The Mobot Project

The MOBOT Project: Longwood

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.