Techincal Manual

DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
Engineering Team Design Project
Technical Manual
Presented by Team Beemo (Team #3)
COEN/ELEC 390/2 (Fall 2011)
12/7/2011
Table of Contents
1
2
3
4
5
Introduction ...................................................................................................... 3
1.1 Document Identification .............................................................................. 3
1.2 System Overview ....................................................................................... 3
1.3 Document Overview ................................................................................... 3
System Description .......................................................................................... 4
2.1 Introduction ................................................................................................ 4
2.2 Operational Scenario .................................................................................. 4
2.3 Hardware Requirements ............................................................................. 4
2.3.1 Functional Requirements ......................................................................... 4
2.3.2 Non-Functional Requirements ................................................................. 5
2.4 Software Requirements .............................................................................. 5
2.4.1 Functional Requirements ......................................................................... 6
2.4.2 Non-Functional Requirements ................................................................. 6
Hardware ......................................................................................................... 8
3.1 Block Diagram ............................................................................................ 9
3.2 Circuit Schematic of BeemoBot ................................................................. 11
3.3 Scope of the BeemoBot System Hardware ................................................ 12
3.3.1 Power Supply ......................................................................................... 12
3.3.2 Microcontroller ....................................................................................... 12
3.3.3 Motor Controller ..................................................................................... 14
3.3.4 GM8 Motor ............................................................................................. 15
3.3.5 Johnny Robot Track Kit .......................................................................... 15
3.3.6 Sharp GP2D12 Analog Proximity Sensors .............................................. 16
3.3.7 Sharp GP2D15 Digital Proximity Sensors ............................................... 16
3.3.8 QRD1114 Line Sensors .......................................................................... 16
3.3.9 Micro-Switches ....................................................................................... 18
3.3.10 Printed Circuit Board (PCB) ................................................................. 18
BeemoBot Assembly ....................................................................................... 20
4.1 Assembly Steps ........................................................................................ 20
4.2 Final Product of BeemoBot ........................................................................ 24
Software .......................................................................................................... 26
5.1 Pseudo-Code ............................................................................................ 26
5.2 BeemoBot’s Expected Behavior ................................................................ 28
5.2.1 Robot Detection ..................................................................................... 28
5.2.2 Robot Touch .......................................................................................... 29
5.2.3 Line Detection ........................................................................................ 30
5.3 Source Code ............................................................................................. 30
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6
7
8
Programming the Atmega8 .............................................................................. 31
Troubleshooting .............................................................................................. 33
References ...................................................................................................... 35
Table of Figures
FIGURE 3.1 - BLOCK DIAGRAM OF THE BEEMOBOT ............................................................. 10
FIGURE 3.2 - SCHEMATIC OF THE BEEMOBOT ELECTRICAL HARDWARE ................................ 11
FIGURE 3.3 - REGULATED POWER SUPPLY CIRCUIT ........................................................... 12
FIGURE 3.4 - ATMEGA8 PINOUT ........................................................................................ 12
FIGURE 3.5 - ATMEGA8 RESET AND ISP PROGRAMMER CIRCUITRY ..................................... 13
FIGURE 3.6 - SN754410A PINOUT ................................................................................... 14
FIGURE 3.7 - MOTOR CONTROL CIRCUITRY ....................................................................... 14
FIGURE 3.8 - SOLARBOTICS GM8 MOTOR WITH BRACKET ................................................... 15
FIGURE 3.9 - JOHNNY ROBOT TAMIYA TRACK KIT ............................................................... 15
FIGURE 3.10 - GP2D12 AND GP2D15 SENSOR CASING .................................................... 16
FIGURE 3.11 - QRD1114 PACKAGE.................................................................................. 16
FIGURE 3.12 - QRD1114 PINOUT..................................................................................... 17
FIGURE 3.13 - QRD1114 PERF-BOARD CIRCUITRY ........................................................... 17
FIGURE 3.14 - MICRO-SWITCH PACKAGE........................................................................... 18
FIGURE 3.15 - BEEMOBOT PCB TOP-DOWN VIEW ............................................................. 19
FIGURE 4.1 - IMAGE SHOWING THE MOTOR MOUNTED ON THE CHASSIS ................................. 20
FIGURE 4.2 - IMAGE SHOWING HOW THE LINE SENSOR IS MOUNTED TO THE CHASSIS .............. 21
FIGURE 4.3 - IMAGE SHOWING HOW THE PCB IS MOUNTED TO THE CHASSIS ......................... 21
FIGURE 4.4 - FIGURE SHOWING HOW THE TRACKS ARE MOUNTED ......................................... 23
FIGURE 4.5 - FIGURE SHOWING ON/OFF BUTTON IS MOUNTED, TO THE RIGHT ....................... 24
FIGURE 4.6 - FINAL ROBOT ASSEMBLY .............................................................................. 24
FIGURE 4.7 - ARTIST'S RENDERING OF ROBOT ASSEMBLY .................................................... 25
FIGURE 5.1 - BEEMOBOT ANALOG (FRONT/REAR) ROBOT DETECTION ................................. 29
FIGURE 5.2 - BEEMOBOT DIGITAL (LEFT/RIGHT) ROBOT DETECTION ................................... 29
Table of Tables
TABLE 2.1 - BEHAVIORAL EXPECTATIONS OF THE BEEMOBOT ................................................ 7
TABLE 3.1 - ELECTRICAL HARDWARE OF THE BEEMOBOT ..................................................... 9
TABLE 5.1 - TROUBLESHOOTING SCENARIOS ..................................................................... 33
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1 Introduction
1.1 Document Identification
This document describes the design of the BeemoBot. This document has been prepared by Team Beemo
for assessment in Concordia University’s COEN/ELEC 390 “Mini Capstone” project.
