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  • 1.
    Abolmasoumi, Amirhossein
    et al.
    Department of Electrical Engineering, Faculty of Engineering, Arak University.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observer design for a class of nonlinear delayed systems with unknown inputs and Markovian jump parameters2012In: ICCAS 2012: 12th International Conference on Control, Automation and Systems, 2012, 1848-1852 p.Conference paper (Refereed)
    Abstract [en]

    The problem of full-order observer design for a class of delayed nonlinear systems with unknown inputs and Markovian jumping parameters is considered. The design method is formulated as solving a set of linear matrix inequalities (LMI's). Extending the results of nonlinear observer design to Markovian jump systems with time-varying delays is the main advantages of this paper. The sufficient LMI conditions are dependent on both the upper and lower bounds of delay. The effectiveness of the proposed method is shown via an illustrative example.

  • 2.
    Abrahamsson, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Positionering av last hos gantrykranar via direktverkan på last1988Report (Other academic)
  • 3.
    Alexhs, Kostas
    et al.
    University of Patras, Department of Electrical and Computer Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    University of Patras, Department of Electrical and Computer Engineering.
    Autonomous quadrotor position and attitude PID/PIDD control in GPS-denied environments2011In: International Review of Automatic Control, ISSN 1974-6059, E-ISSN 1974-6067, Vol. 4, no 3Article in journal (Refereed)
    Abstract [en]

    This article addresses the control problem of an unmanned quadrotor in the absence of absolute position measurement data (e.g. GPS, external cameras). Based on an attached Inertia Measurement Unit, a sonar and an optic flow sensor, the quadrotor’s translational and rotational motion-vector is estimated using sensor fusion algorithms. A control scheme consisted of three Proportional-Integral-Derivative (PID) controllers for the translational motions, combined with three Proportional-Integral-Derivative-second Derivative (PIDD) controllers for the attitude dynamics is utilized in order to achieve accurate position hold and attitude tracking. The controller is implemented on a quadrotor prototype in indoor position hold experiments and aggressive attitude regulation maneuvers.

  • 4.
    Alexis, Kostas
    et al.
    Swiss Federal Institute of Technology.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    University of Patras.
    Experimental Constrained Optimal Attitude Control of a Quadrotor subject to Wind Disturbances2014In: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 12, no 6, 1289-1302 p.Article in journal (Refereed)
    Abstract [en]

    The design and experimental verification of a Constrained Finite Time Optimal Controller (CFTOC) for attitude maneuvers of an Unmanned Quadrotor operating under severe wind conditions is the subject of this article. The quadrotor’s nonlinear dynamics are linearized in various operating points resulting in a set of piecewise affine models. The CFTO–controller is designed for set-point maneuvers taking into account the switching between the linear models and the state and actuation constraints. The control scheme is applied on experimental studies on a prototype quadrotor operating both in absence and under presence of forcible atmospheric disturbances. Extended experimental results indicate that the proposed control approach attenuates the effects of induced wind–gusts while performing accurate attitude set–point maneuvers.

  • 5.
    Alexis, Kostas
    et al.
    Electrical and Computer Science Department, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    Electrical and Computer Science Department, University of Patras.
    Model predictive quadrotor control: attitude, altitude, and position experimental studies2012In: IET Control Theory & Applications, ISSN 1751-8644, E-ISSN 1751-8652, Vol. 6, no 12, 1812-1827 p.Article in journal (Refereed)
    Abstract [en]

    This article addresses the control problem of an unmanned quadrotor in an indoor environment where there is lack of absolute localization data. Based on an attached Inertia Measurement Unit, a sonar and an optic flow sensor, the state vector is estimated using sensor fusion algorithms. A novel Switching Model Predictive Controller is designed in order to achieve precise trajectory control, under the presence of forcible wind–gusts. The quadrotor’s attitude, altitude and horizontal linearized dynamics result in a set of Piecewise Affine models, enabling the controller to account for a larger part of the quadrotor’s flight envelope while modeling the effects of atmospheric disturbances as additive–affine terms in the system. The proposed controller algorithm accounts for the state and actuation constraints of the system. The controller is implemented on a quadrotor prototype in indoor position tracking, hovering and attitude maneuvers experiments. The experimental results indicate the overall system’s efficiency in position/altitude/attitude set–point maneuvers.

  • 6.
    Alexis, Kostas
    et al.
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    On trajectory tracking model predictive control of an unmanned quadrotor helicopter subject to aerodynamic disturbances2014In: Asian journal of control, ISSN 1561-8625, E-ISSN 1561-8625, Vol. 16, no 1, 209-224 p.Article in journal (Refereed)
    Abstract [en]

    In this article a Model Predictive Control (MPC) strategy for the trajectory tracking of an unmanned quadrotor helicopter is presented. The quadrotor’s dynamics are modeled by a set of Piecewise Affine (PWA) systems around different operating points of the translational and rotational motions. The proposed control scheme is dual and is consisted by an integral MPC for the translational motions, followed by a MPC–scheme for the quadrotor’sattitude motions’ tracking. By the utilization of PWA representations, the controller is computed for a larger part of the quadrotor’s flight envelope. Theproposed dual control scheme is able to calculate optimal control actions with robustness against atmospheric disturbances (e.g. wind gusts) and physical constraints of the quadrotor (e.g. maximum lifting forces or fixed thrust limitations in order to extend flight endurance). Extended simulation studies prove the efficiency of the MPC–scheme, both in trajectory tracking and aerodynamic disturbances attenuation.

