Vincenzo Lippiello | Università degli Studi di Napoli "Federico II" (original) (raw)

Papers by Vincenzo Lippiello

International Journal of Control, Automation and Systems, 2022

2015 23rd Mediterranean Conference on Control and Automation (MED), 2015

In this paper a hybrid visual servoing with a dynamic and hierarchical task-priority control fram... more In this paper a hybrid visual servoing with a dynamic and hierarchical task-priority control framework is proposed for the control of an aerial vehicle endowed with a robot arm. The proposed task composition algorithm retains the main benefits of classical image-based and position-based control scheme, that can be suitably combined in a common hybridcontrol framework. Moreover, the under-actuation of the vehicle base has been systematically taken into account within a general formulation, while a dynamic smooth activation/deactivation mechanism is proposed to avoid discontinuity in the control action. Simulations have been proposed to demonstrate the effectiveness of the proposed approach.

2011 IEEE International Conference on Robotics and Automation (ICRA 2011), 2011

This paper presents a closed-form solution for metric velocity estimation of a single camera usin... more This paper presents a closed-form solution for metric velocity estimation of a single camera using inertial measurements. It combines accelerometer and attitude measurements with feature observations in order to compute both the distance to the feature and the speed of the camera inside the camera frame. Notably, we show that this is possible by just using three consecutive camera positions and a single feature correspondence. Our approach represents a compact linear and multirate solution for estimating complementary information to regular essential matrix computation, namely the scale of the problem. The algorithm is thoroughly validated on simulated and real data and conditions for good quality of the results are identified.

Depalletizing robotic systems are commonly de- ployed to automatize and speed up parts of logisti... more Depalletizing robotic systems are commonly de- ployed to automatize and speed up parts of logistic processes. De- spite this, the necessity to adapt the preexisting logistic processes to the automatic systems often impairs the application of such robotic solutions to small business realities like supermarkets. Integrating a robotic system into the supermarket depalletizing process demands a high level of autonomy, based on strong perceptive, executive and gripping capabilities. This abstract describes an integrated robotic depalletizing system designed to be easily deployed into supermarket logistic processes. The system is described along with its main components, showing how the proposed framework performs in a real supermarket scenario.

Springer Tracts in Advanced Robotics, 2022

Springer Tracts in Advanced Robotics, 2022

2019 IEEE International Conference on Systems, Man and Cybernetics (SMC), 2019

Cobots (Collaborative robots) are increasingly employed in industrial workplaces, assisting human... more Cobots (Collaborative robots) are increasingly employed in industrial workplaces, assisting human operators in decreasing the weight and the repetitiveness of their activities. In order to promote the acceptance of cobots, novel interaction paradigms enabling intuitive collaboration between humans and robots are needed. In this work, we propose a variable admittance control framework based on virtual fixtures, in which the damping and the stiffness of the admittance controller are on-line adjusted to increase the effectiveness of the co-manipulation task. Virtual paths are generated to support and guide the operator during collaborative task execution, providing him/her an over-responsive compliant system when the robot is far from the targets and a precise heavy tool in their proximity. The proposed approach has been compared with a fixed admittance controller in an industrial use case consisting of a human operator interacting with a Kuka LBR IIWA arm. The collected results demonstrate the effectiveness of the proposed approach.

ArXiv, 2016

We present a multimodal interaction framework suitable for a human rescuer that operates in proxi... more We present a multimodal interaction framework suitable for a human rescuer that operates in proximity with a set of co-located drones during search missions. This work is framed in the context of the SHERPA project whose goal is to develop a mixed ground and aerial robotic platform to support search and rescue activities in a real-world alpine scenario. Differently from typical human-drone interaction settings, here the operator is not fully dedicated to the drones, but involved in search and rescue tasks, hence only able to provide sparse, incomplete, although high-value, instructions to the robots. This operative scenario requires a human-interaction framework that supports multimodal communication along with an effective and natural mixed-initiative interaction between the human and the robots. In this work, we illustrate the domain and the proposed multimodal interaction framework discussing the system at work in a simulated case study.