1.2 System Overview
The Team Beemo BeemoBot is meant to locate opposing robots and push them outside of a circular area
marked by a black ring on a white board. At the same time, the robot must remain inside the circular area
at all times. The behavior of the robot is controlled by the use of 4 line sensors, 4 analog IR sensors, 2
digital IR sensors and 5 micro switches.
1.3 Document Overview
The following document includes a system overview of the BeemoBot. It will describe the functional and
nonfunctional requirements of the BeemoBot. It then describes in detail the design of the BeemoBot,
starting with hardware and all its components, as well as how to assemble BeemoBot. This is followed by
the overview of the BeemoBot software and algorithms, the source code of the BeemoBot and finally
finished with instructions on how to program an Atmega8 microcontroller to use on BeemoBot.
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2 System Description
This section of the document will provide a general overview of the basis for the BeemoBot system
design. The modules will be divided into hardware (electrical and non-electrical) and software, as well as
its development and implementation.
2.1 Introduction
This BeemoBot system can be divided into several main components, called “modules” from here on. The
first main division of its modules is hardware and software.
The hardware module covers the electrical components of the system, such as the microcontroller,
motors, motor controller, and so on. It also covers the non-electrical hardware module covers the parts of
the system, such as the chassis, wheels, mounting brackets, and so on.
The software module covers exclusively the code used in the system’s microcontroller, which determines
the behavior of the robot.
2.2 Operational Scenario
The BeemoBot’s intended use is to operate in a ring, marked with a black border on a white MDF board.
The ring should be approximately 4” in diameter. The BeemoBot is intended to compete with an opposing
robot in this ring, which is also designed to have the same general behavior as the BeemoBot. This
behavior is to locate and target the opponent, and then attempt to push the opponent outside of the marked
ring. Upon start of the match both robots must face towards the outside of the ring – back to back –
approximately 6” away from the border. They must be activated simultaneously, stand still for at least 5
seconds, and then begin the match,
The BeemoBot may also oppose more than one robot, in a “free-for-all” match.
2.3 Hardware Requirements
This section describes in detail the requirements that must be met for the hardware module of the
BeemoBot that are both electrical and non-electrical
2.3.1 Functional Requirements
2.3.1.1 Inputs
The BeemoBot has several inputs required to operate well. It must respond well to both user inputs and
opponent robot inputs as well. It must also take into account environmental inputs, such as the border of
the ring and any obstacles that may appear inside the ring that is not the opponent.
Firstly the BeemoBot must have a human input – the On/Off switch. This switch will be used by the
operator to activate the BeemoBot once the match is ready to start.
Next the BeemoBot must react to the opposing robot in the ring. The BeemoBot must be able to locate
and track the opponent in the ring. The robot must also have a way to detect if the opponent is making
contact, so it can make appropriate evasive or offensive maneuvers.
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Lastly the BeemoBot must be able to stay within the operating environment, in this case the ring. It must
also handle the placement of an undefined obstacle in the ring (e.g. sand, sticky tape, a low block, etc.).
2.3.1.2 Process
The BeemoBot must have a system in place to process the information it receives while operating in the
ring, such as seeing the opponent, detecting a line and so on. To do this the BeemoBot has need of an onboard “computer”. This computer must process the information coming in through the possible inputs that
have been listed above. It must then determine the appropriate behavior required to deal with these inputs,
and will react accordingly using various maneuvers. These maneuvers will be executed by the electrical
outputs of the hardware.
2.3.1.3 Outputs
The BeemoBot requires a method of performing the appropriate maneuvers and behaviors required to
track the opponent robot and to push it out of the ring as required.
2.3.2 Non-Functional Requirements
The BeemoBot needs to conform to a set of non-functional requirements. The robot must also follow a
list of design constraints listen by the course instructor (from here on called the customer).
2.3.2.1 Performance
The BeemoBot must run the full duration of the match without losing power. It may not lose any
hardware pieces on the track during the match.
2.3.2.2 Design Constraints
The customer has provided a list of available parts which may be used in the robot design. The permitted
electrical hardware components are outlined in Appendix B. If any components not included on this list
wish to be used, it must be proposed to and accepted by the customer. The robot must also conform to a
list of design constraints, also provided by the customer. These general constraints are listed as follows:
1) No robot is allowed to INTENTIONALLY damage its opponent.
2) The use of materials and/or components other than the ones that are listed in the parts list is
possible, but must be authorized PRIOR to use. *Note that this parts list is not yet available.
3) The materials used as “plow”, “shield”, “bumper”, “mounting bracket”, etc. must be as light as
possible. No heavy gage steel, led, concrete, tungsten alloy etc. is allowed.
4) The chassis provided must not be altered in ANY way (i.e. no holes drilling or enlarging, no
cutting, no bending, etc.).
5) All components must be mounted using either machine screws or tie-wraps.
6) No kind of glue is allowed.
