Most recent Robotics Post

This blog entry concerns the mechanics experiment for the latest class I was able to attend (details for later absence has been noted to Prof. Sonek). During this class session, we were tasked with making our robot perform several rudimentary, yet at times challenging, tasks of movement. Amongst these were linear and circular travel. For the former assignment, we also had to record measurements of the robot’s distance, and place that against the results anticipated by the computer software.

While the most enthralling part of these assignments was discovering how much additional motion was generated by even slight increases in the amount of movement we ordered the robot to conduct, my partner and I were cognizant of the learning opportunity before us and diligently recorded data from the each trial. The constant variable in each of our trials was the amount of time the robot was set for, always exactly one second. Varying were the settings dictated for each side wheel. In the first trial, we set one wheel at 69 and the other at 65; the travelled distance physically measured was 42 cm. Our error percentage for this trial was a miniscule .48%, a truly outstanding result!

Other heats did not produce such excellent error percentages, but were nothing to be ashamed of in their own rights. In the second trial, the wheels were set to 79 and 75, respectively and produced a distance of 49 cm. After using our mathematical skills this gave us a 2.06% error percentage. Continuing the trend of upward error percentages, setting the wheels to 89 and 85 rendered a distance of 54 cm and an error percentage of 3.64%.

So what must be taken away from these assignments? First of all, that playing with Lego robots can actually be a very fun way to learn about science! But on a more serious note, it is telling that has the robot’s acceleration and distance grew, so did our error percentage; no matter the effort exerted, our ability to adequately match Labview’s predicted distance decreased. Also not to be missed were the mathematical abilities and formulae which allowed these results to be found. Copied below are the rough data we collected during the experiment.

Wheel rotation
1. Circumference= 15.7
2. # of wheel turns= rotation (degrees)/(360/1 rotation)
3. Distance= (# of wheel turns) x (Circumference)
4. Velocity= Distance (in Meters)/ Time (in Seconds)
5. % Error= (Measured Distance)- (Labview Distance)x1000/ 0.5(Measured+Labview Distance)

Experiment ONE

Time = 1 Second
Power 1 = 69
Power 2 = 65
Circumference = 0.1570

Distance Measured = 42 cm

% Error = (0.002 / 0.42) x 100 = 0.00476= 0.48%

Experiment TWO

Time = 1 second
Power 1 = 79
Power 2 = 75
Circumference = 0.1570

Distance Measured = 49 cm → 0.49
Labview Distance = 0.48103

% Error = (0.01/0.485) x 100 = 2.06%

Experiment THREE

Time = 1 second
Power 1 = 89
Power 2 = 85
Circumference = 0.1570

Distance Measured = 54 cm → 0.54
Labview Distance = 0.56

% Error = (-0.02/0.55) x 100 = 3.64%

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