| 1. |
- Afzali-Far, Behrouz, et al.
(författare)
-
Dynamic isotropy in 3-DOF Gantry Tau robots - An analytical study
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - 9781467380263 ; , s. 854-860
-
Konferensbidrag (refereegranskat)abstract
- 3-DOF Gantry Tau is a type of parallel robot, consisting of six struts configured in three clusters, which provides three translational DOFs. It has increasing industrial use in applications where large workspace and high stiffness are required. In fact, the concept of dynamic isotropy, where all the natural frequencies of a system are equal, can be employed in order to effectively optimize the geometry of robots. However, no study on dynamic isotropy of Gantry Tau robots has yet been reported in the literature. In this paper, the problem of dynamic isotropy in 3-DOF Gantry Tau robots is analytically addressed. Firstly, the kinematics is established based on a general approach with 36 geometric variables. Jacobian and stiffness matrices are also investigated where the struts are considered to be axially flexible. Subsequently, analytical solutions to obtain both a decoupled stiffness matrix and a complete dynamic isotropy are presented. Finally, as an example, dynamically isotropic geometries of a Gantry Tau robot are calculated, for a reference platform, using the developed analytical method.
|
|
| 2. |
- Almeida, Diogo, 1991-, et al.
(författare)
-
Folding Assembly by Means of Dual-Arm Robotic Manipulation
- 2016
-
Ingår i: 2016 IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 1050-4729. - 9781467380263 ; , s. 3987-3993
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we consider folding assembly as an assembly primitive suitable for dual-arm robotic assembly, that can be integrated in a higher level assembly strategy. The system composed by two pieces in contact is modelled as an articulated object, connected by a prismatic-revolute joint. Different grasping scenarios were considered in order to model the system, and a simple controller based on feedback linearisation is proposed, using force torque measurements to compute the contact point kinematics. The folding assembly controller has been experimentally tested with two sample parts, in order to showcase folding assembly as a viable assembly primitive.
|
|
| 3. |
- Båberg, Fredrik, et al.
(författare)
-
Adaptive object centered teleoperation control of a mobile manipulator
- 2016
-
Ingår i: 2016 IEEE International Conference on Robotics and Automation (ICRA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467380263 ; , s. 455-461
-
Konferensbidrag (refereegranskat)abstract
- Teleoperation of a mobile robot manipulating and exploring an object shares many similarities with the manipulation of virtual objects in a 3D design software such as AutoCAD. The user interfaces are however quite different, mainly for historical reasons. In this paper we aim to change that, and draw inspiration from the 3D design community to propose a teleoperation interface control mode that is identical to the ones being used to locally navigate the virtual viewpoint of most Computer Aided Design (CAD) softwares.The proposed mobile manipulator control framework thus allows the user to focus on the 3D objects being manipulated, using control modes such as orbit object and pan object, supported by data from the wrist mounted RGB-D sensor. The gripper of the robot performs the desired motions relative to the object, while the manipulator arm and base moves in a way that realizes the desired gripper motions. The system redundancies are exploited in order to take additional constraints, such as obstacle avoidance, into account, using a constraint based programming framework.
|
|
| 4. |
- Ghadirzadeh, Ali, et al.
(författare)
-
Self-learning and adaptation in a sensorimotor framework
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 9781467380263 ; , s. 551-558
-
Konferensbidrag (refereegranskat)abstract
- We present a general framework to autonomously achieve the task of finding a sequence of actions that result in a desired state. Autonomy is acquired by learning sensorimotor patterns of a robot, while it is interacting with its environment. Gaussian processes (GP) with automatic relevance determination are used to learn the sensorimotor mapping. In this way, relevant sensory and motor components can be systematically found in high-dimensional sensory and motor spaces. We propose an incremental GP learning strategy, which discerns between situations, when an update or an adaptation must be implemented. The Rapidly exploring Random Tree (RRT∗) algorithm is exploited to enable long-term planning and generating a sequence of states that lead to a given goal; while a gradient-based search finds the optimum action to steer to a neighbouring state in a single time step. Our experimental results prove the suitability of the proposed framework to learn a joint space controller with high data dimensions (10×15). It demonstrates short training phase (less than 12 seconds), real-time performance and rapid adaptations capabilities.
|
|
| 5. |
- Guo, Meng, et al.
