AME 3623: Project 3

All components of the project are due by Tuesday, March 9th at 5pm
Groups are the same as for project 1.
Discussion within groups is fine.
Discussion across groups may not be about the specifics of the solution (general programming/circuit issues are fine to discuss).

For this project, you will be calibrating your Sharp distance sensor. Specifically, you will be writing a function that returns a calibrated distance.

At the end of this project, you should be able to:

design mathematical models for transforming raw sensor data into calibrated information,
implement these models in code, and
test the models.

Component 1: Micro-controller Circuit

There are no hardware changes for this project.

Component 2: Sensor Model

Given the data that you already collected, derive a mathematical equation for distance as a function of sensor value. Keep in mind:

The output of the function must be a float in cm
Using a simple mathematical function, you will be able estimate the distance quite well over a reasonable range. For the purposes of navigation with these distance sensors (and nearby obstacles), distance estimates need to be most accurate at 8 cm.
Performing a least-mean-squared fit of your function to your data (i.e., using regression) will treat all points equally in the fitting process. Instead, you must favor 8cm. To do this, use a representative point to define one point that your function must capture well and then select any other parameters to best capture the rest of your data (think carefully about which point should this be)

Component 3: Analog Interface Software

Implement the following function:

float read_distance() will read the analog port attached to the distance sensor and return the calibrated distance in cm.

Component 4: Testing

Write a new version of the sensor_display_step() function that:

Prints the calibrated distance in cm.

Then:

Set up your sensor so that it is pointed in a direction that does not have any obstacles.
Place a flat obstacle at a known distance and record 5 samples from of the sensed value (your calibrated value). The obstacle should be orthogonal to the IR beam emitted from the sensor. Record samples at least from the following distances: 8, 9, 10, 14, 20, 30, 40, 60, 80 cm.
Using a tool such as Excel, Matlab or Python, graph the reported value as a function of distance (cm). Generate curves for both sensors (these could be plotted on the same graph or on different ones)
Do the curves behave as you expect? (if not, then you need to review your implementation)

Hints

You should not have any more calls to delay() in your code, except in setup(). PeriodicAction does what we need here.
As the distance to an object decreases from 8cm, the distance sensor will start to yield smaller values, making interpretation ambiguous. We will not test distances shorter than 8cm.
Your model will likely not extrapolate well beyond 80cm (in fact, it can yield infinite or even negative distances, neither of which make much sense). In these cases, it is appropriate in your read_distance() function to detect this case and simply return 80cm.

What to Hand In

Submit to a set of files to the project3 area on Gradescope by the deadline (not a zip file). These files include:

Documented code. Include your "ino" file. The documentation requirements are the same as in project 1.
Figure: a copy of graph of sensed distance vs true distance.

Other components:

Demonstration/Code Review: All group members must be present. This review must be completed within five days of the deadline. However, it is better to complete these reviews as early as possible.

Grading

For this project, we expect:

A properly configured circuit
- Microprocessor installed
- Sharp sensor installed correctly
Properly written software
- Function that reads from the analog port and returns a well-calibrated distance
- step function that prints out the calibrated distance
Properly documented code
- Project-level documentation at the top of the ino file: name and group number, date and project number
- Function-level documentation above the function definition. Include an abstract description of what the function does; a list of the names, types and units associated with each parameter and return value; and the effects that the function has on the processor or connected components.
- In-line documentation inside of functions: individual lines or small groups of lines have an English description that describes logically what the code is doing
Labeled figures of:
- Sensed vs true distance. The sensed distance should match the true distance over a majority of the range (especially capturing the smaller distances)

andrewhfagg -- gmail.com

Last modified: Wed Mar 10 23:34:48 2021