Robust Flight Controller for a Hexcopter

Robust Flight Controller for a Hexcopter ECE 4600 Group Project Proposal Group 02 Members: Bryan Drobot Curtis Einarson Stephanie English Kelly Riha Supervising Professor: Dr. Witold Kinsner Submission Date: September 27 th, 2013 1

Contents 1 Introduction... 3 2 Specifications... 4 2.1 Hexcopter Properties... 4 2.2 Research... 5 2.3 Hardware & Software... 5 2.3.1 Microcontroller... 5 2.3.1 Sensors... 5 2.3.2 Control and Stabilization... 6 2.4 Simulation and Testing... 6 3 Meeting, Tasks, Milestones, and Divisions of Labour... 7 3.1 Meetings... 7 3.2 Tasks, Milestones and Divisions of Labour... 8 4 Gantt Chart... 9 5 Budget... 10 6 References... 11 List of Figures Figure 1: Site Visit. Left: Hexcopter, Right: Balloon... 7 List of Tables Table 1: Orbo6 Data Sheet... 4 Table 2: Tasks and Milestones... 8 Table 3: Gantt Chartt... 9 Table 4: Budget... 10 2

1 Introduction Unmanned aerial vehicles (UAVs) are aircrafts that are unpiloted (without a human operating it on-board) and remote controlled by a ground pilot or automated with a controlling computer system. UAVs are commonly used in military applications, although they are increasingly being used by the public and government in remote aerial surveillance, transportation, search and rescue, maritime and park patrol, and many other applications. On a smaller scale, UAVs are also becoming popular with hobbyists as it is educational in flight applications as well as an entertaining pastime [1]. Hexcopters are a type of UAV similar to a helicopter but have six rotors that are parallel to the ground. The more common type of UAV is the quadcopter, which is a UAV with only four rotors. The hexcopter is advantageous over the quadcopter as it allows for more stability, lift and maneuverability with the added two blades. The goal of this project is to build a flight control unit for a large hexcopter that will be attached to a balloon filled with helium gas. The balloon use is to aid in the liftoff of the hexcopter. This design will incorporate a 3-axis accelerometer, 3-axis gyroscope, 3-axis magnetometer, altimeter sensors and GPS to aid in the control and flight of this hexcopter. The information acquired by these sensors, as well as control algorithms used in the control unit will be used together with a microcontroller to allow for fully automated flight and control of the hexcopter. The interface between the microcontroller and the other sensors will be through a communication protocol. The data will be gathered and transmitted to a master ground station. This information will allow the team to refine all components of flight for the hexcopter. Current commercial flight controllers cannot handle the size of our proposed large hexcopter. This problem will be addressed and analyzed further in this project. Though Northern Canada is a remote location, it has many communities. The cost of food and services in these locations is much higher than the rest of Canada due to the expensive transport. With the concerns of expensive freight costs continuing to grow and short travel windows due to climate and weather, roadways are expensive for taxpayers and can be dangerous for drivers. Large hexcopters may be a solution to these issues, being able to provide affordable and reliable transport under almost all weather conditions to many remote locations. UAVs will be able to increase the safety of drivers, decrease transport and infrastructure costs, increase travel windows, and reduce the environmental effects of constantly repaired roadways [2]. 3

2 Specifications The goal of this project is to design a flight controller that allows for a more autonomous hexcopter. This project will be split into four sections: hexcopter properties, research, hardware and software, and simulation and testing. 2.1 Hexcopter Properties This project will utilize a non-autonomous hexcopter named Orbo6. Orbo6 was constructed from hobby parts. Under nominal conditions the hexcopter flies for approximately 10 minutes. The hexcopter will have the following system specifications as shown in Table 1. Feature Table 1: Orbo6 Data Sheet Specification Balloon Diameter: 10 Lift: 28 lbs. Air: Helium Frame Diameter: 8 Material: Aluminum 6x G160 Brushless Outrunner No. of Cells: 9 10 LiPo 290kVTurnigy [3] kv: 290 (rpm/v) Weight: 632 g Max Current: 78 A Max Voltage: 37 V Power: 2700 W Resistance: 0.022 Ω No Load Current: 1 A at 11 V Size: 89x64 mm Shaft Diameter: 8 mm Mass: 632 g 6x Turnigy K-force Series 150A OPTO Output: 150 A continuous, 200 A Burst up to 10 seconds 2-6S Brushless ESC (Escape Speed Input Voltage: 2-6 cell Li battery 5-18 cells NiMH Controller) [4] Max Speed: 210,000 rpm (2 Pole); 70,000 rpm (6 Pole); 35,000 rpm (12 Pole) Size: 88 mm x 55 mm x 15 mm (width x length x height) Mass: 125 g 6x APC Propellers 20 x 13 EP [5] Hub Diameter: 1.25 Hub Thickness: 0.56 Shaft Diameter: 1/4 Engine Shaft Diameter Propeller Weight: 4.13 oz. Turnigy nano-tech 4000 mah 5S 45-90C Capacity: 4000 mah LiPo Pack [6] Voltage: 18.5 V / 5 cell Discharge Rate: 45C Constant; 90C Burst Weight: 583 g Size: 159 mm x 50 mm x 36 mm 4

