Showing papers presented at "Mediterranean Conference on Control and Automation in 2014"

Visual servoing of a Quadrotor UAV for autonomous power lines inspection

Abstract: The objective of this work is to achieve real time tracking of power conductors using a Quadrotor Unmanned Air Vehicle (UAV). Two solutions are proposed. For the first solution, the control is directly solved in the 2D image space. The link between image features and the kinematics of the vehicle is achieved using an Image Based Visual Servoing (IBVS) formulation, combined with a Linear Quadratic Servo (LQ-Servo) approach. In the second solution, a partial pose of the vehicle with respect to (wrt) the lines is estimated. Then, a position controller designed in the Cartesian space is used to drive the vehicle to the desired configuration. Experimental results are provided to validate the two approaches.

A remote guidance system for blind and visually impaired people via vibrotactile haptic feedback

Abstract: Trained guide dogs and canes provide the visually impaired with the highest degree of independence; however, they are very limited in guiding the user towards a specific desired location, especially in an unknown environment. The assistance of other people represents a feasible solution, but it does not improve the idea of autonomous guidance and privacy. In this paper we present a remote guidance system which provides the visually impaired with haptic directional cues, useful for navigating in unknown environments. The blind user is equipped with a pair of camera glasses, two vibrotactile bracelets and a cane which is used to avoid potential obstacles. The video captured by the camera glasses is streamed to a remote operator who can properly navigate the impaired person by activating the vibrotactile stimulations. The proposed approach has been validated on a group of blind subjects in an indoor scenario. Results revealed the effectiveness of the proposed strategy for the guidance of visually impaired in unknown environments.

The power-tethered UAV-UGV team: A collaborative strategy for navigation in partially-mapped environments

Abstract: This paper presents the concept of an unmanned robotic team, consisting of an aerial and a ground vehicle, and a power-tethering physical link between them, and proposes a strategy that addresses their collaborative navigation problem. The purpose of such a team is to exploit the technical advantages of differentiated unmanned vehicle classes in an approach that benefits the global navigation objective, but with each agent also directly benefiting from the capabilities of the other at an operational level. This conceptual team aims to address the challenge of prolonged autonomous navigation within environments, for which a limited amount of information is available prior to deployment. To this end, the team works its way through the map, while incrementally exploring and rebuilding the actual environment structure, relying on sampling-based trajectory planning techniques and a 2×2-Dimensional decomposed manifold model of its workspace. A challenging environment model is formulated for simulation purposes of the proposed approach, and the respective results are provided.

Embedded Model Predictive Control on a PLC using a primal-dual first-order method for a subsea separation process

Abstract: The results of a PLC implementation of embedded Model Predictive Control (MPC) for an industrial problem are presented in this paper. The embedded MPC developed is based on the linear MPC module in SEPTIC (Statoil Estimation and Prediction Tool for Identification and Control), and it combines custom ANSI C code generation with problem size reduction methods, embedded real-time considerations, and a primal-dual first-order method that provides a fast and light QP solver obtained from the FiOrdOs code generator toolbox. Since the primal-dual first-order method proposed in this paper is new in the control community, an extensive comparison study with other state-of-the-art first-order methods is conducted to underline its potential. The embedded MPC was implemented on the ABB AC500 PLC, and its performance was tested using hardware-in-the-loop simulation of Statoil's newly patented subsea compact separation process. A warm-start variant of the proposed first-order method outperforms a tailored interior-point method by a factor of 4 while occupying 40% less memory.

MARIS: A national project on marine robotics for interventions

Abstract: The MARIS project arises as initiative of four Departments of Universities which are members of the Inter-University Centre ISME (“Integrated Systems for the Marine Environment”), legally represented by the University of Genoa, and the research unit of Genoa of CNR-ISSIA (”Institute for Studies on Intelligent Systems for Automation?) of the National Council of Research of Italy, with headquarter in Bari. The two institutions qualify for their long-term research experience in the application of ICT to the marine environment, with particular interests directed toward Underwater Robotics, intended in all its methodological, technological and applicative aspects. The initial research consortium has been then enriched by the inclusion of two additional University Departments, which have selected for the highly qualified contributions they can provide to the MARIS project. In this framework, the proposing institutions ISME and CNR-ISSIA have established, as general strategic objective of the project, the one of studying, developing and integrating, technologies and methodologies enabling the development of underwater robotized systems employable for manipulation and transportation activities; within underwater scenarios which are deemed progressively becoming typical for the off-shore industry, for search-and-rescue operations, as well as for underwater scientific missions. Within such ambitious objective, the proposing institutions also intend to demonstrate the achievable operational capabilities, in a proof-of-concept form, by also integrating the results within prototype experimental systems. In fact, on the basis of the knowledge and experiences owned by the consortium; of its available logistic structures, laboratories and equipment; as well on the basis of already available advanced-stage designs for the experimental systems; the consortium is confident on the possibility of coordinately develop all the necessary technological and methodological aspects; while also converging toward their final integration on the mentioned prototype systems; to be in parallel realized; starting from the sub-systems and advanced-stage.

