Showing papers by "Rogelio Lozano published in 2017"
TL;DR: This article deals with the design and real-time implementation of three second order sliding mode controllers for the altitude tracking of a quadrotor aircraft and Lyapunov stability theory is used to prove convergence in finite time of the altitude tracker error.
113 citations
TL;DR: A mathematical model and a control strategy for a special class of underactuated mechanical systems, composed of a quadrotor transporting a cable-suspended payload, and an Interconnection and Damping Assignment-Passivity Based Control (IDA-PBC) is proposed.
Abstract: This paper presents the problem of safe and fast transportation of packages by an Unmanned Aerial Vehicle (UAV) kind quadrotor. A mathematical model and a control strategy for a special class of underactuated mechanical systems, composed of a quadrotor transporting a cable-suspended payload, are proposed. The Euler-Lagrange formulation is used to obtain the dynamic model of the system, where the integrated dynamics of the quadrotor, cable and payload are considered. An Interconnection and Damping Assignment-Passivity Based Control (IDA-PBC) is chosen because of its inherent robustness against parametric uncertainty and unmodeled dynamics. Two cases are considered to obtain two different control laws, in the first case, the designed control law depends on the swing angle of the payload, in the second case the control law does not depend on it. The control objective is to transport the payload from point to point, with swing reduction along trajectory. Experimental results using monocular vision based navigation are shown to evaluate the proposed control law.
89 citations
TL;DR: In this article, two nonlinear controllers based on saturation functions with varying parameters were used for set point regulation and trajectory tracking on an underwater vehicle, which combines the advantages of robust control and easy tuning in real applications.
44 citations
TL;DR: Dual quaternions are proposed as an alternative to the classical Euler angles approach for the kinematic and dynamic modeling for an aerial manipulator based on a quad-rotor vehicle provided with a robotic arm.
Abstract: This contribution presents a modeling technique for an aerial manipulator based on a quad-rotor vehicle provided with a robotic arm. Dual quaternions, which are a little explored but powerful mathematical tool, are proposed as an alternative to the classical Euler angles approach for the kinematic and dynamic modeling. A feedback control law based on dual quaternions is used to validate the proposed model, taking into account the external effects of the robotic limb. Numerical simulations and experiments validate the proposal, opening a path for future research.
38 citations
TL;DR: A disturbance observer is proposed, a sliding mode control was proposed, the gain of control can be decreased and, as a result, the chattering amplitude is reduced and simulation and experimental results are presented to show the effectiveness of the proposed nonlinear algorithm in presence of external disturbances.
Abstract: This paper addresses the problem of designing and experimentally validating a nonlinear robust control to attitude and altitude of a quadrotor unmanned flying vehicle (UAV). First a disturbance observer is proposed, focus on the attitude regulation control problem of a quadrotor in presence of external disturbances based on the angular velocity measurements and the control inputs. The stability analysis of the nonlinear observer scheme is proven via the use of Lyapunov theory. Later, we focus on the altitude dynamics of a quadrotor in the presence of uncertainty like wind gust are presented. A sliding mode control was proposed, the gain of control can be decreased and, as a result, the chattering amplitude is reduced. The objective is to introduce an adaptation in the control law in order to decrease the gain to the minimal value preserving the sliding mode control and keeping his property of a finite-time convergence. Finally, simulation and experimental results in a quadrotor are presented to show the effectiveness of the proposed nonlinear algorithm in presence of external disturbances.
25 citations
TL;DR: In this article, the authors modified the PD control to only use the orientations of the end effector to generate the desired joint angles to avoid the inverse kinematics of the robot.
19 citations
TL;DR: The designs, simulations and real-time experimental results of two energy-based control strategies to stabilize an Unmanned Aerial Vehicles (UAV) using a quaternion representation of the attitude using a logarithmic mapping in the quaternions space are presented.
Abstract: This article presents the designs, simulations and real-time experimental results of two energy-based control strategies to stabilize an Unmanned Aerial Vehicles (UAV) using a quaternion representation of the attitude. The mathematical model is based on Euler-Lagrange formulation using a logarithmic mapping in the quaternion space. The proposed solutions introduce a new approach: a quaternion-energy-based control, which use an energy-based expression defined as a Lyapunov function. The control laws are described with unit quaternions and their axis-angle representation. The proposed algorithms allow the stabilization of the quadrotor in all its states. The strategies ensure the stability of the closed loop system. Simulation results and experimental validations are developed to verify the effectiveness of the proposed controllers.
15 citations
TL;DR: In this article, a Lyapunov-based kinematic controller for outer loop can steer the UAV asymptotically to approach the desired path, under the assumption that the autopilot is well tuned and the airspeed, fightpath angle, and bank angle states converge to the desired response to their commanded values.
