EDGE™

MAV Control System - P09122

- Final Design Review

Erik Bellandi – Project ManagerBen Wager – Lead Engineer

Garrett Argenna – Mechanical EngineeringMichael Pepen – Electrical Engineering

Tahar Allag – Electrical EngineeringRamon Campusano – Computer Engineering

Stephen Nichols – Computer Engineering

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Contents

• Objectives & Deliverables

• Detailed Design– Logic Controller– Sensors – Control System– Test Stand– Power, Weight and Cost

• Design Specifications

• Plan for MSD II

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Project Objectives & Deliverables

Product Description / Project OverviewTo design and build a flight control system for the Micro Aerial Vehicle, that will most quickly lead to a fully autonomous system.

Key Business Goals / Project Deliverables Primary Goals:– Make the MAV as autonomous as possible.

• Achieve desired flight qualities.–Stabilize if unstable or increase damping

• Adaptable• Fully Tested and Integrate with Platform

Secondary Business Goal:– Able to compete in the 2010 EMAV Competition.

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Detailed Design

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Overall System Architecture

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Detailed System Diagram

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Logic Controller Design

• FPGA with microcontroller core– Open-source Plasma CPU core

• License issues with prior Altera Nios Core– Dual core:

• Control system core• Sensor communication core

– UART communication (GPS sensor )– SPI communication (IMU and SD card)– SD communication

• Load programs from SD• Record sensor data

– PWM communication (Pilot Input and Servo Output)

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FPGA System Diagram

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Logic Controller Prototype and Testing

• Open Source Plasma CPU core– Instantiated core on FPGA– Tested UART communication between PC and Plasma core

• SD communication– Initialized SD card into SPI mode– Read MBR and FAT16– Implemented file read capability

• PWM– Implemented and tested PWM feed-through

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Sensor Design• Sensors

– IMU• Acceleration Sensitivity: 2.5 mg’s/LSB • Rotation Sensitivity: 0.07deg/sec /LSB

– GPS• Accuracy: <2.5m • Update Rate: <0.1s

– Airspeed: Pitot-Static Probe• 0 - 0.3 PSI Differential Pressure (Airspeed)

• Sensitivity: 1 V/kPa– Altitude

• 2.2 – 18.9 PSI Absolute Pressure (Altitude)

• Sensitivity: 39.2 mV/kPa– Temperature: Omega Thermistor– Video Camera System

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PCB Physical Layout Design

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System Circuit Diagram

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Pressure Sensor Calculations

• Airspeed Calculation:– Bernoulli:

• Altitude Calculation:– Hydrostatic Pressure:

At Cruise: v = 30 mph, ΔP = 109 Pa, ΔP = 108 Pa, v = 29.88 mph

Resolution : 0.12 mph at cruise

For 10 ft change: ΔP = -0.036 kPa

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Pitot-Static Tube

• United Sensor Inc:– Commercially Available

– Custom Lengths

– Very Small

– Light Weight

– Removable Connectors– Mount through wing tip

Video Camera System

• Specs– Weight: 85 g– Range: 1.5 km– Resolution: 420 Lines– Power: 9V Battery

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Control System Concept

• Requirements:– Receive All Inputs (Pilot Input & Sensor Input)– Create Desired Flight Qualities (Stabilize or increase damping)– Command Surfaces (Flaperons, Elevator, Rudder & Thrust)– Compensate for Environment (Disturbance)– Adaptable for Different Platforms

• Concepts:– Inner-Loop rate feedback for Stability Augmentation– Autopilot controls to maintain attitude, altitude & airspeed

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Control System Concept

• Stability Augmentation System:– If an airplane is marginally stable or unstable, the SAS can provide

proper vehicle stability– Ensure the plane has the appropriate handling qualities; additional

damping can be incorporated using a pitch, roll and yaw damper.