Feedback Control of Foot Eversion in the Adaptive Peroneal Stimulator

Abstract: The limited ability to dorsiflex the foot, known as drop foot, can be treated by functional electrical stimulation. Therein, undesired foot eversion/inversion is a common problem which is usually corrected by tedious manual repositioning of the electrodes. We address this issue by presenting a feedback-control solution featuring three major contributions: (1) an algorithm for inertial sensor-based foot-to-ground angle measurement with periodic drift correction; (2) a three-electrode setup that allows distribution of an overall stimulation intensity to the tibialis anterior muscle and to the superficial peroneal nerve that innervates the fibularis longus muscle, thus decoupling dorsiflexion and eversion control; (3) a run-to-run controller and an iterative learning controller, both of which use step-by-step learning to achieve desired eversion foot-to-ground angles. Experiments with a chronic drop foot patient demonstrate compensation of undesired eversion/inversion within at most two steps, while dorsiflexion angle trajectories are not affected.

A linear quadratic approach to linear time invariant stabilization for a class of hybrid systems

Abstract: In this paper, the problem of linear time invariant state feedback stabilization for a class of hybrid systems is dealt with. The considered class of systems has received a considerable attention in the last years especially as a benchmark for hybrid output regulation, and in this context it turns out to be quite crucial to have stabilization approaches working under minimal hypotheses meanwhile providing linear time invariant solutions. After showing that static linear time invariant state feedback stabilizers might not exist even in the considered simple setting, a new solution is provided by formulating and solving a linear quadratic optimal control problem, which turns out to be a static time varying linear state feedback. It is then shown how such a feedback can be implemented via a stable dynamic time invariant linear state feedback, by exploiting a dynamic extension implementing the stabilized optimal costate dynamics.

Explicit Model Predictive Control and L1–Navigation Strategies for Fixed–Wing UAV Path Tracking

Abstract: A control strategy for fixed-wing Unmanned Aerial Vehicles is proposed and relies on the combination of linear model predictive control laws for the attitude dynamics of the system, along with an implementation of the L 1 -navigation logic that provides attitude reference commands to achieve precise path tracking. The employed predictive controllers ensure the performance characteristics of the critical attitude loops, while respecting the actuation limitations of the platform along with safety considerations encoded as state constraints. Being explicitly computed, these strategies are computationally lightweight and allow for seamless integration on the onboard avionics. Once the desired attitude response characteristics are achieved, tuning the cascaded nonlinear L 1 -navigation law becomes straightforward as lateral acceleration references can be precisely tracked. A wide set of experiments was conducted in order to evaluate the performance of the proposed strategies. As shown high quality tracking results are achieved.

ARIANNA: A smartphone-based navigation system with human in the loop

Abstract: In this paper we present a low cost navigation system, called ARIANNA, primarily designed for visually impaired people. ARIANNA (pAth Recognition for Indoor Assisted NavigatioN with Augmented perception) permits to find some points of interests in an indoor environment by following a path painted or sticked on the floor. The path is detected by the camera of the smartphone which also generates a vibration signal providing a feedback to the user for correcting his/her direction. Some special landmarks can be deployed along the path for coding additional information detectable by the camera. In order to study the practical feasibility of the ARIANNA system for human users that want to follow a pre-defined path (by only using the smartphone feedback signals), we study how to incorporate human behavior models into the feedback control loop. We also implement an Extended Kalman Filter for localization, in which the user coordinates, speed and orientation represent the filter state (whose updating law depends on the user reaction to the vibration signals), while the smartphones sensors provide the set of measurements used for state estimation.

Nonlinear Observer with Time-Varying Gains for Inertial Navigation Aided by Satellite Reference Systems in Dynamic Positioning

Abstract: Preprint version © IEEE Personal use of this material is permitted Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

A waypoint guidance strategy for underwater snake robots

Abstract: In this paper, a waypoint guidance strategy is proposed for an underwater snake robot. The robot is directed to follow a path which is derived using path planning techniques. A first version of the path is derived by the path planner by using the artificial potential field method for obstacle avoidance. Afterwards, by subsampling the derived path, a set of waypoints are chosen along the path. The path is then defined by interconnecting these waypoints by straight lines. Secondly, a straight line path following controller is proposed, to make the underwater snake robot follow the desired path. Simulation results are presented, illustrating the performance of the proposed guidance control strategy for both lateral undulation and eel-like motion.

