Mechatronics Learning Studio
Module 1
Remote
Control Pick-up
Joël Carbonneau, Raymond
Piette, Jennifer Chasse, Dept of Mechanical Engineering,
University of Ottawa
Power Point
Presentation
Video
Objective and Related Work
Our
project was inspired by the first project in the
Mechatronics for the Evil Genius book, which is the project
concerning the mechatronics race car. We say inspired
because we have made several important changes. Firstly, we
made a pick-up truck instead of a simple car type platform.
This aloud more storage room for our electronic parts and
gave us a greater challenge. The second change was the
integration of a remote control in order to control the
speed and the direction of the car from a distance. To do
so, we needed a remote control, which came with a receiver,
and integrate these with the electrical and mechanical
systems. Another change was the addition of a second power
supply in parallel with the first to enable us to switch
from one type of power to the other. Our goal for the
project was to incorporate solar energy, therefore adding a
solar cell on top of our vehicle, this being our second
energy source, the first being a set of four 1.5V batteries
in series. Finally, we added a system of lights to the car.
This part isn’t directly related to mechatronics, but we
used the lights to create a more realistic look for the
vehicle.
Circuits
The first
circuit is for the driving motor. We used 4 AA batteries as the
main option to power the motor, the other being a 6.7V solar
cell. A 3-position switch was used so that one cannot use both
power supplies at the same time, with the 3rd switch
position being the off-position. The resistance value of the
potentiometer is controlled by the rotation of a servomotor. At
the potentiometer’s default position, the resistance value is
high so there isn’t enough current to power the transistor so no
current goes through the motor. Once the resistance value is
decreased, there is enough current to initiate the transistor so
that the motor gets current and the pick-up moves forward. Also,
for speed control, the less the resistance, the more current to
the transistor and therefore through the motor, the faster the
motor turns.
The second circuit is the
lighting circuit. A DIP switch was used due to the high number
of switched needed. When a switch is closed, the current goes
through the resistor and the LED and the LED emits light. We
have LEDs to represent the brake lights, flashers, low and high
beams of a real pick-up truck. In addition, we used the
different LED specifications and Ohm’s Law to find the
appropriate resistance for each LED.
Mechanical Systems
The pick-up truck is
composed of two major subsystems: the steering and the driving
systems. Both are controlled by a remote control. In the
steering system, both front wheels are attached to independent
hinges that are connected to the frame by a pin. The hinges are
connected together through a servomotor, which controls the
angle of the wheels. As for the driving system, the back wheels
are connected to a gearbox – driven by a 6V motor – with a ratio
of 76.5:1 which gives a rear axle angular velocity of 78.4rpm.
The motor is driven by a current as explained earlier.
The frame itself is made
out of basswood, a lightweight yet durable material for this
kind of application. It is held together with only Krazy Glue®
and Epoxy.
Remote Control System
The remote control
(powered by 8 AA batteries) sends a signal to the receiver
installed on the pick-up truck. The receiver is then wired to
two servomotors and is powered by 4 AA batteries. It can control
the position of both servomotors. One servomotor is glued to the
potentiometer to control the resistor value in the motor
circuit. The other servomotor is connected as explained earlier
through rods to the two front wheels to control the steering.
Testing
The testing of the
circuits was done and it has been determined that they work
perfectly. In order to make sure there was not too much current
flowing through any electrical component, we had to vary the
resistor values to see which ones would fit the best in our
circuits. When combining everything, the tests on the pick-up
were conclusive.
Problems
We have come across a
number of problems. Our first problem was the difficulty of
finding certain parts needed. Indeed, we had to order a few.
When we did have the pieces and had everything figured out about
how we would bring everything together, we came across a small
problem; our drill wasn’t strong enough to make the holes in the
chassis. Our solution was to ask a friend for his drill which we
knew was more powerful. We also had to wait a long time for
certain parts to come through the mail and therefore do some
last minute adjustments. We were also very limited in tools. For
example, we had to use a hand saw to cut through 1/8” pieces of
wood. We had to learn how to solder and as the pick-up truck is
very small, we had to work in very tight conditions.
Conclusion
The pick-up was completed
with success, but we would have wanted a higher speed. The
pick-up has a slow start up and operates at slower speed than
intended. This might be due to the weight of the truck that is
relatively important. Though this would cause the truck to have
less torque, and would be complicated to uninstall the gearbox
for modification, therefore we have decided to let the truck as
is. Other than that, the pick-up works perfectly.
Power Point
Presentation
Video
