Summary: This article aims to design a low gain feedback controller for a class of discrete-time feedforward nonlinear systems (DFNSs) with unknown input saturation. Although the design of the low gain feedback control can be converted into the choosing of a parameter, it is difficult to design the control due to the inherent nonlinear dynamics and the unknown input constants. To solve this problem, we first show that the low gain feedback control can be found to stabilize the DFNSs when the saturation is known. Then, by analyzing the dynamics of DFNSs under the saturating input, the relation is built between the parameter and the system state. Finally, we introduce a technology to update the parameter based on different performance, whose effectiveness is illustrated through considering a numerical example.
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