Clustering techniques applied to sensor placement for leak detection and location in water distribution networks

Abstract: This work presents an optimization strategy that maximizes the leak locatability performance of water distribution networks (WDN). The goal is to characterize and determine a sensor configuration that guarantees a maximum degree of locatability while the sensor configuration cost satisfies a budgetary constraint. The method is based on pressure sensitivity matrix analysis and an exhaustive search strategy. In order to reduce the size and the complexity of the problem the present work proposes to combine this methodology with clustering techniques. The strategy developed in this work is successfully applied to determine the optimal set of pressure sensors that should be installed in a district metered area (DMA) in the Barcelona WDN.

Assessment of task ergonomics with an upper limb wearable device

Abstract: Upper Limb Work-related Musculo Skeletal Disorders (ULWMSD) are constantly increasing every year in developed countries. It is estimated that in Italy, in 2007 ULWMSD were the 41,6% of all the work-related pathologies. In this context, the importance to correctly diagnose and treat this kind of pathology is growing. Traditionally the assessment is done using pen-and-paper observational techniques in which movements are manually classified, labelled and compared integrating the results with subjective questionnaires given to the monitored subjects. The main problem with those traditional methods is the lack of objective assessment regarding the motion and the forces exerted, which are inferred by subjects inquiry and the body posture, manually extracted from video tapes. In this context we propose a novel wired system for assessing the muscular effort and posture of the human upper limb for ULWMSDs diagnosis in ecologic environment. The system is composed of inertial units to reconstruct the upper limb posture and EMG sensors to assess the muscle effort. The upper limb is considered as a kinematic chain comprising three degrees of freedom (DoFs) for the shoulder, two DoFs for the elbow and two DoFs for the wrist, while forearm flexor muscles are monitored through EMG. We propose a preliminary validation of the system testing it for assessing posture and muscle effort of a check-out operator during everyday real-life operations.

Thermal modeling, analysis and control using an electrical analogy

Abstract: Modeling and identification of thermal systems is a problem frequently treated in theoretical and application domains. Most of these systems have been modeled using black-box structures whose parameters are identified using temperature measurements. Although black-box models have achieved good results in terms of temperature evolution, they cannot model variables which had not been measured in the identification test. In this article we present a new method to build grey-box thermal models based on electrical equivalent circuits which not only give information about temperatures evolution, but also about heat fluxes and thermal energy stored in the system. The partially unknown parameters of the models are identified using temperature measurements and applying nonlinear optimization techniques. The obtained state space representation can be used to develop a deterministic state space temperature controller that provides better accuracy than classical PID controllers. Our proposal is complemented with various examples of a real application in an electric oven.

Output controller for quadcopters based on mathematical model decomposition

Abstract: In the paper an output control approach for a class of nonlinear MIMO systems is presented. A multicopter with four symmetrical rotors, i.e. a quadcopter, is chosen to illustrate effectiveness of the proposed adaptive control approach based on the high-gain principle so-called “consecutive compensator”. Output controller is designed by decomposition of the mathematical model on two parts. The first one is a static MIMO transformation (more precisely, in the considering case a system of linear equations which relates lift forces generated by the actuators and virtual control inputs). The second one is a few SISO channels. Such trick allows to design a control law in two steps. At the first step we design virtual controls for each SISO channel. Here we apply the mentioned systematic approach “consecutive compensator”. And then after the inverse MIMO transformation we get a set of real lift forces.

Short-term demand forecasting for real-time operational control of the Barcelona water transport network

Abstract: This paper focuses on the forecast of the hourly water demand data of distinct pressure floors of the Barcelona water transport network. Several methods to forecast the hourly water demand are studied and compared with the aim of being applied for the operational control of the Barcelona water transport network. The short-term forecast of the intraday series has a main feature: the double periodicity (daily and hourly). To address this issue several extensions of the classical time-series forecasting methods are proposed: seasonal ARIMA, structural models and the exponential methods without external information. The paper focuses on the daily and hourly forecasts. In the hourly forecast, the exponential smoothing method is the most accurate. On the hand, the seasonal ARIMA and the exponential smoothing are similar in the daily time scale.