2017 26th IEEE International Symposium on Robot and Human Interactive Communication (RO-MAN), 2017

We present a novel multimodal interaction framework supporting robust human-robot communication. ... more We present a novel multimodal interaction framework supporting robust human-robot communication. We consider a scenario where a human operator can exploit multiple communication channels to interact with one or more robots in order to accomplish shared tasks. Moreover, we assume that the human is not fully dedicated to the robot control, but also involved in other activities, hence only able to interact with the robotic system in a sparse and incomplete manner. In this context, several human or environmental factors could cause errors, noise and wrong interpretations of the commands. The main goal of this work is to improve the robustness of humanrobot interaction systems in similar situations. In particular, we propose a multimodal fusion method based on the following steps: for each communication channel, unimodal classifiers are firstly deployed in order to generate unimodal interpretations of the human inputs; the unimodal outcomes are then grouped into different multimodal recognition lines, each representing a possible interpretation of a sequence of multimodal inputs; these lines are finally assessed in order to recognize the human commands. We discuss the system at work in a case study in which a human rescuer interacts with a team of flying robots during Search & Rescue missions. In this scenario, we present and discuss real world experiments to demonstrate the effectiveness of the proposed framework.

Fault Diagnosis and Fault-tolerant Control of Robotic and Autonomous Systems, 2020

Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics, 2018

Collaborative robots are increasingly employed in industrial workplaces, assisting human operator... more Collaborative robots are increasingly employed in industrial workplaces, assisting human operators in decreasing the weight and the repetitiveness of their activities. In this paper, we assume the presence of an operator cooperating with a lightweight robotic arm, able to autonomously navigate its workspace, while the human co-worker physically interacts with it leading and influencing the execution of the shared task. In this scenario, we propose a human-robot co-manipulation method in which the autonomy of the robot is regulated according to the operator intentions. Specifically, the operator contact forces are assessed with respect to the autonomous motion of the robot inferring how the human motion commands diverges from the autonomous ones. This information is exploited by the system to adjust its role in the shared task, leading or following the operator and to proactively assist him during the co-manipulation. The proposed approach has been demonstrated in an industrial use case consisting of a human operator that interacts with a Kuka LBR iiwa arm to perform a cooperative manipulation task. The collected results demonstrate the effectiveness of the proposed approach.

IFAC-PapersOnLine, 2017

The contact kinematics of a robotic hoop and a pole system is obtained by using the Montana's equ... more The contact kinematics of a robotic hoop and a pole system is obtained by using the Montana's equations, considering the case of contact without slipping. The resulting kinematic model is completely nonholonomic. After some mild assumptions, a set of Pfaffian constraints is established. Then, a dynamic model of the system is developed by employing the Lagranged'Alembert formulation. This dynamic model, which represents an underactuated mechanical system, is later used to design a controller which does not need velocity measurements. The proposed method, and its robustness against model uncertainties, is validated through numeric simulations.

2015 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2015

In this paper we propose a new control method for quadrotor autonomous landing on a visual target... more In this paper we propose a new control method for quadrotor autonomous landing on a visual target without linear velocity measurements. Only onboard sensing is exploited, such that only the images of the landing pad from a down-looking camera, along with data from an Inertial Measurement Unit's gyro, are used. The control system consists of an image-based nonlinear observer that estimates online the linear velocity of the vehicle and a backstepping image-based controller that generates attitude, and thrust setpoints to the quadrotor autopilot. Both observer and controller share the same feedback information: spherical visual features. Therefore no further image elaboration is needed for the estimation. This, along with the fact that only simple computations on low-and constant-dimension arrays are involved, makes the proposed solution computationally cheap. Real-hardware experiments on a quadrotor are carried out to verify the validity of the proposed control system.

IEEE Robotics and Automation Letters, 2016

A control framework for nonprehensile planar rolling dynamic manipulation is derived in this lett... more A control framework for nonprehensile planar rolling dynamic manipulation is derived in this letter. By rotating around the center of mass, the manipulator moves a part without grasping it but exploiting its dynamics. Given some assumptions on the shapes of both the object and the manipulator, a state transformation is found rendering the state-space system in a chain of integrators form without internal dynamics, allowing the possibility to exploit linear controls to stabilize the whole system. An analysis of the differential flatness property of the system is also provided. Simulations and experiments validate the derived framework.

