MAE 1203 - Introduction to Mechanical Engineering
Spring 2003

Project Description:

The class project involved the design and construction of a computer-controlled XY stage, with each axis controlled by a separate stepper motor. The motors had a resolution of 200 steps/revolution, and were driven by a four-transistor output stage controlled from the parallel port of a personal computer.

Each group was given two motors, the corresponding motor drive (output stage) and a power supply. The students were also instructed on the basics of how to drive stepper motors by sending sequences of zeros and ones to the transistors that drive the motor coils. A program in GWBasic describing the basic sequence to turn a motor one step in either direction (both half step and full step) was given to them and explained in detail.

Each group had to develop:

A detailed mechanical design of their machine, including assembly drawings and detail drawings of all the required parts. Several design reviews were dedicated to discuss functionality, reliability, cost, manufacturability, assembly, etc.
Each group had to make a cost analysis of their design, locate vendors for parts that needed to be purchased, and have a final budget approved by the instructor before proceed to fabrication.
All machine components that were not purchased off-the-shelf had to be manufactured, assembled and connected to the motors and drive electronics.
The motor drivers had to be interfaced to the parallel port of their PCs. Some laptops have output voltage levels lower than what is required to control the motor drivers, therefore some groups had to build line drivers or a new output stage with different transistors.
Each group had to develop the corresponding software to drive their machines. The students had the choice to use either GWBasic or C++ to develop their code. The machines had to perform the following functional tests:
- Draw straight lines at various slopes
- Draw a circle
- Draw a letter "M"

The machines were graded according to the following criteria:

Functionality: how well could the tasks be performed. Accuracy and resolution (40%)
Quality of manufacture and assembly. Reliability, robustness and overall design quality (40%)
Time of execution (10%)
Other (cost, ease of assembly, manufacturability) (10%)

Instructor: Hector Gutierrez, Assistant Professor, MAE, hgutier@fit.edu