System Draft - isy.liu.se€¦ · System Draft Editor: Marcus B ack Version 1.0 Status Reviewed Martin Szilassy 2014-09-19 Approved Hanna Nyqvist 2014-09-19

System Draft

Editor: Marcus Back

Version 1.0

Status

Reviewed Martin Szilassy 2014-09-19Approved Hanna Nyqvist 2014-09-19

Autonomous mine sweeper: BalrogLiTH

2014-09-19

PROJECT IDENTITY2014/HT, Invenire Periculosa

Linkoping University, Dept. of Electrical Engineering (ISY)

Group membersName Responsibility Phone Email

(@student.liu.se)

Martin Szilassy(MS) Project manager (PM) 070-8840295 marsz918Marcus Back(MB) Responsible for docu-

mentation (DOC)070-6924804 marba751

Victoria Alsen (VA) Chief of tests 073-9409540 vical845Johan Kallstrom (JK) Chief of design 073-0718371 johka546Mikael Hammar (MH) Master of SLAM 070-2658294 mikha087

Daniel Orn (DO) Chief of hardware 073-6448910 danor434Olof Zetterlund (OZ) Chief of information 073-7133822 oloze183Simon Ollander (SO) Internal advisor 073-8322898 simol515

Email list to the whole group: [email protected] site: http://www.isy.liu.se/edu/projekt/tsrt10/2014/bandvagn/

Customer: SAAB Bofors Dynamics, LinkopingCustomer contact: Torbjorn Crona, [email protected]

Course leader: Daniel Axehill, +46 13 284042, [email protected]: Hanna Nyqvist, +46 13 281 353, [email protected]: Martin Lindfors, +46 13 281365, [email protected]

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Invenire [email protected]

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Contents

Document history iv

1 Introduction 1

1.1 Overview of the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Definition of terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Subsystem 1 - Base station 3

2.1 Overview of the subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.4 Dependencies to other systems . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 Subsystem 2 - Balrog 4

3.1 Overview of the subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.2 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.3 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.4 Dependencies to other systems . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.5 Balrog subsystem - Hand controller . . . . . . . . . . . . . . . . . . . . . . 6

3.5.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.5.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.5.3 Dependencies to other systems . . . . . . . . . . . . . . . . . . . . . 6

3.6 Balrog subsystem - Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.6.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.6.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


3.7 Balrog subsystem - Propulsion . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.7.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.7.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7


3.8 Balrog subsystem - Positioning and mapping . . . . . . . . . . . . . . . . . 7

3.8.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.8.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


3.9 Balrog subsystem - Route planning . . . . . . . . . . . . . . . . . . . . . . 8

3.9.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.9.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

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3.10 Balrog subsystem - Control . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.10.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.10.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9


3.11 Balrog subsystem - External communication API . . . . . . . . . . . . . . 9

3.11.1 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3.11.2 Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9


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Document history

Version Date Changes Sign Reviewed

0.1 2014-09-12 First draft MB MS

0.2 2014-09-17 Changes from adviser MB MS

0.3 2014-09-18 Changes from adviser MB MS

1.0 2014-09-19 Version 0.3 approved MB MS

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1 Introduction

This document is a system drawing of an autonomous mine sweeper. Each subsystemis briefly explained with respect to components, tasks and dependencies to other subsys-tems. Further information about what the system shall be able to perform and executeis described in the document ”Requirement Specification”. Each subsystem has beendeveloped by previous projects and the purpose of this year’s project is to improve theperformance of the overall system utilising new sensors and more powerful computationalpower.

1.1 Overview of the system

The autonomous mine sweeping system consists of two main subsystems, the base sta-tion and Balrog. Balrog is a tracked vehicle which is divided into smaller subsystems.Each subsystem perform specific tasks and consists of hardware, software or both. For aschematic overview of the system see figure 1.

Position and mapping

Route planning

Control

Base station

Hand controller

Propulsion

Sensors

IMU

Odometers

Laser scanner

Stereo camera

Mine detection

Obstacle detection

GPS

UltrasonicARM processor

Electric motor

GUI

Balrog

Hardware

SoftwareExt

erna

l com

mun

icat

ion

AP

I

Wireless link

Wireless link

Component

Description

Figure 1: Illustration of the system and its subsystems. Dependencies between subsystemsare illustrated by an arrow pointing from the system towards the dependencies of thatsystem.

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1.2 Definition of terms

The following list is terms used in this document

• Balrog - The autonomous tracked vehicle that will carry out the mine sweeping.

• Hand controller - A remote Xbox hand controller used to control the robot manually.

• Mine - A magnet in the search area to be found by Balrog that represents an actualmine.

• Obstacle - Any kind of item (man made or not) that the robot can not travel through.

• Main control unit - The main computer on the robot.

• Operator - A person controlling Balrog via one of the external interfaces (handcontroller or base station).

• Base station - A software running on a computer. The software communicates withBalrog via Wifi. An operator can use the base station to send commands to Balrogor to read out map data.

• IMU - Inertial measurement unit.

• API - Application programming interface

• PWM - Pulse width modulation

• Service area - The area where Balrog is supposed to search for mines.

• GUI - Graphical User Interface.

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2 Subsystem 1 - Base station

2.1 Overview of the subsystem

Figure 2: Base station

The base station is an ordinary personal computer as shownin figure 2. It communicates with Balrog via Wifi and al-lows the user to monitor the progress of the robot as well ascontrolling it by a limited set of commands. Some configu-ration and troubleshooting of Balrog is also available fromthe base station. The mine sweeping and mapping progressis displayed in a GUI at the base station.

