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Bulldog 1 is an
unexceptional wedge
style sumobot. The
rule set specified a
20cm x 20cm footprint
and a 1kg weight limit.
So the construction of
bulldog is a good
indication of what you
will need to do to
build your own
mini-sumo bot.
unexceptional wedge
style sumobot. The
rule set specified a
20cm x 20cm footprint
and a 1kg weight limit.
So the construction of
bulldog is a good
indication of what you
will need to do to
build your own
mini-sumo bot.
The robotics club of Mt San Antonio College hosted a
mini-sumo competition. So we took the opportunity to
document the creation of a contender, Bulldog 1
mini-sumo competition. So we took the opportunity to
document the creation of a contender, Bulldog 1
Image 1: The sensors
Image 2: View of the top
Image 3: The chassis in construction
Building a mini-sumo competition robot: (All of these parts are
available in Tin Man Robotics)
First choices:
The host of the competition specified that the physical limits of
the robot was 20cm x 20cm but as tall as you wish, and that the
weight limit was 1kg. The bulldozer wedge has been successful
in sumo competition, so we chose to go with it, just because.
Knowing the overall size and weight we chose motors and
wheels that seemed appropriate. The motors are Buelher
gearhead motors that get about 80rpm from 8v. The wheels are
4" airplane landing wheels.
In order to detect the opponents we decided to use two
ultrasonic range finders as a coarse resolution object locator,
and an infrared range finder as a fine resolution object locator.
See image 1 to the left.
For logic control we chose to use the PIC Axe 28X1, just as an
experiment. It has plenty of I/Os and turns out to be very easy
to program.
For motor control we chose the Solarbotics L298 motor driver
kit. It is a nice, easy to use dual motor driver that easily
handles the voltage/ current required by our motors.
For the chassis we tried to use 1/8" acrylic. It was looking so
good, then in testing the night before competition it fell off the
table, DOH!!! So the construction steps below worked for
acrylic and for the 1/8th ABS that we frantically made up the
night before competition.
That takes care of the basic choices we made before getting
into construction.
Construction:
Chassis: With an idea of the overall shape, and the size
dictated by the chosen components, we cut out a plate to bend
into the front and sides (image 3). We clamped it to the
workbench and used a hot air tool to soften and fold the
plastic.
For the acrylic version we cut brace pieces and glued them to
the sides. For the ABS version since we couldn't wait for glue
to dry we folded a top/back/bottom piece and pop-riveted it to
the other piece.
Control board, motor drive board:
We chose a piece of protoboard because it's lighter than a
breadboard, but the layout is the same. The PIC Axe 28X1
needs a 5v regulator, and a couple of resistors for the serial
interface programming cable, and that's it. Very easy. There is
an LED to indicate power on and another to indicate the delay
countdown. There are 4 outputs to the motor drive board.
The ultrasonics took an output and input each. The IR took one
input. There are two QRD1114s to detect the edge of the ring.
They took one input each. Also we combined the two edge
sensor inputs to a AND gate to have a single input to the 28X1
change state for any IR trigger which we needed for the
'Interrupt' function of the 28X1 (it only has one active at a time).
The two buttons are a reset and 1 input to 'start'.
Batteries.:
In Bulldog1 we chose to run a 7.2v NiCd pack. It was about all
we could fit under the 1kg weight limit. In practice it turns out
that the current supply is a little limited. Look for revisions
later.
Sensors:
We mounted the ultrasonics high and wide to look for
opponents. We mounted the IR centered and aimed a little
down. The plan is the ultrasonics will get the opponent close,
and the IR will trigger a charge. The QRD1114s are on the front
edge corners. Rolling over the white edge triggers an
interrupt and the robot backs and turns.
Other considerations:
There was an issue in that the motors with wheels were almost
10cm long. So the chassis width had to be right on. Too small
and the motors would touch. Too wide and the robot would be
more than 20cm wide.
