Change search
Refine search result
12 51 - 78 of 78
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51.
    Wang, Yuquan
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Ögren, Petter
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Singularity analysis of closed-loop inverse kinematics algorithms with respect to manipulator geometric uncertainties2014Manuscript (preprint) (Other academic)
  • 52.
    Wang, Yuquan
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Ögren, Petter
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Colledanchise, Michele
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Marzinotto, Alejandro
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    A Distributed Convergent Solution to the Ambulance Positioning Problem on a Streetmap Graph2014In: / [ed] Boje, Edward, Xia, Xiaohua, IFAC Papers Online, 2014, Vol. 19, p. 9190-9196Conference paper (Refereed)
    Abstract [en]

    In this paper, we combine ideas from multi-agent cooperative coverage control, with problem formulations from the resource allocation field, to create a distributed convergent approach to the ambulance positioning problem. Inspired by coverage control we use the graph version of so-called Voronoi regions, making the solution distributed and reactive, thereby freeing computational resources. The solution is distributed in the sense that each vehicle only needs to know the positions of its neighbors, and the computations of each vehicle only depend on the size of its Voronoi region/set. This implies that considering a problem of twice the size, using twice the number of vehicles will leave the computational load per vehicle unchanged. The freed resources are used to capture the allocation problem in more detail: maximizing an estimate of the victim survival probability instead of more coarse measures of ambulance availability. Using real city street map data from OpenStreetMap (OSM), we provide simulation results illustrating the applicability of our approach. Finally, we prove that the proposed distributed algorithm is convergent in the sense that it finds a local optimum in finite time.

  • 53.
    Ögren, Petter
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Formations and Obstacle Avoidance in Mobile Robot Control2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis consists of four independent papers concerningthe control of mobile robots in the context of obstacleavoidance and formation keeping.

    The first paper describes a new theoreticallyv erifiableapproach to obstacle avoidance. It merges the ideas of twoprevious methods, with complementaryprop erties, byusing acombined control Lyapunov function (CLF) and model predictivecontrol (MPC) framework.

    The second paper investigates the problem of moving a fixedformation of vehicles through a partiallykno wn environmentwith obstacles. Using an input to state (ISS) formulation theconcept of configuration space obstacles is generalized toleader follower formations. This generalization then makes itpossible to convert the problem into a standard single vehicleobstacle avoidance problem, such as the one considered in thefirst paper. The properties of goal convergence and safetyth uscarries over to the formation obstacle avoidance case.

    In the third paper, coordination along trajectories of anonhomogenuos set of vehicles is considered. Byusing a controlLyapunov function approach, properties such as boundedformation error and finite completion time is shown.

    Finally, the fourth paper applies a generalized version ofthe control in the third paper to translate,rotate and expanda formation. It is furthermore shown how a partial decouplingof formation keeping and formation mission can be achieved. Theapproach is then applied to a scenario of underwater vehiclesclimbing gradients in search for specific thermal/biologicalregions of interest. The sensor data fusion problem fordifferent formation configurations is investigated and anoptimal formation geometryis proposed.

    Keywords:Mobile Robots, Robot Control, ObstacleAvoidance, Multirobot System, Formation Control, NavigationFunction, Lyapunov Function, Model Predictive Control, RecedingHorizon Control, Gradient Climbing, Gradient Estimation.

  • 54.
    Ögren, Petter
    Swedish Defence Research Agency (FOI).
    Improved predictability of reactive robot control using Control Lyapunov Functions2008In: 2008 IEEE/RSJ INTERNATIONAL CONFERENCE ON ROBOTS AND INTELLIGENT SYSTEMS, VOLS 1-3, CONFERENCE PROCEEDINGS, 2008, p. 1274-1279Conference paper (Refereed)
    Abstract [en]

    Model based robot control approaches are often designed to allow the verification of certain system properties such as safety or goal convergence. However, designing such controllers is often very time consuming, and most of the time it is not possible to add additional control objectives without jeopardizing the previously proved system properties.

