Tim Slesinger ’14 continued research this summer to find a way to turn one of the most common electronic devices into a powerful navigational tool.
Last summer, he began working with Peter Sheldon, a Randolph physics professor, to find a way to use smartphones and other common electronic devices for inertial navigation, a process which tracks an object’s speed, direction, location, and orientation using only physical forces generated by the motion rather than outside sources such as GPS satellites. They used an iPod Touch to record accelerometer data while riding roller coasters, and then Slesinger worked with that data to try extrapolating the roller coaster’s route.
This summer, Alex Tran ’15 joined the project. They focused on more basic experiments to determine how they can most accurately record and analyze accelerometer information. Most of their experiments involved a one-dimensional motion created by pushing a wheeled cart along a short track.
“We do it over and over again so we can take more data,” Tran said. “The data is very complex. We have to get rid of the noise and estimate the position as best as we can.”
The students used several devices to push on the cart and record accelerometer data so they could see what type of accelerometer was most accurate. “We noticed the accelerometer on the fourth-generation iPod Touch is much better than on the second generation,” Slesinger said. Both recorded data with less noise—which could be caused by magnets or external vibrations—than a professional grade accelerometer. A Samsung Galaxy S3 smartphone had the best accelerometer of all the devices they tested.
If the research team comes up with a reliable way to do inertial navigation with these more affordable devices, it would open up more possibilities for physics teachers to do advanced experiments with their students without breaking the bank.
They also recorded video of each experiment this summer, allowing them to verify whether the cart was traveling at the same speeds that their calculations indicated, and they explored how to incorporate data from the devices’ gyroscopes.
The one-dimensional test is less exciting than a roller coaster, but Slesinger said it will allow him and Tran to perfect the method of processing the accelerometer readings. Then a three-dimensional map would be more attainable. “If we get a perfect, ideal program for the one-dimensional navigation, it will be miles easier to go into the complexity of a three dimension system,” he said.