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  • 1.
    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.))
  • 2.
    Nayl, Thaker
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Modeling, control and path planning for an articulated vehicle2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis is focusing on the modeling, control and path planning problems for an articulated vehicle. Based on a novel error dynamics modeling approach, the nonlinear kinematic model of the vehicle has been transformed in a linear switching model representation, which is also able to take under consideration the effect of slip angles, a factor that significantly deteriorates the overall system approach.According to the proposed switching modeling, a switching model predictive control scheme has been established. Each of the controllers has been fine tuned for dealing with a specific model representation, translational speed, magnitude of slip angles and physical / mechanical constraints. In the proposed control scheme the varying slip angle and speed have been considered as the switching signal for selecting the active controller.The final contribution is related to the path planning problem where an on line path planning algorithm, being able to consider the full kinematic model of the vehicle, have been proposed.The presented algorithm is a variation of the well known Bug-like path planning scheme.The efficiencies of the presented approaches have been evaluated by multiple simulation results.

  • 3.
    Nayl, Thaker
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    On Autonomous Articulated Vehicles2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis is to address the problems of modeling, path planning and path following for an articulated vehicle in a realistic environment and in the presence of multiple obstacles.In greater detail, the problem of the kinematic modeling of an articulated vehicle is revisited through the proposal of a proper model in which the dimensions and properties of the vehicle can be fully described, rather than considering it as a unit point. Based on this approach, nonlinear and linear error kinematics models are proposed that are also able to account for the effect of the slip angles, a factor that can cause dramatic deterioration in the overall performance of the vehicle.Subsequently, two different concepts for addressing the problem of path following for articulated vehicles are proposed. The first concept is based on a switching model predictive control architecture, which relies on multiple switching linear error dynamics models of the articulated vehicle to account for the effect of varying the slip angles and cruising speed as well as the mechanical and physical constraints of the vehicle.The second proposed control concept is a novel nonlinear sliding mode controller that introduces continuous sliding surfaces to reduce chattering effects while tracking a reference trajectory.The sliding mode controller is utilized based on the extracted nonlinear error coordinates of the articulated vehicle. The feasibility of this approach has been demonstrated through multiple experimental tests on a small scale using a fully realistic articulated vehicle.Finally, in the path planning part of the thesis, artificial potential field and bug algorithms are addressed. More specifically, the potential field path planning algorithm is modified by considering the nonlinear kinematic model of the articulated vehicle and correspondingly adapting the repulsive and attractive coefficients.In the case of the well-known bug algorithm, a suitable navigation method for an articulated vehicle for local path planning based on a minimum set of sensors and with decreased complexity for online implementation is also proposed.Furthermore, the performance of the modified potential field method has been experimentally evaluated in multiple path planning scenarios using the previously mentioned small-scale realistic articulated vehicle.

  • 4. Nayl, Thaker
    Projekt: Doktorand2012Other (Other (popular science, discussion, etc.))
  • 5. Nayl, Thaker
    Projekt: Doktorand2012Other (Other (popular science, discussion, etc.))
  • 6.
    Nayl, Thaker
    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.
    A Full Error Dynamics Switching Modeling and Control Scheme for an Articulated Vehicle2015In: International Journal of Control, Automation and Systems, ISSN 1598-6446, E-ISSN 2005-4092, Vol. 13, no 5, p. 1221-1232Article in journal (Refereed)
    Abstract [en]

    In this article, a complete analysis towards the development of a switching modeling and control framework for an articulated vehicle, under the effect of varying slip angles will be presented. The established nonlinear kinematic model, of the nonholonomic articulated vehicle, will be transformed into an error dynamics model, which in the sequel will be linearized around multiple nominal slip angle cases. The proposed control architecture will consist of a switching control scheme, based on multiple model predictive controllers, for the articulated vehicle under varying slip angles. The controllers will be developed in order to improve the performance of the articulated vehicle's path tracking, while compensating the varying slippage effect. The current measured slip angle is being considered as the switching rule and a corresponding switching control scheme is being defined, being able to apply constraints on the states, the control signal and the output variables. Both the non-slip and slip models will be derived to highlight the significance of accounting for slips in path following control and their significant effect on deteriorating the performance of the overall control scheme when not considered. Multiple simulation results will be presented to prove the efficacy of the overall suggested scheme.

