Adaptive Gradient-Descent Extended Kalman Filter for Pose Estimation of Mobile Robots with Sparse Reference Signals

This paper proposes a novel extended Kalman filter (EKF) along with its adaptive variant for effective magnetic, angular rate and gravity (MARG) sensor-only pose estimation of mobile robots operated longer periods in reference-denied environments. First, a gradient-descent orientation-based EKF framework is derived, which formulates the MARG-based pose propagation with both bandpass-filtered and bias compensated external acceleration signals. The proposed approach uses two correction signals beside the orientation update, namely, virtual observations and sparse reference signals are incorporated in the state correction. Next, the instantaneous dynamics is characterized by accelerometer/gyroscope signals-based measures and an adaptive strategy is derived for real-time tuning of EKF parameters. The algorithm is fine tuned in an optimization framework on an appropriate database. This database of ground truth and raw MARG measurements contains 16 robot motion scenarios, where both slow motions and agile maneuvers are performed on different terrains. The conducted analysis highlights that the proposed algorithms outperform the standard approaches, moreover, the adaptive strategy further improves the performance by 13%. The comprehensive performance evaluation demonstrates the efficacy of the new algorithms, thereby these robust approaches are proposed in environments characterized by sparse reference measurements.