13 citations
13 Jun 2017
TL;DR: In this article, a mathematical model for a convertible UAV that combines the capabilities of a flying wing and tricopter with tilt rotors is presented, as well as a control strategy to hover flying.
Abstract: The aim of this paper is to provide a mathematical model for a convertible unmanned aerial vehicle that combines the capabilities of a flying wing and tricopter with tilt rotors. This article presents the mathematical model for airplane and tricopter modes as well as the way they are related during the transition phase. Also is presented a control strategy to hover flying. Finally, it is presented simulation results of tricopter mathematical model under controls developed.
10 citations
TL;DR: An enhanced robust altitude control scheme that indicates the improved performance than the typical sliding mode technique for a Quad-rotor aircraft vehicle is proposed by including an integral action in the sliding mode control architecture in order to eliminate the steady-state error induced by the boundary layer and achieving asymptotic convergence to the desired altitude with continuous control input.
Abstract: An enhanced robust altitude control scheme that indicates the improved performance than the typical sliding mode technique for a Quad-rotor aircraft vehicle is proposed in this article by including an integral action in the sliding mode control architecture in order to eliminate the steady-state error induced by the boundary layer and achieving asymptotic convergence to the desired altitude with continuous control input. The proposed integral sliding mode controller is chosen to ensure the stability and robustness of overall dynamics during the altitude control at a desired height reference on the z-axis. Furthermore, we propose a Control Lyapunov Function (CLF) via Lyapunov theory in order to construct the robust stabilizing controller and demonstrate the stability of the z-dynamics of our system. A suitable sliding manifold is designed to achieve the control objective. At last, the simulations and experimental studies are supported by different tests to demonstrate the robustness and effectiveness of the proposed enhanced robust altiutde control scheme subject to bounded external disturbances in outdoor environment.
10 citations
TL;DR: In this article, the authors proposed a robust nonlinear controller to stabilize an underwater robot, which is based on the backstepping technique with adaptive and integral properties and proved the stability analysis using Lyapunov functions.
13 Jun 2017
TL;DR: In this paper, a real-time trajectory-tracking strategy based on super-twisting control using GPS measurements in order to obtain the horizontal position to accomplish the desired trajectory is proposed.
Abstract: This article addresses the trajectory-tracking problem for a miniature Quadrotor aircraft system using a super-twisting technique in real-time application. This strategy ensures the convergence in finite time to a desired programmed trajectory under bounded external perturbations such as wind gusts. The proposed solution consists of implementing a real-time strategy based on super-twisting control using GPS measurements in order to obtain the horizontal position to accomplish the desired trajectory. A Lyapunov theory is used in order to demonstrate the stability of the system in finite time. Simulation results and experimental autonomous trajectory-tracking flight are presented to evaluate the corresponding efficiency of the proposed control algorithm under external disturbances affecting the aerial vehicle.
01 Jun 2017
TL;DR: In this article, a modified super-twisting controller with a high-order sliding mode observer is used to track a UAV under the assumption that its translational velocities are unavailable and there are unmodeled dynamics and external disturbances.
Abstract: This article deals with the design of a novel algorithm that combines a Modified Super-Twisting Controller with a High Order Sliding Mode Observer to enable an aerial vehicle to track a trajectory under the assumption that i) its translational velocities are unavailable and ii) there are unmodeled dynamics and external disturbances. We present a mathematical justification that ensures the existence of a second-order sliding motion for the combination Controller- Observer. In order to demonstrate the effectiveness of the proposed solutions, a set of simulation results are presented.
25 Jul 2017
TL;DR: In this paper, an automatic controller that solves the attitude stabilization for a quadrotor unmanned aerial system (UAS) was developed. But the controller used a simultaneous strategy of estimation and compensation of uncertainties as well as disturbances.
Abstract: This paper deals with developing an automatic controller that solves the attitude stabilization for a Quadrotor unmanned aerial system (UAS). The controller used a simultaneous strategy of estimation and compensation of uncertainties as well as disturbances. The approach consisted of integrating a neuro-fuzzy system that implemented a set of differential neural networks (DNNs) as consequence section of Takagi-Sugeno (T-S) fuzzy inference. The combination of these two strategies applied on a Quadrotor UAS has the main purpose of forcing a hover flight while the tracking desired angular positions are attained. The control method identified the unknown nonlinearities and bounded external disturbances firstly. This information served to compensate the uncertain section of the Quadrotor dynamics. An additional section in the controller design enforces the stabilization of the tracking error with respect to a given reference trajectory. The control design methodology supported on the Lyapunov stability theory and guaranteed ultimate boundedness of the identification and tracking errors. Academic simulation tests confirmed the superior performance of the proposed algorithm based on the combination of DNNs and T-S techniques.
