In modern engineering, a systematic approach is used in the design, operation, and
construction of an object to reach a desired goal. The first step of the process employs
what is commonly known as the scientific method. The next step involves forming an
interdisciplinary team of specialists from not only the various engineering disciplines,
but from other fields whose knowledge may be useful or even necessary to completing the
project. This step doesn't apply to our project, due the confined nature of the class.
Finally, considerations must be taken into account to ensure that the project is
efficient as well as cost effective.
The goal of the MOBOT Project was to design and build a programmable robot. The robot
had to complete a series of four movements in four given directions over a distance of at
least 6 inches. Power and weight restrictions were applied to ensure the safety of the
students and, more importantly, the teacher. As the goals of the project were made
clearer, our group began discussing possible ideas for the design. There were some
disagreements about whether we should take the electromechanical route or the purely
electrical one. And after some deep thought, we all agreed that the mechanical way would
be the simplest to build and the most merciful on our pocketbooks. Even though we were
coming up with some good ideas, each design seemed to contain some major problems. One
of the reoccurring problems dealt with the synchronization of the driver motor and the
steering system. Finally the team came up with a design that allowed the drive and
steering controls to be independent of one another, but still allowing each one to be
linked in time. This design has now become what is known as LONGWOOD.
The Longwood is divided into two main parts: 1)motion system and 2)logic board. As the
engineer, I was responsible for motion design. Therefore, that will be the focus for the
remainder of this section.
The main components of the motion system consist of a platform, three wheels, a wheel
frame, two motors, and two contact switches. Two of the wheels were connected to a motor
and attached at the front end of the platform. These wheels were only allowed to move
simultaneously in either a forward or reverse direction. The third wheel was hooked up
to the wheel frame and free to rotate approximately 45 degrees in either direction.
Figure 1.1 shows an illustration of how the wheel frame works. The wheel frame and third
wheel were then attached to the platform completing the basic assembly. The second motor
was put near the end of the platform and is used solely to pull the logic board through a
series of contact points. The final step involved setting up a canopy containing the
contact switches across the platform where the switches were free to strike the logic
board.
The fact that the wheel base can be controlled separately from the forward and reverse
motor yielded some advantages that we thought were rather interesting. One of them is
that the robot is able to make a turn while driving in reverse, instead of just forward.
Another feature is that the car is capable of turning and then translating in one
command. Even though this was one of the original parameters which was eliminated
because it complicated matters, we felt that it couldn't hurt to have it anyway. The
theory of the motion design was finished. The only obstacles that remained were the
testing and fine-tuning of Longwood, a machine that was destined for success.
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