Haptic technology | EPFL Graph Search

Haptic technology (also kinaesthetic communication or 3D touch) is technology that can create an experience of touch by applying forces, vibrations, or motions to the user. These technologies can be used to create virtual objects in a computer simulation, to control virtual objects, and to enhance remote control of machines and devices (telerobotics). Haptic devices may incorporate tactile sensors that measure forces exerted by the user on the interface. The word haptic, from the ἁπτικός (haptikos), means "tactile, pertaining to the sense of touch". Simple haptic devices are common in the form of game controllers, joysticks, and steering wheels. Haptic technology facilitates investigation of how the human sense of touch works by allowing the creation of controlled haptic virtual objects. Most researchers distinguish three sensory systems related to sense of touch in humans: cutaneous, kinaesthetic and haptic. All perceptions mediated by cutaneous and kinaesthetic sensibility are ref

Haptic interface design and control with application to surgery simulation

Ulrich Spälter

This thesis proposes a framework for haptic devices interacting with virtual environments. As application of the theoretical results a haptic device for the surgical training of hysteroscopy, a gynecologic intervention, is presented. Surgery simulators, which can be described as 'flight simulators for surgeons', comprise a virtual reality for modeling and visualization of organs, and the haptic device: While the surgeon interactively follows the scene on the computer screen, he perceives the contact forces at the tool handle of the surgical instrument. The haptic device tracks the position of the surgery tool and transforms the virtual contact forces to real forces, which can be actually felt by the surgeon. This thesis treats haptic devices with application to surgery simulators for minimally-invasive surgery. Haptic interfaces are complex mechatronic systems and show inherent trade-offs between haptic realism and system stability. Human factors play an important role, as the human operator can both stabilize or destabilize the system. The haptic perception, which can vary between individuals, as a criterion for haptic rendering quality is still not formalized. The optimization of haptic interfaces, within focus of research since 15 years ago, has remained a complex task. However, with look at the emerging applications for haptics, it has become an even more important topic. For this reason it is necessary to integrate mechanical design, control design, mechatronic elements and human factors in a unifying approach. This thesis highlights the principal trade-offs of haptic interfaces and works out design guidelines for new developments and quantitative information on where and how to optimize haptic systems. As application example a haptic interface for the simulation of hysteroscopy, a gynecologic intervention on the female uterus, has been realized as prototype. The device takes the characteristics of hysteroscopy into account and introduces features like insertion and complete removal of the surgery tool from the haptic interface. A design methodology is proposed, which combines aspects of theoretical kinematics based on Lie-Groups with integrated product development – a systematic approach for engineering tasks. The result, a novel kinematic design, has been realized as haptic interface prototype. The well-known affine parameterization for all stabilizing controllers is shown to be a well-suited tool for haptic control synthesis. It provides insights into the control trade-offs and allows to integrate human factors at controller design stage. The resulting controller, demonstrated by experimental results, can reduce parasitic effects (friction, device dynamics) close to and below the human perception threshhold, thus making the device transparent within the specified bandwidth and suitable for real-time implementation. For numerical controller representation the δ-operator is discussed. It unifies continuous and discrete time domain and has beneficial numerical properties. As there is still no standardized procedure for technical performance evaluation of haptic interfaces methods proposed in literature are summarized. In the near future a large market for haptic technology can be expected with applications from surgery-assist devices and drive-by-wire interfaces in automobiles to entertainment, which highlights the relevance of the treated topic.

