Purpose
The purpose of the Lego Mindstorm Activity was to display and test our familiarity with conversions with a real system.
Apparatus
To do this, we utilized the Lego Mindstorm, a Lego kit that once assembled, could be operated via computer to perform various functions.
Procedure
Our first task, was to assemble the robot. This we accomplished in two person teams in our first week of lab.
Analysis
Once our robot was assembled, per the instructions provided with the syllabus, we used a USB cable to connect a desktop computer and the Lego robot. After activating the software provided, we found that we could control the motion of the wheels connected to the robot in a few noteworthy ways. Namely, the power applied to the wheels as well as how long the power would be applied.
Lastly, the software required the circumference of the wheels in order to perform it’s calculations. To do this, I used a ruler to measure one wheel; a 5 cm diameter was the result.
Then, using some simple trigonometry:
circumference of a wheel = diameter of a wheel * PI
which in my case yielded:
circumference of a wheel = 5 cm * 3.141 = 15.7 cm
When provided with the Legos’ wheel circumference, as well as a time and a power setting, the software would predict how far the Lego had traveled as well as how many wheel rotations had occurred.
When I compared this predicted value with our measured values( using a ruler to actually track how far the robot actually traveled ), I could then determine the error between the predicted and measured observations. These provided the grist for the table below.
| Run | Time (sec) | Power | Wheel Rot (turns) | Wheel Rot(degrees) | Calc Dist (meters) | Measured (meters) | Error % | Average Error % |
| 1 | 1 | 75 | 1.28 | 460.8 | 0.1925 | 0.22 | 3.333333 | 2.682288661 |
| 2 | 1 | 75 | 1.34 | 482.4 | 0.202 | 0.225 | 2.693208 | |
| 3 | 1 | 75 | 1.32 | 475.2 | 0.1983 | 0.215 | 2.020324 | |
| 1 | 1.5 | 50 | 1.21 | 435.6 | 0.1812 | 0.21 | 3.680982 | 2.938697805 |
| 2 | 1.5 | 50 | 1.27 | 457.2 | 0.1908 | 0.21 | 2.39521 | |
| 3 | 1.5 | 50 | 1.22 | 439.2 | 0.1837 | 0.205 | 2.739902 | |
| 1 | 1.5 | 60 | 1.68 | 604.8 | 0.2525 | 0.28 | 2.58216 | 3.416252294 |
| 2 | 1.5 | 60 | 1.59 | 572.4 | 0.2322 | 0.275 | 4.219243 | |
| 3 | 1.5 | 60 | 1.75 | 630 | 0.2613 | 0.3 | 3.447354 |
Analysis
By the final analysis, for each run we found an error that fluctuated between approximately 2.6% and 3.4%; that is, a statistically insignificant variance.
Questions
I didn’t have any truly novel questions at the end of the lab, any variances are likely the result of imprecise motors, imprecise measurements, or both. All in all, I was happy with our results.