  • 7.
    Alexis, Kostas
    et al.
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    Switching model predictive attitude control for a quadrotor helicopter subject to atmospheric disturbances2011In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 19, no 10, 1195-1207 p.Article in journal (Refereed)
    Abstract [en]

    In this article a Switching Model Predictive Attitude Controller for an Unmanned quadrotor Helicopter subject to atmospheric disturbances is presented. The proposed control scheme is computed based on a Piecewise Affine (PWA) model of the quadrotor’s attitude dynamics, where the effects of the atmospheric turbulence are taken into consideration as additive disturbances. The switchings among the PWA models are ruled by the rate of the rotation angles and for each PWA system a corresponding model predictive controller is computed. The suggested algorithm is verified in experimental studies in the execution of sudden maneuvers subject to forcible wind disturbances. The quadrotor rejects the induced wind–disturbances while performing accurate attitude tracking.

  • 8.
    Alexis, Kostas
    et al.
    Department of Electrical and Computer Engineering, University of Patras.
    Papachristos, Christos
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    Model predictive quadrotor indoor position control2011In: 19th Mediterranean Conference on Control & Automation (MED 2011): [Aquis Corfu Holiday Palace], Corfu, Greece, 20 - 23 June 2011, Piscataway, NJ: IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    This article addresses the control problem of quadrotors in environments where absolute-localization data (GPS, positioning from external cameras) is inadequate. Based on an attached IMU and an optical flow sensor the quadrotor’s translational velocity is estimated using an Extended Kalman Filter. Subject to the velocity measurements, the roll, pitch and yaw (RPY) angles, the angular rates and the translational accelerations a switching Model Predictive Controller is designed. The quadrotor dynamics is linearized at various operating points according to the angular rates and the RP angles. The switching is inferred according to the various linearized models of the quadrotor. The controller is applied on a quadrotor prototype in low-altitude position hold maneuvers at very constrained environments. The experimental results indicate the overall system’s efficiency in position/altitude set–point maneuvers.

  • 9.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Characterization of Neato Lidar2015Report (Other academic)
    Abstract [en]

    The Lidars are very useful sensors in many robotic applications. The problem is that the price of these sensors are quite expensive. A cheap version of these sensors is the Neato {Neato Robotics, Inc. https://www.neatorobotics.com/company/} Lidar. In this report we will present different experiments that had been done to characterize this device. Also discuss the possibilities that can be done to improve its performance in the robotics applications.

  • 10.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Cooperative Simultaneous Localization and Mapping2013Other (Other (popular science, discussion, etc.))
  • 11.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Quad Rotor2013Other (Other (popular science, discussion, etc.))
  • 12.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Robot Android control2013Other (Other (popular science, discussion, etc.))
  • 13.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Robot Mapping2013Other (Other (popular science, discussion, etc.))
  • 14.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Robot Navigation2013Other (Other (popular science, discussion, etc.))
  • 15.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Statistical Calibration Algorithms for Lidars2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Robots are becoming increasingly available and capable, are becoming part of everyday life in applications: robots that guide blind or mentally handicapped people, robots that clean large office buildings and department stores, robots that assist people in shopping, recreational activities, etc.Localization, in the sense of understanding accurately one's position in the environment, is a basic building block for performing important tasks. Therefore, there is an interest in having robots to perform autonomously and accurately localization tasks in highly cluttered and dynamically changing environments.To perform localization, robots are required to opportunely combine their sensors measurements, sensors models and environment model. In this thesis we aim at improving the tools that constitute the basis of all the localization techniques, that are the models of these sensors, and the algorithms for processing the raw information from them. More specifically we focus on:- finding advanced statistical models of the measurements returned by common laser scanners (a.k.a. Lidars), starting from both physical considerations and evidence collected with opportune experiments;- improving the statistical algorithms for treating the signals coming from these sensors, and thus propose new estimation and system identification techniques for these devices.In other words, we strive for increasing the accuracy of Lidars through opportune statistical processing tools.The problems that we have to solve, in order to achieve our aims, are multiple. The first one is related to temperature dependency effects: the laser diode characteristics, especially the wave length of the emitted laser and the mechanical alignment of the optics, change non-linearly with temperature. In one of the papers in this thesis we specifically address this problem and propose a model describing the effects of temperature changes in the laser diode; these include, among others, the presence of multi-modal measurement noises. Our contributions then include an algorithm that statistically accounts not only for the bias induced by temperature changes, but also for these multi-modality issues.An other problem that we seek to relieve is an economical one. Improving the Lidar accuracy can be achieved by using accurate but expensive laser diodes and optical lenses. This unfortunately raises the sensor cost, and -- obviously -- low cost robots should not be equipped with very expensive Lidars. On the other hand, cheap Lidars have larger biases and noise variance. In an other contribution we thus precisely targeted the problem of how to improve the performance indexes of inexpensive Lidars by removing their biases and artifacts through opportune statistical manipulations of the raw information coming from the sensor. To achieve this goal it is possible to choose two different ways (that have been both explored):1- use the ground truth to estimate the Lidar model parameters;2- find algorithms that perform simultaneously calibration and estimation without using ground truth information. Using the ground truth is appealing since it may lead to better estimation performance. On the other hand, though, in normal robotic operations the actual ground truth is not available -- indeed ground truths usually require environmental modifications, that are costly. We thus considered how to estimate the Lidar model parameters for both the cases above.In last chapter of this thesis we conclude our findings and propose also our current future research directions.