EPFL2006

Systematic Evaluation Methodology and Performance Metrics for Haptic Interfaces

Evren Samur

The purpose of evaluation procedures for haptic interfaces is to achieve both qualitative and quantitative statements on haptic rendering realism and performance. Since haptics technology is being increasingly used in computer games, surgical simulators, mobile phones etc., there is a need for defining standards for haptic applications. This study aims at meeting this need by establishing a norm for evaluation of haptic interfaces and by identifying significant benchmark metrics. Towards this end, a combined physical and psychophysical experimental methodology is proposed in this work. First, the existing physical performance measures and device characterization techniques were investigated and described in an illustrative way. The physical characterization methods were demonstrated on a novel two degrees-of-freedom haptic interface for colonoscopy simulation. Second, a wide range of human psychophysical experiments were reviewed and the appropriate ones were applied to haptic interactions. The psychophysical experiments were unified as a systematic and complete evaluation method for haptic interfaces. Seven psychophysical tests were derived and implemented for three commercial force-feedback devices. Experimental user studies were carried out and applicability of the tests to a tactile feedback device was also investigated. The physical evaluation resulted in a detailed tutorial-like guideline for device characterization. Testing conditions and methods were described to allow performing identical tests with other devices. The psychophysical evaluation resulted in novel benchmark metrics for haptic interfaces. The performance metrics are expressed in terms of information transfer (bits) and sensory thresholds, which are indeed device specific metrics. They are not only related to the basic physical characteristics of haptic interfaces, but also easier to be linked with the rendering quality perceived by the user. The results prove that the metrics are suitable to compare force-feedback devices. The metrics reveal the basic characteristics of the devices which are not easily derived from the given specifications. The results were also compared with those from human psychophysical experiments with real objects. Significant differences clearly demonstrate the limits of the haptic interfaces. In conclusion, the generic methodology proposed in this work enables users to evaluate the suitability of a haptic interface for a specific purpose, to characterize and compare devices quantitatively and to identify possible improvement strategies in the design of the system.

EPFL2010

Increasing Haptic Fidelity and Ergonomics in Teleoperated Surgery

Laura Santos Carreras

Over the past few decades, surgical procedures have made enormous progress, shifting from traditional open procedures to less and less invasive approaches, with the promise of smaller incisions, less complications, better cosmetic results and shorter recovery times. With these developments came a reduced dexterity and more complex control through the fulcrum effect and modified eye-hand coordination. These complications were greatly mitigated by the recent introduction of surgical robots, allowing the surgeon to sit in a comfortable posture, and restoring natural visuomotor coordination. To date, the issue of the lack of haptic feedback, which initially allowed the surgeon to intervene without vision, identify pathological tissue, feel arteries, etc., has not been resolved, despite the fact that it is crucial in certain interventions. Besides, the added value of haptic feedback is subject to controversy. Surgeons experienced in robotic surgery have adapted to the lack of haptic feedback and learned how to rely only on vision and proprioceptive cues as compensation. Nevertheless, previous studies have shown that substituting haptic information through various sensory channels can increase surgeons' performance. As a complete restoration of the sense of touch is extremely challenging in minimally invasive surgery, the advantages of haptic feedback have to be demonstrated and quantified to justify the additional cost and complexity. This is the aim of the present work. We hypothesized that tactile feedback as well as force is crucial in surgery and we investigated the haptic information involved in several representative surgical tasks. Dedicated hardware and a virtual reality environment to simulate suturing and palpation tasks were developed to address these questions. Ergonomic design guidelines were established based on an in-depth literature review and surgeons' comments gathered in a survey. These guidelines were then used to design and benchmark an ergonomic haptic handle featuring active grasping feedback and additional safety features. The results of the first two studies suggest that the benefits of haptic information highly depend on the surgical task in question. During a suturing task, force feedback significantly increased users' accuracy whereas torque feedback did not result in any significant improvement. In a palpation task, a higher recognition rate was achieved with tactile feedback than with visual sensory substitution. The performance of the haptic device integrating the ergonomic handle was assessed and compared with the standard omega.7 haptic device. Results showed that the index of performance of the original device was not degraded with the additional hardware. The index of performance was slightly increased for a manipulation task involving orientations. The ergonomic assessment of the handle showed a slight decrease of the tension in the adductor pollicis and flexor digitorium muscles, and therefore a potential decrease of fatigue. Although just a subset of surgical tasks could be investigated, the results indicate that haptic feedback and sensory substitution would greatly benefit teleoperated robotic surgery. Providing the surgeon with tactile information can potentially restore the feeling of "contact with the patient" and other surgeries that are highly reliant on the sense of touch could become possible again. This thesis presents a novel multidisciplinary approach to systematically analyzing surgical tasks in order to improve safety in two dimensions. Firstly, in the area of patient safety by providing the surgeon with haptic information to increase performance and reduce the risk of errors and secondly, in the area of surgeon safety by providing a more ergonomic master console. We expect this work to be a first step in establishing a general design method for more ergonomic surgeon consoles and trust that it will inspire research to investigate the sensory mechanisms underlying highly dexterous tasks such as those performed in surgery.

EPFL2012