  • 55.
    Ögren, Petter
    Swedish Defence Research Agency (FOI), Sweden.
    Increasing Modularity of UAV Control Systems using Computer Game Behavior Trees2012In: AIAA Guidance, Navigation, and Control Conference 2012, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper, we argue that the modularity, reusability and complexity of Unmanned Aerial Vehicle (UAV) guidance and control systems might be improved by using a Behavior Tree (BT) architecture. BTs are a particular kind of Hybrid Dynamical Systems (HDS), where the state transitions of the HDS are implicitly encoded in a tree structure, instead of explicitly stated in transition maps. In the gaming industry, BTs have gained a lot of interest, and are now replacing HDS in the control architecture of many automated in-game opponents. Below, we explore the relationship between HDS and BTs. We show that any HDS can be written as a BT and that many common UAV control constructs are quite naturally formulated as BTs. Finally, we discuss the positive implications of making the above mentioned state transitions implicit in the BTs.

  • 56.
    Ögren, Petter
    Swedish Defence Research Agency (FOI).
    Split and Join of Vehicle Formations doing Obstacle Avoidance2004In: 2004 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1- 5, PROCEEDINGS, 2004, p. 1951-1955Conference paper (Refereed)
    Abstract [en]

    In this paper, we study a scenario where a set of vehicles having different origins and/or destinations move in a common region. The goal is to have the vehicles join and leave formations in a completely decentralized manner. When a vehicle traveling along its own path finds itself moving close to another vehicle it automatically switches into follower mode. The vehicle stays in follower mode as long as the path of the other vehicle is beneficial to it. If, at some point, the leader is not moving towards the destination of the follower, the follower leaves the leader and head of on its own. We address this problem for a group of dynamic unicycle robots. Incorporating the split and join capability into a Receding Horizon Control approach to obstacle avoidance we are able to show safety as well as convergence of all vehicles to their destinations under general nonconvex obstacle assumptions. We illustrate the method with a simulation example

  • 57.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Backlund, Adam
    Swedish Defence Research Agency (FOI).
    Harryson, Tobias
    Swedish Air Force, Air Combat School .
    Kristensson, Lars
    Swedish Defence Research Agency (FOI).
    Stensson, Patrik
    Swedish Air Force, Air Combat School.
    Autonomous UCAV Strike Missions using Behavior Control Lyapunov Functions2006Conference paper (Refereed)
    Abstract [en]

    An autonomous Unmanned Combat Aerial Vehicle (UCAV) carrying out a surveillance or strike mission must be able to handle situations where the different mission objectives are in conflict and a tradeoff must be made, e.g. when the time of arrival is in conflict with the prescribed safety distance to an enemy surface to air missile (SAM) site. This paper describes a framework called Behavior Control Lyapunov Functions (BCLF), to handle such tradeoffs. The framework combines the natural idea of different control behaviors for different mission objectives, suggested in the Behavior Based robotics approach, with the mathematical transparency of Control Lyapunov Functions (CLF) from control theory. First, each behavior is represented by a scalar function with certain CLF-like properties, describing to what extent that mission objective is satisfied. The operator then edits a priority table reflecting the order of importance between different objectives, as well as different levels of satisfaction. Based on the table and the current levels of satisfaction the algorithm decides which objectives should be focused on right now, and which should currently be ignored. Finally, the current high priority objectives are transformed into recommended subsets of the available control choices, and passed to the controller. The paper is concluded with simulation examples illustrating the approach.

  • 58.
    Ögren, Petter
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Robotics, perception and learning, RPL.
    Colledanchise, Michele
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Behavior Trees in Robotics and AI: An Introduction2018 (ed. First)Book (Refereed)
    Abstract [en]

    Behavior Trees (BTs) provide a way to structure the behavior of an artificial agent such as a robot or a non-player character in a computer game.  Traditional design methods, such as finite state machines, are known to produce brittle behaviors when complexity increases, making it very hard to add features without breaking existing functionality.  BTs were created to address this very problem, and enables the creation of systems that are both modular and reactive. Behavior Trees in Robotics and AI: An Introduction provides a broad introduction as well as an in-depth exploration of the topic, and is the first comprehensive book on the use of BTs.