IEEE Transactions on Robotics, 2015

In this paper, we propose a nonlinear controller that stabilizes unmanned aerial vehicles in GPS-... more In this paper, we propose a nonlinear controller that stabilizes unmanned aerial vehicles in GPS-denied environments with respect to visual targets by using only onboard sensing. The translational velocity of the vehicle is estimated online with a nonlinear observer, which exploits spherical visual features as the main source of information. With the proposed solution, only four visual features have shown to be enough for the observer to operate in a real scenario. In addition, the observer is computationally light with constant numerical complexity, involving small-dimension matrices. The observer output is then exploited in a nonlinear controller designed with an integral backstepping approach, thus yielding a novel robust control system. By means of Lyapunov analysis, the stability of the closed-loop system is proved. Extensive simulation and experimental tests with a quadrotor are carried out to verify the validity and robustness of the proposed approach. The control system runs fully onboard on a standard processor, and only a low-cost sensing suite is employed. Tracking of a target whose speed exceeds 2 m/s is also considered in the real-hardware experiments. Index Terms-Image-based visual servoing, nonlinear controller, nonlinear observer, unmanned aerial vehicle (UAV), velocity estimation. I. INTRODUCTION A UTONOMOUS control of robotic vehicles requires information of their state, followed by a proper control action. For unmanned aerial vehicles (UAVs), extracting their translational velocity solely from the onboard sensing is still an open issue. Yet, the translational velocity is a key information for UAV control [1]. The most adopted sensing modalities for this purpose are GPS and vision. GPS relies on external source (satellites) for providing vehicle global position information, and as such, it does not operate in cluttered urban areas, is not reliable at low altitudes, suffers from satellite signal cuts, and is a nonpassive sensing modality [2], [3]. On the other hand, vision Manuscript

2015 23rd Mediterranean Conference on Control and Automation (MED), 2015

The design, modeling and control of a 5 degreesof-freedom lightweight robot manipulator is presen... more The design, modeling and control of a 5 degreesof-freedom lightweight robot manipulator is presented in this paper. The proposed robot arm, named Prisma Ultra-Lightweight 5 ARm (PUL5AR), is employed to execute manipulation tasks equipped on board of a vertical takeoff and landing unmanned aerial vehicle. The arm is compact and lightweight. Its mechanics is designed such that it can fold on itself during landing manoeuvres. Moreover, the design is conceived to constrain the center of gravity of the arm as close as possible to vehicle base, thus reducing the total inertia and static unbalancing of the system. Experimental tests have been carried out in order to validate the dynamic model, the communication library, the developed electronics, and the control schemes implemented for the designed robot arm.

IEEE Robotics and Automation Letters, 2018

Aerial manipulation aims at combining the versatility and the agility of some aerial platforms wi... more Aerial manipulation aims at combining the versatility and the agility of some aerial platforms with the manipulation capabilities of robotic arms. This letter tries to collect the results reached by the research community so far within the field of aerial manipulation, especially from the technological and control point of view. A brief literature review of general aerial robotics and space manipulation is carried out as well.

Proceedings of the 16th IFAC World Congress, 2005, 2005

2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013

In this paper an image-based visual-servoing control law for the coordinated landing of a VToL UA... more In this paper an image-based visual-servoing control law for the coordinated landing of a VToL UAV on an actuated landing platform is proposed. The landing platform is carried by a mobile manipulator composed of a mobile platform and a robotic arm. The UAV is endowed with a downward camera employed for the coordination of the landing manoeuvres. The presence of redundancy in the system at the task level, the intrinsic redundancy of the mobile manipulator, and the underactuation of the UAV are explicitly addressed into the proposed control law. The effectiveness of the proposed approach is tested though simulations.

2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013

ABSTRACT This paper proposes two methods for UAV translational velocity estimation based on onboa... more ABSTRACT This paper proposes two methods for UAV translational velocity estimation based on onboard sensing only. Spherical image measurements provided by a single onboard camera along with IMU data consist the main information feeding the estimators. The first algorithm consists of a nonlinear observer, designed using Lyapunov synthesis, while the second is based on the Unscented Kalman filtering technique. Differently with respect to existing approaches, the velocity is directly estimated from the onboard image without the need to fully estimate the vehicle 3D pose. The low computational requirement makes the proposed techniques suitable for applications where the execution time is of prominent importance even if no powerful hardware is available, as it is the case with UAV systems. Experimental results validate the algorithms, and this with the use of only four image features.

