| 1. |
- Altafini, Claudio, et al.
(författare)
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A feedback control scheme for reversing a truck and trailer vehicle
- 2001
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Ingår i: IEEE transactions on robotics and automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1042-296X. ; 17:6, s. 915-922
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Tidskriftsartikel (refereegranskat)abstract
- A control scheme is proposed for stabilization of backward driving along simple paths for a miniaturized vehicle composed of a truck and a two-axle trailer. The paths chosen are straight lines and arcs of circles. When reversing, the truck and trailer under examination can be modeled as an unstable nonlinear system with state and input saturations. The simplified goal of stabilizing along a trajectory (instead of a point) allows us to consider a system with controllable linearization. Still, the combination of instability and saturations makes the task impossible with a single controller. In fact, the system cannot be driven backward from all initial states because of the jack-knife effects between the parts of the multibody vehicle; it is sometimes necessary to drive forward to enter into a specific region of attraction. This leads to the use of hybrid controllers. The scheme has been implemented and successfully used to reverse the radio-controlled vehicle.
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| 2. |
- Altafini, Claudio
(författare)
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Redundant robotic chains on Riemannian submersions
- 2004
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Ingår i: IEEE transactions on robotics and automation. - 1042-296X. ; 20:2, s. 335-340
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Tidskriftsartikel (refereegranskat)abstract
- The main scope of this paper is to introduce the notion of Riemannian submersion for the modeling and control of certain types of redundant robotic chains. in the robotics literature, the redundant case is normally treated only in numerical terms, as the need to resort to pseudoinversion techniques is usually considered a barrier to the use of analytic or geometric methods. Using Riemannian submersions, however, we can single out a particular type of inverse, the horizontal lift, with distinguished properties with respect to the infinitely many possible others. Quite remarkably, for a wide class of robotic chains, characterized by the vanishing of the curvature tensor, such horizontal lift coincides with the curve obtained from the Moore-Penrose pseudoinverse of the Jacobian.
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| 3. |
- Hu, Xiaoming
(författare)
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Formation constrained multi-agent control
- 2001
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Ingår i: IEEE transactions on robotics and automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1042-296X. ; 17:6, s. 947-951
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Tidskriftsartikel (refereegranskat)abstract
- We propose a model independent coordination strategy for multi-agent formation control. The main theorem states that under a bounded tracking error assumption our method stabilizes the formation error. We illustrate the usefulness of the method by applying it to rigid body constrained motions.
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| 4. |
- Jensfelt, Patric, et al.
(författare)
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Active global localization for a mobile robot using multiple hypothesis tracking
- 2001
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Ingår i: IEEE transactions on robotics and automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1042-296X. ; 17:5, s. 748-760
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a probabilistic approach for mobile robot localization using an incomplete topological world model. The method, which we have termed multi-hypothesis localization (MHL), uses multi-hypothesis Kalman filter based pose tracking combined with a probabilistic formulation of hypothesis correctness to generate and track Gaussian pose hypotheses online. Apart from a lower computational complexity, this approach has the advantage over traditional grid based methods that incomplete and topological world model information can be utilized. Furthermore, the method generates movement commands for the platform to enhance the gathering of information for the pose estimation process. Extensive experiments are presented from two different environments, a typical office environment and an old hospital building.
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| 5. |
- Jensfelt, Patric, et al.
(författare)
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Pose tracking using laser scanning and minimalistic environmental models
- 2001
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Ingår i: IEEE transactions on robotics and automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1042-296X. ; 17:2, s. 138-147
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Tidskriftsartikel (refereegranskat)abstract
- Keeping track of the position and orientation over time using sensor data, i.e., pose tracking, is a central component in many mobile robot systems. In this paper, we present a Kalman filter-based approach utilizing a minimalistic environmental model. By continuously updating the pose, matching the sensor data to the model is straightforward and outliers can be filtered out effectively by validation gates, The minimalistic model paves the way for a low-complexity algorithm with a high degree of robustness and accuracy. Robustness here refers both to being able to track the pose for a long time, but also handling changes and clutter in the environment. This robustness is gained by the minimalistic model only capturing the stable and large scale features of the environment. The effectiveness of the pose tracker will be demonstrated through a number of experiments, including a run of 90 min, which clearly establishes the robustness of the method.
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| 6. |
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| 7. |
- Kragic, Danica, et al.
