Roberto Naldi - Academia.edu (original) (raw)
Papers by Roberto Naldi
2009 European Control Conference (ECC)
In this paper the properties of a class of piecewise continuous systems subject to measurement no... more In this paper the properties of a class of piecewise continuous systems subject to measurement noise are studied especially regarding their possibility to be stabilized around a whatever vector whitin a finite set of desired stabilization points. Such a problem is a typical control issue in many real systems (vehicles attitude control, robotic manipulators, etc.). Conditions under which global asymptotic stability to a set of points can be guaranteed have been studied in the past by exploiting the intrinsic "holding" nature of the discretetime control framework, which can be emulated in continuoustime by the introduction of sample-and-hold strategies. Because such conditions can be conservative in some cases, new policies are here introduced and investigated based on the notion of "strategy holding" in time (by providing a slower switching policy sampling time) and space (by using hysteresis regions).
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference
This paper focuses on the problem of robust takeoff and landing for a class of VTOL (Vertical Tak... more This paper focuses on the problem of robust takeoff and landing for a class of VTOL (Vertical Take-Off and Landing) aerial robots. One of the main challenge to be addressed derives from the fact that system dynamics may be remarkably different in case contacts with the landing surface happen or not. To this purpose an overall description of the system
This work presents a control strategy to allow a miniature ducted-fan aerial robot to perform \uf... more This work presents a control strategy to allow a miniature ducted-fan aerial robot to perform \ufb02ight operations in an unknown environment potentially cluttered with obstacles. As a main challenge, it is assumed that the vehicle is completely \u201cblind\u201d, namely that obstacles cannot be sensed a priori so as to be avoided or even detected in real-time by means of contact or force sensors installed on the vehicle. As a consequence, the control design has to be robust with respect to the presence of possible unexpected contacts with the surrounding environment. In order to maintain stability in such a complex scenario, the proposed approach relies both on some mechanical properties of the aircraft layout, such as in particular the relative position of possible contact points with respect to the onboard actuators, and on the presence of a supervisor able to detect the presence of an obstacle only by observing the behavior of the \ufb02ight control loop. The effectiveness of th...
2016 European Control Conference (ECC), 2016
In this paper we present a modular control architecture for unmanned aerial vehicles. Given a sta... more In this paper we present a modular control architecture for unmanned aerial vehicles. Given a stabilizing control law, we aim to improve the performances of the vehicle by means of an internal model regulator. To simplify the design procedure, which especially in the nonlinear case might be fairly complicated, we show how it is possible to compose the separate control modules (stabilization and internal model) in an easy and reliable structure. The proposed technique will be tested on the loitering benchmark: in other words, the UAV is required to follow a target and perform a dynamic trajectory around it.
2009 American Control Conference, 2009
This paper focuses on the design and validation of a control framework for a Ducted-Fan Miniature... more This paper focuses on the design and validation of a control framework for a Ducted-Fan Miniature Aerial Vehicle (MAV) realized by the University of Bologna in order to pursuit simple high level operations like surveillance, video capture, etc. After a description of the aircraft prototype and the nonlinear control law, two different control scenarios are then addressed, the first one characterized by a continuous interaction with the human operator (denoted as Remotely Operated Vehicle Mode), and the second one characterized by preloaded desired references to be followed (Trajectory Mode). Detailed experiments are finally presented to show the effectiveness of the proposed design techniques.
2015 54th IEEE Conference on Decision and Control (CDC), 2015
In this work we present a combined planning and control strategy to let agile autonomous robots n... more In this work we present a combined planning and control strategy to let agile autonomous robots navigating in real-world populated environments by means of range limited sensors. In order to reduce the computational cost of obtaining a dynamically-feasible path, the proposed solution relies on a simple way-points generation subject to geometrical constraints. Conditions ensuring feasibility of the obtained trajectories also in the presence of possible exogenous disturbances such as wind are then derived by taking into account the interconnection between the vehicle dynamics, the low-level stabilizing controller and the trajectory planner. As an application, the navigation of a quadrotor and of a differential wheel robot in an unknown forest environment is proposed. In particular, the proposed framework is employed to let the vehicle moving at the highest possible speed that guarantees no collision with obstacles.