  • 7.
    Nayl, Thaker
    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.
    Effect of Kinematic Parameters on MPC based On-line Motion Planning for an Articulated Vehicle2015In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 70, p. 16-24Article in journal (Refereed)
    Abstract [en]

    The aim of this article is to analyze the effect of kinematic parameters on a novel proposed on-line motion planning algorithm for an articulated vehicle based on Model Predictive Control. The kinematic parameters that are going to be investigated are the vehicle's velocity, the maximum allowable change in the articulated steering angle, the safety distance from the obstacles and the total number of obstacles in the operating arena. The proposed modified path planning algorithm for the articulated vehicle belongs to the family of Bug-Like algorithms and is able to take under consideration, the mechanical and physical constraints of the articulated vehicle, as well as its full kinematic model. During the on-line motion planning algorithm, the MPC controller controls the lateral motion of the vehicle, through the rate of the articulation angle, while driving it accurately and safely over the on-line formulated desired path. The efficiency of the proposed combined path planning and control scheme is being evaluated under numerous simulated test cases, while exhaustive simulations have been made for analyzing the dependency of the proposed framework on the kinematic parameters.

  • 8.
    Nayl, Thaker
    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.
    Kinematic modeling and simulation studies of a LHD vehicle under slip angles2011In: The IASTED International Conference on Modelling, Simulation and Identification, Pittsburgh, USA, ACTA Press, 2011, p. 344-349Conference paper (Refereed)
    Abstract [en]

    In this article a kinematic model for a Load Haul Dumping Vehicle (LHD), with the ability to take under consideration the slipping angles is being derived. This specific type of vehicles consist of two parts, a steering tractor and a trailer, linked together with rigid free joint and can be found various applications, especially in the mine fields. In the rest of the article, exhaustive simulation studies are being provided for evaluating the performance of the model under multiple design and operational variables, such as: a) multiple parameters sets for slip angles, b) different steering angles, c) various wagons’ lengths, and d) various driving paths.

  • 9.
    Nayl, Thaker
    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.
    Online dynamic smooth path planning for an articulated vehicle2013In: 10th International Conference on Informatics in Control, Automation and Robotics, Reykjavik, Iceland, 29-31, July, 2013, 2013, Vol. 2, p. 177-183Conference paper (Refereed)
    Abstract [en]

    This article proposes a novel online dynamic smooth path planning scheme based on a bug like modified path planning algorithm for an articulated vehicle under limited and sensory reconstructed surrounding static environment. In the general case collision avoidance techniques can be performed by altering the articulated steering angle to drive the front and rear parts of the articulated vehicle away from the obstacles. In the presented approach factors such as the real dynamics of the articulated vehicle, the initial and the goal configuration (displacement and orientation), minimum and total travel distance between the current and the goal points, and the geometry of the operational space are taken under consideration to calculate the update on the future way points for the articulated vehicle. In the sequel the produced path planning is being online and iteratively smoothen by the utilization of Bezier lines before producing the necessary rate of change for the vehicle’s articulated angle. The efficiency of the proposed scheme is being evaluated by multiple simulation studies.

  • 10.
    Nayl, Thaker
    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.
    On-Line Path Planning for an Articulated Vehicle based on Model Predictive Control2013In: 2013 IEEE Multi-conference on Systems and Control (Conference on Control Applications), Hyderabad, India, August 28-30, 2013, 2013, p. 772-777Conference paper (Refereed)
    Abstract [en]

    In this article, a novel on–line path planning algorithm for an articulated vehicle, moving in a partially known and sensory based reconstructed environment, andrelying on Model Predictive Control will be presented. The proposed algorithm belongs to the family of bug like path planning algorithms and has the capability to take under consideration the real dynamics of the articulated vehicle.Based on: a) an a prior knowledge of the current and the goal points, and b) a partial sensory based awareness of the surrounding environment, the algorithm is able to tune online the articulated steering angle in order to drive the front and the rear parts of the vehicle from avoiding collision with obstacles, while converging to the goal point. The proposed path planning algorithm is able to produce on–line the next reference way-point, solving the local and sub-optimal problem, while in the sequel a Model Predictive Controller is being utilized forcreating the proper control signal, the rate of the articulated angle based on an error dynamics kinematic model of the vehicle. Multiple simulation results are being presented that prove the efficiency of the suggested scheme.

  • 11.
    Nayl, Thaker
    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.
    Path following for an articulated vehicle based on switching model predictive control under varying speeds and slip angles2012In: 17th-ETFA 2012 - IEEE International Conference on Emerging Technology & Factory Automation,: Krakow, Poland, Sep. 17-21, 2012, Piscataway, NJ: IEEE Communications Society, 2012Conference paper (Refereed)
    Abstract [en]

    This article is focusing on the problem of path following for an articulated vehicle under varying velocities and slip conditions. The proposed control architecture consists of a switching control scheme based on multiple model predictive controllers, fine tuned for dealing with different operating speeds and slip angles. In the presented analysis for the non–holonomic articulated vehicle, the corresponding kinematic model is being transformed into an error dynamics model, which is linearized around multiple nominal slip angle cases and various operating speeds. The existence of the slipping and varying speed has a significant effect on the vehicle’s path following capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple dynamics modeling, the current slip and vehicle’s speed are being considered as the signal selector for the proposed switching model predictive control scheme. The efficacy of the proposed controller is being evaluated byan extended set of simulation results.