7) The maximum robot size is limited by the chassis listed in the parts list. No part (excluding the
wheels when the motors) may stick out for more than 10 mm before start and after finish (before
any interaction with robot).
If any of these constraints are not met, the robot may be disqualified from the competition.
2.4 Software Requirements
This section covers the software requirements needed to be met by the BeemoBot.
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2.4.1 Functional Requirements
2.4.1.1 Inputs
The BeemoBot receives inputs from the hardware, as listen above. These inputs are digitized using
various methods (software ADC, hardware ADC, etc.) and then sent to the microcontroller to be
processed. The software in the microcontroller must understand these inputs. Using the software ADC,
we must “translate” these values to something that will make more sense – from voltage level to distance,
for example.
2.4.1.2 Process
The microcontroller of the BeemoBot must have software that processes the information received from
the input, and uses it to determine the output. For example, if an input shows that an opponent has been
seen to our side, the software must make the decision to turn into the appropriate direction. The turning
maneuver is executed by sending the proper output.
2.4.1.3 Outputs
The outputs sent from the microcontroller on the BeemoBot tell it which maneuvers it must make. The
microcontroller sends this output to the motors, and the motors will turn in the appropriate direction.
2.4.2 Non-Functional Requirements
2.4.2.1 Performance
The BeemoBot must poll its hardware at an appropriate frequency. It should be frequent enough such that
the robot will not “lag” in response to changes in the environment. It must also be slow enough that the
processor has enough time to “decode” the inputs, make the appropriate decision for maneuver and then
send appropriate output.
2.4.2.2 Design Constraints
The BeemoBot is under a list of software-based design constraints. The BeemoBot must conform to
certain behavioral patterns. In Table 2.1, we may observe some of the behavioral expectations provided
by the customer.
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#
Situation
Time allowed, sec
Robot scores
#1
#2
Clear win and clear-like wins
1.
2.
3.
#1 pushes #2 out of the ring. #1 stays in the ring for at least 10 seconds.
#1 pushes #2 out of the ring. #1 stays in the ring for less than 10 seconds.
#1 pushes #2 out of the ring. #1 leaves the ring during the push while being pulled
by #2.
Default wins
#1 and #2 are in the ring. Both of them have moved from their initial positions
4. AND have detected the edge of the ring at least once. #1 is closer to the center.
#2 leaves the ring without being forced to do so. #1 stays within the ring for at
5.
least 10 seconds. #1 has detected the edge of the ring at least once.
#1 and #2 are in the ring. #1 is moving; #2 has stopped. #1 has touched #2 and
6. has detected the edge at least once.
#2 leaves the ring without being forced to do so. #1 stays within the ring for at
7.
least 10 seconds. #1 has never detected the edge of the ring.
8. #1 and #2 are in the ring. #1 has moved from the initial position; #2 has not.
#2 leaves the ring without being forced to do so. #1 leaves the ring in less 10
9.
seconds after #2.
10. #1 and #2 have not moved from their initial (starting) positions.
180
180
5
4
0
0
180
4
2
180
3
2
180
2
0
20
2
0
180
1
0
20
1
0
180
0
0
20
0
0
Table 2.1 - Behavioral expectations of the BeemoBot
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3 Hardware
The general behavior of this robot is that of a sumo bot. The primary function of this robot is to locate
opposing robots and push them outside of a circular area marked by a black boundary line along the
ground. At the same time, the robot must remain inside the circular area at all times. These goals are met
by the implementation of different hardware components. These hardware components can be listed by
category;









Chassis
Tracks
Motors
Printed circuit board (PCB) with IC’s and connectors
Sensors
Micro-switches
2 Battery packs
Mounting brackets with nuts and bolts
Connecting wires
The chassis being used for the BeemoBot is a transparent square piece of 5mm thick Plexiglas measuring
106mm by 112mm. This Plexiglas has been cut to size to fit in the design constraints, and custom drilled
to mount all necessary components.
The robot operates on two Johnny Robot Standard GM tracks. These tracks are mounted on two Standard
GM sprockets and two Idler sprockets. The GM sprockets are each connected to two GM8 Motor shafts.
These are powered and controlled by the Quad-Half H-Bridge located on the PCB. The GM8 motors are
mounted underneath the chassis using L-brackets with nuts and bolts,
All the electrical hardware components of the robot are either mounted on, or connected to, a printed
circuit board (PCB) which has been designed specifically for this project. The microcontroller and motor
controller are both mounted on this board using dual-in-line-pin (DIP) connectors. Some of the capacitors
and resistors needed for the system, as well as the voltage regulator, are also soldered onto the PCB. All
other components are connected to the board using wires and tap-screw connectors.
At each of the four corners of the robot a light sensor is placed underneath the robot chassis facing
straight down, at a height of approximately 3mm off the floor. These light sensors are used to detect the
black electrical tape used to delineate the end of the ring.
On both the front and the rear we will find two analog IR sensors, placed equidistant from the center of
the front of the robot facing straight forwards. They will be placed slightly inside the edge of the chassis.
These four sensors will be used to find and track the opposing robot.
On the center of the sides of the chassis, mounted underneath we will find a digital IR sensor. These
sensors are used to detect if an opposing robot is approaching our robot from the side. We use these
sensors to appropriately maneuver out of the “danger zone”.