2008 47th IEEE Conference on Decision and Control, 2008
In this paper we focus on the problem of modeling and controlling a certain configuration of UAV ... more In this paper we focus on the problem of modeling and controlling a certain configuration of UAV (Unmanned Aerial Vehicle) considering explicitly the interaction with the environment. This innovative problem is particularly interesting in order to employ unmanned aircrafts in tasks and operations which may require explicitly or implicitly contacts between the UAV itself and the environment such as manipulation of remote objects or indoor flight. For a class of VTOL (Vertical TakeOff and Landing) aircrafts we start studying the problem of safe takeoff from hostile terrains and the control of the vehicle when in contact with vertical fixed surfaces.
IFAC Proceedings Volumes, 2014
This paper focuses on the design of a stabilizing control law for an aerial vehicle which is phys... more This paper focuses on the design of a stabilizing control law for an aerial vehicle which is physically connected to a ground station by means of a tether cable. When the cable is taut, the resulting dynamic model is shown to be characterized by a new set of equilibria which untethered aircraft are unable to maintain in steady state. The control objective is to steer the UAV to a desired set-point while maintaining the cable taut at all times. This leads to a nonlinear control problem subject to constraints. A cascade control scheme is proposed and proven to asymptotically stabilize the overall system by means of ISS arguments. Constraint satisfaction is guaranteed using a modified thrust vector control coupled with a reference governor strategy. The effectiveness of the proposed control strategy is shown via numerical simulations.
Proceedings of the American Control Conference
ABSTRACT
2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013
ABSTRACT The SHERPA project funded by the European Community's 7th Framework Program (ICT... more ABSTRACT The SHERPA project funded by the European Community's 7th Framework Program (ICT 600958), addresses the development of a team of ground and aerial robots to act as an aid to alpine search-and-rescue missions. Following the kickoff of the project on February 1st 2013 and the thorough research on the conditions under which such missions are currently conducted, we study the applicability of existing technologies, while envisioning the next steps up to the 4-year horizon of this project and beyond. Here, we present a briefly account of the outcomes of our study, mainly concentrated on setting up meaningful operative scenarios and relevant benchmarks, which will be used throughout the project in order to test the robotic platforms and the software frameworks developed, as well as relevant measures of success for these. This phase of the research activity has been carried out in cooperation with the SHERPA end-users, the Club Alpino Italiano [2], as well as the Swiss Air Rescue [3] and the Institute for Snow and Avalanche Research [4], who are members of the Advisory Board of SHERPA. The complete study summarized in this report can be found in [5].
2015 American Control Conference (ACC), 2015
In this paper we investigate the problem of motion coordination of a class of multi-agent robotic... more In this paper we investigate the problem of motion coordination of a class of multi-agent robotic systems. By means of consensus theory, we implement a decentralized control scheme which relies on the exchange of information between agents in order to obtain a coordinated motion trajectory. The key feature of this approach relies in the fact that consensus is applied to a set of exosystems (one for each agent), which can be thought of as local reference generators. By tracking the generated coordinated reference the desired formation and trajectory is achieved.
Proceedings of the 44th IEEE Conference on Decision and Control
We consider the problem of controlling the vertical, lateral and longitudinal motion of a nonline... more We consider the problem of controlling the vertical, lateral and longitudinal motion of a nonlinear model of a helicopter maintaining a constant yaw-attitude. Given arbitrary references with suitable restrictions on the time derivatives, we design a nonlinear controller which succeeds in enforcing the desired trajectories robustly with respect to uncertainties characterizing the physical and aerodynamical parameters of the helicopter. Engine dynamic of the main rotor is also taken into account in deriving the control law. Simulation results are finally given showing the effectiveness of the method and its ability to cope with uncertainties on the plant and actuator model.
