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ADMITTANCE CONTROL OF AN HAPTIC DEVICE. HAPTIC RENDERING INCLUDES HAPTIC API, HAPTIC CONTROLLER AND HAPTIC DEVICE.
Source publication
Haptic rendering has opened a new range of virtual reality applications, enabling a human user to interact with a virtual world using the sense of touch. This kind of interaction enables to enhance applications such as computer-assisted design, where 3D manipulations are part of the system. However, building an application with an accurate haptic f...
Contexts in source publication
Context 1
... forces returned by the haptic device can be applied on the proxy and integrated into the dynamic engine. Figure 8 shows the flow of data when using admittance mode. It is however too restrictive to plug directly the simulation results to the haptic API as shown on Figure 8. Indeed, values returned by the dynamic engine may have a numerical representation different from the one used by the haptic API, the frame coordinates can be different, and the or- der of magnitude of the values used are likely to be incompatible. ...
Context 2
... 8 shows the flow of data when using admittance mode. It is however too restrictive to plug directly the simulation results to the haptic API as shown on Figure 8. Indeed, values returned by the dynamic engine may have a numerical representation different from the one used by the haptic API, the frame coordinates can be different, and the or- der of magnitude of the values used are likely to be incompatible. ...
Citations
... However, its realization has always been a challenging problem. Many researchers have devoted themselves to this research, a number of methods have been proposed to simulate fracture [6]- [10]. ...
Fracture simulation can create amazing effects in motion pictures, it is widely used into video games and virtual reality systems. In order to achieve a fast and realistic fracture simulation, we propose a new model, which is based on spring mass model and peridynamics theory, for brittle objects fracture. The method can be described as a two-step strategy. First, the geometric model of an object is preprocessed. The model is completely wrapped in an AABB envelop box, which is subdivided into multiple fragments with 3d Voronoi diagram. The intersection of fragments and the model surface is computed by using the Boolean algorithm, and the fragments outside the model surface are clipped to obtain the final fragments. The BSP tree subdivide method is adopted in our preprocessing, which further improves the intersection speed. Second, the fracture is calculated according to spring-mass system based on peridynamics. We vieweach point as a spring node. The seed points are connected according to the rules of the spring-mass model based on peridynamics to form the spring topology. The object fracture is calculated according to the spring-mass model based on peridynamics. To further improve render quality, normal bump texture mapping is employed to render the fracture surface. Experimental results show that the proposed model provides users with improved visual feedback while the computational cost is at the same magnitude of other similar methods. The proposed method is especially suitable for the simulation of brittle object fracturing.
... Furthermore, if the scales between the two simulations are different, the inertia tensor, linear velocity and acceleration need to be scaled. See [11] for more information about scaling properties between two simulations. The mass of the objects in both simulations are set to the same value. ...
... Für einen Vergleich zwischen Physik-Engines auf Basis verschiedener Kriterien wird auf weiterführende Literatur verwiesen (bspw. [307], [308], [309], [310]). ...
... Andere relevante Validierungsaspekte der physikbasierten Simulationsmethodik, bspw. hinsichtlich der hinreichend genauen Abbildung der Kinematik und Dynamik, wurden bereits ausführlich untersucht und werden somit nicht weiter betrachtet (vgl.[169],[309],[308],[381]). Dadurch wird ein direkter Bezug zu der ersten Forschungsfrage bzw. ...
... This engine computes the response forces and the interactions between virtual entities. Glondu et al. [11] compares the four most used physics engines. There are many criteria to select one of the four physics engines. ...
In a world in continuous evolution of information technology and computer science, virtual reality (VR) is a very important technological tool in several areas such as industrial simulations. In this paper, we will present some cases of the uses of VR, mainly in the industrial area, and in ergonomic tests and evaluations. In this work, we will present our approach that allows the use of haptic force feedback using a subjective method. In the first part, we will start with the state of the art by presenting a new approach based on a set of acquisitions in the mobile rolling operation in the real world and in the industrial context. In addition to that, we will study operator muscular forces exercised over a rolling mobile operation (to displace it from one point to another). In particular, we will introduce how we can integrate a subjective method of calculating forces in a VR simulation for a realistic operator interaction and mobile behavior. We will also use certain techniques of virtual reality to immerse the operator, with the system of the relative forces exerted and other information.
This paper comprises three main parts: the first one is a general study of the haptic force feedback techniques in VR applications (haptic rendering). The second part presents the modules, the architecture and how we can integrate these techniques in our application. The final part is a discussion of the developed application and its results with some perspectives.
