Asymmetrical Gating with Application on Maneuvering Target Tracking

A new asymmetrical gate with application in target tracking is proposed. Proposed gate has asymmetric shape that has large probability of target detection in the gate and has more advantages compared with elliptical gate. The gate is defined as the region in which the tracked target is expected to exist and just observation vectors in the gate are used as target detection. An analytical method to compute optimal size of gate is proposed and recursive estimation of asymmetric parameters of gate are studied. Comparison between proposed gate and conventional elliptical gate showed the efficiency of the proposed method in maneuvering target tracking applications and simulation results showed the proficiency of the proposed method. 1. Introduction Tracking is meant to be the estimation of the true values of specifications of target motion, such as the position and velocity, based on the n-dimensional observational vector by the sensors [1–3]. One-dimensional observation vectors are obtained in a direction-finding setup observing just the azimuth angle [4]. Two-dimensional observation vectors are obtained in optical sensors observing the azimuth angle and elevation angle, or in radars observing the range and azimuth angle. Historically, PDA (Probabilistic Data Association) [5], JPDA (Joint PDA) [6], and MHT (Multiple Hypothesis Tracking) [7–9] have drawn attention as target tracking methods in an environment in which false signals from objects other than the target such as clutter exist [10, 11]. In target tracking in such an environment, just the region is considered for each target in which the target is expected to exist at the next sampling time [12]. This region is called the gate. The observation data within the gate are used for tracking. Various gate shapes are conceivable, such as a rectangle, circle, and ellipse. However, it is not known which shape of gate is optimum. If the gate is enlarged, many observation vectors from clutter or objects other than the target fall within the gate, resulting in some difficulties in target tracking. On the other hand, if the gate is made smaller, there is a danger that the observation data from the target to be tracked may not fall within the gate. It is more desirable that the position of the observation vector detected from the target be closer to the center of the gate compared with location of the false signals in the gate [13]. A method of determining the in-gate probability has been proposed in [10]. In this paper, asymmetrical gaussian distribution is introduced. Cross-surface of asymmetrical gaussian