  • 16.
    Alhashimi, Anas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    The application of auto regressive spectrum modeling for identification of the intercepted radar signal frequency modulation2012In: Inventi Impact Telecom, ISSN 2249-1414, Vol. 2012, no 3Article in journal (Refereed)
    Abstract [en]

    In the Electronic Warfare receivers, it is important to know the type of modulation of the intercepted Radar signals (MOP modulation on pulse). This information can be very helpful in identifying the type of Radar present and to take the appropriate actions against it. In this paper, a new signal processing method is presented to identify the FM (Frequency Modulation) pattern from the received Radar pulses. The proposed processing method based on Auto Regressive Spectrum Modelling used for digital modulation classification [1]. This model uses the instantaneous frequency and instantaneous bandwidth as obtained from the roots of the autoregressive polynomial. The instantaneous frequency and instantaneous bandwidth together were used to identify the type of modulation in the Radar pulse. Another feature derived from the instantaneous frequency is the frequency rate of change. The frequency rate of change was used to extract the pattern of the frequency change. Results show that this method works properly even for low signal to noise ratios.

  • 17.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Hostettler, Roland
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    An Improvement in the Observation Model for Monte Carlo Localization2014In: Proceedings of the 11th International Conference on Informatics in Control, Automation and Robotics: Vienna, Austria, 1-3, September, 2014, SciTePress, 2014, 498-505 p.Chapter in book (Refereed)
    Abstract [en]

    Accurate and robust mobile robot localization is very important in many robot applications. Monte Carlo localization (MCL) is one of the robust probabilistic solutions to robot localization problems. The sensor model used in MCL directly influence the accuracy and robustness of the pose estimation process. The classical beam models assumes independent noise in each individual measurement beam at the same scan. In practice, the noise in adjacent beams maybe largely correlated. This will result in peaks in the likelihood measurement function. These peaks leads to incorrect particles distribution in the MCL. In this research, an adaptive sub-sampling of the measurements is proposed to reduce the peaks in the likelihood function. The sampling is based on the complete scan analysis. The specified measurement is accepted or not based on the relative distance to other points in the 2D point cloud. The proposed technique has been implemented in ROS and stage simulator. The result shows that selecting suitable value of distance between accepted scans can improve the localization error and reduce the required computations effectively.

  • 18.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Project: Line Following Robot2013Other (Other (popular science, discussion, etc.))
  • 19.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nayl, Thaker
    Project: Robot Pathplaning2013Other (Other (popular science, discussion, etc.))
  • 20.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    An improvement in the observarion model for Monte Carlo localization2014Conference paper (Refereed)
  • 21.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observation model for Monte Carlo Localization2014Conference paper (Other academic)
  • 22.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems. Department of Computer EngineeringUniversity of Baghdad.
    Pierobon, Giovanni
    Department of Information EngineeringUniversity of Padova.
    Varagnolo, Damiano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Modeling and Calibrating Triangulation Lidars for Indoor Applications2018In: Informatics in Control, Automation and Robotics: 13th International Conference, ICINCO 2016 Lisbon, Portugal, 29-31 July, 2016 / [ed] Kurosh Madani, Dimitri Peaucelle, Oleg Gusikhin, Cham: Springer Publishing Company, 2018, 342-366 p.Conference paper (Refereed)
    Abstract [en]

    We present an improved statistical model of the measurement process of triangulation Light Detection and Rangings (Lidars) that takes into account bias and variance effects coming from two different sources of uncertainty:                                                                           {\$}{\$}(i) {\$}{\$}                 mechanical imperfections on the geometry and properties of their pinhole lens - CCD camera systems, and                                                                           {\$}{\$}(ii) {\$}{\$}                 inaccuracies in the measurement of the angular displacement of the sensor due to non ideal measurements from the internal encoder of the sensor. This model extends thus the one presented in [2] by adding this second source of errors. Besides proposing the statistical model, this chapter considers:                                                                           {\$}{\$}(i) {\$}{\$}                 specialized and dedicated model calibration algorithms that exploit Maximum Likelihood (ML)/Akaike Information Criterion (AIC) concepts and that use training datasets collected in a controlled setup, and                                                                           {\$}{\$}(ii) {\$}{\$}                 tailored statistical strategies that use the calibration results to statistically process the raw sensor measurements in non controlled but structured environments where there is a high chance for the sensor to be detecting objects with flat surfaces (e.g., walls). These newly proposed algorithms are thus specially designed and optimized for inferring precisely the angular orientation of the Lidar sensor with respect to the detected object, a feature that is beneficial especially for indoor navigation purposes.