Selective compliance control for an unmanned aerial vehicle with a robotic arm

Abstract: This paper proposes a compliant control scheme for a quadrotor helicopter equipped with an n-DOFs manipulator. The proposed control scheme is characterized by three layers: the first layer includes a motion planner, which, on the basis of desired trajectory for the end-effector, determines the desired motion for the actuated variables (joint positions, quadrotor position and yaw angle). The second layer, thanks to an impedance filter, provides a selective compliant behavior to the system, in the presence of interaction of the manipulator end-effector with the environment. Finally, the third layer implements a motion controller aimed at tracking the references output by the previous layer. The effectiveness of the proposed approach is tested in simulation.

Application of Advanced Metering Infrastructure in Smart Grids

Abstract: This survey paper is an excerpt of a more comprehensive study on Smart Grid (SG) and the role of Advanced Metering Infrastructure (AMI) in SG. The survey was carried out as part of a feasibility study for creating a Net-Zero community in a city in Ontario, Canada. SG is not a single technology; rather it is a combination of different areas of engineering, communication and management. This paper focuses on AMI which as the foundation of SG is responsible for collecting all the data and information from loads and consumers. AMI is also responsible for implementing control signals and commands to perform necessary control actions as well as Demand Side Management (DSM). In this paper we introduce SG and its features, establish the relationship between smart grid and AMI, explain three main subsystems of AMI and discuss some issues related to design and deployment of AMI.

Indoor positioning system using walking pattern classification

Abstract: In the age of automation the ability to navigate persons and devices in indoor environments has become increasingly important for a rising number of applications. While Global Positioning System can be considered a mature technology for outdoor localization, there is no off-the-shelf solution for indoor tracking. In this contribution, an infrastructure-less Indoor Positioning System based on walking feature detection is presented. The proposed system relies on the differences characterizing different human actions (e.g., walking, ascending or descending stairs, taking the elevator). The motion features are extracted in time domain by exploiting data provided by a 9DoF Inertial Measurement Unit. The positioning algorithm is based on walking distance and heading estimation. Step count and step length are used to determine the walking distance, while the heading is computed by quaternions. An experimental setup has been developed. The collected results show that system guarantee room level accuracy during long trials.

A uniformly semiglobally exponentially stable nonlinear observer for GNSS- and camera-aided inertial navigation

Abstract: Preprint version. © IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.

Vision through other senses: Practical use of Sensory Substitution devices as assistive technology for visual rehabilitation

Abstract: Visual-to-auditory Sensory Substitution Devices (SSDs) are non-invasive sensory aids that provide visual information to the blind via their functioning senses, such as audition. For years SSDs have been confined to laboratory settings, but we believe the time has come to use them also for their original purpose of real-world practical visual rehabilitation. Here we demonstrate this potential by presenting for the first time new features of the EyeMusic SSD, which gives the user whole-scene shape, location & color information. These features include higher resolution and attempts to overcome previous stumbling blocks by being freely available to download and run from a smartphone platform. We demonstrate with use the EyeMusic the potential of SSDs in noisy real-world scenarios for tasks such as identifying and manipulating objects. We then discuss the neural basis of using SSDs, and conclude by discussing other steps-in-progress on the path to making their practical use more widespread.

Electric vehicles charging load reprofiling

Abstract: This paper presents a reference architecture and a control scheme for the aggregation and management of electric vehicle (EV) load at medium voltage level. The focus is put on the problem of EV load reprofiling, aimed at the procurement of active demand (AD) services to interested grid/market actors. The proposed approach achieves AD product composition always guaranteeing the respect of grid constraints as well as user constraints on the charging processes. Simulations are presented to illustrate the effectiveness of the proposed approach.

Monitoring of seagrass by lightweight AUV: A Posidonia oceanica case study surrounding Murter island of Croatia

Abstract: Posidonia oceanica (Neptune Grass) is an endemic species to the Mediterranean Sea. It forms dense and extensive green underwater meadows which provide important ecological functions and services and harbour highly diverse communities; as such it is identified as a priority habitat type for conservation under the EU Habitats Directive (Dir 92/43/CEE). Over the last decades many Posidonia oceanica meadows have disappeared or have been altered. Efficient monitoring is the key of the ecosystem conservation. Monitoring of vast areas covered by Posidonia oceanica is extremely difficult, costly and time consuming and generates pronounced need for new methods and tools. This case study presents potential and promote use of lightweight autonomous underwater vehicles (AUV) with the remote sensing payload as the environmentally non-destructive monitoring method. The study was performed from 2011 to 2013 on the Croatian island Murter during the ”Breaking the Surface” - international interdisciplinary field training of marine robotics and applications. Four AUVs equipped with different payloads were performing the missions in the study area. This paper presents results and analysis of different aspects important for the monitoring such as compliance with the existing monitoring indicators and descriptors used to assess the conservation status of P. oceanica, performance of the AUVs and their sensor sets, cost and time efficiency of the monitoring and geographical-localisation accuracy of the data collected.

