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In this note we extend the design tool presented in [6] for robust stabilization of nonminimum-phase nonlinear systems to the case of output regulation problems. As in [6] we take advantage from a design tool known in the linear literature as “vibrational feedback” to handle the presence of unstable zero dynamics in output regulation problems in presence of uncertainties. This work frames in a research...
This paper attempts to provide a tutorial mode presentation of a time-optimal transfer problem in the geometric framework. The control objective is to change both the orientation and position of a ball sandwiched between two plates in minimum time. The lower plate is fixed and the upper plate can be actuated in two lateral directions. In the geometric framework, the problem of time-optimal reorientation...
This paper discusses the usage of direct methods of calculus of variations for real-time optimization of a final turn-into-the-wind maneuver for autonomous guided parafoil-based delivery systems. It reviews several approaches that are currently being pursued by different developers of such systems and discusses the necessity of usage and applicability of a direct method to optimize the final turn...
This paper examines the capturability of a guidance law that provides a desired angular acceleration of the heading angle to a pursuer. The guidance law has originally been proposed by Fajen and Warren[13], in order to explain the behavior of walking humans. It is shown that the relative rotational motion between a pursuer and an evader can be represented by an equation similar to the equation of...
A novel optimal control algorithm incorporating a cost structure implied by quantity discounts is applied to a differential equation model of an inventory system. Rather than using a demand forecast, this approach is intended to regulate the system in real time in response to inventory variations. Some examples illustrate how the system response is generated and how it is affected by quantity discounts...
A smooth trajectory generator useful in motion control systems is presented. The considered generator is a second order nonlinear system which receives as input a standard reference signal (step, ramp, etc.) and provides as output a smooth reference signal satisfying proper nonlinear constraints on the state variables as, for example, bounds on the first time-derivative x of the output x, or bounds...
A general question one has to face in the study of an optimal control problem is the representation of the closure of the set of trajectories. Loosely speaking, two main problems lie at the basis of the non triviality of this question: the lack of sufficient convexity assumptions (which is at the origin of the introduction of the so-called chattering controls) and the occurrence of unbounded controls...
A computationally effective trajectory generation algorithm of omnidirectional mobile robots is proposed. The algorithm plans a reference path based on Bézier curves for obstacle avoidance. Then the algorithm solves the problem of motion planning for the robot to track the path in a short travel time while satisfying dynamic constraints and robustness to noise. The numerical simulation demonstrates...
This paper presents a constructive methodology to design sliding mode surfaces for a class of underactuated mechanical systems. The surfaces are designed taking advantage of a fictitious output and the Lyapunov theory. The fictitious output is chosen in such a way that the system is minimum-phase. The technique is developed for a class of underactuated mechanical systems with uncertainty in their...
We consider here the problem of finding a controller for a system such that when interconnected to the plant, we get a system which is bisimilar to the desired system. We give necessary and sufficient conditions for the existence of such a controller. The systems we consider are ordinary linear time invariant dynamical systems described by state space equations. We briefly compare our results with...
This paper is devoted to the trajectory tracking and set-point feedback control problems formulated for an articulated tractor-trailer vehicle with off-axle hitching. The Vector Field(s) Orientation (VFO) control method presented in the paper allows treating the two tasks in a unified manner. Proposed concept leads to smooth and non-oscillatory vehicle motion quality together with intuitive geometrical...
Decomposition relationships for nonlinear dynamic system operators into state-space based on vector-matrix series are proposed. The representation for a shift operator on trajectories of nonlinear dynamic system through shift operators on trajectories of multidimensional linear dynamic systems was obtained.
The feedforward control design and motion planning is considered for the realization of highly dynamic output trajectories for a lightweight flexible beam structure with macro-fiber patch actuators. The tracking performance is thereby evaluated in experimental results.
We propose a method to control gliding directions of kinesin-propelled microtubules (MTs) corresponding to their flexural rigidity (EI). We prepared two kinds of MTs having different EI and their trajectories within an electric field were clearly separated. Therefore, this study demonstrated the EI-altered MTs can be workhorses to sort/concentrate various combinations of target molecules loaded on...
High-Squint Mode SAR Imaging poses a greater challenge when compared to broadside SAR due to squint induced azimuth Doppler. The problem becomes more complex when motion errors arise in the flight path, affecting the antenna position with respect to the target region. The paper proposes an Extended Omega-K Algorithm where squint correction and motion error compensation is performed for varying flight...
The article deals with the design of a feedforward controller for a transport system with spatially distributed control input considering input constraints. The feedforward controller is used to compensate transport delays in the input-/output (I/O) behavior of the transport system by realizing exact trajectory tracking of the nominal output along desired trajectories. The proposed method is based...
In this paper, an algorithm to plan a continuous wind-optimal path is proposed, and simulations are made for aircraft trajectories. We consider a mobile which can move in a two dimensional space. The mobile is controlled only by the heading direction, the speed of the mobile is assumed to be constant. The objective is to plan the optimal path avoiding obstacles and taking into account wind currents...
Currently in robotics field, various new forms of robots are emerged that are different from existing robots. One of them is the mobile robot having a tensegrity structure. In this paper, the tensegrity is employed for a design of a mobile robot that can be used in irregular environment. But the tensegrity structure is highly nonlinear; so it is very difficult to control. In order to deal with this...
This paper presents a new adaptive nonlinear control for trajectory tracking of non-affine nonlinear systems. The referred proposed controller which is based on a L2 norm prescribed to minimize a trajectory tracking error has adaptive and optimal characters. Moreover with the systems output feedback, the proposed controller which dose not require any knowledge of nonlinear internal dynamics can be...
In this paper, a multi-surface sliding control (MSSC) is proposed for trajectory tracking of 6 degrees of freedom (6-DOF) inertia coupled aerial vehicles with multiple inputs and multiple outputs (MIMO). It is shown that an iterative MSSC design can be carried out to control flight. Using MSSC on MIMO autonomous flight systems creates confluent control that can account for model mismatches, system...
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