(författare)
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Cue integration for visual servoing
- 2001
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Ingår i: IEEE transactions on robotics and automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1042-296X. ; 17:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- The robustness and reliability of vision algorithms is, nowadays, the key issue in robotic research and industrial applications. To control a robot in a closed-loop fashion, different tracking systems have been reported in the literature, A common approach to increased robustness of a tracking system is the use of different models (CAD model of the object, motion model) known a priori, Our hypothesis is that fusion of multiple features facilitates robust detection and tracking of objects in scenes of realistic complexity. A particular application is the estimation of a robot's end-effector position in a sequence of images. The research investigates the following two different approaches to cue integration: 1) voting and 2) fuzzy logic-based fusion, The two approaches have been tested in association,vith scenes of varying complexity. Experimental results clearly demonstrate that fusion of cues results in a tracking system with a robust performance. The robustness is in particular evident for scenes with multiple moving objects and partial occlusion of the tracked object.
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| 8. |
- Kragic, Danica
(författare)
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Visual Servoing for Manipulation: Robustness and Integration Issues
- 2001
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Ingår i: IEEE transactions on robotics and automation. - 1042-296X. ; , s. 230-
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Tidskriftsartikel (refereegranskat)abstract
- Service robots are gradually extended to operation in everyday environments. To be truly useful, a mobile robot should include facilities for interaction with the envi- ronment, in particular methods for manipulation of objects. One of the most flexible sensory modalities to enable this is computational vision. In this thesis the issue of visual servoing and grasping to facilitate such interaction is investigated. A notorious problem for use of vision in natural environments is robustness with respect to variations in the environment. It is also well-known that no single technique is suitable for different tasks a robot is supposed to perform. Robustness is here investigated using several different approaches. The issues of variability are formulated with respect to visual features, the number of cameras used, and task constraints. It is argued that integration of methods facilitate construction of more robust visual servoing systems for realistic tasks. Traditionally, fusion of visual information has been based on explicit models for uncertainty and integration. The most dominating technique has been use of Bayesian statistics, where strong models are employed. Where a large number of visual features are available it is suggested that it might be possible to perform tasks such as visual tracking using weak models for integration. In particular, integration using voting based methods is analyzed. If the object to be manipulated is known or has been recognized, it is possible to use explicit geometric models to facilitate the estimation of its pose. Consequently, a methodology for tracking of objects using wire-frame models has been developed and evaluated in the context of grasping. Visual servoing can be carried out in the image domain and/or using 3D in- formation. In this context, the tradeoff between explicit models and use of multiple cameras strongly influences the performance of a visual servoing system. The relation between visual features, the number of cameras and their placement has been studied to provide guidelines for a design of such a system. An integration of a multi-ocular vision system, suitable visual techniques and task constraints facilitate flexible manipulation of everyday objects. To demonstrate this the developed techniques have been evaluated in the context of manipulation for opening/closing of doors in an everyday setting. In addition, it is demonstrated how the techniques, together with model based information, may be used for grasping and grasp monitoring in the context of a well-known set of objects. In summary, a toolkit for interaction with everyday objects has been investigated and evaluated for real-world tasks. The developed methods provide a rich basis for real-world manipulation of objects in everyday settings.
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| 9. |
- Norrlöf, Mikael, 1971-
(författare)
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An Adaptive Iterative Learning Control Algorithm with Experiments on an Industrial Robot
- 2002
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Ingår i: IEEE transactions on robotics and automation. - Linköping : Linköping University Electronic Press. - 1042-296X. ; 18:2, s. 245-251
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Tidskriftsartikel (refereegranskat)abstract
- An adaptive iterative learning control (ILC) algorithm based on an estimation procedure using a Kalman filter and an optimization of a quadratic criterion is presented. It is shown that by taking the measurement disturbance into consideration the resulting ILC filters become iteration-varying. Results from experiments on an industrial robot show that the algorithm is successful also in an application.
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| 10. |
- Norrlöf, Mikael, 1971-, et al.
(författare)
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Experimental Comparison of some Classical Iterative Learning Control Algorithms
- 2002
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Ingår i: IEEE transactions on robotics and automation. - Linköping : Linköping University Electronic Press. - 1042-296X. ; 18:4, s. 636-641
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Tidskriftsartikel (refereegranskat)abstract
- This letter gives an overview of classical iterative learning control algorithms. The presented algorithms are also evaluated on a commercial industrial robot from ABB. The presentation covers implicit to explicit model-based algorithms. The result from the evaluation of the algorithms is that performance can be achieved by having more system knowledge.
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