In this paper, we propose a novel single-template strategy based on a mean template set and locally/globally weighted dynamic time warping (LG-DTW) to improve the performance of online signature verification. Specifically, in the enrollment phase, we implement a time series averaging method, Euclidean barycenter-based DTW barycenter averaging, to obtain a mean template set considering intra-user variability among reference samples. Then, we acquire a local weighting estimate considering a local stability sequence that is obtained analyzing multiple matching points of an optimal match between the mean template and reference sets. Thereafter, we derive a global weighting estimate based on the variable importance estimated by gradient boosting. Finally, in the verification phase, we apply both local and global weighting methods to acquire a discriminative LG-DTW distance between the mean template set and a query sample. Experimental results obtained on the public SVC2004 Task2 and MCYT-100 signature datasets confirm the effectiveness of the proposed method for online signature verification.

This paper is concerned with the controller synthesis for feedback systems with saturation based on the LPV system representation. The LPV system representation, combined with use of the detailed structure of saturation nonlinearity, enables us to reduce the conservativeness. In this paper, we develop a new iterative algorithm for designing a linear time-invariant controller which locally stabilizes the nonlinear closed-loop system and achieves the prescribed quadratic control performance. The present design method provides an explicit expression for a guaranteed domain of attraction, and maximizes the estimated region of the plant states for which the stability and the prescribed quadratic performance are satisfied. A numerical example shows the effectiveness of the present design method.