International Journal of Control, Automation and Systems, 2022

2015 23rd Mediterranean Conference on Control and Automation (MED), 2015

In this paper a hybrid visual servoing with a dynamic and hierarchical task-priority control fram... more In this paper a hybrid visual servoing with a dynamic and hierarchical task-priority control framework is proposed for the control of an aerial vehicle endowed with a robot arm. The proposed task composition algorithm retains the main benefits of classical image-based and position-based control scheme, that can be suitably combined in a common hybridcontrol framework. Moreover, the under-actuation of the vehicle base has been systematically taken into account within a general formulation, while a dynamic smooth activation/deactivation mechanism is proposed to avoid discontinuity in the control action. Simulations have been proposed to demonstrate the effectiveness of the proposed approach.

2011 IEEE International Conference on Robotics and Automation (ICRA 2011), 2011

This paper presents a closed-form solution for metric velocity estimation of a single camera usin... more This paper presents a closed-form solution for metric velocity estimation of a single camera using inertial measurements. It combines accelerometer and attitude measurements with feature observations in order to compute both the distance to the feature and the speed of the camera inside the camera frame. Notably, we show that this is possible by just using three consecutive camera positions and a single feature correspondence. Our approach represents a compact linear and multirate solution for estimating complementary information to regular essential matrix computation, namely the scale of the problem. The algorithm is thoroughly validated on simulated and real data and conditions for good quality of the results are identified.

Depalletizing robotic systems are commonly de- ployed to automatize and speed up parts of logisti... more Depalletizing robotic systems are commonly de- ployed to automatize and speed up parts of logistic processes. De- spite this, the necessity to adapt the preexisting logistic processes to the automatic systems often impairs the application of such robotic solutions to small business realities like supermarkets. Integrating a robotic system into the supermarket depalletizing process demands a high level of autonomy, based on strong perceptive, executive and gripping capabilities. This abstract describes an integrated robotic depalletizing system designed to be easily deployed into supermarket logistic processes. The system is described along with its main components, showing how the proposed framework performs in a real supermarket scenario.

Springer Tracts in Advanced Robotics, 2022

Springer Tracts in Advanced Robotics, 2022

2019 IEEE International Conference on Systems, Man and Cybernetics (SMC), 2019

Cobots (Collaborative robots) are increasingly employed in industrial workplaces, assisting human... more Cobots (Collaborative robots) are increasingly employed in industrial workplaces, assisting human operators in decreasing the weight and the repetitiveness of their activities. In order to promote the acceptance of cobots, novel interaction paradigms enabling intuitive collaboration between humans and robots are needed. In this work, we propose a variable admittance control framework based on virtual fixtures, in which the damping and the stiffness of the admittance controller are on-line adjusted to increase the effectiveness of the co-manipulation task. Virtual paths are generated to support and guide the operator during collaborative task execution, providing him/her an over-responsive compliant system when the robot is far from the targets and a precise heavy tool in their proximity. The proposed approach has been compared with a fixed admittance controller in an industrial use case consisting of a human operator interacting with a Kuka LBR IIWA arm. The collected results demonstrate the effectiveness of the proposed approach.

ArXiv, 2016

We present a multimodal interaction framework suitable for a human rescuer that operates in proxi... more We present a multimodal interaction framework suitable for a human rescuer that operates in proximity with a set of co-located drones during search missions. This work is framed in the context of the SHERPA project whose goal is to develop a mixed ground and aerial robotic platform to support search and rescue activities in a real-world alpine scenario. Differently from typical human-drone interaction settings, here the operator is not fully dedicated to the drones, but involved in search and rescue tasks, hence only able to provide sparse, incomplete, although high-value, instructions to the robots. This operative scenario requires a human-interaction framework that supports multimodal communication along with an effective and natural mixed-initiative interaction between the human and the robots. In this work, we illustrate the domain and the proposed multimodal interaction framework discussing the system at work in a simulated case study.

