U.A.R.C. Unmanned Aerial Reconnaissance Copter Summer Critical Design Review. Group# 9 Clint Mansfield Edwin Giraldo Jeremy Brooks

Transcription

1 U.A.R.C. Critical Design Review Group# 9 Clint Mansfield Edwin Giraldo Jeremy Brooks Unmanned Aerial Reconnaissance Copter Summer 2009

2 MOTIVATION Design a low-cost Unmanned Vehicle that can gather information. Military application to protect personnel in unknown terrain. Build a vehicle that t uses little or no user input.

3 GOALS Fly autonomously without user interaction. Utilizes GPS to give headings. Stable hover Low maintenance Lightweight components Data acquisition through the use of streaming video Obstacle avoidance Low power consumption

4 SPECIFICATIONS Small in design (portable) ~2ft. X 2 ft. X 7 in. Electrically powered by a standard 2-cell 7.4 V rechargeable Li-Po battery minute flight time operation. 6 Degrees of freedom monitored by sensors to maintain stability. Throttle is controlled by a 1 2 ms PWM signals sent from µc, one pulse per 20 ms. Fail safe system of less than 15 feet away. ay Step down input voltage to 3.3V and 5V for sensors Avoid obstacles that range 3 feet or less.

5 HARDWARE BLOCK DIAGRAM Speed C # 1 Distance sensor Tilt sensing Analog To Digital Converter i 2 C PWM Output Speed C # 2 Speed C # 3 Speed C # 4 Rotation sensing Digital compass UARC Gps Module UART LEGEND INPUT OUTPUT Edwin Sensors and software coding Clint Control systems and Simulation Jeremy Systems implementation, PCB, and testing CONTROL MEMORY

6 SOFTWARE BLOCK DIAGRAM Orientation Rotation Proximity to Obstacles Failsafe mechanism Level with Horizon? Pitch, Roll, Inversion Physical Distance Manual override to shutdown Main Program Will take in the values of all necessary inputs and implement the digital PID controllers to send out appropriate PWM signal for adjustments to height, speed, orientation, and direction PWM signal PWM signal PWM signal PWM signal Speed Controller Front Motor Speed Controller o Right Motor Speed Controller Rear Motor Speed Controller Left Motor GPS Coordinates X, Y, Z Any data to be stored or read from memory LEGEND INPUT OUTPUT Compass Coordinates Pointing North, South, East, or West Memory CONTROL MEMORY

7 FLIGHT ALGORITHM FLOW Basic States of flight No Yes X = -Xd? Move Left No Ground Take off? Yes Lift Z = Zd? Yes No Move Right Yes X = Xd? No Hover No Y = -Yd? Yes Move Back No Land Z = 0? Move Front No Y = Yd? Yes Yes Ground

8 COMPONENT SELECTION DECISION Microcontroller With the development board; small in design. Enough ports to accept all sensors we have. Easy to program. UART compliant. Produce PWM signals

9 CONTROLLER OPTIONS µc Active CPU PWM RAM Flash I/O Power speed TI MSP430 Coridium ARMmite Microchip 18F4550 ~220 µa 16 MHz 1-ch 128 B 2K 10 GPIO 1-ch ADC ~50 ma 60 MHz 8-ch 8 K 32K 32 GPIO 8-ch ADC UART ~11 µa 48 MHz 2-ch 1 Kb 16K 35 GPIO 13-ch ADC

10 COMPONENT SELECTION DECISION Tilt Sensing Low Power Consumption Small and Lightweight Good Sensitivity Manufacturer Part Number # of Axes Sensitivity Current Draw Price Analog Devices ADXL /- 5g 480uA $ Analog Devices ADXL /- 3g 320uA $34.95 STMicroelectronics LIS3LV02DQ 3 +/-2 or 6 400uA $43.95

