Imap: Inertial Measurement Unit

ImAP:
Inertial Measurement Unit

PROJECT PLAN

Dec08-01

Written By:

Luis Alberto Garcia

Julian Currie

Matt Ulrich

Amardeep Singh Jawandha

Disclaimer. This document was developed as part of the requirements of an electrical and computer engineering course at Iowa State University, Ames, Iowa. The document does not constitute a professional engineering design or a professional land surveying document. Although the information is intended to be accurate, the associated students, faculty, and Iowa State University make no claims, promises, or guarantees about the accuracy, completeness, quality, or adequacy of the information. Document users shall ensure that any such use does not violate any laws with regard to professional licensing and certification requirements. Such use includes any work resulting from this student-prepared document that is required to be under the responsible charge of a licensed engineer or surveyor. This document is copyrighted by the students who produced the document and the associated faculty advisors. No part may be reproduced without the written permission of the senior design course coordinator.

Table of Contents

1 Introduction………………..……………….……………………………………………….……..1

1.1 Definition of Terms…………………….…………………..…………………………..1

1.2 Project Background……………………………………………….….….……………..2

1.3 Problem Statement and Solution…………………………………..……………….…..2

2 ImAP System Overview....………………………….………………..……………...…………...3

2.1 System Description………………………………….…………………………...……..3

2.2 Concept Sketch…………………………………………..…………………..…...……3

2.3 Component Breakdown…………………………………...………………………..…..4

2.4 End-Product Goal…………………………………………………………….………... 4

3Inertial Measurement Unit Overview…………………………………….…………….…………..5

3.1 Goals……………………………………………...……………………………………5

3.2 System Description……………………………....…………………………...……..…5

3.3 User Interface Description…………………..……….………………………………...5

3.4 IMU Block Diagram…………………………………………….….…...……………..6

3.5 Market Research……………………………….…………………….….……………..6

3.6 Functional Requirements…………….………………….…….……………………….8

3.7 Non-Functional Requirements………………………………………….……………...8

4 Deliverables………………………………………………………..………….….…………....…9

4.1 Spring 2008 Deliverables…………………………….…………….…….………….….9

4.2 Fall 2008 Deliverables…………………………………………………………….…...9

Table of Contents (cont’)

5 Resource Requirements……………………………………………….……...………………….10

5.1 Budget………………………………………………………………………..….…….10

5.2 Work Breakdown………………………………………..……………….……………11

6 Project Schedule…………………………………………..……………………….……………12

6.1 Spring Work Breakdown……………………………………….…….……………….12

6.2 Fall Work Breakdown……………………………………………..………………….14

7. Risks……………………………………………………………………………….……………16

Works Cited……………………………………………………………………….……………….17

Sign-Off sheet……………………………………………………………………..………………18

1 Introduction

This section defines introductory materials for the ImAP RSD project.

1.1 Definition of Terms

FAA: Federal Aviation Administration.

FOV: Field-of-View

GPS: Global Positioning System

HABET: High Altitude Balloon Experiments in Technology.

ImAP RSD: Image Acquisition and Processing of Remotely Sensed Data.

HDS: Horizon Detection System.

IMU: Inertial Measurement Unit

FAT: File Allocation Table

SSCL: Space Systems and Controls Lab

ISGC: The Iowa Space Grant Consortium.

PCB: Printed Circuit Board.

PITCH: is rotation around the lateral or transverse axis.

ROLL: is rotation around the longitudinal axis.

WAYPOINTS: are sets of coordinates that identify a point in physical space; they usually include longitude and latitude, and sometimes altitude.

YAW: is rotation about the vertical axis.

Figure 1: Roll, pitch, and yaw are exemplified.

1.2 Project Background

Historically, determining crop health and predicting potential yield of Iowa farmlands has been a long and tedious process. Traditional methods using ground-based radiometers to measure the reflectance of sunlight on crops work for small plots of land but are highly inefficient and labor intensive when data over large spreads of land is required. ImAP RSD addresses the difficulty of acquiring and processing large amounts of field data by moving image sensing from the ground to the sky. (Aurakzai 1).

Every ImAP team will be responsible for a specific subsystem of the project. Each of these teams will also be given a unique name, to distinguish them from all other ImAP teams. This project plan focuses on the problem statement and the solution to this problem as given by team Beta.

1.3 Problem Statement and Solution

This section describes the general ImAP problem statement and solution as well as the more detailed problem statement and solution for the current team. (Aurakzai 1).

General ImAP Problem Statement

Farmer’s cannot determine the health of large areas of crops. This is because it is either cost prohibitive or labor intensive. (Aurakzai 1).