2.2 Components

The components defining the base station are as follows:

• An x86 compatible computer

• A wireless network card

• The application used to connect to Balrog

2.3 Tasks

The base station performs the following tasks:

• Displays estimated position of the vehicle as well as previous position data

• Displays detected mines and contours of detected obstacles

• Displays the probability that the area is fully examined

• Receives and interprets control commands from the GUI

• Forwards control commands to Balrog

• Provides a GUI to configure Balrog

• Receives, presents and saves data obtained from Balrog

2.4 Dependencies to other systems

The base station depends on the external communication API system. It displays selecteddata received from the API.

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3 Subsystem 2 - Balrog

3.1 Overview of the subsystem

Balrog is composed of a mobile mine sweeping platform. The platform is mounted witha computer, later referred to as the main control unit, as well as different sensors. Thesensors are used for navigation, mine detection and obstacle detection purposes. Themovement and control of Balrog is performed by the main control unit. Apart from that,the hand controller and/or the base station is providing operating instructions for Balrog.In image 3 last years Balrog is displayed.

Figure 3: Picture of Balrog from last year

Balrog is divided up into the following subsystems:

• Hand controller

• Sensors

• Propulsion

• Positioning and mapping

• Route planning

• Control

• External communication

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3.2 Components

Balrog is equipped with the following components:

• Main control unit

• Tracks

• Engines

• Laser scanner

• Stereo camera

• Ultrasonic sensors

• IMU

• Odometers

• Magnetometer

• Wifi communication device

3.3 Tasks

Balrog shall be able to perform the following tasks:

• Estimate its current position

• Autonomously navigate in the service area

• Detect and map the positions of mines

• Map and avoid obstacles in the service area

• Provide the base station with collected data of the service area

• Be controlled manually from the hand controller or the base station

3.4 Dependencies to other systems

Balrog is dependent of the following systems:

• The hand controller

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3.5 Balrog subsystem - Hand controller

The system is equipped with a hand controller to facilitate the control of Balrog. Thehand controller communicates wirelessly with Balrog.

3.5.1 Components

• A hand controller

• A wireless communication link

3.5.2 Tasks

The hand controller simplifies controlling Balrog when in manual mode as well as enablingswitching between manual and automatic mode and performing emergency braking. WhenBalrog detects a mine the hand controller will respond by vibrating.

3.5.3 Dependencies to other systems

The hand control is independent of other systems.

3.6 Balrog subsystem - Sensors

In order for the system to execute its tasks, the system is equipped with different sensorsto determine velocity, position and heading. The sensor system can also detect mines andobstacles.

3.6.1 Components

The system consists of the following sensors, for positioning and mapping:

• A laser distance sensor

• A stereo vision camera

• A GPS

• An IMU with an accelerometer, a gyroscope and a magnetometer

• An ultrasonic range finder

• Odometers

3.6.2 Tasks

The main task of the sensor system is to store, handle and provide measurement data ofthe surroundings, to the other subsystems.

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• External communication API

3.7 Balrog subsystem - Propulsion

Balrog is driven by electric motors connected to tracks with control functions enabledthrough the ARM processor.

3.7.1 Components

• Electric motors

• Tracks

• An ARM processor

3.7.2 Tasks

The propulsion system receives commands from the control system. The commands arethen translated into PWM signals to control the motors.


The propulsion is independent of other systems.

3.8 Balrog subsystem - Positioning and mapping

The positioning and mapping system determines the position of Balrog and constructs amap of the search area in real time.

3.8.1 Components

• Software

• Mine detection algorithm

• Obstacle detection algorithm

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3.8.2 Tasks

Several sensors, namely GPS, odometry, laser, IMU (gyroscope and accelerometer) andmagnetometer, contribute to determining the position of Balrog.

The mine detection algorithm detects the mines, represented as magnets, and saves theirpositions and the margin of uncertainty. The obstacle detection algorithm processes sensordata in order to detect obstacles in the search area. With the information from the mineand obstacle detection algorithms this system constructs a map which is used for theroute planning system. The map is based on the search area defined by the operator atthe base station.


• Sensors


3.9 Balrog subsystem - Route planning

This system is responsible of determining the route Balrog has to visit going from oneposition to another.

3.9.1 Components

• Software

3.9.2 Tasks

Given the map, a position of Balrog and a position we want to visit, the route planningsystem calculates a sequence of waypoints Balrog can follow to get to the ending position.The set of positions is continuously updated by the information given by the mappingand positioning system. The set of positions is then provided to the control system.




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3.10 Balrog subsystem - Control

The control system is responsible for steering and driving Balrog.

3.10.1 Components

• Software

3.10.2 Tasks

Given the waypoints generated by the route planning system, the control system is re-sponsible for driving Balrog stably along the route using the position estimated by theposition and mapping system. The control system determines the input signals to theelectric motors and sends the signals to the propulsion system.



• Route planning


• Propulsion

3.11 Balrog subsystem - External communication API

The external communication API is responsible for all communication between the Balrog,the base station and the hand controller.

3.11.1 Components

• Software

3.11.2 Tasks

The single task for the external communication is to convey information between thedifferent subsystems. This is done in real time and the purpose is to make it possible forthe Balrog, the base station and the hand controller to communicate efficiently.

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• Hand controller


• Control

• Route planning

• Sensors

• Basestation

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Documents

System Draft - isy.liu.se€¦ · System Draft Editor: Marcus B ack Version 1.0 Status Reviewed Martin Szilassy 2014-09-19 Approved Hanna Nyqvist 2014-09-19