Most parts are held on with double sided tape. A more
permanent design would use some PCB standoffs.
Programming is essentially
look for an echo from the ultrasonics, turn to face an echo,
turn left to search if there is no echo.
if the left and right echoes are about equal advance and
check the IR range finder
if the IR range finder shows an object close, charge.
if at any time an edge sensor is triggered, stop, reverse
and turn
We hope this info is of help to you in your project. Good luck!
available in Tin Man Robotics)
First choices:
The host of the competition specified that the physical limits of
the robot was 20cm x 20cm but as tall as you wish, and that the
weight limit was 1kg. The bulldozer wedge has been successful
in sumo competition, so we chose to go with it, just because.
Knowing the overall size and weight we chose motors and
wheels that seemed appropriate. The motors are Buelher
gearhead motors that get about 80rpm from 8v. The wheels are
4" airplane landing wheels.
In order to detect the opponents we decided to use two
ultrasonic range finders as a coarse resolution object locator,
and an infrared range finder as a fine resolution object locator.
See image 1 to the left.
For logic control we chose to use the PIC Axe 28X1, just as an
experiment. It has plenty of I/Os and turns out to be very easy
to program.
For motor control we chose the Solarbotics L298 motor driver
kit. It is a nice, easy to use dual motor driver that easily
handles the voltage/ current required by our motors.
For the chassis we tried to use 1/8" acrylic. It was looking so
good, then in testing the night before competition it fell off the
table, DOH!!! So the construction steps below worked for
acrylic and for the 1/8th ABS that we frantically made up the
night before competition.
That takes care of the basic choices we made before getting
into construction.
Construction:
Chassis: With an idea of the overall shape, and the size
dictated by the chosen components, we cut out a plate to bend
into the front and sides (image 3). We clamped it to the
workbench and used a hot air tool to soften and fold the
plastic.
For the acrylic version we cut brace pieces and glued them to
the sides. For the ABS version since we couldn't wait for glue
to dry we folded a top/back/bottom piece and pop-riveted it to
the other piece.
Control board, motor drive board:
We chose a piece of protoboard because it's lighter than a
breadboard, but the layout is the same. The PIC Axe 28X1
needs a 5v regulator, and a couple of resistors for the serial
interface programming cable, and that's it. Very easy. There is
an LED to indicate power on and another to indicate the delay
countdown. There are 4 outputs to the motor drive board.
The ultrasonics took an output and input each. The IR took one
input. There are two QRD1114s to detect the edge of the ring.
They took one input each. Also we combined the two edge
sensor inputs to a AND gate to have a single input to the 28X1
change state for any IR trigger which we needed for the
'Interrupt' function of the 28X1 (it only has one active at a time).
The two buttons are a reset and 1 input to 'start'.
Batteries.:
In Bulldog1 we chose to run a 7.2v NiCd pack. It was about all
we could fit under the 1kg weight limit. In practice it turns out
that the current supply is a little limited. Look for revisions
later.
Sensors:
We mounted the ultrasonics high and wide to look for
opponents. We mounted the IR centered and aimed a little
down. The plan is the ultrasonics will get the opponent close,
and the IR will trigger a charge. The QRD1114s are on the front
edge corners. Rolling over the white edge triggers an
interrupt and the robot backs and turns.
Other considerations:
There was an issue in that the motors with wheels were almost
10cm long. So the chassis width had to be right on. Too small
and the motors would touch. Too wide and the robot would be
more than 20cm wide.
Most parts are held on with double sided tape. A more
permanent design would use some PCB standoffs.
Programming is essentially
look for an echo from the ultrasonics, turn to face an echo,
turn left to search if there is no echo.
if the left and right echoes are about equal advance and
check the IR range finder
if the IR range finder shows an object close, charge.
if at any time an edge sensor is triggered, stop, reverse
and turn
We hope this info is of help to you in your project. Good luck!
Image 4: The chassis ready for parts
