Tag Archives: Robotics

Introduction to Lego Mindstorm

FullSizeRenderRobots have numerous functionalities that vary based on the objectives that the robot is trying to accomplish. Robots can either be a simple design with a drive train and motors or they can be very complex systems that implement the usage of sensors to take digital/analog data and use it to better complete the task. During our last 2 seminar classes we built a basic car with a Lego Mindstorm set. We began building our robot on 9/9/15 by using the different parts in our kits and following the instructions from an online manual. Building the robot was not as obvious as you might have thought! You needed to make sure that pieces were connecting into the proper holes and that the orientation of different pieces was actually correct. It was a little bit tedious but the satisfaction of seeing the final result was definitely rewarding! After we successfully built the robot, we proceeded to test the robot by using prewritten code through a programming language called Labview. The first code made the robot drive move depending on the power output of each motor. On our second class on 9/16/15 we used another prewritten code to test how far the car would travel in 1 second at different power outputs. For any technical readers, the code looked this:

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We used a ruler that was placed parallel to the robot to observe how far the robot moved in the allotted time. We compared our human measurement to the distance that the program in Labview calculated. We tested the robot at different power outputs and calculated our margin of error.

Excel

  1. We measured the diameter of wheel and resulted with 5.5 cm or 0.055 meters. We calculated the circumference and got 0.172788 meters.
  1. The relationship between the degrees the wheel rotated and the number of turns of wheel is that the degree the wheel rotated is equal to the product of number of turns times 360.
  1. Seconds are related to milliseconds because 0.001 seconds is equal to one millisecond or 1000 milliseconds are equal to 1 second.
  1. The distance is related to the number of turns because the distance is the product of the circumference times the number of turns.
  1. At a power level of 75 we measured a distance of 0.275 meters and Labview calculated a distance of 0.2736. The margin of error could be calculated by using the formula: ME = 100 x (dmeasured – dlabview)/daverage. Our margin of error was 0.52%.

 

There are two things that I believe could account for these discrepancies. The first one is the braking of the robot once the allotted time passed. The robot would accelerate and just come to a stop after one second. As a result of this abrupt stop the robot would break so aggressively it would jolt back slightly. I think this effect could definitely account for the difference in the measurement. In addition, I noticed throughout all trials the robot would never drive forward in a perfect straight line. It would always sway towards one side even though the power outputs were equal for both motors. As a result, the distance calculated by Labview differs from the distance we measured since we assumed it traveled in a near perfect line.

 

In my opinion this activity connected to the idea of energy consumption and how it can apply to real vehicles. As we observed during the activity, the higher the power output the more distance the  robot travelled in that one second period. In actual vehicles the same idea occurs. The greater the power, the faster the vehicle travels thus covering more distance. But unlike robotics which don’t release any greenhouse gases, real vehicles actually produce them. This presents the idea of how can we be more energy efficient as a society. We must develop cars that release little to no Carbon Dioxide regardless the power output of the engine. We as a society must look for alternative ways to power cars such as with electricity, which can prove to be advantageous.