  • 59.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Egerstedt, M
    Hu, X
    A Control Lyapunov Function Approach to Multi-Agent Coordination2001Conference paper (Refereed)
    Abstract [en]

    In this paper, the multiagent coordination problem is studied. This problem is addressed for a class of robots for which control Lyapunov functions can be found. The main result is a suite of theorems about formation maintenance, task completion time, and formation velocity. It is also shown how to moderate the requirement that, for each individual robot, there exists a control Lyapunov function. An example is provided that illustrates the soundness of the method

  • 60.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Egerstedt, M
    Hu, X
    A control Lyapunov function approach to multi-agent coordination2002In: IEEE transactions on robotics and automation, ISSN 1042-296X, Vol. 18, no 5, p. 847-851Article in journal (Refereed)
    Abstract [en]

    In this paper, the multiagent coordination problem is studied. This problem is addressed for a class of robots for which control Lyapunov functions can be found. The main result is a suite of theorems about formation maintenance, task completion time, and formation velocity. It is also shown how to moderate the requirement that, for each individual robot, there exists a control Lyapunov function. An example is provided that illustrates the soundness of the method

  • 61.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Egerstedt, M
    Hu, X
    Reactive mobile manipulation using dynamic trajectory tracking2000Conference paper (Refereed)
    Abstract [en]

    A solution to the trajectory tracking problem for mobile manipulators is proposed, that allows for the base to be influenced by a reactive, obstacle avoidance behavior. Given a trajectory for the gripper to follow, a tracking algorithm for the manipulator is designed, and at the same time the base motions are generated in such a way that the base is coordinated with the gripper. Furthermore, it is shown that the method allows arbitrary upper and lower bounds on the gripper-base distance to be set and this can be achieved without introducing deadlocks into the system. The solution also ensures that the control effort, spent on slow base motions, is kept small

  • 62.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Fiorelli, E
    Leonard, N.E.
    Formations with a Mission: Stable Coordination of Vehicle Group Maneuvers2002Conference paper (Refereed)
    Abstract [en]

    In this paper we present a stable coordination strategy for vehicle formation missions that involve group translation, rotation, expansion and contraction. The underlying coordination framework uses artificial potentials and virtual leaders. Symmetry in the framework is exploited to partially decouple the mission control problem into a formation management subproblem and a maneuver management subproblem. The designed dynamics of the virtual leaders play a key role in both subproblems: the direction of motion of the virtual leaders is designed to satisfy the mission while the speed of the virtual leaders is designed to ensure stability and convergence properties of the formation. The latter is guaranteed by regulating the virtual leader speed according to a feedback measurement of an appropriate formation error function. The coordination strategy is illustrated in the context of adaptive gradient climbing missions.

  • 63.
    Ögren, Petter
    et al.
    Swedish Defense Research Agency.
    Fiorelli, Eddie
    Princeton University.
    Leonard, Naomi
    Princeton University.
    Cooperative Control of Mobile Sensor Networks: Adaptive Gradient Climbing in a Distributed Environment2004In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 49, no 8, p. 1292-1302Article in journal (Refereed)
  • 64.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Leonard, N
    Obstacle Avoidance in Formation,2003Conference paper (Refereed)
    Abstract [en]

    In this paper, we present an approach to obstacle avoidance for a group of unmanned vehicles moving in formation. The goal of the group is to move through a partially unknown environment with obstacles and reach a destination while maintaining the formation. We address this problem for a class of dynamic unicycle robots. Using Input-to-State Stability we combine a general class of formation-keeping control schemes with a new dynamic window approach to obstacle avoidance in order to guarantee safety and stability of the formation as well as convergence to the goal position. An important part of the proposed approach can be seen as a formation extension of the configuration space obstacle concept. We illustrate the method with a challenging example.

  • 65.
    Ögren, Petter
    et al.
    Mech. & Aerosp. Eng. Dept., Princeton Univ., NJ, USA.
    Leonard, Naomi Ehrich
    Mech. & Aerosp. Eng. Dept., Princeton Univ., NJ, USA.
    A Convergent Dynamic Window Approach to Obstacle Avoidance2005In: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 21, no 2, p. 188-195Article in journal (Refereed)
    Abstract [en]

    The dynamic window approach (DWA) is a well-known navigation scheme developed by Fox et al. and extended by Brock and Khatib. It is safe by construction, and has been shown to perform very efficiently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. Here we present such a treatment by merging the ideas of the DWA with the convergent, but less performance-oriented, scheme suggested by Rimon and Koditschek. Viewing the DWA as a model predictive control (MPC) method and using the control Lyapunov function (CLF) framework of Rimon and Koditschek, we draw inspiration from an MPC/CLF framework put forth by Primbs to propose a version of the DWA that is tractable and convergent.

