memory of sbRIO. The following figures are made using the saved data. And also, during flight test, display computer of GCS had showed the real time flight path. Using the GCS, we could observe the RUAV conditions and command the operations to RUAV.
Following figures show the ‘Water Drip Shape’ flight path and path error. This operation is repeated 4-times. The maximum path error is 5 meters. Those paths are smaller than other paths. So the RUAV flied near from ours and we could observe the flight RUAV.
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Flight Path(Left) and Error(Right)
Following figures show the ‘Infinity Symbol Shape’ flight path and path error. This operation is repeated 2-times. The maximum path error is 8 meters. Those paths are bigger than ‘Water Drip Shape’ flight path. In this path, RUAV could fly faster speed. This path was used to confirm the high speed flight and the turning the header.
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Flight Path(Left) and Error(Right)
