1,721,000 research outputs found
Sufficient conditions for passivity and stability of interconnections of hybrid systems using sums of storage functions2014 American Control Conference
Full text linkBuilding from recent results on passivity for a class of hybrid systems, we investigate the properties of negative feedback interconnections of such systems. We establish links between the passivity properties of the individual subsystems and passivity, stability, and asymptotic stability of their interconnection. As a main difference to the continuous time counterpart, it is found that the sum of the two storage functions of two individual hybrid subsystems may not be a storage function for their interconnection. This issue motivates exploring additional sufficient conditions that guarantee that passivity and stability of the interconnected system hold using the individual storage functions. Throughout the paper, an application and examples illustrate the definitions and the results obtained
A supervisory control strategy for robot-assisted search and rescue in hostile environments2013 IEEE 18th Conference on Emerging Technologies & Factory Automation (ETFA)
No full textA travelling salesman problem for a class of heterogeneous multi-vehicle systems2012 IEEE 51st IEEE Conference on Decision and Control (CDC)
No full textIn this work we formulate and study a Travelling Salesman Problem (TSP) for a scenario in which two different vehicles cooperate so as to perform a desired task in an optimal way. In particular we consider the problem where a fast vehicle with a short operative range has to be coordinated with a carrier vehicle, typically slower but with virtually infinite operativity range, in order to visit in the shortest time a given collection of points
High-gain output feedback for a miniature UAV
No full textWe consider the problem of output feedback robust stabilization of a ducted-fan aerial vehicle in which high-gain observers are used to overtake the knowledge of the linear and angular velocities of the vehicle in the control law. The proposed result is semiglobal in the attitude dynamics and in the estimation error, and global in the position variables. It is shown how the high-gain control structure is effective notwithstanding the nonminimum-phase behavior of the considered class of systems, provided that the airframe fulfills some geometric properties. The controller relies upon the use of nested saturations and high-gain control laws. Although the theory is specified for a force-torque generation mechanism of a ducted-fan aerial vehicle, the results can be simply extended to the output feedback of many other under-actuated rotorcrafts, such as helicopters. Experimental results are also proposed showing the effectiveness of the control law.We consider the problem of output feedback robust stabilization of a ducted-fan aerial vehicle in which high-gain observers are used to overtake the knowledge of the linear and angular velocities of the vehicle in the control law. The proposed result is semiglobal in the attitude dynamics and in the estimation error, and global in the position variables. It is shown how the high-gain control structure is effective notwithstanding the nonminimum-phase behavior of the considered class of systems, provided that the airframe fulfills some geometric properties. The controller relies upon the use of nested saturations and high-gain control laws. Although the theory is specified for a force-torque generation mechanism of a ducted-fan aerial vehicle, the results can be simply extended to the output feedback of many other under-actuated rotorcrafts, such as helicopters. Experimental results are also proposed showing the effectiveness of the control law
Control of Modular Aerial Robots: Combining Under- and Fully-Actuated Behaviors
No full textThis work presents the design of flight control algorithms for set-point stabilization of a class of modular aerial vehicles obtained by rigidly interconnecting a number of single ducted-fan aircraft. Interestingly enough, for such a modular configuration, certain types of interconnection structure between the different modules may lead to redundancy both in term of the overall number of actuators available onboard and in the number of degrees of freedom that can be actually governed simultaneously. The design of the control policy for such a complex dynamical behavior is handled by defining specific control allocation algorithms for each possible case (for which a taxonomy is given in the paper) and by deriving an overall control structure capable to switch among these policies according to the properties of the selected configuration. This approach results in an architecture that combines classical control schemes for under-actuated air vehicles - such as those employed in most Vertical Take-Off and Landing (VTOL) aircraft - with control strategies for fully-actuated vehicles
A hybrid system for a class of hysteresis nonlinearity: Modeling and compensation2012 IEEE 51st IEEE Conference on Decision and Control (CDC)
No full textIn this paper we present a novel internal model-based control method for hysteresis compensation. A hybrid model is proposed for characterization of the hysteresis nonlinearity of the well-known play operator (Backlash). The proposed model holds the hysteresis nonlinearity and the memory effects of the play operator. Based on the proposed model, a hybrid controller is designed to compensate for the hysteresis nonlinearity of the play operator. Following an internal model approach, the hybrid controller integrates a hybrid integrator dynamics which is able to estimate asymptotically the unknown value of the threshold characterizing the hysteresis and hence to obtain perfect tracking of a periodic reference signal. Simulation results are also presented to show the capability of the hybrid model to present the hysteresis nonlinearity with memory effects, and the effectiveness of proposed hybrid controller to compensate for the uncertain hysteresis nonlinearity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A modular aerial vehicle with redundant actuation2013 IEEE/RSJ International Conference on Intelligent Robots and Systems
No full text
- …
