Unknown disturbance inputs estimation based on a state functional observer design. (Q1410365)

The authors consider the dynamic system \(\dot x=Ax+Bu+Gd(t)\), \(y=Cx\), where \(x\) is the state vector, \(u\) is the known control input, \(d(t)\) models all uncertain, nonlinear and time-varying terms and is regarded as an unknown time-varying input, \(y\) is the output. The constant matrices \(A,B,C,G\) are known and of appropriate dimension. Their objective is to estimate the unknown input plus a linear function of the state vector under less conservative conditions than previous authors.