Lego Mindstorms

Lego Mindstorm is a robotics kit that contains software and hardware to create customizable robotics. For our science lab recently we had to break into groups and assemble this kit in order to put together a robot to be programed to our demands. The kit included a varying supply of lego pieces to make many different types robots, however as a group we worked together to make a robotic car.

After following the instructions and constructing the robotic car, we then had to connect the appropriate wires to the car. Port A side of the car had to be attached to the A mark on the motor, and Port B had to then be attatched the B side with a connector cable. After the motor was attatched to each side of the car, we had to plug it into the computer and begin the programing.

After opening the Lab View program on our monitors we began to learn the different ways of programming the car. In order to run the motor so that the car moved forward, backward, and at various power levels we had to select the motor button. When clicking on the top arrow that appears on the square you can select either port A for the left wheel or port B for the right wheel. The right arrow then shows how fast the wheel will turn, also known as its power. The bottom arrow on the square will then tell you the direction you want the wheel to go, either forward or backward.

By selecting our port A ( also known as the left wheel)  to go forward at a power of 75, and our port C to go forward at a power of 25, the car moved forward and in a circle. This happened because the outside wheel was turning faster than the wheel on the inside.

Next we decided to measure the distance the car would go in 1 second, as well as to measure the cars velocity. In order to do this however, we first needed to take some measurements of the wheels. Each wheel had a diameter of 5.5 cm, which makes its circumference to be .1727 meters. When we entered this information into the computer and ran the car for one second at the speed of 75 power, the computer came back with the car traveling a distance of 17.4cm. However when we measured the car it only went a total of 17.5cm.

This result showed us that there was a difference in the computer calculation and what distance the car actually went. So we therefore decided to calculate the difference in the results. In order to do this we had to find the difference in each result, but subtracting the larger one from the smaller one. This came out to be .1cm. We then have to divide that number by the average of the two results. In order to get the average of the two results you add them together and then divide by 2. Which comes out to be 17.45cm. So the total difference in results comes out to be .1 divided by 17.45 which is .0057.

The number .0057 represents the percent of error in the experiment. Whether it be the computers error or our error. We could have possibly miscalculated the distance that the car traveled by not reading the ruler correctly. We also could have started the car not on the edge of the desk which also could of accounted for the numbers being off. Although there was a .0057% error rate, there  will always be a small percent of error in any experiment. So our small amount was expected.