Throughout the course of two classes Basic Two-Motor NTX Cars were built and tested. A drawing of the NTX car can be found here, 9797-Basic-Car. (http://www.firstroboticscanada.org)
The cars were being tested to see if their changing power levels effected the distance in which the car traveled in one second. The vehicles were timed on the Lego Mindstorm system, as to limit human error. The space was also flat and clear of wires and other obstacles so they did not interact with the distance traveled. Each time the power level was changed all other conditions remained the same.
The results found:
Trial 1-
Time- 1 second
Power 1- 75
Power 2- 75
Circumference of wheels- 0.1700 meters
Distance Measured- 0.275 meters
Distance Computed- 0.275778 meters
Velocity- 0.275778 meters per second
Number of wheel turns- 1.6222 turns
Rotation 1- 584
Rotation 2- 576
Trial 2-
Time- 1 second
Power 1-50
Power 2-50
Circumference of wheels- 0.1700 meters
Distance Measured-0.181 meters
Distance Computed-0.170944 meters
Velocity- 0.170944 meters per second
Number of wheel turns- 2.31389 turns
Rotation 1- 362
Rotation 2- 366
Trial 3-
Time- 1 second
Power 1-100
Power 2-100
Circumference of wheels-0.1700 meters
Distance Measured-0.389 meters
Distance Computed-0.393361
Velocity-0.393361 meters per second
Number of wheel turns-2.31389 turns
Rotation 1-833
Rotation 2- 821
Graph of Power Differences– The graph shows that according to the study done, as you increase the power of your engine you increase the distance it will travel in 1 second. That is something that may be tested an infinite amount of times, because there are an infinite number of power settings.
After running each trial the percent error was found for the difference of computed distance and measured distance.
Percent Error Formula- (D Measured – D computed)⁄(average of D measured and D computed)
Trial 1- (0.275-0.275778) ⁄ 0.275389=0.0028250947
Trial 2- (0.181-0.170944) ⁄ 0.175997= 0.0571373376
Trial 3- (0.389-0.393361) ⁄ 0.3911805 = 0.011483062
Having such low percent differences means the distance measured is similar to the distance computed, and one may infer that means a fairly accurate measurement.
If the experiment were to be redone, it would be best to have more trials. Having three trials at a power level 75, three trails at a 100 and three trials at 50 would give you a better overall average based on how far the cars travel based on their power levels.
Works Cited:
© 2008 Legoengineering.com & Tufts University Center For Engineering Educational Outrea. “9797 NXT LEGO Kit: Basic Car Building Instructions.” 9797 NXT LEGO Kit: Basic Car Building Instructions (n.d.): n. pag. Www.firstroboticscanada.org. Tufts University Center for Engineering Educational Outreach, 2008. Web. 21 Sept. 2015.