Francesco Maria Raimondi

A new fuzzy robust dynamic controller for autonomous vehicles with nonholonomic constraints

Abstract In this paper a novel algorithm with a dynamic fuzzy controller applied to the control of trajectory of vehicles with two independent wheels is proposed. An automatic control of trajectory of a vehicle can behave in a not efficient way. It is necessary to consider the friction of the actuators and possible perturbations coming from the outside environment, as for instance the variable characteristics of the ground where the vehicle moves. These perturbations, which depend also on the contact between the wheel and the ground, involve violations of nonholonomic constraints. Thus it is necessary to compensate for these perturbations to obtain a robust control system. The controller synthetized in this work is able to obtain a term of additive adaptation to the dynamic control law by means of a fuzzy inference mechanism. Asymptotic stability of equilibrium state of fuzzy control system is developed by the Direct Lyapunov method and Barbalats lemma. A series of simulations in Matlab 6.5 confirms the validity of the algorithm.

The treatment of venous leg ulcers - A new therapeutic use of Iloprost

Background:We conducted a study using an intravenous (i.v.) infusion of iloprost in the treatment of venous ulcers to verify whether the association of i.v. iloprost + local therapy + elastic compression has a favorable effect when compared with traditional treatment with local therapy and elastic compression. Study Design:We evaluated the effects of iloprost in 98 consecutive patients with noncomplicated venous ulcers of lower limbs subdivided into 2 groups: the first group (48 patients) received iloprost in saline solution for 3 weeks and the second group (50 patients) received a venous infusion of a saline solution. The patients were examined at baseline time 0 (first visit) and then after 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 days. Results:In the first group, after 90 days, all the ulcers had healed, whereas in the second group only 50% of ulcers had healed after 105 days. At the end of the study, in the second group only 84.09% of ulcers had healed. The statistical analysis showed a significant difference between the first (iloprost group) and the second group (placebo group). Besides, in the first group the cicatrization of the ulcer happened in a shorter period (27.90% after 60 days; 41.86% after 75 days; and 100% after 100 days) whereas in the second group, at the end of the study, in 15.91% of patients the ulcers had not recovered. Conclusion:Iloprost can significantly reduce healing time for venous leg ulcers through several actions.

Optimal Duration of Treatment in Surgical Patients With Calf Venous Thrombosis Involving One or More Veins

The aim of this study was to evaluate different durations of treatment in patients with calf venous thrombosis (CVT) involving 1 or more deep veins. The authors studied 2 groups of patients with postsurgical CVT diagnosed by echo-color Doppler. The first group consisted of 68 patients with CVT involving a single vein, and the second group consisted of 124 patients with CVT involving 2 or more veins. Immediately after diagnosis, all patients were treated with nadroparin calcium and sodium warfarin. Heparin treatment was withdrawn after 5–6 days of treatment, when the international normalized ratio (INR) was stabilized between 2 and 3. Each group was divided into 2 subgroups receiving anticoagulation treatment for 6 or 12 weeks, respectively. The endpoint was proximal extension of the thrombotic lesion, defined as the extension of the thrombus to the popliteal and/or femoral vein. In patients with single-vessel CVT there was no significant difference between the 2 subgroups, whereas in patients with CVT involving 2 or more vessels, a statistically significant difference was observed, the number of cases showing proximal extension of the thrombus being higher among patients treated for 6 weeks. Twelve weeks of anticoagulation treatment is better than 6 weeks only in patients with postsurgical CVT involving 2 or more veins.

Fuzzy motion control strategy for cooperation of multiple automated vehicles with passengers comfort

This paper considers motion control for a cooperative system of automated passenger vehicles. It develops a cooperative scheme based on a decentralized planning algorithm which considers the vehicles in an initial open chain configuration. In this scheme the trajectories are intersections-free, and each trajectory is planned independently of the others. To ensure the stabilization of each vehicle in the planned trajectory, a fuzzy closed loop motion control is presented, where, based on the properties of the Fuzzy maps, the Lyapunovs stability of the motion errors is demonstrated for all the vehicles. Based on the ISO 2631-1 standard, the saturation property of the Fuzzy maps guarantees low values of longitudinal and lateral accelerations, to ensure comfort of the human body during the motion. The validity of this control algorithm is supported by simulation experiments.