General ImAP Problem Solution

ImAP RSD was created to develop a more efficient method of determining crop health using remotely sensed data and image processing. Existing methods used to do this are expensive and labor intensive when large amounts of data are required, so the system developed by ImAP RSD must be low cost and easy to use. The system will be used by the client to provide the service of aerial image collection for remote sensing uses. The goal of the end-product system is to capture extremely accurate, high-resolution aerial images at specific GPS locations. The images collected by ImAP must also be processed to correct images geometrically and to extract usable information from the images so the data can be properly analyzed by prospective users. A last semester’s senior design team, team Alpha, is working on designing a Horizon Detection System (HDS) for ImAP (Aurakzai 1). More information on this part of the system can be found in reference 1.

Beta Team’s Problem Statement

The ImAP design teams are to design a fully functional remote data sensing system that will operate at high altitudes as a payload carried by helium-filled balloons to collect crop health data. Team Beta has the task of designing an inertial measurement unit (IMU) test system to gather information about the payload system’s motion in flight. This computer-based sensor system will be essential in optimizing the payload system’s ability to gather crop health data.

Beta Team’s Specific Problem Solution

The IMU test system will gather data about the angular motion and acceleration of the payload in flight. It will measure balloon oscillation frequency and angular rotation rate to 1.215 degree per second and linear accelerations to 0.01 g for each of the three principle axes. Team Beta will also develop a data logging system that can log data at a 100 Hz or greater rate for two hours with 10 bit or greater precision. SSCL staff and ImAP team members will analyze logged data after each mission.

2 ImAP System Overview

This section gives an overview of the subsystems contained in ImAP.

2.1 System Description

The image capturing system will be mounted as a payload attached to a high-altitude weather balloon. This system will be developed to capture images at predetermined waypoints. The waypoints are GPS locations entered prior to the flight by the user. After the images are collected, image analysis software is used to extract the image intensities, and to make geometric corrections. The final images will be transferred to the plant pathology team who will interpret the images. Data acquired using on-board orientation, light, humidity, pressure, and temperature sensors will be used to better understand atmospheric conditions during the flight.

2.2 Concept Sketch

Figure 2: Conceptual Sketch of ImAP system.

Figure 1 shows a concept sketch of the overall ImAP project. A high-altitude balloon with a payload suspended from it will operate between and 20,000 and 30,000 ft. above the earth. Within the payload, five subsystems will be connected to the primary processor, which are explained on the following page in 2.2 Component Breakdown. As discussed earlier, the focus of the ImAP Beta team will be the Inertial Measurement Unit, which will be explained in greater detail later.

2.3 Component Breakdown

Information about the other five subsystems connected to the primary processor is listed in Table 1.

Subsystem Name / Description
Inertia Measurement Unit / Used to determine the angular velocity and linear accelerations of the payload for dynamics-based correction
Horizon Detection System / Used to determine the spatial orientation of the payload with respect to the horizon
GPS / Used to determine the location and altitude of the balloon and payload
Pointing System / The control and mechanical structure used to physically position the camera correctly
Camera System / The actual camera and method for taking photos at the correct time and rate

Table 1: Subsystem Description

2.4 End-Product Goal

The ImAP system goal is to have an end-product that will capture extremely accurate, high-resolution aerial images at specific GPS locations. The images collected will be processed to correct images geometrically and to extract usable information from the images so the data can be properly analyzed by the prospective users.

3 Inertial Measurement Unit (IMU) Overview

3.1 Goals

Below is an outline of the project goals for the Beta team during the Fall 2007 and Spring 2008 semesters.

Spring 2008 Semester Goals

The following goals will be achieved during Spring 2008:

·  Research the most efficient and cost effective way to determine or estimate one's current position based upon a previously determined position, or fix and advance that position based upon known speed, elapsed time, and course. We will build a Inertial Measurement Unit for the above mentioned navigational purposes

·  Design the Inertial Measurement Unit

·  Construct a single prototype of the Inertial Measurement Unit

Fall 2008 Semester Goals

The following goals will be achieved during Fall 2008:

·  Test the prototype

·  Create and maintain an operations manual

·  Test the product on a HABET flight

·  Fix bugs in the system

·  Finalize the operations manual

3.2 System Description

The IMU system detects changes in angular momentum and acceleration about and along three orthogonal axes. This data is collected by rate gyros and accelerometers, respectively, and is output for use by the total ImAP RSD system during flight. This data and select internal parameter monitoring data will be stored via a data logging system for post-flight analysis.

3.3 User Interface Description

The data collected during flight will need an appropriate user interface for transferring data to a computer for post-flight analysis. Possible solutions are being considered and compared against each other for their effectiveness and implantation benefits. A USB port or removable storeage devices are possible solutions.

3.4 IMU Block Diagram

Figure 3: IMU Block Diagram.

