Figure 4

(a) Effect of EKF algorithm on tilt estimation performance: grey solid and black dashed lines represent estimated tilt angle of the cell phone without or with EKF algorithm, respectively. (b) Benchmarking of tilt estimation: grey solid and black dashed lines represent tilt angle estimated by a high fidelity sensor and the cell phone sensor, respectively. Tilt angle was sampled at a rate of 50 Hz for both sensors.