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There are 2 micro switches on both the front and rear of the robot located behind aluminum bumpers.
These micro switches help determine whether the force applied by the opposing robot is on the left, right
or center of the bumper.
In the following table you will find all of the electrical hardware components required to build the
BeemoBot.
Component Label Part Number Part Description
Qty
C1
0.33uF
Ceramic Capacitor
1
C2
0.1uF
Ceramic Capacitor
1
D1
LED
Green LED
1
IC1
Atmega8
8-Bit Microcontroller
1
IC2
SN754410
Quad Half H-Bridge
1
J1
LM7805
5V Voltage Regulator
1
J2
N/A
Power Switch
1
J3
N/A
12xAA NiMH Battery Pack
1
IR Proximity Sensor (10-80cm)
4
Microswitch
4
J4, J5, J6, J7
GP2D12
J8-J11
N/A
J13, J14, J15, J17
QRD1114
Reflective Object Sensor
4
J16, J18
GP2D15
IR Proximity Sensor (24cm)
2
J19, J20
GM8
Servo DC Motor
2
R1-R4
20kΩ
Metal-Film Resistor
4
R5
220Ω
Metal-Film Resistor
1
R6-R9
10kΩ
Metal-Film Resistor
4
R10, R11
12kΩ
Metal-Film Resistor
2
R12-R15
160Ω
Metal-Film Resistor
4
Table 3.1 - Electrical Hardware of the BeemoBot
3.1 Block Diagram
The following Figure shows the general implementation of the hardware components with each other in
the form of a block diagram.
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Figure 3.1 - Block Diagram of the BeemoBot
10 | T e c h n i c a l M a n u a l
3.2 Circuit Schematic of BeemoBot
The following figure shows the full schematic of the BeemoBot electrical hardware. The labeled parts
correspond to those in Table 2.1.
Figure 3.2 - Schematic of the BeemoBot Electrical Hardware
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3.3 Scope of the BeemoBot System Hardware
In the following section you will find detailed information of each hardware component, both electrical
and non-electrical, which together create the BeemoBot.
3.3.1 Power Supply
The BeemoBot is supplied by twelve AA NiMH rechargeable batteries. At 1.2V per battery, this totals
14.4V of supply voltage to the robot. Most components of the BeemoBot need a 5V source voltage, thus a
voltage regulator is required. The BeemoBot uses the LM7805, a voltage regulator which allows an input
voltage of 7 to 35V, with a constant output of approximately 5V.
A small power supply circuit is needed for the BeemoBot, consisting of the battery, two coupling
capacitors, a power switch and a common ground. The power supply circuit may be seen in Figure 4.3
Figure 3.3 - Regulated Power Supply Circuit
3.3.2 Microcontroller
The BeemoBot’s “computer” is actually an Atmel Atmega8 8-bit microcontroller. This microcontroller
provides 3 input/output (I/O) ports, PA, PB and PC. Each port has 8 pins (labeled 0-7). This totals to 24
available I/O pins. Of these pins we have 6 analog to digital converters (ADC) available and two
hardware interrupt pins. The BeemoBot only uses software interrupts, as such the hardware interrupt pins
are used only as regular I/O pins. The BeemoBot does, however, use 4 ADC pins for the IR proximity
sensors.
Figure 3.4 - Atmega8 Pinout
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1
The Atmega8 is powered using the 5V regulated voltage VC from the power supply circuit, shown in
Figure 3.3. This voltage is applied to pins 7 and 20 (VCC and Vref). The common ground is connected to
pins 8 and 22 (both labeled GND). On pin 21, Aref, we connect a coupling capacitor of 0.1μF to ground.
This is for the functionality of the ADC.
Pin 1 is reserved for a reset circuit, as shown in Figure 3.5. This circuit, however, is optional, and is not
included in the final BeemoBot, as its main purpose is for testing. If the reset circuitry is connected,
pressing the reset pin will result in the robot’s software algorithm resetting to the beginning.
To program the Atmega8 microcontroller the user must connect a small programming circuit on a
separate breadboard. It is required that pins 1, 16, 17 and 18 are connected to an ISP connector. This ISP
connector is then plugged into the parallel port your computer to allow for programming. More
instructions on programming the microcontroller can be found in Section 6 of this document.
The microcontroller is placed on the PCB in its proper connecter. This can be seen in Section 3.3.10 of
this document.
Figure 3.5 - Atmega8 Reset and ISP Programmer Circuitry
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3.3.3 Motor Controller
Figure 3.6 - SN754410A Pinout
2
The quad half H-bridge motor controller is the “messenger” between the microcontroller and the motors.
Its function is to take the motor control signals outputted from the microcontroller and use them to make
the motors go forwards, reverse, or stop. The motor controller logic is powered by 5V, and is applied to
VCC1. VCC2 is powered by the battery voltage (14.4V). This 14.4V source is used to power the motors
through pins 1Y, 2Y 3Y and 4Y. 1,2EN and 3,4EN are always connected to the 5V source.
Pins 1A, 2A, 3A and 4A are connected to the appropriate motor control pins on the microcontroller. The
input to these pins determines the direction of the motors. For the BeemoBot, pins 1A and 2A control the
left motor, 3A and 4A control the right motor.
The motor controller is placed on the PCB in its proper connecter. This can be seen in Section 3.3.10 of
this document.