(författare)
-
Hybrid control of multi-robot systems using embedded graph grammars
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 9781467380263 ; , s. 5242-5247
-
Konferensbidrag (refereegranskat)abstract
- We propose a distributed and cooperative motion and task control scheme for a team of mobile robots that are subject to dynamic constraints including inter-robot collision avoidance and connectivity maintenance of the communication network. Moreover, each agent has a local high-level task given as a Linear Temporal Logic (LTL) formula of desired motion and actions. Embedded graph grammars (EGGs) are used as the main tool to specify local interaction rules and switching control modes among the robots, which is then combined with the model-checking-based task planning module. It is ensured that all local tasks are satisfied while the dynamic constraints are obeyed at all time. The overall approach is demonstrated by simulation and experimental results.
|
|
| 6. |
- Hang, Kaiyu, et al.
(författare)
-
On the Evolution of Fingertip Grasping Manifolds
- 2016
-
Ingår i: IEEE International Conference on Robotics and Automation. - : IEEE Robotics and Automation Society. - 9781467380263 ; , s. 2022-2029
-
Konferensbidrag (refereegranskat)abstract
- Efficient and accurate planning of fingertip grasps is essential for dexterous in-hand manipulation. In this work, we present a system for fingertip grasp planning that incrementally learns a heuristic for hand reachability and multi-fingered inverse kinematics. The system consists of an online execution module and an offline optimization module. During execution the system plans and executes fingertip grasps using Canny’s grasp quality metric and a learned random forest based hand reachability heuristic. In the offline module, this heuristic is improved based on a grasping manifold that is incrementally learned from the experiences collected during execution. The system is evaluated both in simulation and on a SchunkSDH dexterous hand mounted on a KUKA-KR5 arm. We show that, as the grasping manifold is adapted to the system’s experiences, the heuristic becomes more accurate, which results in an improved performance of the execution module. The improvement is not only observed for experienced objects, but also for previously unknown objects of similar sizes.
|
|
| 7. |
- Ortega, T., et al.
(författare)
-
Performance Without Tweaking Differentiators via a PR controller : Furuta Pendulum Case Study
- 2016
-
Ingår i: 2016 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467380263 ; , s. 3777-3782
-
Konferensbidrag (refereegranskat)abstract
- Performance of mechatronics systems can deteriorate significantly under the presence of delays in measurements. On the other hand, intentional introduction of a delay in a feedback control law may be beneficial in achieving good performance without relying on accurately tuned estimates for derivatives of measured signals. In this context, a proper design of retarded control laws represents an important challenge, and this paper gives a step forward to obtain better control laws for underactuated mechanical systems under the presence of time delays in measurements. Particularly, a Proportional-Retarded (PR) control law is designed for stabilization of an underactuated rotational inverted pendulum, known as the Furuta pendulum. Experiments over a laboratory platform as well as a comparison with a Linear Quadratic Regulator (LQR) are performed to show the advantages of the proposed scheme.
|
|
| 8. |
- Pieropan, Alessandro, et al.
(författare)
-
Robust tracking of unknown objects through adaptive size estimation and appearance learning
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 9781467380263 ; , s. 559-566
-
Konferensbidrag (refereegranskat)abstract
- This work employs an adaptive learning mechanism to perform tracking of an unknown object through RGBD cameras. We extend our previous framework to robustly track a wider range of arbitrarily shaped objects by adapting the model to the measured object size. The size is estimated as the object undergoes motion, which is done by fitting an inscribed cuboid to the measurements. The region spanned by this cuboid is used during tracking, to determine whether or not new measurements should be added to the object model. In our experiments we test our tracker with a set of objects of arbitrary shape and we show the benefit of the proposed model due to its ability to adapt to the object shape which leads to more robust tracking results.
|
|
| 9. |
- Pokorny, F. T., et al.
(författare)
-
High-dimensional Winding-Augmented Motion Planning with 2D topological task projections and persistent homology
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 9781467380263 ; , s. 24-31
-
Konferensbidrag (refereegranskat)abstract
- Recent progress in motion planning has made it possible to determine homotopy inequivalent trajectories between an initial and terminal configuration in a robot configuration space. Current approaches have however either assumed the knowledge of differential one-forms related to a skeletonization of the collision space, or have relied on a simplicial representation of the free space. Both of these approaches are currently however not yet practical for higher dimensional configuration spaces. We propose 2D topological task projections (TTPs): mappings from the configuration space to 2-dimensional spaces where simplicial complex filtrations and persistent homology can identify topological properties of the high-dimensional free configuration space. Our approach only requires the availability of collision free samples to identify winding centers that can be used to determine homotopy inequivalent trajectories. We propose the Winding Augmented RRT and RRT∗ (WA-RRT/RRT∗) algorithms using which homotopy inequivalent trajectories can be found. We evaluate our approach in experiments with configuration spaces of planar linkages with 2-10 degrees of freedom. Results indicate that our approach can reliably identify suitable topological task projections and our proposed WA-RRT and WA-RRT∗ algorithms were able to identify a collection of homotopy inequivalent trajectories in each considered configuration space dimension.
|
|
| 10. |
- Pokorny, Florian T., et al.
