Constrained nonlinear control allocation with singularity avoidance using sequential quadratic programming

• Published in: IEEE transactions on control systems technology Vol. 12; no. 1; pp. 211 - 216
• Main Authors: Johansen, T.A., Fossen, T.I., Berge, S.P.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2004; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuators; Allocations; Applied sciences; Avoidance; Azimuth; Computer science; control theory; systems; Constraint optimization; Control systems; Control theory. Systems; Controllability; Energy consumption; Exact sciences and technology; Force control; Maneuverability; Maneuvers; Motion control; Nonlinearity; Quadratic programming; Singularities; Surges; Thrusters; Energy consumption; Singularity; Saturation; Resource allocation; Non linear control; Quadratic programming; Convex programming; Constrained optimization; Control constraint; Azimuth; Maneuverability; Power control; Sequential method; Controllability; Non convex analysis; State constraint
• ISSN: 1063-6536; 1558-0865
• DOI: 10.1109/TCST.2003.821952

Control allocation problems can be formulated as optimization problems, where the objective is typically to minimize the use of control effort (or power) subject to actuator rate and position constraints, and other operational constraints. Here we consider the additional objective of singularity avoidance, which is essential to avoid loss of controllability in some applications, leading to a nonconvex nonlinear program. We suggest a sequential quadratic programming approach, solving at each sample a convex quadratic program approximating the nonlinear program. The method is illustrated by simulated maneuvers for a marine vessel equipped with azimuth thrusters. The example indicates reduced power consumption and increased maneuverability as a consequence of the singularity-avoidance.