Below is an image showing how the motor controller is connected to the motors, the microcontroller and
to the power sources.
Figure 3.7 - Motor Control Circuitry
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3.3.4 GM8 Motor
Figure 3.8 - Solarbotics GM8 Motor with Bracket
3
The motors are used to move the BeemoBot forwards and backwards, as well as make it turn. The ones
used on BeemoBot are two Solarbotics GM8 motors. By applying a voltage to one lead and a grounding
the other, the motor will turn. If this voltage is reversed, the motor will turn in the opposite direction.
These directions are determined by the motor controller described in the previous section.
The motors are held in place using GM8 mounting brackets, also provided by Solarbotics. Additional
hardware, such as nuts and bolts, is required to mount the motor to the chassis.
3.3.5 Johnny Robot Track Kit
The actual “wheels” being used on the BeemoBot are not actually wheels, but a set of tracks, specifically
the Johnny Robot Tamiya Track Kit. This kit includes 40 plastic tracks with pins, where 20 track bits are
used for each track. Also included are two GM standard sprockets, and two GM idler sprockets. The GM
sprockets are mounted to the GM8 motors, and the idler sprockets are mounted to the chassis using an Lbracket and shoulder bolts.
Figure 3.9 - Johnny Robot Tamiya Track Kit
4
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3.3.6 Sharp GP2D12 Analog Proximity Sensors
Figure 3.10 - GP2D12 and GP2D15 Sensor Casing
5
For BeemoBot to see and track its opponent, it needs long-range proximity sensors. These sensors are
used to know where, and how far, the opponent is. The BeemoBot uses four GP2D12 analog proximity
sensors (two on the front, two on the rear) to spot and follow its opponent.
The GP2D12 is connected to VCC, GND and also has an output VO. This output has a varying voltage,
from X to X, depending on the distance of the object being seen. This output is connected to one of the 4
allotted ADC pins on the microcontroller.
3.3.7 Sharp GP2D15 Digital Proximity Sensors
For BeemoBot to know when it is being approached from the side we use digital proximity sensors. The
GP2D15 is a digital proximity sensor which outputs logic LO when no object is seen within a 24cm
range, and logic HI when an object is seen within a 24cm range.
The GP2D15 has the same casing as the GP2D12, as well as the same pin-out. However the GP2D15
requires an additional resistor in the circuitry, from the VCC pin to the 5V source. This additional resistor
is soldered on to the PCB, as is shown in Section 3.3.10 of this document.
3.3.8 QRD1114 Line Sensors
Figure 3.11 - QRD1114 Package
16 | T e c h n i c a l M a n u a l
6
Figure 3.12 - QRD1114 Pinout
7
The BeemoBot may not exit the ring at any time. The ring is delineated using black electrical tape on a
white MDF board. For BeemoBot to see when it has approached a line, it needs line sensors. For
BeemoBot we chose the QRD1114 analog line sensors. These sensors will output a different voltage level
depending on the reflectivity of the surface it is pointing at.
For the BeemoBot, we use these analog line sensors as digital sensors. To accomplish this, we must add
some additional circuitry to the QRD1114. This additional circuitry can be seen in Figure 3.13 We add
two resistors, R1 and R2. R2 is connected to pin 3 (cathode) of the QRD1114 is used to control the
brightness of the infrared diode in the QRD1114. R2 is used to digitize the signal. It is connected to pin 1
(the emitter) of the sensor, and to VCC. Pin 1 is also connected to the microcontroller. Using this set-up
we will get a logic HI whenever the sensors sees the black line. When the sensor sees the white surface, it
will output logic LO.
The circuitry shown in Figure 3.13 is soldered to perf-board. This perf-board will have three wires
connected to it – VCC (to the resistors), GND (connected to pins 2 and 4) and VO, connected to pin 1. A
small hole should also be drilled in the perf-board for mounting, which is discussed later in Section 4 of
this document.
Figure 3.13 - QRD1114 Perf-Board Circuitry
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3.3.9 Micro-Switches
8
Figure 3.14 - Micro-Switch Package
The BeemoBot requires knowing when an opponent is making contact. On the sides we have the digital
proximity sensors, which allow us to know when we are being approached from the side and need to turn.
For the front and rear, however, we need a different method of knowing when contact is being made. As
the GP2D12 analog sensors have a small dead zone when objects are very close, we use micro-switches
paired with bumpers. These allow us to know when, and at what angle, we have made contact.
The micro-switches have 3 pins, which allow use to use it as either normally-open (NO) or normally
closed (NC). BeemoBot uses NO micro-switches, with an active LO signal. This means that when we are
not making contact, the switches will output logic HI to the microcontroller. When contact is made we
will output logic LO. A pull-up resistor is required for use with the micros-witches. These resistors are
soldered onto the PCB, as shown in Section 3.3.10 of this document.
3.3.10 Printed Circuit Board (PCB)
BeemoBot assembly requires a “hub” of sorts, with which all the components may be connected to each
other, as well as to the power supply. BeemoBot has a custom designed printed circuit board (PCB) with
which to do this. On the PCB you will find the following components:





LM7805 Voltage Regulator
Coupling capacitors
Resistors
DIP connectors for Atmega8 and H-Bridge
Top-screw connectors
By properly soldering on the necessary components, inserting the Atmega8 and H-Bridge, and connecting
the leads from each component to its respective connecter, we will have assembled all the electrical
hardware components needed to build BeemoBot.