2017 26th IEEE International Symposium on Robot and Human Interactive Communication (RO-MAN), 2017

We present a novel multimodal interaction framework supporting robust human-robot communication. ... more We present a novel multimodal interaction framework supporting robust human-robot communication. We consider a scenario where a human operator can exploit multiple communication channels to interact with one or more robots in order to accomplish shared tasks. Moreover, we assume that the human is not fully dedicated to the robot control, but also involved in other activities, hence only able to interact with the robotic system in a sparse and incomplete manner. In this context, several human or environmental factors could cause errors, noise and wrong interpretations of the commands. The main goal of this work is to improve the robustness of humanrobot interaction systems in similar situations. In particular, we propose a multimodal fusion method based on the following steps: for each communication channel, unimodal classifiers are firstly deployed in order to generate unimodal interpretations of the human inputs; the unimodal outcomes are then grouped into different multimodal recognition lines, each representing a possible interpretation of a sequence of multimodal inputs; these lines are finally assessed in order to recognize the human commands. We discuss the system at work in a case study in which a human rescuer interacts with a team of flying robots during Search & Rescue missions. In this scenario, we present and discuss real world experiments to demonstrate the effectiveness of the proposed framework.

Fault Diagnosis and Fault-tolerant Control of Robotic and Autonomous Systems, 2020

Proceedings of the 15th International Conference on Informatics in Control, Automation and Robotics, 2018

Collaborative robots are increasingly employed in industrial workplaces, assisting human operator... more Collaborative robots are increasingly employed in industrial workplaces, assisting human operators in decreasing the weight and the repetitiveness of their activities. In this paper, we assume the presence of an operator cooperating with a lightweight robotic arm, able to autonomously navigate its workspace, while the human co-worker physically interacts with it leading and influencing the execution of the shared task. In this scenario, we propose a human-robot co-manipulation method in which the autonomy of the robot is regulated according to the operator intentions. Specifically, the operator contact forces are assessed with respect to the autonomous motion of the robot inferring how the human motion commands diverges from the autonomous ones. This information is exploited by the system to adjust its role in the shared task, leading or following the operator and to proactively assist him during the co-manipulation. The proposed approach has been demonstrated in an industrial use case consisting of a human operator that interacts with a Kuka LBR iiwa arm to perform a cooperative manipulation task. The collected results demonstrate the effectiveness of the proposed approach.

IFAC-PapersOnLine, 2017

The contact kinematics of a robotic hoop and a pole system is obtained by using the Montana's equ... more The contact kinematics of a robotic hoop and a pole system is obtained by using the Montana's equations, considering the case of contact without slipping. The resulting kinematic model is completely nonholonomic. After some mild assumptions, a set of Pfaffian constraints is established. Then, a dynamic model of the system is developed by employing the Lagranged'Alembert formulation. This dynamic model, which represents an underactuated mechanical system, is later used to design a controller which does not need velocity measurements. The proposed method, and its robustness against model uncertainties, is validated through numeric simulations.

2015 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2015

In this paper we propose a new control method for quadrotor autonomous landing on a visual target... more In this paper we propose a new control method for quadrotor autonomous landing on a visual target without linear velocity measurements. Only onboard sensing is exploited, such that only the images of the landing pad from a down-looking camera, along with data from an Inertial Measurement Unit's gyro, are used. The control system consists of an image-based nonlinear observer that estimates online the linear velocity of the vehicle and a backstepping image-based controller that generates attitude, and thrust setpoints to the quadrotor autopilot. Both observer and controller share the same feedback information: spherical visual features. Therefore no further image elaboration is needed for the estimation. This, along with the fact that only simple computations on low-and constant-dimension arrays are involved, makes the proposed solution computationally cheap. Real-hardware experiments on a quadrotor are carried out to verify the validity of the proposed control system.

IEEE Robotics and Automation Letters, 2016

A control framework for nonprehensile planar rolling dynamic manipulation is derived in this lett... more A control framework for nonprehensile planar rolling dynamic manipulation is derived in this letter. By rotating around the center of mass, the manipulator moves a part without grasping it but exploiting its dynamics. Given some assumptions on the shapes of both the object and the manipulator, a state transformation is found rendering the state-space system in a chain of integrators form without internal dynamics, allowing the possibility to exploit linear controls to stabilize the whole system. An analysis of the differential flatness property of the system is also provided. Simulations and experiments validate the derived framework.