11 COMPONENT SELECTION Analog Devices ADXL330 Accelerometer Triple axis V 3V operation Analog output Vref 1.4V

12 COMPONENT SELECTION DECISION Rotation Sensing Low Power Consumption Small and Lightweight Good Sensitivity Manufacturer Part Number # of Axes Range Current Draw Price Analog Devices ADXRS º/ sec. 5mA $64.95 STMicroelectronics LISY300AL º / sec. 4.8mA $29.95 Invensense IDG º / sec 9.5mA $74.95

13 COMPONENT SELECTION Analog Devices ADXRS614 Gyroscope 50 /sec rate sensitivity Single axis 5 5V operation Analog output Vref 2.3V

14 COMPONENT SELECTION DECISION Height Sensing Obstacle Avoidance Low Power Consumption Small and Lightweight Good Sensitivity Manufacturer Part Number Technology Range Current Draw Price Maxbotix EZ0 Ultrasonic ma $27.95 Sharp GP2Y0A02YK0F Infrared ma $15.95

15 COMPONENT SELECTION Ultrasonic Range Finder - Maxbotix LV- EZ0 Multiple signal output 2 5V operation 6 254in range with 1 inch resolution Refresh rate every 49 millisecs Vref 51.2mV At 6 inches

16 FLIGHT HARDWARE Frame Carbon Fiber Design Includes: Motor mounts Propellers Main gears Brushed Motors Set of clockwise and counterclockwise blades

17 SPEED CONTROLLERS Castle Creations Thunderbird - 9 9A, 15V Max. Weight: 8g Auto Motor Cut-off Fully Programmable

18 MOTORS/PROPS Feigao Brushless Motor S 6A, Inrunner 2283 RPM/V Weight: 43.4g Dia. Propellers 2-Piece Black Nylon Folding Design

19 POWER SUPPLY Thunder Power Lithium Polymer (Li-po) 7.4V, 2 cell, 2100mAh Max. Continuous Current: 31.5A Max Burst Current: 50A Weight: 95g Rechargeable

20 FLIGHT DYNAMICS A good dynamical derivation will allow for realistic simulation design UARC is modeled as a symmetrical rigid body There are 6 degrees of freedom The system is controlled by four inputs being F - total thrust on z-axis T1 - torque about x-axis T2 - torque about y-axis T3 - torque about z-axis Since the number of input actuators is less than the DOF, the system is under actuated UARC body frame B will be represented in inertial frame E.

21 FLIGHT DYNAMICS (CON T) The equations of motion are derived d through h Newton - Euler formulation These lead to the following

22 FLIGHT DYNAMICS (CON T) Ultimately the following equations of translation and rotation can be derived Below represent the actuator control inputs. These control inputs relate the thrust induced from the individual motors to the square of angular velocity and other aerodynamic coefficients from the prop.s Vertical force input Roll actuator input Pitch actuator input Yaw moment input

23 SIMULATION Translational Dynamics

24 SIMULATION (CON T) SIMULATION (CON T) Rotational Dynamics

25 SIMULATION (CON T) Now the whole system can be compiled DC motors are simulated to real as possible Desired angles are implemented to induce translation along x and y axis

26 OPEN LOOP

27 VALUES USED FOR SIMULATION VARIABLE VALUE Jz kg*m^2 Jx kg*m^2 Jy kg*m^2 phi_d -1 rad/sec theta_d 1 rad/sec psi_d 0 length 0.3 m mass kg b 2 gravity 9.8 m/sec^2

28 2D DESIGN PROTOTYPE 2 Degrees of freedom Will assist in feedback control implementation Uses final design hardware

29 SIMULATION 2D Design and Dynamics Translational Rotational

30 Translational

31 Rotational

32 CONTROL SYSTEM There are many theoretical and implemented control techniques for the quad rotor A couple methods considered Linear Quadratic Regulator (LQR) Proportional Integral Derivative (PID) Advantages LQR is an optimal controller which minimizes error input to the plant, among stability PID control is simple, can be analog or digital, and it s a reliable classic Disadvantages LQR requires a precise linear dynamical model of the plant, if not precise system will become unstable A digital PID requires limiting conditions to prevent integral overflow and derivative spikes and must have a constant sampling time UARC will implement basic digital PID controllers for stability