49th IEEE Conference on Decision and Control (CDC), 2010
53rd IEEE Conference on Decision and Control, 2014
ABSTRACT
AIAA Guidance, Navigation and Control Conference and Exhibit, 2008
info:eu-repo/semantics/publishe
info:eu-repo/semantics/publishe
2009 European Control Conference (ECC)
In this paper the properties of a class of piecewise continuous systems subject to measurement no... more In this paper the properties of a class of piecewise continuous systems subject to measurement noise are studied especially regarding their possibility to be stabilized around a whatever vector whitin a finite set of desired stabilization points. Such a problem is a typical control issue in many real systems (vehicles attitude control, robotic manipulators, etc.). Conditions under which global asymptotic stability to a set of points can be guaranteed have been studied in the past by exploiting the intrinsic "holding" nature of the discretetime control framework, which can be emulated in continuoustime by the introduction of sample-and-hold strategies. Because such conditions can be conservative in some cases, new policies are here introduced and investigated based on the notion of "strategy holding" in time (by providing a slower switching policy sampling time) and space (by using hysteresis regions).
Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference
This paper focuses on the problem of robust takeoff and landing for a class of VTOL (Vertical Tak... more This paper focuses on the problem of robust takeoff and landing for a class of VTOL (Vertical Take-Off and Landing) aerial robots. One of the main challenge to be addressed derives from the fact that system dynamics may be remarkably different in case contacts with the landing surface happen or not. To this purpose an overall description of the system
This work presents a control strategy to allow a miniature ducted-fan aerial robot to perform \uf... more This work presents a control strategy to allow a miniature ducted-fan aerial robot to perform \ufb02ight operations in an unknown environment potentially cluttered with obstacles. As a main challenge, it is assumed that the vehicle is completely \u201cblind\u201d, namely that obstacles cannot be sensed a priori so as to be avoided or even detected in real-time by means of contact or force sensors installed on the vehicle. As a consequence, the control design has to be robust with respect to the presence of possible unexpected contacts with the surrounding environment. In order to maintain stability in such a complex scenario, the proposed approach relies both on some mechanical properties of the aircraft layout, such as in particular the relative position of possible contact points with respect to the onboard actuators, and on the presence of a supervisor able to detect the presence of an obstacle only by observing the behavior of the \ufb02ight control loop. The effectiveness of th...
2016 European Control Conference (ECC), 2016
In this paper we present a modular control architecture for unmanned aerial vehicles. Given a sta... more In this paper we present a modular control architecture for unmanned aerial vehicles. Given a stabilizing control law, we aim to improve the performances of the vehicle by means of an internal model regulator. To simplify the design procedure, which especially in the nonlinear case might be fairly complicated, we show how it is possible to compose the separate control modules (stabilization and internal model) in an easy and reliable structure. The proposed technique will be tested on the loitering benchmark: in other words, the UAV is required to follow a target and perform a dynamic trajectory around it.
2009 American Control Conference, 2009
This paper focuses on the design and validation of a control framework for a Ducted-Fan Miniature... more This paper focuses on the design and validation of a control framework for a Ducted-Fan Miniature Aerial Vehicle (MAV) realized by the University of Bologna in order to pursuit simple high level operations like surveillance, video capture, etc. After a description of the aircraft prototype and the nonlinear control law, two different control scenarios are then addressed, the first one characterized by a continuous interaction with the human operator (denoted as Remotely Operated Vehicle Mode), and the second one characterized by preloaded desired references to be followed (Trajectory Mode). Detailed experiments are finally presented to show the effectiveness of the proposed design techniques.
2015 54th IEEE Conference on Decision and Control (CDC), 2015
In this work we present a combined planning and control strategy to let agile autonomous robots n... more In this work we present a combined planning and control strategy to let agile autonomous robots navigating in real-world populated environments by means of range limited sensors. In order to reduce the computational cost of obtaining a dynamically-feasible path, the proposed solution relies on a simple way-points generation subject to geometrical constraints. Conditions ensuring feasibility of the obtained trajectories also in the presence of possible exogenous disturbances such as wind are then derived by taking into account the interconnection between the vehicle dynamics, the low-level stabilizing controller and the trajectory planner. As an application, the navigation of a quadrotor and of a differential wheel robot in an unknown forest environment is proposed. In particular, the proposed framework is employed to let the vehicle moving at the highest possible speed that guarantees no collision with obstacles.