01 Jun 2017
TL;DR: A quadcopter capable of tracking a human face using an embedded system which consists of an autopilot for controlling the vehicle and an Odroid computer for image processing is presented.
Abstract: This paper presents a quadcopter capable of tracking a human face using an embedded system which consists of an autopilot for controlling the vehicle and an Odroid computer for image processing. Image acquisition is performed by a fisheye monocular camera. A digital treatment consisting of a Gaussian filter and a histogram equalization is applied, reducing false positives in the detection algorithm. The detection algorithm used is a cascade classifier (Haar algorithm), which is trained to detect a human face in an image. Depending on the displacement of the detected face, a Kalman filter is implemented to estimate the position and velocity which are used to follow the person.
13 Jun 2017
TL;DR: In this article, an adaptive PD control law by using a modified MIT rule was presented, where the adjustment mechanism of the MIT rule has been implemented with three types of sliding-mode control, i.e., classical sliding mode control, second order sliding mode (2-SM), and high order slidingmode control (HOSM).
Abstract: This paper presents an adaptive PD control law by using a modified MIT rule. The adjustment mechanism of the MIT rule has been implemented with three types of sliding-mode control, i.e., classical sliding-mode control, second order sliding-mode (2-SM), and high order sliding-mode control (HOSM). The proposed controllers have been designed for the directional and lateral dynamics of a fixed-wing mini aerial autonomous vehicle (MAV). Several simulations have been carried out in order to analyze the modified MIT rule.
01 Jun 2017
TL;DR: In this article, a control strategy for two planar vertical take-off and landing (PVTOL) vehicles cooperating to transport a rigid body load without any explicit exchange of state information between them is presented.
Abstract: This paper presents a control strategy for two planar vertical take-off and landing (PVTOL) vehicles cooperating to transport a rigid body load without any explicit exchange of state information between them. This means that the vehicles have only access to their own state variables. The solution and stability analysis is based on a passivity approach.
01 May 2017
13 Jun 2017
TL;DR: In this work, a positioning task for a platoon of six aerial robots is guided by the MLCS methodology, where the robots are clustered in a set of triangular formations and each triangle is controlled for reaching its desired goal.
Abstract: In robotics, the navigation problem can be split in planning, execution, checking and correction. An approach to deal with these tasks is based on the Multi-Layer Control scheme (MLCS). In this technique, each layer is responsible for an individual step of the formation control problem, such as; to define and optimize the desired robot pose; to avoid or minimize collision risks; to control the robots for accomplishing the formation, and so on. In this work, a positioning task for a platoon of six aerial robots is guided by the MLCS methodology. The procedure is developed as follows: first, the off-line planning layer organizes the desired formation according to the current robot position; then, the robots are clustered in a set of triangular formations; and finally, each triangle is controlled for reaching its desired goal. Simulation results illustrate and validate the proposal.
01 Oct 2017
TL;DR: A guidance law for tracking straight-line segment and a constant-altitude circular orbits are proposed for a fixed wing unmanned aerial vehicle (UAV) based on the notion of vector fields, which are used to generate desired commands to the inner-loop attitude controller.
Abstract: In this paper, a guidance law for tracking straight-line segment and a constant-altitude circular orbits are proposed for a fixed wing unmanned aerial vehicle (UAV). Both guidance laws are based on the notion of vector fields, which are used to generate desired commands to the inner-loop attitude controller. Ground track heading error and lateral following error approach zero asymptotically even in an environment with presence of constant wind disturbance. Finally we use the MAV3DSim to validate the develop guidance laws using hardware in the loop simulation.
14 May 2017
TL;DR: The main idea is assist a professional physiotherapist in the design and performance of exercises routines for his patients using the prototype of an exoskeleton for knee and ankle.
Abstract: The Exoskeleton for Lower Limb Training with Instrumented Orthosis (ELLTIO) is a mechatronic device that can be used to assist in passive kinesitherapy to increase human muscles strength and resistance (1). This paper presents an alternative for passive rehabilitation process using an exoskeleton for knee and ankle. The main idea is assist a professional physiotherapist in the design and performance of exercises routines for his patients using the prototype. The knee and ankle joint's movements are recorded and storage during the exercises to propose a similar computer generated trajectories which the exoskeleton on should follow. An adaptive controller is implemented to track the trajectories and adapt the user parameters.
01 Jun 2017
TL;DR: In this article, a reduction-based controller is proposed to stabilize a quad rotor-UAV in presence of time-delay and disturbances, which is based on the reduction approach, i.e., the system transformation into one without delay which might be stabilized using a regular controller.
