Showing papers by "N.H. McClamroch published in 2002"

Tracking and maneuver regulation control for nonlinear nonminimum phase systems: application to flight control

Abstract: We study the problem of tracking control and maneuver regulation control for a nonlinear nonminimum phase control system. First, a tracking controller, consisting of feedforward and static-state feedback, is designed to guarantee uniform asymptotic trajectory tracking. The feedforward is determined by solving a stable noncausal inversion problem. Constant feedback gains are determined based on linear quadratic regulator (LQR) optimization and assumed satisfaction of a robustness inequality. A maneuver regulation controller is obtained from the tracking controller by introducing a suitable state projection that is related to the LQR feedback gains. Properties of the closed loop, including local asymptotic convergence of the transverse errors are described. A multivariable flight control problem is used to demonstrate the approach.

Feedback control of triaxial attitude control testbed actuated by two proof mass devices

Abstract: The triaxial attitude control testbed (TACT) has been developed as part of a research program on spacecraft multibody rotational dynamics and control. In the paper, an attitude control problem for the TACT actuated by two proof mass devices is studied. Under the assumption of uniform gravity, proof masses generate control moments about the roll and pitch axes of the base body. The control objective is to accomplish attitude stabilization about all three axes using only two proof mass actuators. Analysis shows that there do not exist stabilizing continuous time-invariant feedback controllers. For feedback design, we simplify the complex multibody equations of motion and we develop a discontinuous time-invariant feedback controller. The resulting closed loop shows exponentially converging responses for rotational maneuvers about all three axes.

Local equilibrium controllability of the triaxial attitude control testbed

Abstract: Local configuration controllability and local equilibrium controllability of the Triaxial attitude control testbed (TACT) are studied The TACT is controlled only by a class of actuators referred to as shape actuators This implies that there is a conserved quantity and there is a base body equilibrium manifold at each fixed shape Thus, the TACT states are not small time locally controllable at equilibrium But a weaker configuration controllability and equilibrium controllability property may be satisfied at an equilibrium Important symmetric product formulas and properties are obtained These properties explicitly show dynamic coupling and symmetry of the TACT Based on these properties, local equilibrium controllability analysis is carried out for the TACT with fully actuated shape variables Sufficient conditions for local equilibrium controllability are presented for three examples

Attitude control of a tilted air spindle testbed using proof mass actuators

Abstract: The attitude dynamics of an air spindle and platform testbed, controlled by two proof mass actuators fixed to the platform, are studied assuming that the air spindle is not exactly vertical. A tilt angle of the air spindle induces a gravity moment that has a long term effect on the rotational dynamics. A mathematical model is used to study the free dynamics with the proof masses fixed, as a basis for parameter identification and to explain the longer term dynamics that have been observed in experiments. Feedback compensation for these gravity effects is discussed.