2.2 Research The team reviewed and researched existing technologies for the implementation of robust flight controllers. Research was not limited to six rotor UAVs and as the project develops, innovative alternatives will be considered. The team investigated GPS issues such as accuracy, algorithmic issues for stabilization and control, power concerns aimed at flight duration, and physical structural matters relating to UAVs. Research will be an ongoing process throughout the year as new issues arise and as the project is refined and specifications evolve. 2.3 Hardware & Software Hardware and software will be divided into three sections: microcontroller, sensors, and control and stabilization. 2.3.1 Microcontroller The team will be selecting a cost-effective microcontroller suitable for the project. Regardless of the specific microcontroller it will be required to have: 50 100 I/O pins; High performance and low power consumption; A real-time operating system; Control of 6 ESCs; Multiple interfacing protocols for communication between the controllers and devices (sensors and ESCs); Communication between sensors and the ground station; and Programming language C, as the team members are all fluent in it. 2.3.1 Sensors Appropriate sensors will be chosen and interfaced with the microcontroller. This project will work in the 3-axis flight domain of roll, pitch, and yaw around the center of mass. The sensors will include, but are not limited to, if time permits: Accelerometer 3-axis, gyroscopes 3-axis; and magnetometer 3-axis; o The combination of the following three sensors will help stabilize the hexcopter. Altimeter; o Barometric sensor to measure pressure and convert to an altitude. GPS; and o Gives current location during flight. o The controller will responds to GPS commands sent from a ground station. 5

Radio Transceiver. o Allows for communication with ground station. o Utilize amateur radio bands between 1.8 248000 MHz [7]. 2.3.2 Control and Stabilization Currently, the hexcopter is non-autonomous. It is manually controlled by a handheld radio controller. The team intends to implement algorithms in order to control and stabilize the hexcopter more autonomously. In order to properly stabilize the hexcopter a closed loop feedback controller and filters will be designed. The hexcopter position will be defined by its GPS coordinates as well as its own coordinates from the gyroscope, accelerometer, and magnetometer. The discrepancy from its actual and intended position will be corrected through the algorithms within some acceptable error. There are various control algorithms that the team will consider in order to optimize the design. 2.4 Simulation and Testing The team will follow a strict set of testing procedures to ensure fluid development of the project. Initially, subsystem and system verification will take place. Each sensor will be verified to determine manufacture s specifications are accurate. The control algorithms will be tested in MATLAB and other programs as needed. The team will develop an experimental setup in order to start performance testing under simulated working conditions. These experiments will include testing the microcontroller singularly with the ESC, motor, and propeller to ensure proper speed control. Laboratory testing will simulate of near perfect weather conditions in the primary stages. Once all performance specifications are met then tethered testing and full field testing of the hexcopter will take place. 6

3 Meeting, Tasks, Milestones, and Divisions of Labour 3.1 Meetings To the team, meetings were deemed beneficial in synchronizing research and study. Over the summer before the current fall semester, the team met every two weeks on Saturdays with the academic advisor, Dr. Kinsner. Every other week, meetings were scheduled with all the team members. For the fall and winter semesters the team has and plans to continue to meet 2-3 times a week along with once a week with our advisor. A site visit in mid-july was scheduled to see Isopolar s airship hangar at St Andrew s Airport to explore technologies the team would be using for the project. The team obtained firsthand experience with Orbo6 while discussing specifications with one of the industry supervisors, Barry Prentice. A second site visit is scheduled late September for more detailed technical specifications. Figure 1 shows the hexcopter and the balloon which makes up Orbo6. Figure 1: Site Visit. Left: Hexcopter, Right: Balloon 7

3.2 Tasks, Milestones and Divisions of Labour Based on the time restrictions of the project and the team strengths, the following table of tasks and milestones has been proposed as seen below in Table 2. Table 2: Tasks and Milestones Task # Task List Start Day Finish Day Predecessor(s) Member in Charge Phase 1 Literature Review 1 Hexcopter Algorithms Apr-11 Sep-01 None Curtis 2 Structural Issues Apr-11 Sep-01 None Stephanie 3 Coordination Issues Apr-11 Sep-01 None Bryan 4 Power Supply Apr-11 Sep-01 None Kelly 5 Research of Hexcopter System Apr-11 Sep-01 None Group Phase 2 Hardware Design 5 High Level Flat Hexcopter Sep-01 Sep-22 5 Group 6 Power Supply Design Sep-01 Oct-27 4 Kelly 7 Controller Design Sep-01 Oct-27 2,3,5 Curtis & Stephanie 8 Casing Nov-10 Nov-24 2 Bryan Phase 3 Software Design 9 Control Algorithm Oct-01 Nov-24 7 Kelly & Bryan 10 Communication Oct-01 Nov-24 5,7 Curtis & Stephanie Phase 4 Building 11 Prototype Nov-03 Nov-24 7,9,10 Group 12 Individual System Testing Nov-24 Dec.22 11 Kelly & Bryan 13 Integrating System Dec-22 Jan-05 12 Curtis & Stephanie Phase 5 Testing 14 Laboratory Testing Jan-05 Jan-12 13 Group 15 Tethered Testing Jan-12 Feb-02 14 Group 16 Full Field Testing Feb-02 Feb-23 15 Group Phase 6 Final Report & Presentation 17 Final Report Feb-05 Mar-10 16 Group 18 Presentation Mar-16 Mar-21 Group 8