... While an update rate of 10 fps is considered as the minimum frequency to achieve "real time" animation (MacKenzie and Ware, 1993), actual graphic update rates are usually around 30 fps to appear continuous. The physics simulation can have similar or higher update rates, up to around 100 Hz in some cases (Ritchie et al., 2008;Glondu et al., 2010). To keep stable force interactions, the haptic rendering update rate is usually around 1000 Hz (Basdogan and Srinivasan, 2002;Ho et al., 1999), much higher than that of graphic rendering. ...
... The performance of several popular PSEs was evaluated by Glondu et al. (2010). Havok, PhysX, Bullet and Open Tissue were put into four different tests, where they are evaluated based on computation time, stability and accuracy. ...
Purpose
– The purpose of this paper is to give a comprehensive survey on the physics-based virtual assembly (PBVA) technology in a novel perspective, to analyze current drawbacks and propose several promising future directions.
Design/methodology/approach
– To provide a deep insight of PBVA, a discussion of the developing context of PBVA and a comparison against constraint-based virtual assembly (CBVA) is put forward. The core elements and general structure are analyzed based on typical PBVA systems. Some common key issues as well as common drawbacks are discussed, based on which the research trend and several promising future directions are proposed.
Findings
– Special attention is paid to new research progresses and new ideas concerning recent development as well as new typical systems of the technology. Advantages of PBVA over CBVA are investigated. Based on the analysis of typical PBVA systems and the evolution of PBVA, the core elements of the technology and the general structure of its implementation are identified. Then, current PBVA systems are summarized and classified. After that, key issues in the technology and current drawbacks are explored in detail. Finally, promising future directions are given, including both the further perfecting of the technology and the combination with other technologies.
Originality/value
– The PBVA technology is put into a detailed review and analysis in a novel way, providing a better insight of both the theory and the implementation of the technology.
... The possibility of implementing a modular haptic display system that relies on physical simulation and haptic rendering was presented in [20]. Four physical simulation libraries were evaluated: Havok, PhysX, Bullet and OpenTissue. ...
Virtual environments (VE) are becoming a popular way to interact with virtual objects in several applications such as design, training, planning, etc. Physics simulation engines (PSE) used in games development can be used to increase the realism in virtual environments (VE) by enabling the virtual objects with dynamic behavior and collision detection. There exist several PSE available to be integrated with VE, each PSE uses different model representation methods to create the collision shape and compute virtual object dynamic behavior. The performance of physics based VEs is directly related to the PSE ability and its method to represent virtual objects. This paper analyzes different freely available PSEs –Bullet and the two latest versions of PhysX (v2.8 and 3.1) – based on their model representation algorithms, and evaluates them by performing various assembly tasks with different geometry complexity. The evaluation is based on the collision detection performance and their influence on haptic-virtual assembly process. The results have allowed the identification of the strengths and weaknesses of each PSE according to its representation method. NOMENCLATURE CAD Computer Aided Design CD Convex Decomposition FPS Frames per Second HACD Hierarchical Approximate Convex Decomposition min minutes mm millimeters ms milliseconds N Newton PBM Physics-based modelling PSE Physics simulation engines sec Seconds STL Standard Tessellation Language TCT Task Completion Time VPS Voxmap Point Shell VR Virtual Reality VE Virtual Environment 1. INTRODUCTION Several authors have proposed various VE with different applications, ranging from games to surgical training, assembly planning, design analysis, etc. However, each application has different requirements, e.g. surgical planning requires a precise modeling of tissue properties while games may require speed and realistic graphical rendering. On the other hand, applications developed for assembly planning or training require the virtual models to be represented with high physical and geometrical accuracy in order to enable the assembly of parts. In such systems the way a virtual model is represented within the PSE affects the performance of the system and the assembly simulation [1]. CAD models are commonly used in the design stage of new components and contain analytic and topological information that is used to build a precise geometric description of the model, where the surfaces are described by NURBS and other splines. Nevertheless, the exchange of data between CAD and VR applications is difficult due to the mathematical complexity of polynomial functions, which are unpractical to handle in real time collision detection applications [2] [3]. For this reason, tessellated representations of CAD models are
... However, there are several challenges when integrating haptics with PSEs, e.g. synchronization, non-effective collision detection, high computational cost and a negative impact on the performance of the application (Seugling and Rölin, 2006), mainly because simulation engines have not been developed for haptic rendering, where the update frequency is over 1 kHz while the physics simulation update rate is around 100 Hz (Ritchie et al., 2008a, b;Glondu et al., 2010). ...
... The previous comparative evaluations to investigate the performance of PSEs were carried out without considering the integration of haptic rendering. Regarding this, Glondu et al. (2010) introduced the possibilities of implementing a modular haptic display system that relies on physics simulation and haptic rendering. Four physics simulation libraries were evaluated: Havok, PhysX, Bullet and OpenTissue. ...
