EDGE™

MAV Control SystemProject # P09122

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

• Background

• Project Planning

• Concept Development– Control System– Logic Controller– Sensors– Test Stand

• Future Work

• Risk Assessment

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Background

• Past – Focused on small scale

surveillance.

• Future– MAV rules have changed so

now focus is on autonomy with small size being secondary.

– Fly autonomously indoors and outdoors

– Goal is to compete in the EMAV 2010 competition

MIT Autonomous UAV Aerobatics Project

MAV 2006 Model

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Project Planning

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Project Overview & 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.

• Stabilize Flight• Adaptable• Fully Tested and Integrate with Platform

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

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Identify Customer Needs

Needs Hierarchy1. Control Capability

1. Be as autonomous as possible.2. Create a stable flight.

1. Command the control surfaces appropriately.3. Have a video relay system.4. Process data from all inputs..

2. Adaptability1. Calibrated for the platform characteristics.2. Compensate for environmental conditions.3. Compensate for various payloads.4. Have interchangeable sensors.

3. Receive Inputs1. Work simultaneously with remote input.2. Measure the current conditions.3. Have GPS capability.

4. Weight and Size1. Be light weight2. Fit within MAV platform

5. Independence1. Be independent of the platform.

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Identify Customer NeedsRelative Importance of Needs (1=Highest)

# Need Needs To Importance

1.1 Autonomous as Possible As many autonomous functions as resources permit

7

1.2 Create Stable Flight Compensate for instability 1

1.2.1 Command Surfaces Move Surface appropriate direction and amount 1

1.3 Video Relay Capture and relay surroundings to fly remotely 10

2.1 Process Data Receive Data and determine action 4

2.2 Calibrated for platform Control based on Aerodynamics of platform 8

2.3 Compensate for Environment

Correct and Recover from environmental disturbance

3

2.4 Compensate for Payload Adjust aerodynamics based on payloads 11

2.5 Interchangeable Sensors Upgradeable and Replaceable 12

3.1 Simultaneous with Remote Work concurrently and assist during remote input

5

3.2 Measure Conditions Collect data of all in-flight conditions 2

3.3 GPS Capability Measure and program position 13

4.1 Light Weight Minimize weight <0.5kg 9

4.2 Fit with MAV Platform All onboard components must fit within platform 9

5.1 Independent from platform Not reliant on other projects, configurable and testable

6

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Establish Target Specifications

List of MetricsNumber Metric Importance Units

1 Recover from 5mph gust 4 Mph, m/s

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

5 m, ft

3 Have at least 6 changeable parameters 8 #

4 Weight less then 0.5 kg. 7 kg, lb

5 Fit within MAV platform 2.25”x2.25”x8” 6 in, cm

6 All testing matrices completed 1 #

7 Receive and process remote signal 2 Y/N

8 Transmit data to ground unit 9 List

9 Process and use data from all sensors 3 Y/N – List

10 Determine it’s position within 1 meter 10 m, ft

11 Fly a designated pattern within 2 meters 11 m, ft

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Concept Development

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Overall System Architecture

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Control System Concept

• Requirements:– Receive All Inputs (Pilot Input & Sensor Input)– Create Stable Flight– Command Surfaces (Elevons, Elevator, Rudder & Thrust)– Compensate for Environment (Disturbance)– Adaptable for Different Platforms

• Concept: PID Feedback Control for Each Input

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Overall Control System Concept

PID Feedback Control for Each Input

out

State Outputs

In1Out1

Sensor Models

Commands Plane States

Plane Dynamics Model

PID

PID Controller for each input

In1Out1

Conversions

in

Command Inputs

Logic Controller Functions

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Preliminary System Model

Logic Controller Functions

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Flight Dynamics Model

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Logic Controller

• Selection Criteria– Control Capability

– Adaptability– Inputs Receivable– Weight & Size– Cost– Complexity– Time to get working

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Logic Controller

• Concepts– Last Year’s O-Navi Controller– Purchase different commercial fully developed board– Design and build from parts

O-Navi Microcontroller

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Logic Controller Design

• Logic Controller Design Concepts– MCU only– MCU and FPGA– FPGA only

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Detailed System Diagram

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FPGA Selection

• Selection Criteria– Familiarity– Price– Manual solderability– Power efficient– I/O pins

• Selection: Altera Cyclone III- EP3C16E144C8N– Package: EQFP– Logic elements: 15408– I/O pins: 84– Cost: $26.70 – CMOS process: 65nm

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FPGA System Diagram

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Sensor Concepts

• Required Measurements– 3-Axis Translation

– 3-Axis Rotation

– Airspeed

– Altitude

– Angle of Attack

Sensor Concept Matrix

Measurement NeedsAircraft Translation 3 uni-axial accels 3-axis accel IMU IMU+GPSAircraft Rotation 3 uni-axial gyros 3-axis gyro IMU IMU+GPS OpticsAirspeed Pitot-Static Probe AnemometerAltitude Press & Temp Sensors Altimeter OpticsAngle of Attack Guide Vane Multi Hole Pressure Anemometer Num Approx

Sensor ConceptsC B A D E

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IMU Selection

• Selection Criteria– Cost– Dimension– Gyro range (deg/sec)– Acceleration range (g)– band width– Power Usage– Output

