Table of Contents
The information shown below represents the major things we have accomplished and/or have been working on up to this stage of the project.
It is important to note that the diagram displayed below is subject to change and may or may not represent components chosen for actual project implementation.
The proposed system level diagram is shown below:
Breaking the above diagram down further we can separate each outcome that must be achieved:
From the above diagram it can be seen that there are four major components to our system. They are as follows (in no particular order):
- PC - MATLAB GUI
- Power Supply
- Microcontroller and Motor Control
- Mechanical Coupling of Motor and Slotted Line (and base design)
It should be noted as well that the green dashed box indicated by the third bullet point above ("Microcontroller and Motor Control") has been expanded to show the wiring needed for the control of the stepper motor.
Below is a portion of a chart taken from Adafruit comparing the different kinds of Arduinos. It can be found at the following link:
Below is the Uno and Due comparison:
From this chart it can be seen that the advantages that the Due has over the Uno are:
- A much faster processor
- More memory
- More I/O pins availible
From these three things listed above it can be seen that the Due is probably the better choice.
A brief explanation of memory in the microcontroller used on avr-based Arduino boards is as follows:
- Flash memory (program space), is where the Arduino sketch is stored.
- SRAM (static random access memory) is where the sketch creates and manipulates variables when it runs.
- EEPROM is memory space that programmers can use to store long-term information.
The Uno has 1 kb of EEPROM. This is a negligible point to bring up in comparison with the Due. However, if the Arduino's are compared with the previous microcontroller used (Parallax Inc BS2-IC) the following is important to note:
- Speed: 20 MHz
- Flash Size: 2 kb EEPROM
- RAM Size: 32 b
From the information listed above it is important to see that the best microcontroller for our project is still the Arduino Due because of the numerous ways it outperforms the Uno.
Below is a capture of a chart provided by MathWorks for the various Arduino boards and their compatibility with MATLAB and Simulink:
From this chart it should be noted that a although the support package is shown to be listed for the Due it is actually compatible with the Uno as well.
It should also be noted that an advantage that the the Due has over the Uno is that it has interactive monitoring available with MATLAB.
- Final Comments
From everything above it can be seen that the Due is the best microcontroller board to purchase.
Viewing the expanded view of the microcontoller and motor wiring diagram shown in the subsystems decomposition section it should be noted that the code uploaded was as follows:
Back in the systems design phase of the design process we showed the following chart of potential motors for use in our project:
In the original implementation of the project the motor that was selected for use was a stepper motor. In the later innovations on our project the stepper motor that was chosen for implementation is shown above as the Anaheim Automation Stepper Motor. A key reason this motor was chosen for implementation was the fact that the motor has a built in driver thus reducing the real estate needed for mounting purposes.
A stepper motor was also chosen to continue to be used for the following reasons:
- Accuracy and repeatability
- Responsiveness and quick acceleration - stepper motors have low rotor inertia, allowing the motor to quickly get up to speed.
- Excellent torque for their size
- Positioning stability - stepper motors have a great advantage of being able to be held completely motionless in their stopped position unlike other motors.
- Open loop control - this kind of control is simpler, more reliable and less expensive then feedback based control (closed loop control). It is also important to note that assuming a stepper motor is properly sized for its load, it should never miss a step.
- Cost and reliability - this technology is reliable and proven. Also a stepper motor is the most cost effective method of precise position control.
- CITATION: All six bullet points above are either direct quotations or paraphrased from this document from NMB Technologies Corporation: NMBTC Step Motor Engineering
Here we must post about the motor couplings we have purchased and how we currently plan to test each one to determine the best option.
Our options currently are as follow:
- Flexible Drive Shaft
- Helical Flexible Shaft Coupling (clamp-on)
- Helical Flexible Shaft Coupling (set screws)
- High Precision Bellows Flexible Shaft Coupling
Based upon these we plan to test them by building a prototype of:
System Base/Motor Mount
Mr. Kraynik in ME shop suggests using aluminum for "hood"
- aluminum is relatively lightweight, cost effective, and easy to machine
- CNC machining of the part would be very expensive
MATLAB Network Analyzer Data Acquisition Code
This section of the subsystems design phase is not easily shown on EDGE. Hence, during the review with the customer a demonstration of the code will be shown in the lab.
Currently, there are some problems with understanding the data received from the network analyzer. Hence, this section of the project is still being fine tuned.
Post Subsystems Design Review Notes
- Check max current limit of power supply to make sure we aren't able to downsize to a smaller supply with a lower max current limit - the one presently being used might be overkill
- Detail the drawing of the base for how we're going to route the wires and detail the boxes for the circuitry