2008 47th IEEE Conference on Decision and Control, 2008
In this paper we focus on the problem of modeling and controlling a certain configuration of UAV ... more In this paper we focus on the problem of modeling and controlling a certain configuration of UAV (Unmanned Aerial Vehicle) considering explicitly the interaction with the environment. This innovative problem is particularly interesting in order to employ unmanned aircrafts in tasks and operations which may require explicitly or implicitly contacts between the UAV itself and the environment such as manipulation of remote objects or indoor flight. For a class of VTOL (Vertical TakeOff and Landing) aircrafts we start studying the problem of safe takeoff from hostile terrains and the control of the vehicle when in contact with vertical fixed surfaces.
IFAC Proceedings Volumes, 2014
This paper focuses on the design of a stabilizing control law for an aerial vehicle which is phys... more This paper focuses on the design of a stabilizing control law for an aerial vehicle which is physically connected to a ground station by means of a tether cable. When the cable is taut, the resulting dynamic model is shown to be characterized by a new set of equilibria which untethered aircraft are unable to maintain in steady state. The control objective is to steer the UAV to a desired set-point while maintaining the cable taut at all times. This leads to a nonlinear control problem subject to constraints. A cascade control scheme is proposed and proven to asymptotically stabilize the overall system by means of ISS arguments. Constraint satisfaction is guaranteed using a modified thrust vector control coupled with a reference governor strategy. The effectiveness of the proposed control strategy is shown via numerical simulations.
Proceedings of the American Control Conference
ABSTRACT
2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013
ABSTRACT The SHERPA project funded by the European Community's 7th Framework Program (ICT... more ABSTRACT The SHERPA project funded by the European Community's 7th Framework Program (ICT 600958), addresses the development of a team of ground and aerial robots to act as an aid to alpine search-and-rescue missions. Following the kickoff of the project on February 1st 2013 and the thorough research on the conditions under which such missions are currently conducted, we study the applicability of existing technologies, while envisioning the next steps up to the 4-year horizon of this project and beyond. Here, we present a briefly account of the outcomes of our study, mainly concentrated on setting up meaningful operative scenarios and relevant benchmarks, which will be used throughout the project in order to test the robotic platforms and the software frameworks developed, as well as relevant measures of success for these. This phase of the research activity has been carried out in cooperation with the SHERPA end-users, the Club Alpino Italiano [2], as well as the Swiss Air Rescue [3] and the Institute for Snow and Avalanche Research [4], who are members of the Advisory Board of SHERPA. The complete study summarized in this report can be found in [5].
2015 American Control Conference (ACC), 2015
In this paper we investigate the problem of motion coordination of a class of multi-agent robotic... more In this paper we investigate the problem of motion coordination of a class of multi-agent robotic systems. By means of consensus theory, we implement a decentralized control scheme which relies on the exchange of information between agents in order to obtain a coordinated motion trajectory. The key feature of this approach relies in the fact that consensus is applied to a set of exosystems (one for each agent), which can be thought of as local reference generators. By tracking the generated coordinated reference the desired formation and trajectory is achieved.
Proceedings of the 44th IEEE Conference on Decision and Control
We consider the problem of controlling the vertical, lateral and longitudinal motion of a nonline... more We consider the problem of controlling the vertical, lateral and longitudinal motion of a nonlinear model of a helicopter maintaining a constant yaw-attitude. Given arbitrary references with suitable restrictions on the time derivatives, we design a nonlinear controller which succeeds in enforcing the desired trajectories robustly with respect to uncertainties characterizing the physical and aerodynamical parameters of the helicopter. Engine dynamic of the main rotor is also taken into account in deriving the control law. Simulation results are finally given showing the effectiveness of the method and its ability to cope with uncertainties on the plant and actuator model.
49th IEEE Conference on Decision and Control (CDC), 2010
53rd IEEE Conference on Decision and Control, 2014
ABSTRACT
AIAA Guidance, Navigation and Control Conference and Exhibit, 2008
info:eu-repo/semantics/publishe
info:eu-repo/semantics/publishe