There are numerous publically available smart phone applications designed to track the speed and position of the user. By accessing the phones built in GPS receivers, these applications record the position over time of the phone and report the record on the phone itself, and typically on the application's website. These applications range in cost from free to a few dollars, with some, that advertise greater functionality, costing significantly higher. This paper examines the reliability of the data reported through these applications, and the potential for these applications to be useful in certain conditions where monitoring and recording vehicle or pedestrian movement is needed. To analyze the reliability of the applications, three of the more popular and widely used tracking programs were downloaded to three different smart phones to represent a good spectrum of operating platforms. Several tests were conducted to evaluate the applications ability to measure speed, elevation change, and positioning on aerial imagery. The data reported by the applications in each test was compared to a Race Logic VBOX VB20SL3 Data Acquisition Unit that was also used in the same tests. The VBOX unit was used as a standard against which to measure the applications efficacy since this unit is specifically designed to monitor and record vehicle movement1. The results show that under certain conditions, speed, positioning on aerial imagery, and elevation change as recorded by applications were relatively accurate for conditions where the recorded period occurred over a long duration of time. The results from this testing shows that recording the motion of a vehicle or pedestrian over a long duration of time, greater than 10 seconds, with minimal changes in velocity can be properly documented by the use of a smart phone running a commonly available applications.

I n the 2016 SAE publication "Data Acquisition using Smart Phone Applications," Neale et al., evaluated the accuracy of basic fitness applications in tracking position and elevation using the GPS and accelerometer technology contained within the smart phone itself [1]. This paper further develops the research by evaluating mid-level applications. Mid-level applications are defined as ones that use a phone's internal accelerometer and record data at 1 Hz or greater. The application can also utilize add-on devices, such as a Bluetooth enabled GPS antenna, which reports at a higher sample rate (10 Hz) than the phone by itself. These mid-level applications are still relatively easy to use, lightweight and affordable [2], [3], [4], but have the potential for higher data sample rates for the accelerometer (due to the software) and GPS signal (due to the hardware). In this paper, Harry's Lap Timer™ was evaluated as a smart phone mid-level application. Used in conjunction with the external antenna Sky Pro GPS, the speed, acceleration and position recorded by Harry's Lap Timer™ tracking technology is compared to a well-known and validated data acquisition unit. The speed, position, and acceleration data of Harry's Lap Timer™ was compared to the VBOX 20 Hz VB20SL3 with a RLVB IMU 03 3-axis accelerometer. The research presented here demonstrates that mid-level tracking software like Harry's Lap Timer™ collects comparable data at a sample rate between 1-10 Hz for many testing situations.

<div class="section abstract"><div class="htmlview paragraph">Technology is ever advancing in the world around us, and it is no different when it comes to data acquisition systems used in accident reconstruction. In 2016, the SAE publication “Data Acquisition Using Smart Phone Applications,” Neale et al. evaluated the accuracy of basic fitness applications in tracking position within the smart phone itself [<span class="xref">1</span>]. In 2018, a follow up publication “Mid-Range Data Acquisition Units Using GPS and Accelerometers” tested the Harry’s Lap Timer^TM application for use in smart phones and compared the data to the Race Logic VBOX [<span class="xref">2</span>]. In this paper, another data acquisition system, the MoTeC C185, was tested. The MoTeC C185 data logger contains an internal 3-axis accelerometer and was also equipped with an external Syvecs 50Hz GPS Module with 6-axis accelerometer. A test vehicle was instrumented with the MoTeC C185, Race Logic VBOX, and Harry’s Lap Timer^TM. Data collected by the MoTeC C185 was then compared to data collected by the other acquisition systems to validate the capabilities of the MoTeC C185. The purpose of this paper is to validate the MoTeC data acquisition system to provide an alternative for use in the field of accident reconstruction.</div></div>