The PCB design may be seen in Figure 3.15.
The PCB is not the only way to connect the components. A breadboard of appropriate size may also be
used. This is, however, not as stable as the PCB. On the PCB all components are fastened firmly, and will
not loosen during operation. This is not true for a breadboard, where wires may pop out of their slots.
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Figure 3.15 - BeemoBot PCB Top-Down View
To create the PCB you may either send the design to a PCB manufacturer and have it made for you, or
obtain access to a PCB etching station. When etching, ensure that you have proper instruction and follow
the safety rules.
Note that the above figure shows the top-down view of the PCB. When printing this board, the image is
reversed and printed to the BOTTOM of the board. All components soldered to the board are placed
through the TOP of the board, and then the pins soldered onto the pads, located on the bottom of the
board.
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4 BeemoBot Assembly
4.1 Assembly Steps
NOTE: Unless otherwise specified, all bolts being used in the assembly process are 1/8’ machine screws
that are threaded from the head to the very end. Washers and hex nuts are used to fasten components
tightly together.
Step 1: Attaching the GM8 Motors and Idler L-bracket
a)
b)
c)
d)
Attach left motor to the front left of the bottom of the chassis.
Attach right motor to the front right of the bottom of the chassis
Attach left L-bracket to the rear left of the bottom of the chassis
Attach right L-bracket to the front right of the bottom of the chassis
Insert bolt from bottom to top in each bracket hole and through the appropriate holes in the chassis, with
the washer already on the bolt. Place the nut on the bolt and screw clockwise until very tight.
Figure 4.1 - Image showing the motor mounted on the chassis
Step 2: Attaching QRD1114 line sensors
a)
b)
c)
d)
Attach front-left line sensor
Attach front-right line sensor
Attach rear-left line sensor
Attach read-right line sensors
Insert bolt from the top down through the appropriate pre drilled hole for line-sensor mounting. Place nut
on the bolt and screw tight. Place another hex nut on the bolt and twist until the desired height. Place the
QRD1114 perf-board circuit on the bolt through the pre-drilled hole. Place a third hex nut on the bolt and
screw until tight. Repeat for all line sensors.
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Figure 4.2 - Image showing how the line sensor is mounted to the chassis
Step 3: Attaching the PCB
Insert a bolt from top-to-bottom in each of the 3 PCB mounting holes, located on the PCB. Attach a nut to
each bolt and turn them all tightly. Attach another nut to each bolt, approximately 60mm from the first
nut. Line up the bolts with the PCB mounting holes located on the chassis. Insert all bolts through. Place a
nut on each of the bolts and turn until tight.
Figure 4.3 - Image showing how the PCB is mounted to the chassis
Step 4: Attaching proximity sensor brackets and sensors
a)
b)
c)
d)
e)
Attach main left bracket
Attach main right bracket
Attach 4 mini L-brackets
Attach front cross bracket
Attach rear cross bracket
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f) Attach left GP2D15 L-bracket
g) Attach right GP2D16 L-bracket
Place the main brackets on the chassis such that the mounting holes line up with the bolts used to mount
the motors and L-brackets. Place nuts on each bolt and fasten tightly.
Mount the 4 mini L-brackets underneath the top part of each main bracket, as shown, using bolts and nuts.
Next attach the front and rear cross brackets. Lastly attach the two GP2D15 L brackets as shown.
Mount two GP2D12s on the front cross-bracket, ensuring they face squarely forward and no other
components or wires are in their line of sight. Do the same for the other two GP2D12s on the rear crossbracket.
Mount the GP2D15s on their appropriate L-brackets, located on the sides of the robot.
Step 5: Attaching GM8 sprocket, idler and Tamiya tracks
a) Attach left sprocket
b) Attach left idler
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c)
d)
e)
f)
Attach left track
Attack right sprocket
Attach right idler
Attach right track
To attach the sprocket, simply slide it onto the GM8 drive shaft. It should fit tight and snug. Next screw
the wheel onto the driveshaft.
To attach the idler, use a shoulder bolt and hex nuts to fasten it firmly to the L-brackets mounted under
the chassis.
With the tracks unfastened (one pin missing), place them around the two wheels. Pull the two ends
together firmly but gently, and insert last pin.
Figure 4.4 - Figure showing how the tracks are mounted
Step 6: Attaching the battery pack
Place the battery pack between the cross-brackets that were used to mount the GP2D12s. Fasten to the
robot using tie-wraps.
Step 7: Attaching On/Off button
Insert the on/off switch through the appropriate whole located on the proximity sensor brackets. Fasten
securely using a hex nut.
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Figure 4.5 - Figure showing On/Off button is mounted, to the right
Step 8: Connecting wires and ICs
Using the schematic and PCD circuit design, place all the wires in their appropriate connectors. If the
wires are too long, cut the slack, strip the end of the wire and connect it to the top-screw connectors on
the board. Place the microcontroller and motor controller in their appropriate connectors, taking care to
note the correct orientation.
4.2 Final Product of BeemoBot
Assembly of the BeemoBot is now complete. The following figures are a photograph of the finished
product, as well as an artist’s 3D rendering of the robot.