  • 23.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Varagnolo, Damiano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Calibrating distance sensors for terrestrial applications without groundtruth information2017In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 17, no 12, 3698-3709 p., 7911206Article in journal (Refereed)
    Abstract [en]

    This paper describes a new calibration procedure for distance sensors that does not require independent sources of groundtruth information, i.e., that is not based on comparing the measurements from the uncalibrated sensor against measurements from a precise device assumed as the groundtruth. Alternatively, the procedure assumes that the uncalibrated distance sensor moves in space on a straight line in an environment with fixed targets, so that the intrinsic parameters of the statistical model of the sensor readings are calibrated without requiring tests in controlled environments, but rather in environments where the sensor follows linear movement and objects do not move. The proposed calibration procedure exploits an approximated expectation maximization scheme on top of two ingredients: an heteroscedastic statistical model describing the measurement process, and a simplified dynamical model describing the linear sensor movement. The procedure is designed to be capable of not just estimating the parameters of one generic distance sensor, but rather integrating the most common sensors in robotic applications, such as Lidars, odometers, and sonar rangers and learn the intrinsic parameters of all these sensors simultaneously. Tests in a controlled environment led to a reduction of the mean squared error of the measurements returned by a commercial triangulation Lidar by a factor between 3 and 6, comparable to the efficiency of other state-of-the art groundtruth-based calibration procedures. Adding odometric and ultrasonic information further improved the performance index of the overall distance estimation strategy by a factor of up to 1.2. Tests also show high robustness against violating the linear movements assumption.

  • 24.
    Alhashimi, Anas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Varagnolo, Damiano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Joint Temperature-Lasing Mode Compensation for Time-of-Flight LiDAR Sensors2015In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, no 12, 31205-31223 p.Article in journal (Refereed)
    Abstract [en]

    We propose an expectation maximization (EM) strategy for improving the precision of time of flight (ToF) light detection and ranging (LiDAR) scanners. The novel algorithm statistically accounts not only for the bias induced by temperature changes in the laser diode, but also for the multi-modality of the measurement noises that is induced by mode-hopping effects. Instrumental to the proposed EM algorithm, we also describe a general thermal dynamics model that can be learned either from just input-output data or from a combination of simple temperature experiments and information from the laser’s datasheet. We test the strategy on a SICK LMS 200 device and improve its average absolute error by a factor of three.

  • 25.
    Alhashimi, Anas W.
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Varagnolo, Damiano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Statistical modeling and calibration of triangulation Lidars2016In: ICINCO 2016: Proceedings of the 13th International Conference on Informatics in Control, Automation and Robotics / [ed] Peaucelle D.,Gusikhin O.,Madani K, SciTePress, 2016, 308-317 p.Conference paper (Refereed)
    Abstract [en]

    We aim at developing statistical tools that improve the accuracy and precision of the measurements returned by triangulation Light Detection and Rangings (Lidars). To this aim we: i) propose and validate a novel model that describes the statistics of the measurements of these Lidars, and that is built starting from mechanical considerations on the geometry and properties of their pinhole lens - CCD camera systems; ii) build, starting from this novel statistical model, a Maximum Likelihood (ML) / Akaike Information Criterion (AIC) -based sensor calibration algorithm that exploits training information collected in a controlled environment; iii) develop ML and Least Squares (LS) strategies that use the calibration results to statistically process the raw sensor measurements in non controlled environments. The overall technique allowed us to obtain empirical improvements of the normalized Mean Squared Error (MSE) from 0.0789 to 0.0046

  • 26.
    Andersson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Klimatzoner SAAB 90001989Report (Other academic)
  • 27.
    Andersson, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Automation and traction control of articulated vehicles2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Articulated machines such as load-haul-dump machines, wheel loaders and haulers operate in many different environments and driving conditions. In particular they need to be able to perform well with road conditions and loads that can change drastically, setting hard requirements on performances and robustness. The control challenges for off-road vehicles are hence quite different from standard cars or trucks, which mostly drive on regular roads. An important aspect characterising this is the fact that wheel slip may cause severe damage to the wheels and ground. Particularly, tyre lifespan is a serious problem since for instance in a modern hauler the tyres often represents 20%-25% of a hauler overall operating cost. Better traction control algorithms can strongly contribute to reducing tyre wear and hence operating costs.Increasing fuel prices and increasing environmental awareness have influenced all the main vehicle manufacturers so that the commitment towards less fuel consumption has become one of the main goals for development. During the last few years’ hybrid vehicles have been vigorously developed. For wheel loaders, in particular, the series hybrid concept seems to be suitable whereby a diesel engine generates electricity for a battery that serves as the power source of the individual wheel motors, enabling regenerative braking as well as partial recovery of the energy necessary to lift the load. Hence, traction control algorithms should be adapted for use with individual wheel drives.Load-haul-dump machines, wheel loaders and haulers are sometimes used in cyclic operations in isolated areas, which is a typical driver for automation. The use of the loadhaul-dump machine in underground hard rock mines such as iron ore mines is one example where the conditions for automation are excellent. The working conditions for a driver in the cabin are monotone. The working conditions are improved by moving the driver from the machine to a control room and alternate between different remote operations, for instance between load-haul-dump machines and remote controlled rock breaker. Moving the driver from the cabin to the control room also have a positive effect on the personnel costs since one operator can handle several machines.However, for the automation to be successful, the cycle time and loading capacity of an automated machine has to match a manual machine operated by skilled drivers. A challenge is the remote bucket filling, where traditional tele remote loading is based only on slightly delayed video feedback from the machine. This is in sharp contrast to the manual loading where the driver close the loop based on non-delayed 3D vision of the machine relative the pile as well as listening to the noise and sensing the vibrations of the machine.

