Assessing the influence of sensitivity and frequency on the performance of the Midge

Abstract

The Midge is a wearable badge created by the Socially Perceptive Computing Lab, Pattern Recognition and Bioinformatics group of the Delft University of Technology, with as goal to analyse human behaviour. The badge has a digital motion processor (DMP) that can determine its orientation. This DMP makes use of an inertial measurement unit (IMU), that houses an accelerometer, a gyroscope and a magnetometer, to calculate its movement in a 3D-space. For both of the accelerometer and gyroscope the Full Scale Range (FSR) can be changed, in addition to the frequency. In this paper, the effects of both elements are analysed to determine if they influence the accuracy of the data gathered. The results show that the changing the FSR does not influence the accuracy of neither the two sensors nor the performance of the DMP. On the other hand, it was found that changing the frequency does influence the performance of the Midge. Even though the frequency did not affect the measurements of the accelerometer and gyroscope directly, the performance of the DMP was affected. The DMP performed best with a frequency of 150 Hz. Using a higher frequency also captured local extremes and turning points from the sensors and the interpreted orientation more precisely.