Figure 4.6 - Final Robot Assembly
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Figure 4.7 - Artist's rendering of robot assembly
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5 Software
The following sections will show the pseudo-code for the BeemoBot, as well as a flowchart and images
depicting the general behavior of the BeemoBot. It will also include the C program code used in the
BeemoBot as well as how to program the microcontroller with this code.
5.1 Pseudo-Code
The following depicts the algorithm of the robot in an easy to follow C-like pseudo-code. Note that when
the BeemoBot changes its direction flag, it means that it reverses its front and rear. Reverse now becomes
forward, forward becomes reverse, and so on.
MAIN
/////////INITIALISE/////////////////
//initialise Digital input
set line sensor states to 0
set contact sensor states to 0
set Left & Right IR sensor states to 0
//initilaise Analogue Sensor pins and Data values
Enable 60Hz interrupt
Enable ADC for Front & Back IRsensors
//initialise digital output pins
set Motor control Pins as outputs
set winning LED pin as output
//Delay initialise
Enables 1000Hz interrupt on Timer2 for interuptable delay.
//initialise global state variables
Direction = 0 (forward)
////////////////////////////////////////
//5 SECOND DELAY////
do nothing for 5 seconds
////While(1) Loop////
///GET SENSOR DATA/////
Check line sensor data
Check contact sensors
Check Front & Back IR sensors
Check Left & Right IR sensors
////IF A LINE IS DETECTED/////
if a line is detected
if front left sensor detected the line
Set direction flag to 1
go forward
turn counter clockwise
if front right sensor detected the line
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set direction flag to 1
go forward
turn clockwise
if rear left sensor detected the line
set direction flag to 0
go forward
turn clockwise
if rear right sensor
set direction flag to 0
go forward
turn counter clockwise
if both Front sensors detected the line
set direction flag to 1
go forward
if both rear sensors detected the line
set direction flag to 0
go forward
/////ELSE IF ROBOT MAKES CONTACT/////
if a robot makes contact
if robot makes contact on front left
set direction flag to 0
move forward and left into robot
if robot makes contact on front right
set direction flag to 0
move forward and right
if robot makes contact behind to left
set direction flag to 1
move forward and right into robot
if robot makes contact behind to right
set direction flag to 1
move forward and left into robot
if robot makes contact on both front sensors
set direction flag to 1
move forward into robot
if robot makes contact on both rear sensors
set direction flag to 0
move forward into robot
if robot makes contact at front and back
turn clockwise to evade being stuck
///ELSE IF ROBOT IS SEEN BY FRONT/BACK IR SENSORS////
if a robot is seen detected at front or back
if robot is seen on front left
set direction flag to 0
move forward and left toward robot
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if robot is seen on front right
set direction flag to 0
move forward and right toward robot
if robot is seen behind to left
set direction flag to 1
move forward and right toward robot
if robot is seen behind to right
set direction flag to 1
move forward and left toward robot
if robot is seen by both front sensors
set direction flag to 0
move forward toward robot
if robot is seen behind
set direction flag to 1
move forward toward robot
///ELSE IF ROBOT IS SEEN TO LEFT OR RIGHT///
if a robot is seen to left or right
if robot is seen to left
turn counter clockwise
then move forward
if robot is seen to right
turn clockwise
then move forward
///IF NOTHING IS DETECTED////
else
Move forward
5.2 BeemoBot’s Expected Behavior
5.2.1 Robot Detection
In the figure below we can see a visual representation of what happens when BeemoBot detects an
opponent. In Figure 5.1 (a) we see that BeemoBot is looking for an opponent with its digital IR sensors.
In Figure 5.1 (b) an opponent has entered BeemoBot’s field of vision. Next BeemoBot will turn to face its
opponent, as can be seen in Figure 5.1 (c). BeemoBot knows that its opponent is straight in front if both
digital IR sensors are asserted. If an opponent is seen in the rear, the BeemoBot will change its direction
flag, reversing its front and back, and will track the opponent in the new front direction.
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Figure 5.1 - BeemoBot Analog (Front/Rear) Robot Detection
Figure 5.2 - BeemoBot Digital (Left/Right) Robot Detection
In the figure above we can see a visual representation of what happens when one of BeemoBot’s digital
IR sensors is asserted. These sensors are placed on the left and right of the robot. If Figure 5.2 (a) we see
that BeemoBot is checking for a robot at its side. In Figure 5.2 (b) we see that the digital proximity sensor
has been asserted. It will then turn to face the opponent, as can be seen in Figure 5.2 (c).
5.2.2 Robot Touch
BeemoBot knows when it is making contact with another robot by means of micro-switches located on its
front and rear. When both contact switches are asserted, BeemoBot knows its making head-on contact
with its opponent and will move in that direction. If, for example, only the front left sensor is being
asserted, BeemoBot will turn counter-clockwise to the left, until both contact switches are asserted. Once
both are asserted, it will move straight forward. These contact switches are also located on the rear of
BeemoBot. If one or both of the rear contact switches is asserted, BeemoBot will change its direction flag,
reverse its front and rear, and then move in its new forward direction.
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5.2.3 Line Detection
START
Etc...
