Smooth Time-varying Control Law Research Articles

Local Exponential Regulation of Nonholonomic Systems in Approximate Chained Form with Applications to Off-Axle Tractor-Trailers

Most of drift-less nonholonomic systems cannot be exactly converted to an nonholonomic chained form, a wealth of design tools developed for the control of nonholonomic chained form are thus not directly applicable to such systems. Nevertheless, there exists a class of systems that may be locally approximated by the nonholonomic chained form around certain equilibrium points. In this work, we propose a discontinuous and a smooth time-varying control laws respectively for the approximated nonholonomic chained form, guaranteeing local exponential convergence of state to the desired equilibrium point. An tractor towing off-axle trailers is taken as an example to illustrate the approaches.

Control of a planar space robot: Theory and experiments

In this paper the attitude control problem of planar space robot is addressed and new feedback control scheme is proposed. Since control laws are synthesized via theory of geometric phase, the proposed control laws contain smooth functions of states and time. The usefulness and validity of this control scheme can be demonstrated by hardware experiments. In experiments to simulate the space environment prototype of the planar space robot is floated by air on the horizontal plane. Experimental results show that the proposed smooth time-varying control laws stabilize the attitude of the planar space robot sufficiently.

Global time-varying stabilization of underactuated surface vessel

This note considers the stabilization problem of an underactuated surface vessel. Three global smooth time-varying control laws are proposed with the aid of different techniques. The first proposed control law makes the state of the closed-loop system asymptotically converge to zero, while the second and the third control laws make the state of the closed-loop system globally exponentially converge to zero. Moreover, the exponential convergence rate of the state of the closed-loop system can be arbitrarily assigned with the third control law. Simulation results show that the proposed control laws are effective.