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This paper introduces a novel control law that dynamically modifies the reference of a pre-compensated nonlinear system so as to ensure the satisfaction of convex constraints. This is done by translating the state space constraints into a constraint on the Lyapunov function which is then limited by modulating the velocity of the applied reference. The main advantage of this approach is that it systematically...
The paper focuses on spatially distributed control systems where the controller sensing and actuation topology is inherited from that of the plant. Specifically, the paper considers distributed systems composed of discrete-time linear parametervarying subsystems interconnected over general graph structures. These distributed systems are subject to a communication latency of one sampling period, where...
In this paper, the problem of stabilization of bilinear control systems is considered. Based on the technique of linear matrix inequalities and quadratic Lyapunov function, the so-called stabilizability ellipsoid is designed, such that the trajectory of the closed-loop system, starting inside the ellipsoid asymptotically tends to zero. The results obtained allow to design an approximation of the stabilizability...
The paper presents the design of a reference governor that manages directly the state and input references for constrained output regulation problems. In particular, for the class of weakly input redundant linear systems, the proposed method leads to a taxonomy in terms of non-intrusive and intrusive reference models, on the basis of the effect of reference manipulation on the tracking error. While...
For a closed-loop system composed of a linear controlled plant and an MPC feedback strategy we show how to verify that closed-loop state trajectories either enter or avoid a given set of unsafe states. The search for the safety certificate is formulated as a mixed-integer linear programming problem which yields non-conservative certificates. The optimal control commands generated by the MPC policy...
This paper presents a real-time path planning algorithm for UAVs to avoid collision with other aircraft. Reachable sets are used to represent the collection of possible trajectories of obstacle aircraft. It is used in collision prediction for UAVs in path planning. Once a collision is detected, a sampling-based method is used to generate a collision avoidance path. A second collision check is performed...
In this paper, we discuss event-triggering scheme with sliding mode control where sensors are distributed over network. Here, a decentralized event-triggering mechanism is proposed where event is observed at each sensor nodes with local information for possible triggering and control update is done whenever a centralized event is triggered. In order to achieve this, the states are sampled at any one...
This paper presents a Therapist-in-the-Loop (TIL) framework for robotics-assisted mirror rehabilitation therapy integrated with adaptive Assist-as-Needed (ANN) training, to be adjusted based on the impairment and disability level of the patient's affected limb. Closed-loop system stability has been investigated using a combination of the Circle Criterion and the Small-Gain Theorem to account both...
The paper contains a detailed analysis of the application of the passification approach to the problem of rendering the hyperbolic upright equilibrium of the simplified model of the Furuta pendulum globally attractive. It is shown that any smooth feedback control passifying the system with the naturally defined storage functions does not provide the desired property. Based on the idea of the VSS-like...
Energy level stabilization problem for one-degree-of-freedom Hamiltonian systems in presence of bounded input (force) disturbances is considered. It is shown that for arbitrary uniformly bounded force disturbances with sufficiently small bound speed-gradient control law ensures ultimate boundedness of energy error. As an auxiliary result the new sufficient conditions for ultimate boundedness of Lyapunov...
A discontinuous control law exponentially stabilizing a simple nonholonomic system is discussed and analyzed in detail. Basic properties, such as existence and uniqueness of the closed loop system trajectories, and simple robustness issues are studied. Continuous modifications of the considered discontinuous control law are proposed and discussed in detail. The considered controller is representative...
In this paper we study the tracking problem for the class of non-holonomic systems in chained form. In particular, with as outputs the first and last state component of the chained form, we suggest a solution for the output tracking problem by combining a time-varying state feedback controller with an observer for the chained form system. For the stability analysis of the “certainty equivalence type”...
Polytopic models cover a large class of nonlinear dynamic systems. An algorithm is proposed that partitions the state-space into a number of disjoint clusters on which a gain-scheduling controller is defined. Then, an iterative synthesis algorithm based on LMIs is developed that guarantees globally robust stability of the closed loop system. Finally, an analysis method is presented that makes it possible...
In this paper, a non linear autopilot for a missile pitch axis is designed over a wide flight envelope. The controller is obtained by a Linear Parametrically Varying (LPV) synthesis applied to the H¥/loop-shaping criterion. The resulting controller depends on the angle of attack, the Mach number and the altitude. Robust stability and performance are firstly checked by means of linear analysis and...
We consider the problem of stabilizing a discrete-time large scale uncertain system consisting of interconnected subsystems via decentralized controllers. The norms of the controls are a priori bounded and the uncertainties are supposed to be cone-bounded. In a neighbourhood of the origin system can be stabilized by decentralized nonlinear feedbacks. We use a receding horizon type control, if the...
The notion of generally quasipassive system is introduced. It is shown that for affine nonlinear control systems the general quasipassivity property plus output-to-state stability under zero input plus nonnegativity of certain pseudoscalar product of storage function's and OSS-Lyapunov function's differentials implies the existence of output feedback making the closed loop system UB. The result gives...
In this work we consider a class of nonlinear flat systems evolving on the tangent bundle TG of a Lie-Group G. For this class of systems every set of local coordinate functions is a local flat output. As a consequence, the canonical projection of TG on G acts as a global flat output, called flat information. It is shown that a stabilization control law for such a system induces canonically a control...
In this paper we design a position controller for an autonomous mobile robot, a nonlinear nonholonomic control system. The designed time invariant non smooth stabilizing control law assures limitation of the velocity inputs, human like driving behaviour and smooth trajectories. The global asymptotic stability of the closed loop system is proved using the Lyapunov stability theory and the In-variance...
In this paper the problem of posture regulation for the unicycle mobile robot is solved via the explicit construction of a control Lyapunov function. The construction is achieved via dynamic extension of the inputs along with a non-smooth factorization of the first storage function considered, before a standard backstepping procedure is carried out. The control law obtained is non-smooth and time-varying,...
In this note it is shown how the n-dimensional rigid body equation naturally leads to Hamilton's canonical equation and how this may be used for controller and observer designs by using the geometry of mechanical systems on manifolds avoiding the parameterization of Lie group SO(n). Based on this approach, it is possible to focus on the intrinsic property of the system and to show closed-loop stability,...
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