(författare)
-
Topological Trajectory Clustering with Relative Persistent Homology
- 2016
-
Ingår i: 2016 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467380263 ; , s. 16-23
-
Konferensbidrag (refereegranskat)abstract
- Cloud Robotics techniques based on Learning from Demonstrations suggest promising alternatives to manual programming of robots and autonomous vehicles. One challenge is that demonstrated trajectories may vary dramatically: it can be very difficult, if not impossible, for a system to learn control policies unless the trajectories are clustered into meaningful consistent subsets. Metric clustering methods, based on a distance measure, require quadratic time to compute a pairwise distance matrix and do not naturally distinguish topologically distinct trajectories. This paper presents an algorithm for topological clustering based on relative persistent homology, which, for a fixed underlying simplicial representation and discretization of trajectories, requires only linear time in the number of trajectories. The algorithm incorporates global constraints formalized in terms of the topology of sublevel or superlevel sets of a function and can be extended to incorporate probabilistic motion models. In experiments with real automobile and ship GPS trajectories as well as pedestrian trajectories extracted from video, the algorithm clusters trajectories into meaningful consistent subsets and, as we show in an experiment with ship trajectories, results in a faster and more efficient clustering than a metric clustering by Frechet distance.
|
|
| 11. |
- Siddiqui, J. Rafid, 1984-, et al.
(författare)
-
Towards visual mapping in industrial environments : a heterogeneous task-specific and saliency driven approach
- 2016
-
Ingår i: 2016 IEEE International Conference on Robotics and Automation (ICRA). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467380263 ; , s. 5766-5773
-
Konferensbidrag (refereegranskat)abstract
- The highly percipient nature of human mind in avoiding sensory overload is a crucial factor which gives human vision an advantage over machine vision, the latter has otherwise powerful computational resources at its disposal given today’s technology. This stresses the need to focus on methods which extract a concise representation of the environment inorder to approach a complex problem such as visual mapping. This article is an attempt of creating a mapping system, which proposes an architecture that combines task-specific and saliency driven approaches. The proposed method is implemented on a warehouse robot. The proposed solution provide a priority framework which enables an industrial robot to build a concise visual representation of the environment. The method is evaluated on data collected by a RGBD sensor mounted on a fork-lift robot and shows promise for addressing visual mapping problems in industrial environments.
|
|
| 12. |
- Tourani, S., et al.
(författare)
-
Rolling shutter and motion blur removal for depth cameras
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. - 9781467380263 ; , s. 5098-5105
-
Konferensbidrag (refereegranskat)abstract
- Structured light range sensors (SLRS) like the Microsoft Kinect have electronic rolling shutters (ERS). The output of such a sensor while in motion is subject to significant motion blur (MB) and rolling shutter (RS) distortion. Most robotic literature still does not explicitly model this distortion, resulting in inaccurate camera motion estimation. In RGBD cameras, we show via experimentation that the distortion undergone by depth images is different from that of color images and provide a mathematical model for it. We propose an algorithm that rectifies for these RS and MB distortions. To assess the performance of the algorithm we conduct an extensive set of experiments for each step of the pipeline. We assess the performance of our algorithm by comparing the performance of the rectified images on scene-flow and camera pose estimation, and show that with our proposed rectification, the performance improvement is significant.
|
|
| 13. |
- Viña Barrientos, Francisco, 1990-, et al.
(författare)
-
Adaptive control for pivoting with visual and tactile feedback
- 2016
-
Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : Institute of Electrical and Electronics Engineers (IEEE). - 1050-4729. - 9781467380263 ; 2016-June, s. 399-406
-
Konferensbidrag (refereegranskat)abstract
- In this work we present an adaptive control approach for pivoting, which is an in-hand manipulation maneuver that consists of rotating a grasped object to a desired orientation relative to the robot's hand. We perform pivoting by means of gravity, allowing the object to rotate between the fingers of a one degree of freedom gripper and controlling the gripping force to ensure that the object follows a reference trajectory and arrives at the desired angular position. We use a visual pose estimation system to track the pose of the object and force measurements from tactile sensors to control the gripping force. The adaptive controller employs an update law that accommodates for errors in the friction coefficient, which is one of the most common sources of uncertainty in manipulation. Our experiments confirm that the proposed adaptive controller successfully pivots a grasped object in the presence of uncertainty in the object's friction parameters.
|
|