A new kinematic and dynamic direct adaptive fuzzy control of constrained mobile wheeled vehicles

In this paper a new kinematic and dynamic adaptive fuzzy control is applied to a trajectory tracking problem of a constrained vehicle with two independent wheels. The vehicle dynamics and kinematics are completely unknown. A dynamical and kinematical adaptive control provide to on line estimation of the dynamic and kinematic parameters of the vehicle model. Moreover the parameters of the kinematic control law are obtained using a fuzzy controller and they are time varying and dependent on tracking errors. The stability of the kinematic and dynamic adaptive fuzzy control system and the convergence of tracking errors to zero are proved using Lyapunovs method and Barbalats lemma. The effectiveness and efficiency of the proposed controller are demonstrated through simulation studies

Hierarchical fuzzy/Lyapunov control for horizontal plane trajectory tracking of underactuated AUV

A new hierarchical closed loop fuzzy control system for horizontal plane trajectory tracking of underactuated Autonomous Underwater Vehicles (AUV) is presented. A model for the AUV is formulated introducing a polar coordinates transformation for the velocities in the body fixed frame. It is employed to control the unactuated sway direction, the longitudinal position and the yaw by using the surge force and the yaw torque only. The highest level control is developed by employing a fuzzy inference system for obtaining the guidance control laws. The properties of the fuzzy system ensure forward surge velocity, fast convergence and Lyapunovs stability of the motion errors. A new low level kinetic controller is presented for ensuring that the actual velocities of the AUV converge to the fuzzy guidance control laws. The control algorithm efficiency is confirmed through simulation experiments in a Matlab environment.

Fuzzy/Kalman Hierarchical Horizontal Motion Control of Underactuated ROVs

A new closed loop fuzzy motion control system including on-line Kalmans filter (KF) for the two dimensional motion of underactuated and underwater Remotely Operated Vehicle (ROV) is presented. Since the sway force is unactuated, new continuous and discrete time models are developed using a polar transformation. A new hierarchical control architecture is developed, where the high level fuzzy guidance controller generates the surge speed and the yaw rate needed to achieve the objective of planar motion, while the low level controller gives the thruster surge force and the yaw torque control signals. The Fuzzy controller ensures robustness with respect to uncertainties due to the marine environment, forward surge speed and saturation of the control signals. Also Lyapunovs stability of the motion errors is proved based on the properties of the fuzzy maps. If Inertial Measurement Unit data (IMU) is employed for the feedback directly, aleatory noises due to accelerometers and gyros damage the performances of the motion control. These noises denote a kind of non parametric uncertainty which perturbs the model of the ROV. Therefore a KF is inserted in the feedback of the control system to compensate for the above uncertainties and estimate the feedback signals with more precision.

Trajectory decentralized fuzzy control of multiple UAVs

This paper considers a complete position and heading rate control system for multiple unmanned aerial vehicles (UAVs) with constant altitude. A decentralized trajectory planning algorithm is proposed, where the UAVs will avoid collisions while moving. In order to stabilize the UAVs in the reference planned trajectories and ensure the boundedness of the control velocities, a fuzzy control law is proposed with Lyapunovs stability proof. Simulation experiments developed in Matlab environment confirm the effectiveness and the robustness of the proposed control algorithm with respect to possible turbulence disturbances perturbing the nominal motion of the UAVs.

Fuzzy EKF Control for Wheeled Nonholonomic Vehicles

In this paper a new fuzzy extended Kalman robust control system for position and orientation tracking of nonholonomic vehicles with two wheels actuated by two independent DC motors is presented. The problem of robustness and localization are solved simultaneously. About the robustness, some perturbations coming from the outside environment and depending on the contact between the wheels and the ground, involve violations of the nonholonomic constraints. The fuzzy controller of this work is able to obtain a dynamic term of robustness with respect to the perturbations above. However, by using encoders only, the measures of actual position and orientation of the vehicle are with Gaussian noises. Therefore, before the feedback, we use a discrete time extended Kalman filter (EKF), to obtain on-line estimates of the filtered state from the observations of the noised outputs provided from more odometric sensors. Simulations with Matlab 7.0 software confirm the goodness of the proposed control system

A Magnetostrictive Electric Power Generator for Energy Harvesting From Traffic: Design and Experimental Verification

In this paper, we propose an approach to the design of a magnetostrictive electric power generator for energy harvesting from traffic, and we validate it experimentally. We use the dynamic Preisach hysteresis model (DPM) for magnetostrictive materials, operating in hysteretic and time-varying nonlinear regimes to design and simulate a magnetostrictive electrical power generator. The DPM is a development of the classical Preisach model, which is able to include the dynamical features in the mathematical model of hysteresis. We measure the output power capability of the generator, and we show how it is comparable to other energy-harvesting technologies.