Imperial College London


Faculty of MedicineInstitute of Global Health Innovation

Visiting Professor



+44 (0)7554 342 293robert.istepanian Website




Central FacultyFaculty BuildingSouth Kensington Campus






BibTex format

author = {Song, T and Collins, EG and Istepanian, RH},
doi = {10.1002/1099-1239(200101)11:1<41::AID-RNC546>3.0.CO;2-O},
journal = {International Journal of Robust and Nonlinear Control},
pages = {41--57},
title = {Improved closed-loop stability for fixed-point controller realizations using the delta operator},
url = {<41::AID-RNC546>3.0.CO;2-O},
volume = {11},
year = {2001}

RIS format (EndNote, RefMan)

AB - A stable discrete-time control system may achieve a lower than predicted performance or even become unstable when the discrete-time control law is implemented with a fixed-point digital control processor due to the finite word length (FWL) effects, which depends on the control law state-space realization and the discrete-time operator (e.g., the delta operator or the forward-shift operator) used to represent the control law. To improve the closed-loop stability (and as a byproduct, performance) when the control law is implemented, a state-space approach that selects the control law realization to optimize a stability-related objective function is developed using the delta operator. Analytical and numerical comparison of the fixed-point performance of delta control laws with the performance of the corresponding forward-shift control laws quantifies the improved closed-loop stability of the delta realizations over those of the corresponding forward-shift realizations. It is also shown that there exists a simple mapping between the optimal FWL forward-shift control law realizations and the optimal FWL delta control law realizations. The results are illustrated by delta and forward-shift control law realizations of a discrete-time H∞ control law designed for a teleoperation motion-scaling system.
AU - Song,T
AU - Collins,EG
AU - Istepanian,RH
DO - 10.1002/1099-1239(200101)11:1<41::AID-RNC546>3.0.CO;2-O
EP - 57
PY - 2001///
SN - 1049-8923
SP - 41
TI - Improved closed-loop stability for fixed-point controller realizations using the delta operator
T2 - International Journal of Robust and Nonlinear Control
UR -<41::AID-RNC546>3.0.CO;2-O
VL - 11
ER -