  • 28.
    Andersson, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Laser Navigation System for Automatic Guided Vehicles: From Research Prototype to Commercial Product2013Report (Other academic)
  • 29.
    Andersson, Ulf
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Trajectory estimation and control of autonomous guided vechicles1989Licentiate thesis, comprehensive summary (Other academic)
  • 30.
    Andersson, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Bortolin, Gianantonio
    Volvo CE.
    Backén, Staffan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Estimation of side-slip angles of a Volvo A25E articulated all-wheel drive hauler based on GPS/INS measurements2011In: Proceedings of SAE 2011 Commercial Vehicle Engineering Congress and Exhibition, Society of Automotive Engineers, Incorporated , 2011Conference paper (Refereed)
    Abstract [en]

    Traction control for off-road vehicles such as articulated all-wheel drive haulers is of great importance to improve the vehicle performance. A well-known method to reduce the slip and thereby improve the traction is to engage differential locks in the driveline of the vehicle. The drawbacks of differential locks engaged are for instance increased wear, increased fuel consumption but also reduced turnability of the vehicle. Therefore, the differentials should be locked only when necessary, ideally only when slip occurs or is about to occur. A number of methods to detect slip has been reported in the literature. Some of them utilize dynamical models of the vehicle where side-slip angles are important inputs. This paper describes an off-line estimator for the side-slip angles of an articulated vehicle based on measurements from Global Positioning System (GPS) and Inertial Navigation System (INS). The current implementation is a proof of concept and the intention is to develop a system that can be used as a reference for on-line estimators. By comparing measurements from two GPS/INS units, mounted on the front and rear part of the vehicle, it is possible to estimate the side-slip angles of both the front and rear part. The method has been tested on a Volvo A25E articulated all-wheel drive hauler equipped with two high precision GPS/INS units (NovAtel's SPAN-CPT). Tests have been performed when driving on asphalt, gravel and snow. The results from the tests are discussed.

  • 31.
    Andersson, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Broström, Fredrik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tyre parameter estimation based on control of individual wheel drives2014In: International Journal of Vehicle Autonomous Systems, ISSN 1471-0226, E-ISSN 1741-5306, Vol. 12, no 3, 247-265 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes a method to estimate tyre parameters for traction control applications based on control of individual wheel drives. The tyre parameters that are estimated are the rolling radius in driven mode (i.e. the rolling radius when the input torque to the wheel is zero) and the tyre longitudinal elasticity factor. The rolling radius in driven mode and the tyre longitudinal elasticity factor depend on several factors, among them the normal load. An important property of the method is that no transfer of load occurs during the estimation phase since the actual velocity of the vehicle is kept constant. Results from tests with ArtiTRAX, a 240 kg electric vehicle that carries 80 kg extra weight in three different front axle and rear axle distributions, are presented.

  • 32.
    Andersson, Ulf
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Mrozek, Kent
    Åström, Kalle
    Hyyppä, Kalevi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Path design and control algorithms for articulated mobile robots1997In: Proceedings of the International Conference on Field and Service Robotics / [ed] Alexander Zelinsky, 1997, 405-411 p.Conference paper (Refereed)
  • 33.
    Andrikopoulos, George
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    HUmanoid Robotic Leg via pneumatic muscle actuators: implementation and control2017In: Meccanica (Milano. Print), ISSN 0025-6455, E-ISSN 1572-9648Article in journal (Refereed)
    Abstract [en]

    In this article, a HUmanoid Robotic Leg (HURL) via the utilization of pneumatic muscle actuators (PMAs) is presented. PMAs are a pneumatic form of actuation possessing crucial attributes for the implementation of a design that mimics the motion characteristics of a human ankle. HURL acts as a feasibility study in the conceptual goal of developing a 10 degree-of-freedom (DoF) lower-limb humanoid for compliance and postural control, while serving as a knowledge basis for its future alternative use in prosthetic robotics. HURL’s design properties are described in detail, while its 2-DoF motion capabilities (dorsiflexion–plantar flexion, eversion–inversion) are experimentally evaluated via an advanced nonlinear PID-based control algorithm.

  • 34.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Arvanitakis, John
    Department of Electrical and Computer Engineering, University of Patras.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    A switched system modeling approach for a pneumatic muscle actuator2012In: 2012 IEEE International Conference on Industrial Technology, ICIT 2012, Piscataway, NJ: IEEE Communications Society, 2012, 833-839 p.Conference paper (Refereed)
    Abstract [en]

    The aim of this article is to present a switched system approach for the dynamic modeling of Pneumatic Muscle Actuators (PMAs). PMAs are highly non-linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last two decades, various modeling approaches have been presented that describe the behavior of PMAs. While most mathematical models are characterized by simplicity and accuracy in describing the attributes of PMAs, they are limited to static performance analysis. Static models are proven to be insufficient for real time control applications, thus creating the need for the development of dynamic PMA models. A collection of experimental and simulation results are being presented that prove the efficiency of the proposed approach.