A model matching framework for the synthesis of series elastic actuator impedance control

Abstract: The fundamental goal of robot impedance control is to shape a given system's behavior to match that of a predefined desired dynamic model. A variety of techniques are used throughout the literature to achieve this goal, but in practice, most robots ultimately rely on straightforward architectures akin to PD control that have intuitive physical interpretations convenient for the control designer. This is particularly true of systems employing series elastic actuators (SEAs) in spite of the potential that more complex controllers have for improving impedance rendering in devices with higher order dynamics. The model matching framework presented here leverages H ∞ control approaches, that are yet to gain widespread use in the robotics community, to significantly simplify the impedance control design task. This framework provides a novel means by which to synthesize a dynamic feedback controller for an SEA that accommodates a wide range of desired impedances and available feedback. The ease of employing this synthesis approach and its potential benefits for SEA control are discussed in light of the limitations of other existing techniques. This discussion, and the insight gained from a series of simulations comparing impedance controllers designed using established passivity-based techniques to controllers born out of our model matching framework, lay the foundation for further adoption of H ∞ synthesis in SEA control.

UAV equipped with a robotic manipulator

Abstract: The aim of this article is design and control system developing of multirotational UAV equipped with a robotic manipulator. As a combined model of the robot a quadrocopter and a two-link manipulator were chosen. The mathematical model of this robot, its dynamic equations and problem of trajectory tracking are described in this paper. Mutual reactive influence of the robotic manipulator and the UAV is considered. The main result of this paper is development of the control system of this robot based on feedback linearization, PD-controller and compensation of the robotic manipulator disturbing effects.

Recursive adaptive control for an underwater vehicle carrying a manipulator

Abstract: 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.

A Petri Net model for a building energy management system based on a demand response approach

Abstract: In recent years, the necessity to avoid the stress condition of the utility systems, to reduce the peak capacity and the energy consumption, led to the development of suitable building energy management systems in the smart city context. This paper presents a conceptual architecture of a district management system that monitors the district power consumption and sends demand reduction signals to the Building Energy Management Systems (BEMSs). Moreover, the BEMS management strategy is described in a Demand Response approach and the BEMS control unit is modeled in a Petri Net framework.

Detectability and observer design for linear descriptor systems

Abstract: In this paper, a method is proposed to design Luenberger type observer for a class of linear descriptor systems satisfying complete detectability condition. The method is based on the properties of restricted system equivalent, derived here from a given descriptor system by means of simple matrix theory. Using restricted system equivalent form, equivalence between the detectability of a given descriptor system and that of a normal system has been established. Coefficient matrices of the proposed observer have been synthesized using pole placement technique of normal system theory and LMI approach based on the Lyapunov stability theory.

Suspended load motion control using multicopters

Abstract: This paper presents a distributed kinematic control law for group coordination for several multicopters and a payload suspended with wires from each multicopter. The complete system with constraints on the wires are modeled in 6 degrees of freedom (DOF), using the Udwadia-Kalaba equation. Velocity controllers for the multicopters are developed to realize the desired motion set by the kinematic controller. This results in a system where the group of multicopters are able to maneuver the payload to a desired position while keeping a desired formation. The results are verified by simulations.

A novel cooperative adaptive cruise control approach: Theory and hardware in the loop experimental validation

Abstract: In this paper we propose and experimentally validate within an ad hoc Hardware In the Loop (HIL) environment a novel approach for the control of a fleet of vehicles. In particular, the Cooperative Adaptive Cruise Control (CACC) for vehicles platooning is extended to the case when, due to the recent advances on vehicular wireless technologies, each vehicle can communicate not only with its follower but also with a subset of vehicles in the fleet. In so doing, a network of dynamical system emerges, and it is shown that the platooning problem is equivalent to find a control algorithm so that the resulting network is asymptotically stable. It is analytically shown that the decentralized control algorithm guarantee exponential stability despite heterogeneous time-varying communication delays which are unavoidable when wireless protocol are used. Finally, experimental results show the effectiveness and the robustness of the control approach also to variations of the leader velocity, as well as to generic topologies of the underlining network emerging from the communication features.