• Autopilot: Reduce Pilot Workload (Time Permitting)– Attitude Hold – Maintain desired roll, pitch and heading– Altitude Hold – Maintain desired altitude– Velocity Hold – Maintain desired velocity

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Flight Dynamics Analysis

• Force Equations:

• Moment Equations:

• Body Angular Velocities:

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Flight Dynamics Analysis

• Dynamic Modes:– Longitudinal Motion

• Phugoid (Long Period)• Short Period

– Lateral Motion• Spiral Mode• Roll Mode• Dutch Roll Mode

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Ex: Short Period Mode• Longitudinal Motion

– Heavily damped longitudinal motion with a period of a few seconds

– Characterized by a change in angle of attack and pitch rate

– If heavily damped or has a high frequency, aircraft responds to elevator input with no overshoot

– If lightly damped or has a low frequency, aircraft will be difficult to control

– Approximate State-Space Model:

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Flight Dynamics Analysis

• Desired Flight Qualities– Based on DoD and FAA aircraft flight

quality specs

Flight Quality Specifications For out Application

Mode Metric Min Max

Phugoid Mode Damping Ratio, ζ 0.04 -

Short-period Mode Damping Ratio, ζsp 0.30 2.00

Spiral Mode Time to Double Amplitude (sec), td 1.40 -

Roll Mode Roll Time Contsant (sec), τ - 1.40

Dutch Roll Mode Damping Ratio, ζ* 0.08 -

Dutch Roll Mode Natural Freqency (rad/sec), ωn 0.40 -

Dutch Roll Mode Magnitude of real part of complex root, ζωn* 0.15 -

* Which ever criteria yields the larger value of ζ

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Flight Dynamics Analysis

• Test Case: F-16 Aircraft– Open-Loop “Unaugmented” Flight Qualities

Motion Mode ζ ωn ζ*ωn τ Doubling Time Level Comments

Longitudinal Phugoid 0.2354 0.0093 1Short Period 0.2415 0.0636 3 Unacceptable flying qualities

Lateral Spiral 48.1079 1Roll 18.9951 -- Does not meet Level 3 Standards

Dutch Roll 0.0017 3.3355 0.0057 3 However damping does not meet Level 3 standards

Unaugmented Rankings for F-16 Aircraft (Category A, Class IV)

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Overall Control System Concept

Stability Augmentation System

Autopilot System

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Short Period Mode with Control System

• Stability Augmentation System– Rate Feedback

– Angle of Attack– Pitch Rate

– Closed-loop State-Space A Matrix:

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Flight Dynamics Analysis

• Test Case:

• Gain Calculations for Short Period Mode:– Calculated to achieve Level 1 flight qualities for Category A, Class IV

Gains k1 0.3396 ζ 0.35k2 0.0906 ωn 0.0636 rad/sec

Augmented Short Period

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Detailed System Model

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Open-Loop System Trimmed Flight Simulation

0 5 103.6103

3.6103

3.6103

3.6103

3.6103

3.6103Trimmed Flight

Time (sec)

Alp

ha (

deg)

0 5 10-8

-6

-4

-2

0x 10

-6

Time (sec)

Q (

deg/s

ec)

0 5 103.6102

3.6102

3.6103

3.6103

3.6103

3.6103

Time (sec)

Theta

(deg)

0 5 10-4

-3

-2

-1

0x 10

-3

Time (sec)

z

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Simulation with & without Stability Augmentation

• Elevator deflection to show short period mode

0 5 102

4

6

8

10

Time (sec)

The

ta (

deg)

0 5 10-100

0

100

200

300

Time (sec)

z (f

t)

0 5 103

4

5

6Elevator Step w/o SAS

Time (sec)

Alp

ha (

deg)

0 5 10-2

0

2

4

Time (sec)

Q (

deg/

sec)

0 5 103.61

3.615

3.62

3.625

3.63

3.635Elevator Step w/ SAS

Time (sec)

Alp

ha (

deg)

0 5 10-0.1

-0.05

0

0.05

0.1

Time (sec)

Q (

deg/

sec)

0 5 103.6

3.65

3.7

3.75

Time (sec)

The

ta (

deg)

0 5 10-2

0

2

4

6

Time (sec)

z (f

t)

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Test Stand Design

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Test Stand Architecture

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Test Stand Motor and Encoder Circuit Diagram

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Test Stand Electronics Circuit Diagram

