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A transformation of the Position Based Visual Servoing Problem into a convex optimization problem
KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.ORCID iD: 0000-0002-4032-4830
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.ORCID iD: 0000-0003-0177-1993
2012 (English)In: 2012 IEEE 51st Annual Conference on Decision and Control (CDC), IEEE , 2012, 5673-5678 p.Conference paper (Refereed)
Abstract [en]

Here we address the problem of moving a camera from an initial pose to a final pose. The trajectory between the two poses is subject to constraints on the camera motion and the visibility, where we have bounds on the allowed velocities and accelerations of the camera and require that a set of point features are visible for the camera. We assume that the pose is possible to retrieve from the observations of the point features, i.e., we have a Position Based Visual Servoing Problem with constraints. We introduce a two step method that transforms the problem into a convex optimization problem with linear constraints. In the first step the rotational motion is restricted to be of a certain type. This restriction allows us to retrieve an explicit solution of the rotational motion that is optimal in terms of minimizing geodesic distance. Furthermore, this restriction guarantees that the rotational motion satisfies the constraints. Using the explicit solution, we can formulate a convex optimization problem for the translational motion, where we include constraints on workspace and visibility.

Place, publisher, year, edition, pages
IEEE , 2012. 5673-5678 p.
, Proceedings of the IEEE Conference on Decision and Control, ISSN 0191-2216
Keyword [en]
Camera motions, Convex optimization problems, Explicit solutions, Geodesic distances, Linear constraints, Point features, Position based visual servoing, Rotational motion, Translational motions, Two step method
National Category
Other Mathematics
URN: urn:nbn:se:kth:diva-118868DOI: 10.1109/CDC.2012.6426022ISI: 000327200405155ScopusID: 2-s2.0-84874261523ISBN: 978-1-4673-2066-5OAI: diva2:609046
51st IEEE Conference on Decision and Control, CDC 2012; Maui, HI; United States; 10 December 2012 through 13 December 2012

QC 20130304

Available from: 2013-03-04 Created: 2013-03-04 Last updated: 2016-02-24Bibliographically approved
In thesis
1. Reactive control and coordination of redundant robotic systems
Open this publication in new window or tab >>Reactive control and coordination of redundant robotic systems
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Redundant robotic systems, in terms of manipulators with one or twoarms, mobile manipulators, and multi-agent systems, have received an in-creasing amount of attention in recent years. In this thesis we describe severalways to improve robotic system performance by exploiting the redundancy.

As the robot workspace becomes increasingly dynamic, it is common towork with imperfect geometric models of the robots or its workspace. Inorder to control the robot in a robust way in the presence of geometric uncer-tainties, we propose to assess the stability of our controller with respect to acertain task by deriving bounds on the geometric uncertainties. Preliminaryexperimental results support the fact that stability is ensured if the proposedbounds on the geometric uncertainties are fulfilled.

As a non-contact measurement, computer vision could provide rich infor-mation for robot control. We introduce a two step method that transformsthe position-based visual servoing problem into a quadratic optimization prob-lem with linear constraints. This method is optimal in terms of minimizinggeodesic distance and allows us to integrate constraints, e.g. visibility con-straints, in a natural way.

In the case of a single robot with redundant degrees of freedom, we canspecify a family of complex robotic tasks using constraint based programming(CBP). CBP allows us to represent robotic tasks with a set of equality andinequality constraints. Using these constraints we can formulate quadraticprogramming problems that exploit the redundancy of the robot and itera-tively resolve the trade-off between the different constraints. For example, wecould improve the velocity or force transmission ratios along a task-dependent direction using the priorities between different constraints in real time.

Using the reactiveness of CBP, we formulated and implemented a dual-armpan cleaning task. If we mount a dual-arm robot on a mobile base, we proposeto use a virtual kinematic chain to specify the coordination between the mobilebase and two arms. Using the modularity of the CBP, we can integrate themobility and dual-arm manipulation by adding coordination constraints intoan optimization problem where dual-arm manipulation constraints are alreadyspecified. We also found that the reactiveness and modularity of the CBPapproach is important in the context of teleoperation. Inspired by the 3Ddesign community, we proposed a teleoperation interface control mode thatis identical to the ones being used to locally navigate the virtual viewpoint ofmost Computer Aided Design (CAD) softwares.

In the case of multiple robots, we combine ideas from multi-agent coopera-tive coverage control, with problem formulations from the resource allocationfield, to create a distributed convergent approach to the resource positioningproblem.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xii, 62 p.
TRITA-CSC-A, ISSN 1653-5723 ; 2016:05
reactive control, dual-arm manipulation, mobile manipulation, ambulance positioning.
National Category
Robotics Control Engineering Computer Systems
Research subject
Computer Science
urn:nbn:se:kth:diva-182680 (URN)978-91-7595-870-5 (ISBN)
Public defence
2016-03-22, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20160224

Available from: 2016-02-24 Created: 2016-02-22 Last updated: 2016-02-24Bibliographically approved

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Wang, YuquanThunberg, JohanHu, Xiaoming
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