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Active Constraint

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Sigurd Skogestad – One of the best experts on this subject based on the ideXlab platform.

  • systematic design of Active Constraint switching using classical advanced control structures
    Industrial & Engineering Chemistry Research, 2020
    Co-Authors: Adriana Reyeslua, Sigurd Skogestad
    Abstract:

    An important task of the supervisory control layer is to maintain optimal operation. To achieve this, we need to change control objectives when Constraints become Active (or inActive) as a result o…

  • systematic design of Active Constraint switching using classical advanced control structures
    Industrial & Engineering Chemistry Research, 2020
    Co-Authors: Adriana Reyeslua, Sigurd Skogestad
    Abstract:

    An important task of the supervisory control layer is to maintain optimal operation. To achieve this, we need to change control objectives when Constraints become Active (or inActive) as a result of disturbances. In most process plants, the supervisory layer uses classical PID-based advanced control structures, but there is no systematic way of designing such structures. Here, we propose a systematic procedure to design the supervisory control layer using single-loop classical advanced control structures, such that the process achieves steady-state optimal operation when the Active Constraints change. The Active Constraints can be on the manipulated variable (MV, input) or on the controlled variable (CV, output). In this paper, we consider all three possible cases: CV–CV switching, which involves selectors; CV–MV switching, which does not need any special structure if we pair according to the input saturation pairing rule; and MV–MV switching, which uses split range control or some similar structure. We illustrate our methodology with two case studies.

  • Systematic design of Active Constraint switching using selectors
    Computers & Chemical Engineering, 2020
    Co-Authors: Dinesh Krishnamoorthy, Sigurd Skogestad
    Abstract:

    Abstract Selector logic is a simple and effective tool to switch between different controlled variables associated with change in Active Constraints. Selector blocks have been extensively used in the process control industry for decades, but their design has been based on engineering intuition and experience. Currently, there is a lack of systematic procedure to design selectors for Active Constraint switching. In this paper, we address this gap and provide a systematic procedure, which can be applied without the need for detailed process models. Illustrative examples are used to demonstrate the proposed framework.

Haixiang Zang – One of the best experts on this subject based on the ideXlab platform.

George A Rovithakis – One of the best experts on this subject based on the ideXlab platform.

  • stability of Active Constraints enforcement in sensitive regions defined by point clouds for robotic surgical procedures
    European Control Conference, 2019
    Co-Authors: Theodora Kastritsil, Zoe Doulgeri, Dimitrios Papageorgiou, Iason Sarantopouloslr, George A Rovithakis
    Abstract:

    Robotic minimally invainvasive surgery provides images from the intraoperative field including organs and sensitive anatomic structures whose protection from non-voluntary destruction is imperative. To assist the surgeon, control methods that discourage motions towards these sensitive areas are advocated in the related literature. In this work, an Active Constraint controller is proposed and is proved to guarantee that sensitive/forbidden areas defined by a point cloud are never violated by the tool tip while the closed loop system remains passive and its state bounded under the exertion of a human guiding force. Experimental results are given utilizing a KUKA LWR4+ kinesthetically guided in a virtual surgical environment.

  • ECC – Stability of Active Constraints Enforcement in Sensitive Regions Defined by Point-Clouds for Robotic Surgical Procedures
    2019 18th European Control Conference (ECC), 2019
    Co-Authors: Theodora Kastritsil, Zoe Doulgeri, Iason Sarantopouloslr, Dimitrios G. Papageorgiou, George A Rovithakis
    Abstract:

    Robotic minimally invainvasive surgery provides images from the intraoperative field including organs and sensitive anatomic structures whose protection from non-voluntary destruction is imperative. To assist the surgeon, control methods that discourage motions towards these sensitive areas are advocated in the related literature. In this work, an Active Constraint controller is proposed and is proved to guarantee that sensitive/forbidden areas defined by a point cloud are never violated by the tool tip while the closed loop system remains passive and its state bounded under the exertion of a human guiding force. Experimental results are given utilizing a KUKA LWR4+ kinesthetically guided in a virtual surgical environment.

Ferdinando Rodriguez Y Baena – One of the best experts on this subject based on the ideXlab platform.

  • Deformation invariant bounding spheres for dynamic Active Constraints in surgery
    Proceedings of the Institution of Mechanical Engineers. Part H Journal of engineering in medicine, 2014
    Co-Authors: Stuart A. Bowyer, Ferdinando Rodriguez Y Baena
    Abstract:

    Active Constraints are collaborative robot control strategies, which can be used to guide a surgeon or protect delicate tissue structures during robot-assisted surgery. Tissue structures of interest often move and deform throughout a surgical intervention, and therefore, dynamic Active Constraints, which adapt and conform to these changes, are required. A fundamental element of an Active Constraint controller is the computation of the geometric relationship between the Constraint geometry and the surgical instrument. For a static Active Constraint, there are a variety of computationally efficient methods for computing this relative configuration; however, for a dynamic Active Constraint, it becomes significantly more challenging. Deformation invariant bounding spheres are a novel bounding volume formulation, which can be used within a hierarchy to allow efficient proximity queries within dynamic Active Constraints. These bounding spheres are constructed in such a way that as the surface deforms, they do n…

  • Active Constraints/virtual fixtures: A survey
    IEEE Transactions on Robotics, 2014
    Co-Authors: Julia Peltason, Nina Riether, Ferdinando Rodriguez Y Baena, Britta Wrede, I. Lutkebohle, S A Bowyer, Brian L. Davies, Y. Baena Rodriguez
    Abstract:

    Active Constraints, also known as virtual fixtures, are high-level control algorithms which can be used to assist a human in man-machine collaborative manipulation tasks. The Active Constraint controller monitors the robotic manipulator with respect to the environment and task, and anisotropically regulates the motion to provide assistance. The type of assistance offered by Active Constraints can vary, but they are typically used to either guide the user along a task-specific pathway or limit the user to within a “safe” region. There are several diverse methods described within the literature for applying Active Constraints, and these are surveyed within this paper. The Active Constraint research is described and compared using a simple generalized framework, which consists of three primary processes: 1) Constraint definition, 2) Constraint evaluation, and 3) Constraint enforcement. All relevant research approaches for each of these processes, found using search terms associated to “virtual fixture,” “Active Constraint” and “motion Constraint,” are presented.

  • IROS – A dynamic Active Constraints approach for hands-on robotic surgery
    2013 IEEE RSJ International Conference on Intelligent Robots and Systems, 2013
    Co-Authors: Joshua G. Petersen, Ferdinando Rodriguez Y Baena
    Abstract:

    Toward the goal of developing a hands-on robotic surgery control strategy which simultaneously utilizes the various strengths of both the surgeon and robot, we present a dynamic Active Constraint approach tailored for hands-on surgery. Forbidden region Active Constraints are used to prevent motion into areas which have been deemed dangerous by the surgeon, helping to overcome some of the disadvantages of fully Active systems such as loss of tactile feedback, limited workspace, and limited field-of-view. The computer graphics technique of metaballs is used to represent point cloud data from an imaging system with an analytical, differentiable surface and a dynamics-based controller is proposed which controls the robot to lie on the zero set of the generated time-varying implicit function for which the motion is either known or unknown. This controller has been incorporated into a recursive null-space approach to allow for unimpeded motion along the surface and for further extension to joint optimization in the future. This methodology is demonstrated in simulation and on a lightweight, seven-degree-of-freedom serial manipulator.

Theodora Kastritsil – One of the best experts on this subject based on the ideXlab platform.

  • stability of Active Constraints enforcement in sensitive regions defined by point clouds for robotic surgical procedures
    European Control Conference, 2019
    Co-Authors: Theodora Kastritsil, Zoe Doulgeri, Dimitrios Papageorgiou, Iason Sarantopouloslr, George A Rovithakis
    Abstract:

    Robotic minimally invasive surgery provides images from the intraoperative field including organs and sensitive anatomic structures whose protection from non-voluntary destruction is imperative. To assist the surgeon, control methods that discourage motions towards these sensitive areas are advocated in the related literature. In this work, an Active Constraint controller is proposed and is proved to guarantee that sensitive/forbidden areas defined by a point cloud are never violated by the tool tip while the closed loop system remains passive and its state bounded under the exertion of a human guiding force. Experimental results are given utilizing a KUKA LWR4+ kinesthetically guided in a virtual surgical environment.

  • ECC – Stability of Active Constraints Enforcement in Sensitive Regions Defined by Point-Clouds for Robotic Surgical Procedures
    2019 18th European Control Conference (ECC), 2019
    Co-Authors: Theodora Kastritsil, Zoe Doulgeri, Iason Sarantopouloslr, Dimitrios G. Papageorgiou, George A Rovithakis
    Abstract:

    Robotic minimally invasive surgery provides images from the intraoperative field including organs and sensitive anatomic structures whose protection from non-voluntary destruction is imperative. To assist the surgeon, control methods that discourage motions towards these sensitive areas are advocated in the related literature. In this work, an Active Constraint controller is proposed and is proved to guarantee that sensitive/forbidden areas defined by a point cloud are never violated by the tool tip while the closed loop system remains passive and its state bounded under the exertion of a human guiding force. Experimental results are given utilizing a KUKA LWR4+ kinesthetically guided in a virtual surgical environment.