Residual Reservoir Computing Neural Networks for Time-series Classification

. We introduce a novel class of Reservoir Computing (RC) models, a family of efficiently trainable Recurrent Neural Networks based on untrained connections. Aiming to improve the forward propagation of input information through time, we augment standard Echo State Networks (ESNs) with linear reservoir-skip connections modulated by an untrained orthogonal weight matrix. We analyze the mathematical properties of the resulting reservoir systems and show that the dynamical regime of the proposed class of models is controllably close to the edge of stability. Experiments on several time-series classification tasks highlight the striking performance advantage of the proposed approach over standard ESNs.