Abstract: This works deals with the problem to stabilize a Quad rotor-UAV in presence of time-delay and disturbances. The proposed controller is based on the reduction approach, i.e. the system transformation into one without delay which might be stabilized using a regular controller. Mathematical induction method allows to develop a new transformation based on the fundamental theorem of calculus. A closed-loop stability analysis based on Lyapunov theory is address to prove the feasibility of the controller. The proposed technique is applied to an experimental platform with 4 DOF (degrees of freedom) specifically designed to bring a secure and easy way to tune and test experimental controllers.
01 Jun 2017
TL;DR: A novel autonomous take-off and landing approach which uses a discrete-time finite-horizon suboptimal nonlinear control strategy to achieve a smooth landing on specific colored platform by color-based tracking.
Abstract: This paper presents a novel autonomous take-off and landing approach which uses a discrete-time finite-horizon suboptimal nonlinear control strategy to achieve a smooth landing on specific colored platform. By color-based tracking we can improve the performance of the position landing by correcting the position given by the GPS. The signal of the GPS is not always reliable since the accuracy strongly depends on the environment situation and the correction by vision servoing is then necessary. Experimental results using the proposed approach show a better performance than those where the GPS signal is only used to perform the take-off and landing tasks in a completely autonomous way in presence of wind gusts.
01 Jun 2017
TL;DR: An advanced control is proposed which is based on quaternion representation and self-adapts to the characteristics of the payload it stabilises and may help to construct more polyvalent and efficient gimbals which would further facilitate their expansion.
Abstract: Inertial Stabilised Platform, better known as gimbal are becoming increasingly popular, with a large range of products now available in mainstream shops. Most of these items are nonetheless controlled using very basic algorithms that do not offer best achievable performances. First, each axis is controlled independently of one another. Then, they make use of trigonometry for their calculation. Lastly, their behaviour depends on the type of payload or on the orientation of this latter. Present paper proposes an advanced control which aims at solving these classic control issues without requiring as much computational power. It is based on quaternion representation and self-adapts to the characteristics of the payload it stabilises. Although only simulation could be performed to check the performances of such control, results look very promising and may help to construct more polyvalent and efficient gimbals which would further facilitate their expansion.
03 Oct 2017
TL;DR: An experiment to test the existence of mental workload (MWL) and adaptability of a human operator (HO) in handling force augmenting devices (FADs) and it can be observed that HO undergoes MWL to handle a FAD with high augmentation factor.
Abstract: This short communication article presents an experiment to test the existence of mental workload (MWL) and adaptability of a human operator (HO) in handling force augmenting devices (FADs). An experiment is conducted where the HOs of three different ages are allowed to handle a FAD with high augmentation factor. Augmentation factor gives the factor by which the HO’s force is amplified. It is observed that the HOs were unable to stabilize the FAD for the first time. With the help of these experiments, it is observed that a human adapts itself to achieve a stable HA-FAD interaction. In another perspective, it can be observed that HO undergoes MWL to handle a FAD with high augmentation factor.
01 Jun 2017
TL;DR: In this paper, the attitude and angular velocity from a nine degrees of freedom (DoF) inertial measurement unit (IMU) were obtained using a Kalman Filter (KF).
Abstract: This paper presents a theoretical and practical implementation of a Kalman Filter (KF) to obtain the attitude and angular velocity from a nine degrees of freedom (DoF) inertial measurement unit (IMU). These include three DoF from an accelerometer, three from a magnetometer and the last three from a gyroscope. It differs from other attitude filters in two main aspects, the model representation and how the information is acquired from the IMU. The quaternion model presented has an analogous linear representation that can be used, in conjunction with the the an algorithm that is presented in order to extract the attitude information from the IMU, leading to a considerable lower computational cost in order to avoid the calculation of Jacobians matrices or gradients.
01 Jun 2017
TL;DR: In this article, a Generalized Proportional Integral (GPI) controller is synthesized in order to stabilize both attitude and position of a four rotor mini helicopter in real-time flight.
Abstract: In this paper a Generalized Proportional Integral controller is synthesized in order to stabilize both attitude and position a four rotor mini helicopter. The main idea to use this kind of controller is to avoid the use of derivative terms and asymptotic observers in the design of the control law and consequently their respective numeric algorithms for the real-time implementation. So, these asymptotic observers and derivative terms are replaced by integral state reconstructor. The synthesized GPI control law is tested by numerical simulation considering a quadrotor dynamical model obtained by Euler-Lagrange formalism and obtained results are satisfactory and they suggest that the synthesized GPI control law can be tested in real-time flights.