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Power Budget

QTY Device Vmax (V) Imax (A) Pmax (W) Weight (g) MISC1 Receiver 4.8 0.500 2.4 7.31 Receiver battery 6 0 100 1200mAH1 IMU 5.25 0.057 0.29925 161 GPS 3.3 0.033 0.1089 122 Pressure sensors 5 0.02 0.2 31 FPGA 3.3 0.1 0.33 31 EEPROM 3.3 0.02 0.066 11 Xtal 3.3 0.025 0.0825 21 sd card 3.3 0.025 0.0825 21 RF-Logger 3.3 0.1 0.33 2 Target board1 Thermistor 5 0.01 0.05 11 PCB 1001 camera + transmitter 0 85 Power N/A1 camera Battery 0 33.8 Power N/A1 SD slot 0 12.7

Control Board Total Power (W) 3.94915Control board electronics Total Weight (g) 380.8

Control board

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Weight

Material Type Weight per Unit Quantity Weight (grams)

Analog Devices IMU Sensor 16.00 1 16.00Tyco Electronics GPS Sensor 12.00 1 12.00Airspeed Differential Pressure Sensor Sensor 2.30 1 2.30Altimeter Absolute Pressure Sensor Sensor 0.50 1 0.50

Pitot-Static Probe Sensor 30.80 1 30.80

Thermistor Sensor 6.50 1 6.50

Video Camera and Transmitter Video 85.00 1 85.00Video Camera Battery Video 33.80 1 33.80FPGA Controller 3.00 1 3.00Controller Battery Controller 100.00 1 100.00EEPROM Controller 1.00 1 1.00Xtal Controller 2.00 1 2.00Micro SD Socket Controller 12.70 1 12.70Micro SD Card Controller 2.00 1 2.00PCB Board Controller 100.00 1 100.00MSP430 Wireless Target Board (RF Logger) Telemetry 2.00 1 2.00Pressure Sensor Tubing 1/8 Barbed Tee Sensor 0.50 1 0.50Pressure Sensor Tubing 12" Sensor 12.00 3 36.00

Total Weight: 446.10

P09122 MAV Controls - Electronics and Sensors Weight Budget

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Cost Breakdown

Sensors $841.36

Controller $610.02

Video $55.77

Kit Planes $200.00

Test Stand $752.25

Total Cost: $2459.40

Sensors, 841.36, 34%

Video, 55.77, 2%

Kit Plane, 200.00, 8%

Microcontroller, 610.02, 25%

Test Stand, 752.25, 31%

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Design Specifications

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Establish Target Specifications

List of Metrics# Metric Importance Units Accomplished? Comments

1 Recover from 5mph gust 4 Mph, m/s Depends on System Damping

2 Fly straight and level within a meter over a distance of 50 m

5 m, ft Implement Attitude Holds

3 Have at least 6 changeable parameters

8 # Currently have 4 changeable gains, more to follow

4 Weight less then 0.5 kg. 7 kg, lb Y Weight = 0.4461 kg

5 Fit within MAV platform 2.25”x2.25”x8”

6 in, cm Y Estimated size: 2” x 2” x 2”

6 All testing matrices completed 1 # MSD II

7 Receive and process remote signal

2 Y/N Y 6 channel receiver including override for S.A.S.

8 Transmit data to ground unit 9 List Storing data to SD card

9 Process and use data from all sensors

3 Y/N – List Y 5 sensors with 9 measured parameters

10 Determine it’s position within 1 meter

10 m, ft GPS within 2.5 m, coupled with IMU

11 Fly a designated pattern within 2 meters

11 m, ft Investigating attitude and position holds

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MSD II Plan & Future Work

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Unfinished MSD I Actions

• Get aerodynamics coefficients from Datcom– Ran into problems using Datcom

– Everything else is dependent on aerodynamic coefficients

• Develop Continuous Control Gains

• Discretize System Model

• Develop Discrete Control Gains

• Generate Control Law Code

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Current Schedule & Progress

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Risk AssessmentRisk Probability Severity Overall Risk Mitigation

Component Interfacing

Low High Med Thoroughly research all components and datasheets

Damage when interfacing electronics

Low High Med Again thoroughly research components and datasheets and

Difficulty Discretizing Control System

Low High Med Research digital controls and consult with faculty

Having hardware soon enough to prototype and test

Med Med Med Complete component selection as soon as possible and order

Test Stand Safety Low High Med Test stepper motor driver with motor unattached, test procedures, protective cover for test stand, and emergency stop

Other team’s delays prevent integration

Low Low Low Test system with test fixture and flight testing with either OTS kit plane or previous year’s MAV platform.