  • 35.
    Andrikopoulos, Georgios
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Design, development and control of a human-inspired two-arm robot via Pneumatic Artificial Muscles2017In: 2017 25th Mediterranean Conference on Control and Automation, MED 2017, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2017, 241-246 p., 7984125Conference paper (Refereed)
    Abstract [en]

    In this article, the design and implementation of a 10 Degree-of-Freedom (DoF) human-inspired two-arm robot is presented. Multiple Pneumatic Artificial Muscles (PAMs) in antagonistic formations are incorporated for undertaking the two arms' movements, while the design goal is the replication of human-like motion patterns, described by smoothness, inherent compliance and accuracy. To evaluate the feasibility of the proposed concept, the 10-DoF robot is developed and experimentally tested in open and closed-loop control scenarios via the use of a multiple Advanced Nonlinear PID (ANPID) based scheme.

  • 36.
    Andrikopoulos, Georgios
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    On the design, development and motion control of a HUmanoid Robotic Leg via pneumatic artificial muscles2017In: 2016 IEEE International Conference on Robotics and Biomimetics, ROBIO 2016, Piscataway, NJ, 2017, 1637-1642 p., 7866562Conference paper (Refereed)
    Abstract [en]

    In this article, the design and implementation of a HUmanoid Robotic Leg (HURL) is presented. The motion of the HURL is achieved via pneumatic muscle actuators, a pneumatic form of actuation possessing crucial attributes for the implementation of a biomimetic design that mimics the motion characteristics of a human ankle. The HURL's properties are described in detail, while its 2-DoF motion capabilities (dorsiflexion - plantar flexion, eversion - inversion) are experimentally evaluated via an advanced nonlinear PID-based control algorithm

  • 37.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Arvanitakis, Ioannis
    Department of Electrical and Computer Engineering, University of Patras.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Multi-parametric constrained optimal control of a pneumatic artificial muscle2012In: 10th Portuguese Conference in Automatic Control: University of Madeira, July 16-18, 2012, 135-140 p.Conference paper (Refereed)
    Abstract [en]

    The Pneumatic Artificial Muscle (PAM) is a highly non-linear form of actuation that is characterized by a decrease in the actuating length when pressurized. Its non-linear nature and time-varying parameters cause difficulties in modelling their characteristics and designing controllers for high-performance positioning systems. In this article, the control problem of a PAM is considered. A constrained linear and PieceWise Affine (PWA) system model approximation is utilized and a controller composed of: a) a feedforward term regulating control input at specific setpoints, and b) a Constrained Finite Time Optimal Controller (CFTOC) handling any deviations from the system’s equilibrium points is synthesized. Simulation studies are used to investigate the efficacy of the suggested controller.

  • 38.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Arvanitakis, Ioannis
    Electrical and Computer Engineering Department, University of Patras.
    Manesis, Stamatis
    Electrical and Computer Engineering Department, University of Patras.
    Switching model predictive control of a pneumatic artificial muscle2013In: International Journal of Control, Automation and Systems, ISSN 1598-6446, E-ISSN 2005-4092, Vol. 11, no 6, 1223-1231 p.Article in journal (Refereed)
    Abstract [en]

    In this article, a switching Model Predictive Controller (sMPC) for a Pneumatic Artificial Muscle (PAM) is presented. The control scheme is based on a switching PieceWise Affine (PWA) system model approximation that is able to capture the high nonlinearities of the PAM and improve the overall model accuracy, and is composed of: a) a feed-forward term regulating control input at specific reference set-points, and b) a switching Model Predictive Controller handling any deviations from the system's equilibrium points. Extended simulation studies indicate the overall scheme's efficiency.

  • 39.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Arvanitakis, John
    Electrical and Computer Engineering Department, University of Patras.
    Manesis, Stamatis
    Electrical and Computer Engineering Department, University of Patras.
    Piecewise affine modeling and constrained optimal control for a pneumatic artificial muscle2013In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 61, no 2, 904-916 p.Article in journal (Refereed)
    Abstract [en]

    In this article, the modeling and control problem of a Pneumatic Artificial Muscle (PAM) is being considered. The PAM is an actuator characterized by a decrease in the actuating length when pressurized. Its non-linear nature and time-varying parameters cause difficulties in modeling their characteristics, as well as in designing controllers for high-performance positioning systems. A constrained linear and PieceWise Affine (PWA) system model approximation is formulated and a control scheme composed of: a) a feedforward term regulating control input at specific setpoints, and b) a Constrained Finite Time Optimal Controller (CFTOC) handling any deviations from the system’s equilibrium points is being synthesized. Extended experimental studies are utilized to prove the efficacy of the suggested controller.

