Experimental evaluation of haptic control for human activated command devices

Haptics refers to a widespread area of research that focuses on the interaction between humans and machine interfaces as applied to the sense of touch. A haptic interface is designed to increase the realism of tactile and kinesthetic sensations in applications such as virtual reality, teleoperation, and other scenarios where situational awareness is considered important, if not vital. This paper investigates the use of electric actuators and non-linear algorithms to provide force feedback to an input command device for providing haptics to the human operator. In particular, this work involves the study and implementation of a special case of feedback linearization known as inverse dynamics control and several outer loop impedance control topologies. It also investigates the issues concerned with force sensing and the application of model based controller functions in order to vary the desired inertia and the desired mass matrix. Results of the controllers’ abilities to display any desired impedance and provide the required kinesthetic constraint of virtual environments are shown on two experimental test rigs designed for this purpose.peer-reviewe

Experimental Evaluation of the Projection-based Force Reflection Algorithms for Haptic Interaction with Virtual Environment

Haptic interaction with virtual environments is currently a major and growing area of research with a number of emerging applications, particularly in the field of robotics. Digital implementation of the virtual environments, however, introduces errors which may result in instability of the haptic displays. This thesis deals with experimental investigation of the Projection-Based Force Reflection Algorithms (PFRAs) for haptic interaction with virtual environments, focusing on their performance in terms of stability and transparency. Experiments were performed to compare the PFRA in terms of performance for both non-delayed and delayed haptic interactions with more conventional haptic rendering methods, such as the Virtual Coupling (VC) and Wave Variables (WV). The results demonstrated that the PFRA is more stable, guarantees higher levels of transparency, and is less sensitive to decrease in update rates

HAPTIC AND VISUAL SIMULATION OF BONE DISSECTION

Marco AgusIn bone dissection virtual simulation, force restitution represents the key to realistically mimicking a patient– specific operating environment. The force is rendered using haptic devices controlled by parametrized mathematical models that represent the bone–burr contact. This dissertation presents and discusses a haptic simulation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. A physically based model was used to describe the burr– bone interaction, including haptic forces evaluation, bone erosion process and resulting debris. The model was experimentally validated and calibrated by employing a custom experimental set–up consisting of a force–controlled robot arm holding a high–speed rotating tool and a contact force measuring apparatus. Psychophysical testing was also carried out to assess individual reaction to the haptic environment. The results suggest that the simulator is capable of rendering the basic material differences required for bone burring tasks. The current implementation, directly operating on a voxel discretization of patientspecific 3D CT and MR imaging data, is efficient enough to provide real–time haptic and visual feedback on a low–end multi–processing PC platform.

Haptic and visual simulation of bone dissection

Tesi di dottorato: Università degli Studi di Cagliari, Facoltà di Ingegneria, Dipartiemnto di Ingegneria Meccanica, XV Ciclo di Dottorato in Progettazione Meccanica.In bone dissection virtual simulation, force restitution represents the key to realistically mimicking a patient--specific operating environment. The force is rendered using haptic devices controlled by parametrized mathematical models that represent the bone--burr contact. This dissertation presents and discusses a haptic simulation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. A physically based model was used to describe the burr--bone interaction, including haptic forces evaluation, bone erosion process and resulting debris. The model was experimentally validated and calibrated by employing a custom experimental set--up consisting of a force--controlled robot arm holding a high--speed rotating tool and a contact force measuring apparatus. Psychophysical testing was also carried out to assess individual reaction to the haptic environment. The results suggest that the simulator is capable of rendering the basic material differences required for bone burring tasks. The current implementation, directly operating on a voxel discretization of patient-specific 3D CT and MR imaging data, is efficient enough to provide real--time haptic and visual feedback on a low--end multi--processing PC platformInedit

Tangible interfaces for remote communication and collaboration

Thesis (M.S.)--Massachusetts Institute of Technology, Program in Media Arts & Sciences, 1998.Includes bibliographical references (leaves 57-59).Scott Brenner Brave.M.S

Simulateur collaboratif de chirurgie d'instrumentation du rachis scoliotique en réalité virtuelle avec interface haptique logicielle