3.5 Market Research

Market research is being conducted to determine the best system components for the IMU. Rate gyros, accelerometers, microprocessors, and data loggers will be selected based on the previously stated functional requirements.

Others have solved this problem by taking pictures from planes, UAV, RCA planes and kites. Our product should be able to go up to about 30,000 feet. Due to these high altitudes, an airplane seems like the best option, but the price tag is very high.. Therefore there is a demand for our product in the market.

PARTS / REASONS
Microcontroller: ATmega128 / ·  Low power requirements
·  Fast processing speed
·  Industry standard processor
·  Versatile: Will be used to process data logged from IMU and Horizon Detection System
·  Cost effective
·  Internal ADC
Accelerometer: ADXL330 / ·  Low sensitivity change Vs Temperature
·  Low Zero-g level change Vs Temperature
·  Low acceleration noise density
·  3 Axis, 3.6g
·  Cost effective
Rate-Gyro: MLX90609 / ·  300/s
·  Low zero rate drift
·  Analog and Digital output possible
·  Temperature sensor built in
·  Low Zero rate Temperature drift
·  Low Output Noise power spectral density
Data Logger: Logomatic V1.0 / ·  On chip FAT file system
·  Simple interface to microcontroller’s USART
1 GB SD Card / ·  Known to work in the Logomatic
·  Cheap data storage device

3.6 Functional Requirements

This subsection discusses in detail the functional requirements of the ImAP RSD project for the spring 2008 semester. The following subsections are included:

FR01:

IMU shall measure balloon oscillation frequency and angular rotation rate to 1.215 degree per second.

FR02:

IMU shall measure linear acceleration to 0.01g for each of the three principle axes.

FR03:

Data logging system shall log at a 100HZ+ rate with 10 bit or greater precision.

FR04: IMU shall receive power from a 11.1 V nominal lithium-ion battery

FR05: IMU shall function for a minimum of 2 hours using a 4 Amp-hour battery pack

FR06: IMU shall operate over a temperature range of -25˚ C to +85˚ C

4 Deliverables

4.1 Spring 2008 Deliverables

The following will be delivered for spring 2008:

·  A comprehensive project plan

·  A thorough bounded design report

4.2 Fall 2008 Deliverables

The following will be delivered for fall 2008:

·  An operational IMU

·  An accurate data logger

·  Poster

·  IRP presentation

5 Resource Requirements

5.1 Budget

Spring 2008 Budget

Item / Cost
SD Card Reader / $ 3.67
1 GB SD Card / $ 14.99
MLX9069 Gyro / $ 59.95
ADXL330 Accelerometer / $34.95
Two Break Away Headers – Straight / $ 5.00
Break Away Female Headers / $ 1.50
Logomatic V1 board / $59.95
Subtotal / $ 180.01
Student labor $10/Hr / $4680.00
Total / $4860.01

Fall 2008 Budget

Item / Cost
Parts and materials
Printed Circuit Board / $ 33.00
2 MLX90609 gyros / $119.9
Atmel Mega 128 Processor / $9.15
Subtotal / $ 162.05
Student labor $10/Hr / $ 5020.00
Total / $ 5182.05

5.2 Work Breakdown

Spring 2008 Work Breakdown per Team Member

Personnel / Gyro and Accelerometer Research / Microcontroller and Flash Memory Research / Gyro and Accelerometer testing / Microcontroller and Flash Memory Testing/Programming / Operational Manual / Documentation, planning & organization / Total Hours
Luis / 20 / 10 / 20 / 18 / 20 / 30 / 118
Julian / 10 / 20 / 10 / 35 / 20 / 20 / 115
Matt / 25 / 8 / 20 / 15 / 15 / 30 / 113
Amardeep / 20 / 10 / 20 / 20 / 25 / 20 / 115
Total / 75 / 48 / 70 / 88 / 80 / 100 / 461

Table 5: Work Breakdown Spring 2008

Fall 2008 Work Breakdown per Team Member

Personnel / IMU Circuit Board Design & Testing for Data Acquisition / Gyro and Accelerometer Calibration / System Integration / Operational Manual / Documentation, planning & organization / Total Hours
Luis / 30 / 25 / 25 / 25 / 20 / 125
Julian / 50 / 7 / 35 / 20 / 20 / 132
Matt / 30 / 35 / 15 / 20 / 20 / 120
Amardeep / 40 / 25 / 10 / 25 / 25 / 125
Total / 150 / 92 / 85 / 90 / 85 / 502

Table 6: Work Breakdown Fall 2008

6 Project Schedule

6.1 Spring 2008 Project Schedule

The following pages contain the project schedule of tasks for Spring 2008. The tasks are divided into three main tasks: documentation, system design research, and system implementation.

Figure 4a: Spring 2008 Gantt Chart Task Breakdown