Comparing the GPS capabilities of the Samsung Galaxy S, Motorola Droid X, and the Apple iPhone for vehicle tracking using FreeSim_Mobile

In this paper, we present a comparison of the Samsung Galaxy S™ [1], the Motorola Droid X™ [2], and the iPhone 4™ [3] using the real-time vehicle tracking application FreeSim_Mobile [4,5]. Using the built-in GPS receiver and the web capabilities of these smart phones, coupled with a V2I architecture, we are able to send a continuous flow of location data to a central server for processing by FreeSim [6–8], a real-time traffic simulator. The proportional model algorithm [9] is then used on this data to determine the time to traverse a section of roadway in order to report in real-time the current flow of traffic. In this paper we analyze the capability of two different Android-based [10] phones, the Samsung Galaxy S and the Motorola Droid X, on reporting accurate and reliable locations and compare them to a vehicle tracking device and the iPhone 4, which has been previously shown to be as accurate as a vehicle tracking device [4,5]. Drivers equipped with a Samsung Galaxy S, Motorola Droid X, iPhone 4, and vehicle tracking device manually timed how long it took to travel along a 0.98 mile/1.58 kilometer section of roadway. All four devices reported their location and the vehicle tracking device also reported the current speed. The amount of time to traverse the test section of roadway was determined using the proportional model algorithm [9] and compared to the actual amount of time it took to traverse the test section of roadway as manually timed. The results of the vehicle tracking device had an average error factor of 0.79% from the actual time to traverse the section of roadway, whereas the Samsung Galaxy S was 4.59%, the Motorola Droid X was 0.84%, and the iPhone 4 was found to have an error factor of 0.60%. The case study furthers the feasibly that mobile phones can act as an alternative means for probe vehicles as the iPhone 4 and Motorola Droid X are relatively as accurate as a vehicle tracking device.