  • 12.
    Nayl, Thaker
    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.
    Path Planning With Obstacle Avoidance and Sliding Mode Control for An Articulated Vehicle.2014Conference paper (Refereed)
    Abstract [en]

    A dynamic obstacle avoidance technique and control strategy to derive an articulated vehicle has been proposed. The strategy consists of two elements: a path planning and controller scheme to make the vehicle track a reference path. Potential field algorithm is exploited to generate a free collision on-line reference path in dynamic environments. The potential field is modified, by considering the nonlinear kinematic model, of the articulated vehicle. The proposed sliding mode controller is capable of making the vehicle move in minimum error displacement.

  • 13.
    Nayl, Thaker
    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.
    Real-Time Bug-LIke Dynamic Path Planning for an Articulated Vehicle2014In: Informatics in Control, Automation and Robotics, Switzerland: Springer International Publishing , 2014, p. 201-215Chapter in book (Refereed)
    Abstract [en]

    This article proposes a novel real time bug like algorithm for performing a dynamic smooth path planning scheme for an articulated vehicle under limited and sensory reconstructed surrounding static environment. In the general case, collision avoidance techniques can be performed by altering the articulated steering angle to drive the front and rear parts of the articulated vehicle away from the obstacles. In the presented approach factors such as the real dynamics of the articulated vehicle, the initial and the goal configuration (displacement and orientation), minimum and total travel distance between the current and the goal points, and the geometry of the operational space are taken under consideration to calculate the update on the future way points for the articulated vehicle. In the sequel the produced path planning is iteratively smoothed online by the utilization of Bezier lines before producing the necessary rate of change for the vehicle’s articulated angle. The efficiency of the proposed scheme is being evaluated by multiple simulation studies that simulate the movement of the articulated vehicle in open and constrained spaces with the existence of multiple obstacles.

  • 14.
    Nayl, Thaker
    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.
    Switching model predictive control for an articulated vehicle2012Conference paper (Refereed)
    Abstract [en]

    In this article a switching model predictive control scheme for an articulated vehicle under varying slip angles is being presented. For the non–holonomic articulated vehicle, the non–linear kinematic model that is able to take under consideration the effect of the slip angles is extracted. This model is transformed into an error dynamics model, which in the sequence is linearized around multiple nominal slip angle regions. The existence of the slip angles has a significant effect on the vehicle’s path tracking capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple error dynamic models, the varying slip angle is being considered as the switching rule and a corresponding switching mode predictive control scheme is being designed.

  • 15.
    Nayl, Thaker
    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.
    Switching model predictive control for an articulated vehicle under varying slip angle2012In: 20th IEEE Mediterranean Conference on Control and Automation: Barcelona, Spain, July 3-6, 2012, Piscataway, NJ: IEEE Communications Society, 2012, p. 884-889Conference paper (Refereed)
    Abstract [en]

    In this article a switching model predictive control scheme for an articulated vehicle under varying slip angles is being presented. For the non–holonomic articulated vehicle, the non–linear kinematic model that is able to take under consideration the effect of the slip angles is extracted. This model is transformed to an error dynamics model, which in the sequence is linearized around multiple nominal slip angle cases. The existence of the slip angles has a significant effect on the vehicle’s path tracking capability and can significantly deteriorate the performance of the overall control scheme. Based on the derived multiple error dynamic models, the varying slip angle is being considered as the switching rule and a corresponding switching mode predictive control scheme is being designed that it is also able to take under consideration: a) the constrains on the control signals and b) the state constraints. Multiple simulation results are being presented that prove the efficacy of the overall suggested scheme.

  • 16.
    Nayl, Thaker
    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.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nyberg, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Design and experimental evaluation of a novel sliding mode controller for an articulated vehicle2018In: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 103, p. 213-221Article in journal (Refereed)
    Abstract [en]

    This article presents the design and experimental evaluation of a novel sliding mode control scheme, being applied to the case of an articulated vehicle. The proposed sliding mode controller is based on a novel continuous sliding surface, being introduced for reducing the chattering phenomenon, while achieving a better tracking performance and a fast minimization of the corresponding tracking error. The derivation of the sliding mode controller relies on the fully nonlinear kinematic model of the articulated vehicle, while the overall stability of the control scheme is proven based on the Lyapunov's stability condition. The performance of the established control scheme is being experimentally evaluated through multiple path tracking scenarios on a small scale and fully realistic articulated vehicle

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