RÉSUMÉ La scoliose est une déformation tridimensionnelle de la colonne vertébrale qui nécessite, dans les cas graves, une intervention chirurgicale invasive et très délicate visant à redresser la colonne. Les outils disponibles pour l’entraînement des médecins, tels que les cadavres et les rachis synthétiques, présentent des inconvénients majeurs : les jeunes cadavres disponibles atteints de scoliose se font rares; le réalisme du comportement biomécanique est questionnable; ces deux types d’outils ne peuvent être réutilisés; ils ne représentent pas toute la variété des cas scoliotiques. Les technologies de la réalité virtuelle et les simulations numériques peuvent offrir des solutions pour contourner ces inconvénients. Afin d’aborder cette problématique, l’objectif général de la recherche a consisté à élaborer un prototype logiciel de simulateur collaboratif de chirurgie d’instrumentation du rachis scoliotique en réalité virtuelle incluant un retour d’effort logiciel pour les manoeuvres correctrices principales de la chirurgie, offrant ainsi un outil d’entraînement et d’apprentissage alternatif aux outils traditionnels. Ce projet est entré dans la continuité des travaux de recherche d’étudiants et d’associés de recherche de la Chaire de recherche industrielle CRSNG/Medtronic en biomécanique de la colonne vertébrale, et s’est distingué principalement par la mise en place de l’aspect collaboratif pour un contexte d’entraînement réaliste avec des participants distants, ainsi que le développement et l’évaluation d’une interface haptique logicielle. La revue bibliographique a suggéré que la chirurgie orthopédique ne semble pas encore bénéficier du potentiel offert par la réalité virtuelle et les interfaces haptiques quant à la simulation et à l’entraînement virtuel autant que d’autres types de chirurgies. La plupart des chirurgies pour lesquelles des simulateurs ont été développés impliquent des organes démontrant une certaine compliance, un espace de travail relativement restreint et des forces de faibles amplitudes, pouvant être simulées à l’aide de systèmes haptiques commerciaux génériques. Au contraire, la chirurgie d’instrumentation du rachis scoliotique nécessite l’application d’efforts de grande amplitude pour des mouvements relativement lents à peu de degrés de liberté, requérant un système haptique spécifique. De plus, les modèles physiques, bien que plus complexes et lourds en termes de temps de calculs que les modèles géométriques, sont nécessaires à l’obtention d’une expérience haptique réaliste. À la lumière de ces observations, nous avons émis deux hypothèses de recherche. La première hypothèse supposait que les principales manoeuvres correctrices effectuées lors d’une chirurgie d’instrumentation du rachis scoliotique peuvent être modélisées et simulées en réalité virtuelle immersive à l’aide d’une interface haptique logicielle et d’un modèle biomécanique personnalisé à ±15 % des valeurs d’efforts réelles telles que perçues par des chirurgiens experts. La seconde hypothèse supposait qu’une boucle de rendu haptique multifréquence, basée sur un algorithme de prédiction / correction, permettra d’atteindre la fréquence minimale requise (1000 Hz) pour un retour d’effort fonctionnel dans un contexte d’entraînement réaliste.---------ABSTRACT Scoliosis is a three-dimensional deformation of the spine requiring, in severe cases, a highly delicate and invasive surgical operation to correct the spinal deformities. Available tools for surgical training, such as cadavers and synthetic spines, have major drawbacks: limited availability of young cadaveric spines with scoliosis; questionable behaviour realism; destruction after first use; limited variability in scoliotic cases for training. Virtual reality technologies and computer simulations can offer solutions to these drawbacks. To address this problem, the general objective of this research consisted in elaborating the software prototype of a collaborative virtual reality scoliosis instrumentation surgery simulator, including force feedback for the main corrective surgical manoeuvres, as an alternative training and learning tool. This project has been a continuation of previous work from graduate students and research associates of the NSERC/Medtronic Industrial Research Chair in Spine Biomechanics, and focused on setting up and testing the collaborative aspect for a realistic training context with remote participants, as well as developing and evaluating a software haptic interface. The literature review suggested that orthopaedic surgery does not seem to benefit from virtual reality technologies and haptic interfaces regarding simulation and virtual training as much as other types of surgeries. Most surgeries for which simulators have been developed involve organs with a certain compliance, a relatively confined workspace and “delicate” forces, and can be simulated with generic commercial haptic devices. On the contrary, scoliosis instrumentation surgery involves the application of high forces through moderately slow and of few degrees of freedom movements, requiring a haptic device specific to scoliosis surgery. Also, physical models, although more complex and computationally expensive than geometric models, are necessary for a realistic haptic experience. In light of these observations, we stated two hypotheses. The first hypothesis was that the main corrective manoeuvres of scoliosis instrumentation surgery can be modeled and simulated in immersive virtual reality with a software haptic interface and a patient-specific biomechanical model at ±15 % of the actual force values as perceived by expert surgeons. The second hypothesis was that a multirate haptic rendering loop, based on a prediction / correction algorithm, will achieve the minimal required update rate (1000 Hz) for a functional force feedback in a realistic training context

Playful Materialities: The Stuff That Games Are Made Of

Game culture and material culture have always been closely linked. Analog forms of rule-based play (ludus) would hardly be conceivable without dice, cards, and game boards. In the act of free play (paidia), children as well as adults transform simple objects into multifaceted toys in an almost magical way. Even digital play is suffused with material culture: Games are not only mediated by technical interfaces, which we access via hardware and tangible peripherals. They are also subject to material hybridization, paratextual framing, and processes of de-, and re-materialization

Playful Materialities

Game culture and material culture have always been closely linked. Analog forms of rule-based play (ludus) would hardly be conceivable without dice, cards, and game boards. In the act of free play (paidia), children as well as adults transform simple objects into multifaceted toys in an almost magical way. Even digital play is suffused with material culture: Games are not only mediated by technical interfaces, which we access via hardware and tangible peripherals. They are also subject to material hybridization, paratextual framing, and processes of de-, and re-materialization