Not Cow Tipping - Car Tipping! (page 3)

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Author: Lexie S.


Analysis of Hypothesis

It was originally thought that as the degree of decline increased, the tipping time of the robot would occur sooner and that the tipping point would decrease. It was also thought that it was possible to prevent the tipping of the robot with the knowledge of the tipping point. It was proved that the hypothesis was partially right. The part that stated that the robot would tip quicker as the degree of decline increased was correct. This was shown by the data set averages. The 0º variation had an average tipping time of 2360 ms, while the 6º variation had an average tipping time of 1844 ms, and the 9º variation average was 1495 ms.

However, when the hypothesis stated that the tipping point would decrease as the degree of decline increased was incorrect. When graphed, nearly all of the accelerometer measurements had similar rising trends before and after the tipping time occurred. (See Statistical Analysis for graphs). Furthermore, it was found that it was not possible to prevent the robot from tipping at all levels with the parameters used. This was only proved effective on a level surface, in the 0º variation. The prevention program was put into action at least two times in all trials. It clearly works to get the robot back into the range in which the robot will not tip over, so if it can be modified somewhat to have a smaller "tip-safe" accelerometer range or to pause longer before returning to full speed, it could potentially still be successful.

Questions for Further Research

Fairness of the Experiment

Of the factors within the control of the materials used, the experiment was fair. However, when the degree of decline, the dependent variable, was changed, the speed was also changed. The LEGO MINDSTORMS NXT 2.0 robot did not have a speed control option for the motors, only a control on the percentage of the NXT's available power that the motor would receive. The best that could be done was to acknowledge the change of speed, which was calculated based upon the straight trials. If this experiment would be repeated, it would be best to have a type of robot that had a speed control, not just a power control. In addition, even if this could or could not be found, it would more fair if the batteries were changed every variation to ensure maximum power and the maximum possible fairness of the experiment.

Other Areas of Interest
  1. How does changing the wheel surface/texture affect the tipping point of a vehicle?
  2. How does changing the width of a wheel affect the tipping point of a vehicle?
  3. How does changing how early a program that cuts a robot's speed when it is out of a non-tip range affect the tipping point of the given robot?

These would be areas of further study because they all concern the tipping point of robots. The first two questions about the wheel surface and the wheel width are more concerned with non-electronic ways to prevent tipping. They also observe the tipping point like in the original, completed experiment. The third question investigates what the second part of this experiment only touched the surface of: an electronic stability control system that would use an accelerometer. If the previously mentioned factors are truly factors that help determine the likely-hood of a vehicle tipping, then changing these accordingly can help decrease both costs and the chances of tipping. Wheels are already necessary in vehicles and the U.S. government is making electronic stability control systems mandatory in all new cars starting in 2012, so using a low-cost but still high-end accelerometer based system would greatly decrease the cost from the current $250 system. In addition, both would make future vehicles, manned and unmanned, safer for human transportation.


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