  • 66.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Leonard, N.E.
    A Probably Convergent Dynamic Window Approach to Obstaclen Avoidance2002Conference paper (Refereed)
    Abstract [en]

    The dynamic window approach is a well known navigation scheme developed in Fox et al. (1997) and extended in Brock and Khatib (1999). It is safe by construction and has been shown to perform very e#ciently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. Here we present such a treatment.

  • 67.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Leonard, N.E.
    A tractable convergent dynamic window approach to obstacle avoidance2002Conference paper (Refereed)
    Abstract [en]

    The dynamic window approach is a well known navigation scheme developed by Fox et. al. [1] and extended by Brock and Khatib [2]. It is safe by construction and has been shown to perform very efficiently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. A first step towards such a treatment was presented in [4]. Here we continue that work with a computationally tractable algorithm resulting from a careful discretization of the optimal control problem of the previous paper and a way to construct a continuous Navigation Function. Inspired by the similarities between the Dynamic Window Approach and the Control Lyapunov Function and Receding Horizon Control synthesis put forth by Primbs et. al. [3] we propose a version of the Dynamic Window Approach that is tractable and provably convergent.

  • 68.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Martin, C.F.
    Optimal Vaccination Strategies for the Control of Epidemics in Highly Mobile Populations2000Conference paper (Refereed)
    Abstract [en]

    Our goal is to calculate optimal vaccination patterns for a rapidly spreading disease in an urbanized highly mobile population. The goal being to determine if vaccination can effect a disease for which there is low immunity in the population. Different types of structured SIR models are investigated. We construct a model appropriate for a traveling urbanized population and introduce a control in terms of a vaccination program. Linear constraints, a quadratic cost on the control and a linear cost on the number of infected are imposed. In this setting we calculate optimal vaccination patterns using the maximum principle of Pontryagin

  • 69.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Martin, C.F
    Vaccination Strategies for Epidemics in Highly Mobile Populations2002In: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 127, no 2-3, p. 261-276Article in journal (Refereed)
    Abstract [en]

    Our goal is to calculate optimal vaccination patterns for a rapidly spreading disease in an urbanized highly mobile population. The goal being to determine if vaccination can effect a disease for which there is low immunity in the population. Different types of structured SIR models are investigated. We construct a model appropriate for a traveling urbanized population and introduce a control in terms of a vaccination program. Linear constraints, a quadratic cost on the control and a linear cost on the number of infected are imposed. In this setting we calculate optimal vaccination patterns using the maximum principle of Pontryagin. The numerics are performed using Matlab.

  • 70.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Petersson, L
    Egerstedt, M
    Hu, X
    Reactive mobile manipulation using dynamic trajectory tracking: design and implementation2000Conference paper (Refereed)
    Abstract [en]

    A solution to the trajectory tracking problem for mobile manipulators is proposed and implemented on a real robotic system. Given a trajectory for the gripper to follow, a tracking algorithm for the manipulator is designed, and at the same time the base motions are generated in such a way that the base is coordinated with the gripper while reactively avoiding obstacles. Furthermore, it is shown that the method allows arbitrary upper and lower bounds on the gripper-base distance to be set, and this can be achieved without introducing deadlocks into the system

  • 71.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Robinson, John W.C.
    Swedish Defence Research Agency (FOI), Department of Aeronautics .
    A Model Based Approach to Modular Multi-Objective Robot Control2011In: Journal of Intelligent and Robotic Systems, ISSN 0921-0296, E-ISSN 1573-0409, Vol. 63, no 2, p. 257-282Article in journal (Refereed)
    Abstract [en]