33 CONTROL SYSTEM

34 CONTROL SPECIFICATIONS Digital implementation in C Must limit error overflow and integral runaway Sampling frequency must be at least 250 Hz, which is approximately 4 milliseconds Must limit PWM duty cycle between 1000 and 2000 us Establish PWM change in duty cycle through pidupdate pidout = pid_gyro + pid_accel PWM_M1 M1 = MINDUTY + DUTYCYCLE + pidout PWM_M2 = MINDUTY + DUTYCYCLE - pidout STATE DUTYCYCLE (us) IDLE 0 LIFT 550 HOVER 500 LAND 450

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36 FUNCTIONS init_coridium(); // starts up the coridium microprocessor void init_sensors ( ); // initializes sensors void init_pid (double p_gain, double i_gain, double d_gain, piddata *pid); // initialize pid gains and overflow limits double pid_controller (double setpoint, double processvalue, piddata *pid_st); // update controlled plant input signal Void setpwm(int pidout); // set pwm for each individual motor depending on pid output Int getgyro_x ( ); // get corresponding sensors signals from max127 ADC Int getgyro_y ( ); Int getaccel_x ( ); // get accelerometer values to determine phi and x acceleration Int getaccel_y ( ); // get accelerometer values to determine theta and y acceleration Int getaccel_z ( ); // get accelerometer values to determine z acceleration Int getultratop ( ); // get top ultrasonic sensor reading Int getultrabot () ); // get bottom ultrasonic sensor reading

37 TESTING Thrust Vs. Amperage Force (N Newtons) Current Consumption (Amps) Amps Duty Cycle Force 0.22 A 4.23% lbs 0.79 A 4.73% lbs 1.41 A 5.27% lbs 2.15 A 5.65% lbs

38 TESTING Digital output from normalized Gyro sensor m steady state % variance fro -150 CW movement Flat CCW movement Flat Note: 250 Hz through a first order low-pass filter with cutoff at 1KHz.

39 TESTING Digital output from normalized accelerometer sensor CW movement Flat CCW movement Flat Note: 250 Hz through a first order low-pass filter with cutoff at 1KHz.

40 TESTING Ultrasonic normalized distance sensor Note: 250 Hz through a first order low-pass filter with cutoff at 1KHz.

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42 PROJECT BUDGET Item Vendor Cost Spent Draganflyer airframe ebay $ $85.90 TI MSP430 Microcontroller Digi-key $59.06 $24.53 Brushless Motors; pinion gears; adapter ring (X4) BP Hobbies $ $ Speed Controllers (X2) Graves RC $54.34 $54.34 Gryo Breakout Board (X2) Sparkfun $ $ Triple Axis Accelerometer Sparkfun $34.95 $34.95 Coridium ARMmite Microcontroller Sparkfun $59.08 $59.08 Ultrasonic Range Finder - Maxbotix LV-EZ0 (X2) SuperDroid $61.60 $ D Assembly Lowes $6.62 $6.62 Max127 A/D converter I 2 C compliant (X4) Maxim IC $ $0.00 Over/Under Dual Voltage detector (X2) Intersil $7.20 $ Lipo Battery Charger On hand $21.95 $ V Rechargeable Battery 2100 mah ebay $ PCB Pending $0.00 $0.00 Passive Components Various $35.00 $35.00 $1, $640.90

43 PROJECT PROGRESS 0% 20% 40% 60% 80% 100% Research 95% Hardware Design 80% Coding 25% Parts Acquisition 85% Hardware Testing 80% Software Testing 25% Assembly and Integration 15% System Testing 0%

44 PROJECT MILESTONE

45 CONCLUSION Issues PID values to maintain stability are trial and error. Incorporating fail-safe system. GPS implementation. Digital compass. Improvements Digital battery indicator. GUI system to transmit manual coordinates. Improved obstacle avoidance system.