• Selection: Analog Devices- ADIS16350– Resolution: 14bit– Measurement : 300 (deg/sec)– Interface: I2C/SPI– Voltage: 5V Current: 33mA– Price $528.00– DOF 6 axis

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GPS Selection

• Selection Criteria– Accuracy– Voltage Supply– Power Consumption– Battery Backup – Built in Antenna– Baud rate

• Selection: Tyco Electronics (Vincotech) V23993-A1082-A– Accuracy: <2.5m – Voltage: 1.75-1.85V Current 35mA– Antenna : Included – Baud rate: 4800-34400bps Updates: <0.1s – Dimensions: 0.55 x 0.45 x 0.095'' Weight: <0.05oz – Channels: 12– Price: $55.60

– Package connection– Dimensions – Weight – Price – Acquisition rate – Channel Tracking

A1082-A

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Airspeed Sensor Selection

• Selection Criteria– Differential Pressure Sensor:

• Cost • Sensitivity • Active Range• Linearity • Dimensions

• Selection: Freescale MPXV7002– Range: 0 - 0.3 PSI-D– Sensitivity: 1 V/kPa– Cost: $15.78

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Altimeter Sensor Selection

• Selection Criteria– Absolute Pressure Sensor:

• Cost • Sensitivity • Active Range• Linearity • Dimensions

• Selection: Freescale MPXH6130A– Range: 2.2 – 18.9 PSIA– Sensitivity: 39.2 mV/kPa– Cost: $15.09

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Airspeed Sensor Selection

• Selection Criteria Calculation:– Bernoulli:

Need sensor with range close to 0 to 0.015 psi

Smallest Range Available: 0 to 0.3 psiSensitivity = 1 V/psi

For 1mV electronics accuracy:

Low Speed: ΔP = 1 Pa, v = 3 mph, ΔP = 2 Pa, v = 1.81 m/s = 4 mph

Resolution: 1 mph

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

Resolution : 0.12 mph at cruise

Cruise: v = 30 mph = 13.4112 m/sStandard Density: ρ = 1.21 kg/m3

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Altimeter Sensor Selection

• Selection Criteria Calculation– Hydrostatic Pressure:

Need Absolute Pressure Sensor

Standard Patm = 101.3 kPa = 14.69 psi

Say altitude of 1000 ft = 300 m assuming ρ = constant = 1.21 kg/m3

Considering normal variations or pressure and temperature want margin:

Want range around: 75 kPa < P < 125 kPa = 10.8 psi < P < 18.13 psi

Closest Range: 2.2 psi to 18.9 psiSensitivity: 39.2 mv/kPa

For 100 ft change: ΔP = -0.36 kPa

For 10 ft change: ΔP = -0.036 kPa

For 1 mV change: Δh = 7 ft

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Test Stand Architecture

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Test Stand Concept

Multi-Axis Controlled Test Stand

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Test Stand Motor Selection

• Selection Criteria– Cost– Holding Torque (oz-in)– Step Angle (deg)– Power (w)– Resistance (ohms)– Weight (g)

• Selection: Danaher Motion: 26M048B1B-V19– Bipolar Holding Torque (oz-in):3.00– Weight (g): 57.2– Step Angle (deg): 1.00– Cost: $26.

26M048B1B-V19

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Test Stand Motor Selection

• Selection Criteria Calculation– Torque

Inner Motor: I = 17 lbmin2 (from CAD Model)

Outer Motor: I = 150 lbmin2

Need to calculate max α we want for the test stand

Say max roll rate = 10 rpm (F-18 = 120 rpm)If reaches roll rate by 45 deg (1/8 rev) with constant α

Using Rotational Kinematics: Solving for α:

Calculating Torque:

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MSD I Future Work

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Control System

• Review & Finalize Non-Linear Plant Model

• Finish Feedback Conversions

• Model Sensors

• Linearize Plant and Sensor Models

• Develop Continuous Control Gains

• Discretize System Model

• Develop Discrete Control Gains

• Generate Control Law Code

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Logic Controller

• Review Component Documentation

• Familiarize with NIOS II–Instantiate NIOS II core on FPGA–Store program code in Flash

• Implement Serial Protocols

• Investigate SD Card Data Storage Potential

• Begin Prototyping All Component Communication

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Sensors

• Temperature Sensor Selection

• Determine Pitot-Tube Hardware and Location

• Review Sensor Documentation

• Develop Sensor Power Strategy

• Research Sensor Modeling Theory

• Develop PCB layout software knowledge

• Research Method for Digitizing Analog Sensors

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Test Stand

• Research & Select Motor Drivers

• Research & Select Encoders

• Select Power Supply

• Select Transceiver Module

• Develop Communication Module

• Develop User Interface

• Refine Test Stand Design–Structure–Wire Routing

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Other

• Develop Power Budget– Primary and Secondary Systems– Test Stand

• IMU Stage• Motors

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Current Schedule & Progress

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MSD I Projected Progress

• Complete Tasks Listed in Future Work

• Finish Detail Design Early– Start Ordering Sensors and Components Early

• EE’s Can Start Modeling Sensors• CE’s Can Start Checking Communication

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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.