  • 40.
    Andrikopoulos, Georgios
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Unander-Scharin, Åsa
    Luleå University of Technology, Department of Arts, Communication and Education, Music and dance.
    Towards the Development of a Novel Upper-Body Pneumatic Humanoid: Design and Implementation2016In: 2016 European Control Conference, ECC 2016, Piscataway, NJ: Institute of Electrical and Electronics Engineers (IEEE), 2016, 395-400 p., 7810317Conference paper (Refereed)
    Abstract [en]

    In this article, the conceptual design of a 14 Degree-of-Freedom (DOF) upper-body pneumatic humanoid is presented. The movement capabilities of this novel robotic setup are achieved via Pneumatic Artificial Muscles (PAMs), a form of actuation possessing crucial attributes for the development of biologically-inspired robots. To evaluate the feasibility of the humanoid’s design properties, a 5-DOF robotic arm is developed and experimentally tested, while being studied from the scope of implementing a robotic structure capable of producing smooth and human-like motion responses, while maintaining the inherent compliance provided by the PAM technology.

  • 41.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    A Survey on applications of pneumatic artificial muscles2011In: 19th Mediterranean Conference on Control and Automation, MED 2011, Piscataway, NJ: IEEE Communications Society, 2011, 1439-1446 p.Conference paper (Refereed)
    Abstract [en]

    The aim of this article is to present a survey on applications of Pneumatic Artificial Muscles (PAMs). PAMs are highly non–linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been a significant increase in the industrial and scientific utilization of PAMs due to their advantages such as high strength and small weight, while various types of PAMs with different technical characteristics have been appeared in the relative scientific literature. This article will summarize the key enabling applications in PAMs that are focusing in the following areas: a) Biorobotic, b) Medical, c) Industrial, and d) Aerospace applications

  • 42.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Adaptive internal model control scheme for a pneumatic artificial muscle2013In: European Control Conference (ECC), July 17-19, Zurich, Switzerland 2013, 2013, 772-777 p.Conference paper (Refereed)
    Abstract [en]

    The Pneumatic Artificial Muscle (PAM) is a highly non-linear form of actuation that is characterized by a decrease in the actuating length when pressurized. Its nonlinear nature and time-varying parameters cause difficulties in modeling their characteristics and designing controllers for high-performance positioning systems. In this article, the model identification and control problem of a PAM is being considered. The identification of the PAM’s model parameters is being carried out by a Recursive Least Square (RLS) based algorithm, while an Internal Model Control (IMC) structure is being synthesized. Experimental studies are being utilized to prove the overall efficiency of the suggested control scheme, regarding: a) set-point tracking performance through selected positioning scenarios, b) robustness through disturbance cancellation, and c) adaptability through hysteresis shift compensation.

  • 43.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Advanced nonlinear PID-based antagonistic control for pneumatic muscle actuators2014In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 61, no 12, 6926-6937 p., 6786031Article in journal (Refereed)
    Abstract [en]

    In this paper, the positioning control problem of pneumatic muscle actuators (PMAs) is being considered. A two-degree-of-freedom nonlinear proportional-integral-derivative structure is being synthesized, providing ameliorated compensation of the PMAs' nonlinear hysteretic phenomena and advanced robustness through disturbance cancellation. Experimental studies are being utilized to prove the overall efficiency of the proposed control scheme with regard to set-point tracking performance for the position control of a single PMA, torsion angle control of a nonsymmetrical antagonistic PMA setup, and disturbance rejection in both single and antagonistic control scenarios.

  • 44.
    Andrikopoulos, Georgios
    et al.
    University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    University of Patras.
    An experimental study on thermodynamic properties of pneumatic artificial muscles2012In: 2012 20th Mediterranean Conference on Control & Automation: Barcelona, Spain, July 3-6, 2012, Piscataway, NJ: IEEE Communications Society, 2012, 1334-1340 p.Conference paper (Refereed)
    Abstract [en]

    In the past fifty years, several attempts have been made to model the characteristics of Pneumatic Artificial Muscles (PAMs). PAM models based on their geometrical properties are the most commonly found ones in the scientific literature. In the process of deriving those models a lot of assumptions and simplifications are made due to the fact that PAM is a highly non-linear form of actuation. The purpose of this study is to propose additional considerations for future model improvements that will augment the overall model accuracy, and will best describe the relationship between force, displacement and non-linear thermal properties of PAM actuators through extensive observation and analysis of its thermodynamic characteristics during long-run operation experiments. In this article multiple experimental results will be presented that prove the relation between the thermodynamic properties of the PAMs, especially in iterative operations, and the accuracy on the muscle's force-prolongation relationship.

  • 45.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Design and Development of an Exoskeletal Wrist Prototype via Pneumatic Artificial Muscles2015In: Meccanica (Milano. Print), ISSN 0025-6455, E-ISSN 1572-9648, Vol. 50, no 11, 2709-2730 p.Article in journal (Refereed)
    Abstract [en]

    Full or partial loss of function in the shoulder, elbow or wrist is an increasingly common ailment caused by various medical conditions like stroke, occupational and sport injuries, as well as a number of neurological conditions, which increases the need for the development and improvement of upper limb rehabilitation devices. In this article, the design and implementation of the EXOskeletal WRIST (EXOWRIST) prototype is presented. This novel robotic appliance’s motion is achieved via pneumatic artificial muscles, a pneumatic form of actuation possessing crucial attributes for the development of an exoskeleton that is safe, reliable, portable and low-cost. Furthermore, the EXOWRIST’s properties are presented in detail and compared to the recent wrist exoskeleton technology, while its two degrees-of-freedom movement capabilities (extension-flexion, ulnar-radial deviation) are experimentally evaluated via a PID- based control algorithm. Experimental results involving initial testing of the proposed exoskeleton on a healthy human volunteer for the preliminary evaluation of the EXOWRIST’s attributes are also presented.

