David & Ahmed’s Ultrasonic (and Light) Sensor Investigation

Content

 We first attempted to find a relationship between the reflected light value from the light sensor and the distance away from the light sensor. However, using a standard piece of chipboard, the reflected light scaled value had no discernable relationship to distance, even when outliers were excluded. So, we changed our investigation to one of the ultrasonic sensor.

We performed our investigation by attaching a piece of chipboard to a raised beam above the tracks, so it faced the Ultrasonic sensor. By setting the motor at a constant speed, we were able to measure the speed of the tracks by using a ruler to measure distance traveled and the timer inside LabVIEW to measure time. By using that constant speed, we were able to find where the chipboard was at all times. Our code had the Ultrasonic sensor take a reading every tenth of a second, and we were able to compare the reading taken by the Ultrasonic sensor to the actual measured distance at that time. We graphed both the readings from the Ultrasonic sensor and the actual distance on the same graphs, and used the difference between the measurements to find the standard deviation from the actual measurements.

Our tests aimed at determining several properties of the ultrasonic sensor readings, including:

  • The accuracy of the readings at minmum distances (<5cm).
  • The accuracy of reading the distance of a moving object at constant speed.
  • The optimal distances at which the readings are most accurate.
Results
  • Within approximately 3cm, the Ultrasonic sensor does not give reliable data.
  • The total standard deviation of the readings from the expected values is 2.639249198 cm (excluding the outliers that ?read 255cm at very low ranges)
  • The optimal distance range is 5-30cm.
Gallery
Video

 This video expressed the first test of our investigation, in which we calculated the distance travelled by the cardboard in one second and compared it to the ultrasonic sensor readings.

Attachments

 Here You can find the data expressing our results and their analysis. Certain values from the Light Value vs Distance file have been removed because the light sensor read 0 when the carboard was further than a certain distance away.

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