—Explicit formulas of smooth time-varying state feedbacks, which make the origin of an underactuated surface vessel globally uniformly asymptotically stable, are proposed. The construction of the feedback extensively relies on the backstepping approach. The feedbacks constructed are time-periodic functions.
The paper shows that a large class of underactuated vehicles cannot be asymptotically stabilized by either continuous nor discontinuous state feedback. Furthermore , stabilization of an underactuated surface vessel is considered. Controllability properties of the surface vessel is presented, and a continuous periodic time-varying feedback law is proposed.… (More)
We solve both the global practical stabilization and tracking problem for an underactuated ship, using a combined integrator backstepping and averaging approach. Exponential convergence to an arbitrarily small neighbourhood of the origin and of the reference trajectory, respectively, is proved. Simulation results are included. R esum e: Nous r esolvons a la… (More)
—In this paper, we address the tracking problem for an underactuated ship using two controls, namely surge force and yaw moment. A simple state-feedback control law is developed and proved to render the tracking error dynamics globally-exponentially stable. Experimental results are presented where the controller is implemented on a scale model of an… (More)
This paper gives a treatment of various aspects related to snake locomotion. A mathematical model and a physical implementation of a modular snake robot are presented. A control strategy is also developed, yielding a general expression for different gait patterns. Two forms of locomotion have been simulated with the mathematical model, and experiments with… (More)
| We consider tracking control of a surface vessel with only two control inputs. The surface vessel model has certain similarities with chained form systems , but cannot be transformed to chained form. In particular, the model has a drift vector eld as opposed to the drift-free chained form systems. It is shown, however, that methods developed for tracking… (More)
— In this paper we propose a Leader/Follower output feedback synchronization scheme for control of the attitude of two satellites when angular velocity measurements are not available. Nonlinear observers are used to estimate the angular velocities. The attitudes of the satellites are represented by unit quaternions, and the control design is based on… (More)
We consider the control of a hovercraft having only two control inputs with three degrees of freedom. The model is obtained from equations of a simpliied ship which is nonlinear and underactuated. Using a coordinate transformation the model is given by polynomial equations which describe its kinematics and dynamics. Two control laws are proposed. The rst… (More)