Figure 6.3 - Line Detection
The BeemoBot is bi-directional. Because of this, when the BeemoBot detects a line head-on, it does not
turn around. Instead, a flag is set which reverses the front and the back in the code. The BeemoBot then
moves in its new forward direction. If the line has been approached at an angle, the BeemoBot will set
the flag, move into the new forward direct, turn approximately 30° away from the line and then continue
forward again, waiting once again for an input from one of its sensors.
5.3 Source Code
The actual code listing may be found in Appendix A.
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6 Programming the Atmega8
Step 1: Open AVR Studio 5
Step 2: Create new project by going to [File  New  Project…]
Step 3: From the list of installed templates make sure AVRGCC is selected and select ‘C Executable
Project’ from the list and give your project a recognizable name. Press ‘Ok’ when done.
Step 4: You should now see the ‘Device Selection’ screen, select Atmega8 from the list of devices. You
can use the search function in the top right of the screen to speed up this process. Press Ok
Step 5: Write your code
Step 6: Put AVR Studio in to release mode, do this by looking for a dropdown box in the toolbar, by
default it will say ‘Debug’, select ‘Release’ instead.
Step 7: Compile the code by either selecting [Build  Build Solution], or hit F7. Depending on the length
of the code this process may take a few seconds to process.
Step 8: Once everything has compiled successfully, open ‘ponyprog.exe’
Step 9: Click Device. In the AVR submenu and select Atmega8
Step 10: Select [Setup  Calibration], then proceed to hit [Yes], followed by [OK].
Step 11: Select [Setup  Interface Setup], this will bring you to the I/O port setup window.
Step 12: Ensure that the settings are as follows: Parallel, AVR ISP I/O, if multiple parallel ports are on the
machine make sure the correct one is selected, and then press [OK].
Step 13: Click [File  Open Device File  <your file name>  Default  Binary  <your .hex file>].
The code will then appear in ponyprog.exe’s main window in hex format.
Step 14: Connect the programming circuit on a breadboard as shown in Figure 3.5 in this document.
Step 15: Plug your interface cable into the parallel port of your computer.
Step 16: Plug the other end of the interface cable into the ISP connectors located on your breadboard.
Step 17: Turn ON the 5V supply to power the Atmega8. If you do not do this you may receive the error
message ‘unidentified or missing device -21’ when writing to the chip.
Step 18: In ponyprog.exe, click Write All, ponyprog.exe will write to the chip and then verify its write.
Step 19: If all was successful, your program is now loaded on to your Atemga8 microcontroller.
Step 20: Insert the microcontroller into its allotted socket on the BeemoBot PCB.
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7 Troubleshooting
The following table outlines some troubleshooting scenarios.
Component
QRD1114
GP2D12
GP2D15
Micro-switch
Issue
Asserting on white
surface
Not asserting on
black surface
Asserting when an
object is not within
80cm range
Not asserting when
an object is within
80cm range
Asserting when an
object is not within
24cm
Not asserting when
an object is within
24cm
Asserting when not
depressed
Not asserting when
depressed
Solution
Ensure that voltage VO of line sensor is within 0-1V range
when within 3mm of a white surface. If not, increase the
value of R1 (refer to Figure 3.13 - QRD1114 Perf-Board
Circuitry)
Ensure that voltage VO of the line sensor is within 3-5V range.
If not, decrease value of R2 (refer to Figure 3.13)
Check voltage level on output VO of the sensor (refer to Figure
3.2). Voltage level should be almost 0V when no object is
within range
Check voltage level on output VO of the sensor. Ensure that
the correct voltage level is being output for set distances
(refer to Figure 3.2).
Check the voltage level on output VO of the sensor, when no
object is in range. Ensure the voltage level is near 0V. If not,
increase the value of the resistor connected to the sensor
(refer to Figure 3.2)
Check the voltage level on output VO of the sensor, when no
object is in range. Ensure the voltage level is between 3-5V
(refer to Figure 3.2)
Ensure that the micro-switch is connected normally-open.
Ensure that the micro-switch is connected normally-open.
Table 7.1 - Troubleshooting Scenarios
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8 References
1
- Atmega8 Pinout” Atmel http://www.futurlec.com/Pictures/ATMega8.gif (accessed December 3rd
2011)
2
- SN754410A Pinout” Texas Instruments
“http://lizarum.com/assignments/htink/images/motors/sn754410.jpg” (accessed December 3rd 2011)
3
- Solarbotics GM8 Motor with Bracket” Solarbotics
http://www.solarbotics.com/assets/images/gm8/gm8-front-img_3148_pl.JPG (accessed December 3rd
2011)
4
- Johnny Robot Tamiya Track Kit” Tamiya http://www.robotshop.com/Images/xbig/fr/kit-chenillestamiya-johnny-robot-B.jpg (accessed December 3rd 2011)
5
- GP2D12 and GP2D15 Sensor Casing” Sharp http://www.solarbotics.com/assets/images/35080/35080front-dcn1503_pl.jpg (accessed December 3rd 2011)
6
- QRD1114 Package” Fairchild Semiconductor http://www.hvwtech.com/products/97/35120_PV.jpg
(accessed December 3rd 2011)
7
- QRD1114 Pinout” Fairchild Semiconductor http://megads.com/files/datasheets/qrd1114-datasheet9b.png (accessed December 3rd 2011)
8
- Micro-Switch Package” Tamiya http://pics.towerhobbies.com/image/t/tamx7516.jpg (accessed
December 3rd 2011)
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