    Two broad classes of robot controllers are the modular, and the model based approaches. The modular approaches include the Reactive or Behavior Based designs. They do not rely on mathematical system models, but are easy to design, modify and extend. In the model based approaches, a model is used to design a single controller with verifiable system properties. The resulting designs are however often hard to extend, without jeopardizing the previously proven properties. This paper describes an attempt to narrow the gap between the flexibility of the modular approaches, and the predictability of the model based approaches, by proposing a modular design that does the combination, or arbitration, of the different modules in a model based way. By taking the (model based) time derivatives of scalar, Lyapunov-like, objective functions into account, the arbitration module can keep track of the time evolution of the objectives. This enables it to handle objective tradeoffs in a predictable way by finding controls that preserve an important objective that is currently met, while striving to satisfy another, less important one that is not yet achieved. To illustrate the approach a UAV control problem from the literature is solved, resulting in comparable, or better, performance.

  • 72.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI), Department of Aeronautics and Systems Technology,.
    Robinson, John W.C.
    Swedish Defence Research Agency (FOI), Department of Aeronautics .
    Receding Horizon Control of UAVs using Gradual Dense-Sparse Discretizations2010Conference paper (Refereed)
    Abstract [en]

    In this paper we propose a way of increasing the eciency of some direct Receding Horizon Control (RHC) schemes. The basic idea is to adapt the allocation of compu- tational resources to how the iterative plans are used. By using Gradual Dense-Sparse discretizations (GDS), we make sure that the plans are detailed where they need to be, i.e., in the very near future, and less detailed further ahead. The gradual transition in discretization density re ects increased uncertainty and reduced need for detail near the end of the planning horizon. The proposed extension is natural, since the standard RHC approach already contains a computational asymmetry in terms of the coarse cost-to-go computations and the more detailed short horizon plans. Using GDS discretizations, we bring this asymmetry one step further, and let the short horizon plans themselves be detailed in the near term and more coarse in the long term. The rationale for dierent levels of detail is as follows. 1) Near future plans need to be implemented soon, while far future plans can be rened or revised later. 2) More accurate sensor information is available about the system and its surroundings in the near future, and detailed planning is only rational in low uncertainty situations. 3) It has been shown that reducing the node density in the later parts of xed horizon optimal control problems gives a very small reduction in the solution quality of the rst part of the trajectory. The reduced level of detail in the later parts of a plan can increase the eciency of the RHC in two ways. If the discretization is made sparse by removing nodes, fewer computations are necessary, and if the discretization is made sparse by spreading the last nodes over a longer time-horizon, the performance will be improved.

  • 73.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Smith, Christian
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Karayiannidis, Yiannis
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Kragic, Danica
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    A Multi Objective Control Approach to Online Dual Arm Manipulation2012In: Robot Control, International Federation of Automatic Control , 2012, p. 747-752Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a new way to exploit the redundancy of dual arm mobile manipulators when performing inherently bi-manual tasks using online controllers. Bi-manual tasks are tasks that require motion of both arms in order to be carried out efficiently, such as holding and cleaning an object, or moving an object from one hand to the other. These tasks are often associated with several constraints, such as singularity- and collision avoidance, but also a high degree of redundancy, as the relative positions of the two grippers is far more important than the absolute positions, when for example handing an object from one arm to the other. By applying a modular multi objective control framework, inspired by earlier work on sub-task control, we exploit this redundancy to form a subset of the joint space that is feasible, i.e. not violating any of the constraints. Earlier approacher added the additional tasks in terms of equality constraints, thereby reducing the dimension of the feasible subset until it was a single point. Here however, we add the additional tasks in terms of inequalities, removing parts of the feasible set rather than collapsing its dimensionality. Thus, we are able to handle an arbitrary number of constraints, instead of a number corresponding to the dimension of the feasible set (degree of redundancy). Finally, inside the feasible set we choose controls stay in the set, while simultaneously minimizing some given objective. The proposed approach is illustrated by several simulation examples.

