Challenge A
The vehicle must be able to track a path on a smooth surface. The
path will be made with black tape and will involve lines and curves (Note:
no curve will have an angle less than 50 degrees). The vehicle should be
able to, from any random part of the testing surface, move forward until
it comes in contact with any part of the path. It must then recognize the
path and continue to travel along it. The success of the tracker will be
determined by its ability to navigate the course without touching any of
the impediments placed on it.
Note that on the day of the competition, your tracker will be allowed to
make only one run. It is this single run that will be used to judge its
performance. Therefore all adjustments need to be made prior to the moment
of competition.
Attention must be placed on the soldering of the PC board, as this is the
'brain' of the tracker.
Each team will submit only one tracker.
Challenge B
In this segment of the competition, teams must design and build
an electrically powered car that meets the following specifications:
1. The car must fit the following dimensions: 30 cm x 60 cm x 30 cm. A height
extension may be granted for antennae or other decorations placed on the
car. When turning corners, the car may exceed these dimensions (only slightly).
However, the car must be fully operable with the dimensions provided above.
2. The car must be able to go up a 3 m grade of 20 degrees, while pulling
a weight of 8 oz. The car must therefore have a "trailer hitch"
located at its rear.
3. All power must be supplied by no more than two (2) AA batteries.
4. The body of the car must be three-dimensional.
5. The car may be decorated in whatever fashion desired but its basic frame
must meet the size dimensions above.
6. The power source must be switch-controlled to conserve on battery power.
7. An area 6 cm x 6 cm will be reserved for placing the car name.
8. There should be no sharp edges on the vehicle.
Power: The vehicle will be powered by electrical motors
provided by the RISE leader and these motors should provide the only source
of propulsion.
Motors/Gears Ratios: There are no regulations concerning
these items.
Battery Type: AA alkaline (choose one brand) batteries.
Testing Surface/Track
The length of the level segment of the track will be 5 m and the slope will
be 3 m long, at an angle of 20 degrees above the horizontal, amounting to
a total track length of 8 m.
The track will be constructed from untreated plywood with hinges used to
attach the level surface at an angle to the inclined surface.
The Race
All cars must be submitted for the competition at least a full 1/2 hour
prior to testing.
At the time of the race, the car, with motor off, will be taken to the starting
point. At this time, the trailer will be hitched to it and the complete
device will be placed on the racing course with the wheels in contact with
the ground. All this will occur with the car turned off. When the signal
is given, the car must be switched on and scoring will begin. No alterations
can be made to any part of the car at the starting line.
Any pushes to the car will result in the vehicle being disqualified. The
winner of the race will be the car that scores the best time in pulling
the weight over the full length of the course. NOTE that every second or
part thereof is important in the scoring. So make every effort during the
design and testing phase to shave valuable seconds off your timing.
One team member must wait at the finish line with the judges to retrieve
the car. However, no team member may touch the car while it is on the track.
Judges have the option to inspect the car prior to the beginning of the
race.
Parameters to be tested
Steepest grade climbed in degrees
Steepest grade climbed carrying a 100 gram mass
Highest speed in m/s
Range in m/s
Stylish car
Best teamwork
Sturdy, robust car
Parts
You will be supplied with a kit of parts. Feel free to add to this list
or improvise (from parts found around your homes) if you feel it will enhance
the performance of your vehicle. However, neither the motor nor batteries
may be replaced.
Chassis
The chassis is the part on which you mount your motor, gears and wheels.
Good materials for the chassis are:
Foam Core
Wood (Balsa and pine - Be careful with balsa wood. Although it is light,
it splinters easily.)
Corrugated cardboard
Wheels
The wheels in your kit should be adequate but can be substituted by others
if they aren't the right size needed, as indicated by your calculations,
for optimum vehicle performance.
A good substitute might be wheels from old toys. Old cars are also good
places to find axles. If you decide to use the wheels in the kits but find
that you would like them to be a bit bigger, you will need to decide on
some creative method of increasing the size of your wheels.
Drive Train
If you will be using pulleys for your drive train, you will need to manufacture
them yourself. Use smooth material to reduce friction in your drive train.
In addition, the use of a lubricant will be helpful in reducing overall
friction.
Determining Gear Ratio
There are a number of ways to determine what gear ratio is needed. First,
if you are using the gears included in your kit, you will already know the
ratio. You can then use this ratio to determine the best drive wheels needed
to make a winning design.
First: determine the gear ratio:
For gear system,
G-ratio=Nf/Nd - where Nf is the number of teeth on the follower and Nd
the number of teeth of the driver.
For pulley system, G-ratio=Df/Dd where Df is the diameter of the follower
pulley and Dd the diameter of the driver.
Second: Find speed of the wheel
The motor spins at ___rpm
Therefore,
Vd, the speed of the drive wheel is given by:
Vd = Vm/G-ratio
Since this produces a resulting wheel speed in rpm's, we need to convert
this to rps's.
Therefore, from this motor, the highest speed at which the motor will spin
the wheel is Vd, whatever value this amounts to be.
Third: Calculate circumference of the wheel. Getting this
value will tell you how far the car will travel in one revolution of the
wheel.
Divide expected speed by the drive speed.
Fourth: Determine the wheel diameter
Dw = Circumference/Pi
The wheel must have a diameter that is bigger than the diameter of the drive
gear. If this is not true, then choose smaller pulleys or gears.
If you are designing for a set wheel size:
First: Calculate the circumference of the wheel.
Second: Find the wheel speed by determining (through guess
work) how fast your vehicle should travel.
Vd = Expected Speed/Circumference
Third: Determine the rpm of the drive wheel and hence the
rps.
Fourth: Determine the gear ratio.
What do you think would be the formula for the gear ratio?
Fifth: Design transmission.
Lab Notebook
Every effort must be made on the part of teams, to ensure that your lab
notebook is complete and neat. It must be presented along with the vehicles
1/2 an hour before the race.
Also test for range by having girls make an electronic counter as per instructions
in the Electric Car, teacher's book.
Range is tested by counting the number of laps and multiplying
then by the circumference of the lap (Pi x diameter).
Power is measured by seeing the steepest grade climbable/navigable
by car.
Speed is measured by timing a fixed number of laps.
Speed = distance(range)/time
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