Elisabetta Cataldi

Experimental validation of a new adaptive control scheme for quadrotors MAVs

In this paper, an adaptive trajectory tracking controller for quadrotor MAVs is presented. The controller exploits the common assumption of a faster orientation dynamics w.r.t. the translational one, and is able to asymptotically compensate for parametric uncertainties (e.g., displaced center of mass), as well as external disturbances (e.g., wind). The good performance of the proposed controller is then demonstrated by means of an extensive experimental evaluation performed with a commercially-available quadrotor MAV.

Recursive adaptive control for an underwater vehicle carrying a manipulator

The low level control for an underwater vehicle equipped with a manipulator is addressed in this paper. The end-effector trajectory is assumed to be properly inverted into vehicle and joint desired trajectories to be sent to the respective low level controllers. Off-the-shelf manipulators are often equipped with low level position or velocity joint control thus preventing the design of a controller at system level, i.e., taking into account the whole dynamic interactions. Design for the vehicle controller taking into account the presence of the manipulator is achieved resorting to an adaptive, recursive approach. A stability analysis is provided to analytically support the proposed controller. After physical considerations a minimal set of dynamic parameters is used in order to implement a light version of the controller. Numerical simulations validate the proposed approach.

Basic interaction operations for an underwater vehicle-manipulator system

In this paper an underwater vehicle-manipulator system is considered in order to accomplish two operations, namely to turn a valve and to push a button. Realistic assumptions, such as imperfect knowledge of the environment, have been considered with the purpose to design the proper interaction control scheme. In addition, due to the poor knowledge of the underwater dynamics, model-based approaches have been avoided. The UVMS is characterized by 13 Degrees-Of-Freedoms (DOFs) and a proper task-priority, inverse kinematics controller has been designed to take into account all the DOFs, however, this paper focuses on the interaction part. The redundancy exploitation is an ongoing activity being the interaction approach fully decoupled, and thus compatible, with the redundancy resolution scheme. The validation has been achieved resorting to a realistic mathematical model, including the main dynamic effects.

6D physical interaction with a fully actuated aerial robot

This paper presents the design, control, and experimental validation of a novel fully-actuated aerial robot for physically interactive tasks, named Tilt-Hex. We show how the Tilt-Hex, a tilted-propeller hexarotor is able to control the full pose (position and orientation independently) using a geometric control, and to exert a full-wrench (force and torque independently) with a rigidly attached end-effector using an admittance control paradigm. An outer loop control governs the desired admittance behavior and an inner loop based on geometric control ensures pose tracking. The interaction forces are estimated by a momentum based observer. Control and observation are made possible by a precise control and measurement of the speed of each propeller. An extensive experimental campaign shows that the Tilt-Hex is able to outperform the classical underactuated multi-rotors in terms of stability, accuracy and dexterity and represent one of the best choice at date for tasks requiring aerial physical interaction.

Experiments on coordinated motion of aerial robotic manipulators

In this paper a three layer control architecture for multiple aerial robotic manipulators is presented. The top layer, on the basis of the desired mission, determines the end-effector desired trajectory for each manipulator, while the middle layer is in charge of computing the motion references in order to track such end-effectors trajectories coming from the upper layer. Finally the bottom layer is a low level motion controller, which tracks the motion references. The overall mission is decomposed in a set of elementary behaviors which are combined together, through the Null Space-based Behavioral (NSB) approach, into more complex compounds behaviors. The proposed framework has been tested conducting an experimental campaign.

Underwater Intervention Robotics: An Outline of the Italian National Project MARIS

The Italian national project MARIS (Marine Robotics for InterventionS) pursues the strategic objective of studying, developing and integrating technologies and methodologies enabling the development of autonomous underwater robotic systems employable for intervention activities, which are becoming progressively more typical for the underwater offshore industry, for search-and-rescue operations, and for underwater scientific missions. Within such an ambitious objective, the project consortium also intends to demonstrate the achievable operational capabilities at a proof-of-concept level, by integrating the results with prototype experimental

Adaptive control of arm-equipped quadrotors. Theory and simulations

The paper presents an adaptive control for an aerial vehicle equipped with a manipulator, the latter is assumed to be already driven by a joint-based controller. The proposed control generates the vehicle thrusts by properly taking into account the physical interaction with the arm. Being adaptive, it estimates and then compensates the dynamics of the whole system. Moreover, the proposed approach is based on the Newton-Euler formulation, i.e., it is recursive. A stability analysis is provided to analytically support the developed controller. A reduced version is proposed to greatly simplify the controller by taking into account only the gravitational terms. Numerical simulations confirm the controller performance as compared with the effort and error of a benchmark controller.

Advanced ROV Autonomy for Efficient Remote Control in the DexROV Project

In this paper, we present DexROV, a funded EC Horizon 2020 project that proposes to implement novel operation strategies for underwater semi-autonomous interventions. These costly and demanding operations are more and more often performed by ROVs (Remotely Operated Vehicles), contributing to risks cutting for human divers. However ROV operations require offshore structures, hosted on a support vessel with a crew of a significant amount of personnel necessary to properly handle and operate the robotic platform. One of the key goals of DexROV is to delocalize on-shore the manned support as much as possible, reducing the crew onboard the support vessel and consequently the whole operation costs and risks. The Control Center is located onshore, far away from the actual operation location. Operators interact with the ROV through a simulation environment that exploit 3D models of the environment built online relying on the perception and modeling capabilities of the robotic system and transmitted via satellite communication. Currently ROVs lack the dexterous capabilities needed to perform many kind of operations, for which human divers are still necessary. DexROV addresses this problem, equipping the ROV with two 6 DoF (Degrees of Freedom) dexterous manipulators with anthropomorphic end-effectors and providing semi-autonomous capabilities. The control will rely on a multi-task priority approach that will help the operator to focus on the main operation, leaving the low-level tasks to be autonomously performed by the ROV.

Impedance Control of an aerial-manipulator: Preliminary results

In this paper, an impedance control scheme for aerial robotic manipulators is proposed, with the aim of reducing the end-effector interaction forces with the environment. The proposed control has a multi-level architecture, in detail the outer loop is composed by a trajectory generator and an impedance filter that modifies the trajectory to achieve a complaint behaviour in the end-effector space; a middle loop is used to generate the joint space variables through an inverse kinematic algorithm; finally the inner loop is aimed at ensuring the motion tracking. The proposed control architecture has been experimentally tested.

Adaptive Trajectory Tracking for Quadrotor MAVs in Presence of Parameter Uncertainties and External Disturbances

This paper presents an adaptive trajectory tracking control strategy for quadrotor micro aerial vehicles (MAVs). The proposed approach, while maintaining the common assumption of an orientation dynamics faster than the translational one, removes the assumption of absence of external disturbances and of geometric center coincident with the Center of Mass (CoM). In particular, the trajectory tracking control law is made adaptive with respect to the presence of external forces and moments (e.g., due to wind) and to the uncertainty of parameters of the dynamic model, such as the position of the CoM. A stability analysis is presented to analytically support the proposed controller, while numerical simulations are provided in order to validate its performance.