IEEE Transactions on Robotics, 2015

In this paper, we propose a nonlinear controller that stabilizes unmanned aerial vehicles in GPS-... more In this paper, we propose a nonlinear controller that stabilizes unmanned aerial vehicles in GPS-denied environments with respect to visual targets by using only onboard sensing. The translational velocity of the vehicle is estimated online with a nonlinear observer, which exploits spherical visual features as the main source of information. With the proposed solution, only four visual features have shown to be enough for the observer to operate in a real scenario. In addition, the observer is computationally light with constant numerical complexity, involving small-dimension matrices. The observer output is then exploited in a nonlinear controller designed with an integral backstepping approach, thus yielding a novel robust control system. By means of Lyapunov analysis, the stability of the closed-loop system is proved. Extensive simulation and experimental tests with a quadrotor are carried out to verify the validity and robustness of the proposed approach. The control system runs fully onboard on a standard processor, and only a low-cost sensing suite is employed. Tracking of a target whose speed exceeds 2 m/s is also considered in the real-hardware experiments. Index Terms-Image-based visual servoing, nonlinear controller, nonlinear observer, unmanned aerial vehicle (UAV), velocity estimation. I. INTRODUCTION A UTONOMOUS control of robotic vehicles requires information of their state, followed by a proper control action. For unmanned aerial vehicles (UAVs), extracting their translational velocity solely from the onboard sensing is still an open issue. Yet, the translational velocity is a key information for UAV control [1]. The most adopted sensing modalities for this purpose are GPS and vision. GPS relies on external source (satellites) for providing vehicle global position information, and as such, it does not operate in cluttered urban areas, is not reliable at low altitudes, suffers from satellite signal cuts, and is a nonpassive sensing modality [2], [3]. On the other hand, vision Manuscript

2015 23rd Mediterranean Conference on Control and Automation (MED), 2015

The design, modeling and control of a 5 degreesof-freedom lightweight robot manipulator is presen... more The design, modeling and control of a 5 degreesof-freedom lightweight robot manipulator is presented in this paper. The proposed robot arm, named Prisma Ultra-Lightweight 5 ARm (PUL5AR), is employed to execute manipulation tasks equipped on board of a vertical takeoff and landing unmanned aerial vehicle. The arm is compact and lightweight. Its mechanics is designed such that it can fold on itself during landing manoeuvres. Moreover, the design is conceived to constrain the center of gravity of the arm as close as possible to vehicle base, thus reducing the total inertia and static unbalancing of the system. Experimental tests have been carried out in order to validate the dynamic model, the communication library, the developed electronics, and the control schemes implemented for the designed robot arm.

IEEE Robotics and Automation Letters, 2018

Aerial manipulation aims at combining the versatility and the agility of some aerial platforms wi... more Aerial manipulation aims at combining the versatility and the agility of some aerial platforms with the manipulation capabilities of robotic arms. This letter tries to collect the results reached by the research community so far within the field of aerial manipulation, especially from the technological and control point of view. A brief literature review of general aerial robotics and space manipulation is carried out as well.

Proceedings of the 16th IFAC World Congress, 2005, 2005

2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013

In this paper an image-based visual-servoing control law for the coordinated landing of a VToL UA... more In this paper an image-based visual-servoing control law for the coordinated landing of a VToL UAV on an actuated landing platform is proposed. The landing platform is carried by a mobile manipulator composed of a mobile platform and a robotic arm. The UAV is endowed with a downward camera employed for the coordination of the landing manoeuvres. The presence of redundancy in the system at the task level, the intrinsic redundancy of the mobile manipulator, and the underactuation of the UAV are explicitly addressed into the proposed control law. The effectiveness of the proposed approach is tested though simulations.

2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), 2013

ABSTRACT This paper proposes two methods for UAV translational velocity estimation based on onboa... more ABSTRACT This paper proposes two methods for UAV translational velocity estimation based on onboard sensing only. Spherical image measurements provided by a single onboard camera along with IMU data consist the main information feeding the estimators. The first algorithm consists of a nonlinear observer, designed using Lyapunov synthesis, while the second is based on the Unscented Kalman filtering technique. Differently with respect to existing approaches, the velocity is directly estimated from the onboard image without the need to fully estimate the vehicle 3D pose. The low computational requirement makes the proposed techniques suitable for applications where the execution time is of prominent importance even if no powerful hardware is available, as it is the case with UAV systems. Experimental results validate the algorithms, and this with the use of only four image features.