  • 46.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Electrical and Computer Engineering Department, University of Patras.
    Development and control of a hybrid controlled vertical climbing robot based on pneumatic muscle actuators2011In: Journal of Control Engineering and Technology (JCET), ISSN 2223-2036, Vol. 1, no 2, 53-58 p.Article in journal (Refereed)
    Abstract [en]

    This article presents the development and control of a novel hybrid controlled vertical climbing robot based on Pneumatic Muscle Actuators (PMAs). PMAs are highly non–linear pneumatic actuators where their elongation is proportional to the internal pressure. The vertical sliding of the robot is based on four PMAs and through the combined and sequential contraction–extension of the pneumatic muscles and cylinders, upward and downward movements are executed. For controlling the movement of the robot and to cope with the high non–linearities of the system, a simplified and highly functional hybrid control scheme, based on PID and On/Off control, has been adopted. The efficacy of the proposed scheme is presented through multiple experimental results where it is shown that the utilized controller is able to provide fast (on/off) and accurate (PID) translations to the robot.

  • 47.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Incorporation of Thermal Expansion in Static Force Modeling of Pneumatic Artificial2015In: IEEE Mediterranean Conference on Control and Automation, Torremolinos, Spain, June, 16-19, 2015 / [ed] V. Munoz, Piscataway, NJ: IEEE Communications Society, 2015, 414-420 p., 7158784Conference paper (Refereed)
    Abstract [en]

    In this article, the thermal expansion effect is considered as the main cause of the gradual shift in the force- displacement relationship, which describes the operation of Pneumatic Artificial Muscles (PAMs). A modified static force modeling approach is proposed, based on fundamental PAM modeling techniques, while incorporating the geometrical properties that are being affected by the thermal build-up occurring during PAM’s continuous operation. The effects of thermal expansion are documented via experimental studies and the acquired data are utilized for the validation of the proposed modeling method. Further evaluation is performed via comparison of modeling accuracy between the proposed modeling approach and the fundamental static force modeling techniques.

  • 48.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Motion control of a novel robotic wrist exoskeleton via pneumatic muscle actuators2015In: Proceedings of 2015 IEEE 20th International Conference on Emerging Technologies & Factory Automation (ETFA 2015): Luxembourg, 8-11 Sept. 2015, Piscataway, NJ: IEEE Communications Society, 2015, 7301464Conference paper (Refereed)
    Abstract [en]

    In this article, the motion control problem of a robotic EXOskeletal WRIST (EXOWRIST) prototype is considered. This novel robotic appliance’s motion is achieved via pneumatic muscle actuators, a pneumatic form of actuation possessing crucial attributes for the development of an exoskeleton that is safe, reliable, portable and low-cost. The EXOWRIST’s properties are presented in detail and compared to the recent wrist exoskeleton technology, while its two degrees- of-freedom movement capabilities (extension-flexion, ulnar- radial deviation) are experimentally evaluated on a healthy human volunteer via an advanced nonlinear PID-based control algorithm.

  • 49.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Non-linear control of pneumatic artificial muscles2013In: 21st IEEE Mediterranean Conference on Control and Automation, June 25-28, Platanias, Chania, Crete, Greece, 2013, 2013, 729-734 p., 6608804Conference paper (Refereed)
    Abstract [en]

    In this article, the control problem of Pneumatic Artificial Muscles is being considered. A non-linear PID structure is being synthesized, providing ameliorated compensation of the PAMs’ non-linear hysteretic phenomena and advanced robustness. Experimental studies are being utilized to prove the overall efficiency of the proposed control scheme regarding: a) set-point tracking performance for the position control of a single PAM and torsion angle control of an antagonistic PAM setup, as well as b) disturbance rejection in both single and antagonistic control scenarios.

  • 50.
    Andrikopoulos, Georgios
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras , Electrical and Computer Engineering Department, University of Patras.
    Novel Considerations on Static Force Modeling of Pneumatic Muscle Actuators2016In: IEEE/ASME transactions on mechatronics, ISSN 1083-4435, E-ISSN 1941-014X, Vol. 21, no 6, 2647-2659 p., 7501612Article in journal (Refereed)
    Abstract [en]

    In this article, an overview of the most significant static force modeling approaches of Pneumatic Muscle Actuators (PMAs) is presented, while a modified static force modeling approach, which is based on fundamental PMA modeling techniques, is proposed. In addition, the thermal expansion effect is considered as the main cause of the gradual shift in the PMA’s force-displacement relationship and the geometric properties, which are being affected by the thermal build-up occurring during PMA’s continuous operation, are incorporated into the static force models. The effects of thermal expansion are documented via experimental studies and the acquired force-displacement data are utilized for the validation of the proposed modeling method in PMAs of different nominal dimensions and at constant test pressures. Finally, an additional evaluation is performed via the comparison of the accuracy between the proposed model and the existing geometric static modeling approaches.

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