4 Gantt Chart Using the team s tasks and milestones, from Table 2, the following Gantt chart has been proposed as seen below in Table 3. Table 3: Gantt Chart Task # Task List April May June July August September October November December January February March 7 14 21 28 5 12 19 26 2 9 16 23 30 7 14 21 28 4 11 18 25 1 8 15 22 29 6 13 20 27 3 10 17 24 1 8 15 22 29 5 12 19 26 2 9 16 23 2 9 16 23 Phase1 Literature Review 1 Hexcopter Algorithms 2 Structural Issues 3 Coordination Issues 4 Power Supply 5 Research of Hexcopter System Phase2 Hardware Design 5 High Level Flat Hexcopter 6 Power Supply 7 Controller 8 Casing Phase3 Software Design 9 Control Algorithm 10 Communication Phase4 Building 11 Prototype 12 Individual System Testing 13 Integrating System Phase5 Testing 14 Laboratory Testing 15 Tethered Testing 16 Full Field Testing Phase6 Final Report 17 Final Report 18 Presentation 9

5 Budget After considering the necessary expenses and resources, the team has proposed the following budget seen in Table 4. Table 4: Budget Current Rate: 1.0283 Item Description Q uantity Cost per Item Cost Total Supplied By Motor Turnigy G160 Brushless Outrunner 290kv 6 $ 73.31 $ 439.86 Donated by ISOPolar Airships Propellers APC Propellers 20x13 EP 6 $ 22.50 $ 135.00 Donated by ISOPolar Airships Frame Custom Made by ISO POLAR Airships 1 $ - $ - Donated by ISOPolar Airships Battery Turnigy 4000mah 5S 45~90C Lipo Pack 11 $ 63.19 $ 695.09 Donated by ISOPolar Airships Battery Charger Turnigy Accucel-6 50W 6A Balancer/Charger 1 $ 22.99 $ 23.64 Donated by ISOPolar Airships Speed Controller Turnigy K-Force 150A 2-6S Brushless ESC 6 $ 77.11 $ 462.67 Donated by ISOPolar Airships Battery Charger Power Pyramid PS12KX 12 Amp 13.8V Power Supply 1 $ 63.85 $ 65.66 Donated by ISOPolar Airships Microcontroller NXP LPC 1768 1 $ 34.19 $ 34.19 Donated by ISOPolar Airships Transmitter 1 $ 150.00 $ 154.25 Donated by ISOPolar Airships Sensors 9 DoF Sensor Stick 1 $ 102.57 $ 105.48 Donated by ISOPolar Airships GPS 50 Channel GS407 Helical GPS Receiver 1 $ 89.95 $ 92.50 Donated by ISOPolar Airships GPS GS407 Breakout Board 1 $ 2.95 $ 3.03 Donated by ISOPolar Airships Altimeter Altitude/Pressure Sensor - MPL3115A2 Breakout 1 $ 15.37 $ 15.81 Donated by ISOPolar Airships Power Distribution Hexacopter Power Distribution Board RB-Trs-27 1 $ 19.99 $ 20.56 Donated by ISOPolar Airships Miscellanious 1 $ 400.00 $ 400.00 ECE Department Department Cost $ 400.00 Shipping $ - Taxes $ - Brokerage Fee $ - Total $ 400.00 Donated Cost $ 2,112.73 Taxes $ 253.53 Total $ 2,366.25 O verall Total $ 2,766.25 10

6 References [1] The UAV. The UAV Unmanned Aerial Vehicle (1 st Ed.) [Online]. Available: http://www.theuav.com/index.html [2] B. Prentice. (2013, April 24). Ice Roads, airships could work together (1 st Ed.) [Online]. Available: http://www.isopolar.com/ice-roads-airships-could-work-together/ [3] Hobby King. Turnigy G160 Brushless Outrunner 290kv (160 Glow) [Online]. Available: http://www.hobbyking.com/hobbyking/store/ 19040 turnigy_g160_brushless_outrunner_290kv_1 60_glow_.html [4] Hobby King. Turnigy K-Force 150A OPTO 2-6S Brushless ESC [Online]. Available: http://www.hobbyking.com/hobbyking/store/ 8920 turnigy_k_force_150a_opto_2_6s_brushless_e sc.html [5] APC Propellers. (2009) 20x13EP [Online]. Available: http://www.apcprop.com/productdetails.asp?productcode=lp20013ep [6] HobbyKing. Turnigy nano-tech 4000mah 5S 45~90C Lipo Pack [Online]. Available: http://www.hobbyking.com/hobbyking/store/ 14611 turnigy_nano_tech_4000mah_5s_45_90c_lip o_pack.html [7] Standard for the Operation of Radio Standards in the Amateur Radio Service, Standard RBR-4, September 2007. 11