Isabelle Fantoni

Energy based control of the Pendubot

This paper presents the control of an underactuated two-link robot called the Pendubot. We propose a controller for swinging the linkage and raise it to its uppermost unstable equilibrium position. The balancing control is based on an energy approach and the passivity properties of the system.

Non-Linear Control for Underactuated Mechanical Systems

From the Publisher: This book deals with the application of modern control theory to some important underactuated mechanical systems. It presents modelling and control of the following systems:||- the inverted pendulum||- a convey-crane system||- the pendubot system||- the Furuta pendulum||- the inertia wheel pendulum||- the planar flexible-joint robot||- the planar manipulator with two prismatic and one revolute joints||- the ball & beam system||- the hovercraft model||- the planar vertical and take-off landing (PVTOL) aircraft||- the helicopter model on a platform||- the helicopter model||In every case the model is obtained in detail using either the Euler-Lagrange formulation or the Newtons second law. We develop control algorithms for every particular system using techniques such as passivity, energy-based Lyapunov functions, forwarding, backstepping or feedback linearization techniques.||This book will be of great value for PhD students and researchers in the areas of non-linear control systems.

Optic flow-based vision system for autonomous 3D localization and control of small aerial vehicles

The problem considered in this paper involves the design of a vision-based autopilot for small and micro Unmanned Aerial Vehicles (UAVs). The proposed autopilot is based on an optic flow-based vision system for autonomous localization and scene mapping, and a nonlinear control system for flight control and guidance. This paper focusses on the development of a real-time 3D vision algorithm for estimating optic flow, aircraft self-motion and depth map, using a low-resolution onboard camera and a low-cost Inertial Measurement Unit (IMU). Our implementation is based on 3 Nested Kalman Filters (3NKF) and results in an efficient and robust estimation process. The vision and control algorithms have been implemented on a quadrotor UAV, and demonstrated in real-time flight tests. Experimental results show that the proposed vision-based autopilot enabled a small rotorcraft to achieve fully-autonomous flight using information extracted from optic flow.

Stabilization of the inverted pendulum around its homoclinic orbit

The inverted pendulum has been used as a benchmark for motivating the study of nonlinear control techniques. We propose a simple controller for balancing the inverted pendulum and raise it to its upper equilibrium position while the cart displacement is brought to zero. The control strategy is based on an energy approach of the cart and pendulum system.

Global stabilization of a PVTOL aircraft model with bounded inputs

We propose a global stabilizing control design for the planar vertical takeoff and landing (PVTOL) aircraft, with bounded inputs. The approach is based on the use of non-linear combinations of linear saturation functions bounding the thrust input and the rolling moment to arbitrary saturation limits. We provide global convergence of the state to the origin, using a relatively simple algorithm.

Stabilization of a nonlinear underactuated hovercraft

We consider the control of a hovercraft having only two control inputs with three degrees of freedom. The model is obtained from equations of a simplified ship which is nonlinear and underactuated. Using a co-ordinate transformation the model is given by polynomial equations which describe its kinematics and dynamics. Two control laws are proposed. The first one controls the velocity of the hovercraft. The other one stabilizes both its position and the (underactuated) side velocity and provides global convergence to the origin. The convergence analysis is based on a Lyapunov approach. Copyright

Modeling and control of a small autonomous aircraft having two tilting rotors

This paper presents recent work concerning a small tiltrotor aircraft with a reduced number of rotors. After several attempts, the final design consists of two propellers mounted laterally. The direction of the thrust can be redirected by tilting the propellers laterally and longitudinally. A theoretical analysis of this mechanism proves its effectiveness and the experimental results show that this aerodynamical configuration is very promising. A model of the full birotor dynamics is also presented in this paper and a controller based on the backstepping procedure is synthesized performing also an autonomous flight.

Stabilization of the Furuta pendulum around its homoclinic orbit

We present an energy based control approach to control the Furuta pendulum. A controller is proposed for swinging the pendulum and raise it to its uppermost unstable equilibrium position. The passivity properties of the system are used as a guideline in the control strategy. The stability analysis is carried out by using a Lyapunov technique.

An adaptive vision-based autopilot for mini flying machines guidance, navigation and control

The design of reliable navigation and control systems for Unmanned Aerial Vehicles (UAVs) based only on visual cues and inertial data has many unsolved challenging problems, ranging from hardware and software development to pure control-theoretical issues. This paper addresses these issues by developing and implementing an adaptive vision-based autopilot for navigation and control of small and mini rotorcraft UAVs. The proposed autopilot includes a Visual Odometer (VO) for navigation in GPS-denied environments and a nonlinear control system for flight control and target tracking. The VO estimates the rotorcraft ego-motion by identifying and tracking visual features in the environment, using a single camera mounted on-board the vehicle. The VO has been augmented by an adaptive mechanism that fuses optic flow and inertial measurements to determine the range and to recover the 3D position and velocity of the vehicle. The adaptive VO pose estimates are then exploited by a nonlinear hierarchical controller for achieving various navigational tasks such as take-off, landing, hovering, trajectory tracking, target tracking, etc. Furthermore, the asymptotic stability of the entire closed-loop system has been established using systems in cascade and adaptive control theories. Experimental flight test data over various ranges of the flight envelope illustrate that the proposed vision-based autopilot performs well and allows a mini rotorcraft UAV to achieve autonomously advanced flight behaviours by using vision.

Modeling and Control of a Small Autonomous Aircraft Having Two Tilting Rotors

This paper presents recent work concerning a small tiltrotor aircraft with a reduced number of rotors. The design consists of two propellers which can tilt laterally and longitudinally. A model of the full birotor dynamics is provided, and a controller based on the backstepping procedure is synthesized for the purposes of stabilization and trajectory tracking. The proposed control strategy has been tested in simulation