Subspace system identification

We give a general overview of the state-of-the-art in subspace systemidentification methods. we have restricted ourselves to the most important ideas anddevelopments since the methods appeared in the late eighties. first, the basis of linearsubspace identification are summarized. different algorithms one finds in literature (suchas n4sid, moesp, cva) are discussed and put into a unifying framework. further, acomparison between subspace identification and prediction error methods is made on thebasis of computational complexity and precision of methods by applying them to a glasstube manufacturing process.