  • 74.
    Ögren, Petter
    et al.
    Swedish Defence Res. Agency, Stockholm.
    Svenmarck, Peter
    Swedish Defence Res. Agency, Stockholm.
    A New Control Mode for Teleoperated Differential Drive UGVs2007In: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-14, 2007, p. 446-471Conference paper (Refereed)
    Abstract [en]

    This paper proposes a control mode that enables the users of teleoperated non-holonomic differential drive unmanned ground vehicles (UGVs) to interact with the unmanned vehicles in a new way. By introducing an intermediate control layer, a user interface that is very similar to so-called first person shooter (FPS) computer games, e.g. Doom and Half Life, can be created. The advantages of such interfaces is that they are intuitive, and that literally millions of potential future UGV-operators already have spent hundreds of hours training with them. The control mode gives the user direct control of the position and orientation of the on-board camera, while the actual orientation of the vehicle is abstracted away using feedback linearization. Thus, the idea is similar to using inverse kinematics to directly control the position and orientation of a robot arm gripper. The paper first describes the predominant direct vehicle control model, as well as the FPS interfaces. It is then shown how the proper choice of intermediate control layer can make the two equivalent

  • 75.
    Ögren, Petter
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP. KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Svenmarck, Peter
    FOI.
    Lif, Patric
    FOI.
    Norberg, Martin
    FOI.
    Söderbäck, Nils Emil
    Swedish Defence Research Agency (FOI).
    Design and implementation of a new teleoperation control mode for differential drive UGVs2014In: Autonomous Robots, ISSN 0929-5593, E-ISSN 1573-7527, Vol. 37, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose and implement a new control mode for teleoperated unmanned ground vehicles (UGVs), that exploits the similarities between computer games and teleoperation robotics. Today, all teleoperated differential drive UGVs use a control mode called Tank Control, in which the UGV chassis and the pan tilt camera are controlled separately. This control mode was also the dominating choice when the computer game genre First Person Shooter (FPS) first appeared. However, the hugely successful FPS genre, including titles such as Doom, Half Life and Call of Duty, now uses a much more intuitive control mode, Free Look Control (FLC), in which rotation and translation of the character are decoupled, and controlled separately. The main contribution of this paper is that we replace Tank Control with FLC in a real UGV. Using feedback linearization, the orientation of the UGV chassis is abstracted away, and the orientation and translation of the camera are decoupled, enabling the operator to use FLC when controlling the UGV. This decoupling is then experimentally verified. The developments in the gaming community indicates that FLC is more intuitive than Tank Control and reduces the well known situational awareness problem. It furthermore reduces the need for operator training, since literary millions of future operators have already spent hundreds of hours using the interface.

  • 76.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Winstrand, Maja
    Swedish Defence Research Agency (FOI).
    Combining Path Planning and Target Assignment to Minimize Risk in a SEAD Mission2005Conference paper (Refereed)
  • 77.
    Ögren, Petter
    et al.
    Department of Autonomous Systems Swedish Defence Research Agency.
    Winstrand, Maja
    Minimizing Mission Risk in Fuel Constrained UAV Path Planning2008In: Journal of Guidance Control and Dynamics, ISSN 0731-5090, E-ISSN 1533-3884, Vol. 31, no 5, p. 1497-1500Article in journal (Refereed)
  • 78.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Wirkander, Sven-Lennart
    Swedish Defence Research Agency (FOI).
    Stefansson, Anna
    Swedish Defence Research Agency (FOI).
    Pelo, Johan
    Swedish Defence Research Agency (FOI).
    Formulation and Solution of the UAV Paparazzi Problem2006Conference paper (Refereed)
    Abstract [en]

    Many UAV path planning problems dealing with multiple targets are formulated as instances of classical optimization problems such as the Traveling Salesperson Problem (TSP), Vehicle Routing Problem (VRP), and the Assignment Problem (AP). In their basic forms, all these problems minimize the length of the flight path to be flown by the UAVs. Even though this is often a reasonable choice, we argue that in instances when the targets are able to hide, or move, an objective function accounting for the target value, as well as the chance of actually finding the target is more natural. In some sense, the problem is similar to the one faced by a Paparazzi photographer, deciding where to go to get snapshots of non cooperative celebrities. Hence we formulate the so-called Paparazzi utility function, and show how it can be applied to UAV path planning problems similar to the TSP, VRP and AP

12 51 - 78 of 78
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf