Péter Galambos

Merged physical and virtual reality in collaborative virtual workspaces: The VirCA approach

Recently emerging paradigms of the so called Future Internet induce significant changes in consumer and industrial ICT applications. Remote collaboration in mixed physical and virtual realities made possible thanks to the increasing network bandwidth further empowered by the achievements of Internet of Things, Cloud Computing and Internet of Services. This enticing vision brings benefits for several application fields ranging from STEM education to smart factories. The paper discusses some new possibilities through the VirCA (Virtual Collaboration Arena) framework as a pilot realization. A brief introduction is given to VirCA focusing on the basic concepts and features that make it well suited for collaborative work in mixed virtual and physical reality. Through a concrete life-like example, the paper illustrates the way of involving real industrial devices into remote collaboration scenarios and reviews the typical uses of such a shared infrastructure considering the relationship of the virtual and real entities.

Non-simplex enclosing polytope generation concept for Tensor Product model transformation based controller design

In polytopic model-based controller synthesis, the vertices of the model determine the achievable performance characteristics. This paper introduces a new concept, that allows for the sophisticated construction of non-simplex enclosing polytopes. The non-simplex structures in general, have much better descriptor properties than the simplex one that leads to less conservative synthesis. The paper demonstrates the workflow of controller design for a nonlinear system through the example of the TORA (Translational Oscillator with a Rotational Actuator) system. The numerical results clearly show that the proposed approach is capable of excluding non-stabilizable regions located between the exact convex hull and the enclosing simplex. The non-simplex polytope leads to an increased number of vertices but it practically does not influence the viability of Tensor-Product (TP) formalization and the feasibility of controller design while the achievable control performance can be improved significantly.

Nonlinear soft tissue mechanics based on polytopic Tensor Product modeling

Achieving reliable force control is one of the main design goals of robotic teleoperation. It is essential to grant safe and stable performance of these systems, regarding HMI control, even under major disturbing conditions such as time delay or model parameter uncertainties. This paper discusses the systematic derivation of polytopic qLPV model from the nonlinear dynamics of typical soft tissues of the human body based on recent experimental results. The derivation is based on the Tensor Product (TP) Model Transformation. The presented method is a crucial step in laying the foundations of adequate force control in telesurgery. The proposed approach could form the basis of LMI-based controller design.

Affine Tensor Product Model Transformation

This paper introduces the novel concept of Affine Tensor Product (TP) Model and the corresponding model transformation algorithm. Affine TP Model is a unique representation of Linear Parameter Varying systems with advantageous properties that makes it very effective in convex optimization-based controller synthesis. The proposed model form describes the affine geometric structure of the parameter dependencies by a nearly minimum model size and enables a systematic way of geometric complexity reduction. The proposed method is capable of exact analytical model reconstruction and also supports the sampling-based numerical approach with arbitrary discretization grid and interpolation methods. The representation conforms with the latest polytopic model generation and manipulation algorithms. Along these advances, the paper reorganizes and extends the mathematical theory of TP Model Transformation. The practical merit of the proposed concept is demonstrated through a numerical example.

A Hands-On Demonstration of Control Performance Optimization Using Tensor Product Model Transformation and Convex Hull Manipulation

In polytopic model based controller synthesis, the vertices of the model determine the achievable performance. This paper demonstrates a complete and tractable design process exposing the polytopic qLPV model generation and a polytopeshaping technique through the example of the TORA (Translational Oscillator with a Rotational Actuator) system. The demonstrated apparatus allows for systematically improving the control performance through the manipulation of the polytopic structure based on the MVSA (Minimal Volume Simplex Analysis) algorithm. The proposed approach fits to the framework of TP Model Transformation.

Testing and verification through virtual product models: A survey and look ahead

Modern engineering design and simulation software (CAD, CAM, CAE) allow for extensive use of virtual prototypes along the product and production development reducing the cost and time of physical prototyping. These software technologies in turn has also important role in testing and verification against the various regulations. This paper reviews the recent progress of virtual verification (ViVer) technology and the underlying emerging concepts with special focus on the role of certification service providers. The paper covers multiple aspects of the ViVer concept serving as a conceptual guideline for the development of virtual verification systems of the future.

Cyber-Physical Control

Antal Bejczy Center for Intelligent Robotics, Óbuda University, Bécsi út 96/b, Budapest H-1034, Hungary University Research and Innovation Center, Óbuda University, Bécsi út 96/b, Budapest H-1034, Hungary School of Astronautics, Harbin Institute of Technology, P.O. Box 3015, Yikuang Street 2, Nangang District, Harbin 150080, China National Taiwan University of Science and Technology, Taipei 106, Taiwan

A novel methodology for usability assesment of rheological soft tissue models

The task to distinguish between soft tissues by testing their mechanical properties is often referred to as the primary cognitive role of haptic devices. It is a common view that todays surgical simulators that are using haptic interfaces should rely on simple mechanical models of soft tissues, instead of complex, parameterized finite element models, thus enhancing real-time operation and focusing on the most representative mechanical effects. This paper proposes a user-trial validation method for tissue models and their polytopic representation by creating an experimental framework for soft tissue characterization, using the da Vinci Research Kit. The characterization methdodology relies on haptic feedback from the manipulated real tissue, extending the functionality of surgical simulators using virtual tissue models created by the previously proposed soft tissue modeling method. Results showed that the tissue model represents the tissue behavior sufficiently well for use in haptic simulators, based on user experience. Furthermore, it was concluded that silicon phantoms can mimic the behavior of real tissues in various surgical scenarios, especially when using teleoperation manipulation.

A Low-Cost Experimental Device for Compliant Physical Human-Robot Interaction

Cobotix is one of the latest paradigm changes emerged in the era of modern industrial robotics at the focal point of the so-called Industry 4.0 concept. Safe physical human-robot contact is the core enabling technology and therefore, it has special importance in research and also in education of robotics engineers. This paper introduces a low-cost, yet complete experimental and educational purpose compliant robot that allows for studying the main principles of physical human-robot interaction. The setup consists of a NOVINT Falcon 3-axis haptic device with parallel mechanism and a 3-axis force sensor, which allows for sensing the interaction forces between the robot and the environment. The controller is implemented on a Real-time Linux platform. The resulted software is open source and shared with the robotics community.

Polytopic model based interaction control for soft tissue manipulation

Reliable force control is one of the key components of modern robotic teleoperation. The performance of these systems, in terms of safety and stability, largely depends on the controller design, as it is desired to deal with various disturbing conditions, such as uncertainties of the model parameters or latency-induced problems. This work presents a polytopic quasi-linear parameter-varying (qLPV) model derived from a previously verified nonlinear soft tissue model, along with a model-based force control scheme that involves a tensor product polytopic state feedback controller. The derivation is based on the Tensor Product (TP) Model Transformation. The proposed force control scheme is verified and evaluated through numerical simulations.