Purpose
– In this study, a new methodology to evaluate the performance of physics simulation engines (PSEs) when used in haptic virtual assembly applications is proposed. This methodology can be used to assess the performance of any physics engine. To prove the feasibility of the proposed methodology, two-third party PSEs – Bullet and PhysXtm – were evaluated. The paper aims to discuss these issues.
Design/methodology/approach
– Eight assembly tests comprising variable geometric and dynamic complexity were conducted. The strengths and weaknesses of each simulation engine for haptic virtual assembly were identified by measuring different parameters such as task completion time, influence of weight perception and force feedback.
Findings
– The proposed tests have led to the development of a standard methodology by which physics engines can be compared and evaluated. The results have shown that when the assembly comprises complex shapes, Bullet has better performance than PhysX. It was also observed that the assembly time is directly affected by the weight of virtual objects.
Research limitations/implications
– A more comprehensive study must be carried out in order to evaluate and compare the performance of more PSEs. The influence of collision shape representation algorithms on the performance of haptic assembly must be considered in future analysis.
Originality/value
– The performance of PSEs in haptic-enabled VR applications had been remained as an unknown issue. The main parameters of physics engines that affect the haptic virtual assembly process have been identified. All the tests performed in this study were carried out with the haptic rendering loop active and the objects manipulated through the haptic device.
... This is mainly because the typical frequency of haptics simulations is over 1 kHz, while in the physics simulations it is around 100 Hz [24]. Glondu [25] introduced the possibilities of implementing a modular system that relies on physical simulation and haptic rendering. Four physical simulation libraries were evaluated: Havok, PhysX, Bullet and OpenTissue, and Havok resulted in the best average computation time, stability and friction accuracy. ...
Virtual reality systems can be used to simulate, analyze and optimize manufacturing processes including assembly. Haptic technologies enable the user to feel the force feedback from the virtual environment, leading to a more intuitive and natural way to simulate the assembly process during the design phase of new components even before any physical prototype is created. This paper presents the development of a haptic virtual reality platform to perform, plan and evaluate virtual assemblies of components. The system allows real-time manipulation and interaction of virtual components. Physics simulation engines are used to enable physic based behavior and collision detection of virtual objects in the virtual environment. One of the outstanding characteristics of the proposed platform is that the user can modify various simulation parameters during run-time, such as the weight of virtual objects, model representation algorithm and the physics simulation engine being used, which is very important in order to evaluate the influence of each parameter on the performance of virtual assembly tasks.
... But for the field of robotics there are only few detailed evaluations available that take into account the wide variety of robotic requirements. In [6] this question is addressed in the context of haptic rendering by performing three run-time tests using Bullet, PhysX and Havok. A wide range of physics engines is tested in [2] using the Physical Abstraction Layer (PAL) in six different run-time experiments. ...
Detailed simulations of robotic systems, including their components and dynamics, play an increasingly important role in the development of new robotic systems and their applications. There are many physics engines with a mature development stage, but all of them suffer from fundamental inaccuracies due to the approximative character of the internal calculations. This article provides an in-detail evaluation of the physics engines Bullet, ODE and PhysX with a focus on robotics and legged locomotion. We present a variety of runtime experiments which provide an insight into these engines, their strengths and weaknesses. Our findings offer valuable information for the application-specific selection of a physics
engine for robotics simulations.
... synchronization, non-effective collision detection, high computational cost and a negative impact on the performance of the application [3]. This is due to the fact that simulation engines are not adapted to haptic rendering, mainly because the typical frequency of haptics simulations is over 1 kHz and around 100 Hz for physics simulations [4,5]. ...
... Glondu et al. [4] introduced the possibilities of implementing a modular haptic display system that relies on physical simulation and haptic rendering. With this in mind, four physical simulation libraries are evaluated: Havok, PhysX, Bullet and OpenTissue. ...
Virtual Reality (VR) applications are employed in engineering situation to simulate real and artificial situations where the user can interact with 3D models in real time. Within these applications the virtual environment must emulate real world physics such that the system behaviour and interaction are as natural as possible and to support realistic manufacturing applications. As a consequence of this focus, several simulation engines have been developed for various digital applications, including VR, to compute the physical response and body dynamics of objects. However, the performance of these physics engines within haptic-enabled VR applications varies considerably. In this study two third party physics engines - Bullet and PhysXtm- Are evaluated to establish their appropriateness for haptic virtual assembly applications. With this objective in mind five assembly tasks were created with increasing assembly and geometry complexity. Each of these was carried out using the two different physics engines which had been implemented in a haptic-enabled virtual assembly platform specifically developed for this purpose. Several physics-performance parameters were also defined to aid the comparison. This approach and the subsequent results successfully demonstrated the key strengths, limitations, and weaknesses of the physics engines in haptic virtual assembly environments.
