Nataliya Stefanova

Examples of Haptic System Development

In this section, several examples of task-specific haptic systems are given. They give an insight into the process of defining haptic interactions for a given purpose and illustrate the development and evaluation process outlined in this book so far. Examples were chosen by the editors to cover different basic system structures. Section 14.1—Tactile You-Are-Here-Maps illustrates the usage of a tactile display in an assistive manner, enabling a more autonomous movement of people with visual impairments. Section 14.2—User Interface for Automotive Applications presents the development of a haptic interface for a new kind of user interaction in a car. It incorporates touch input and is able to simulate different key characteristics for intuitive haptic feedback. Section 14.3—HapCath describes a comanipulation system to provide additional haptic feedback in cardiovascular interventions. The feedback is intended to reduce exposure for both patient and physician and to permit new kinds of diagnosis during an intervention.

Characteristic of a force sensing guide wire for minimally invasive cardiac surgery

In minimal invasive cardiac surgery (MICS), the surgeon is missing haptic feedback of the guide wire for navigation through the vessels. A wide range of guide wires with various properties and performance characteristics are available to reduce the risk of complications during the intervention. This paper presents a force sensing guide wire for cardiac catheterization, which provides the surgeon a haptic feedback on the guide wire tip. Three conventional wires for the recanalization of chronic total coronary occlusions (CTO) are investigated and general design requirements for the force sensing guide wire are determined. A comparison of the developed with the conventional guide wires concerning the tip force is conducted. The measured tip force of the force sensing guide wire is 50 mN, which is slightly lower than two of the compared conventional wires. As a result, the guide wire offers a good compromise between a soft, low-traumatic and hard guide wire tip.

Single-transducer acoustic levitator with equidistant vertical positioning capability

We present an acoustic levitator experiment in air, in which objects can be vertically positioned to several equidistant locations. The setup consists of only one single-element transducer and one reflector. The main objective of this work was to investigate whether it is possible to move and position an object vertically in such a setup with only one narrowband single-element transducer and only one reflector, without moving the transducer or reflector at all. The key idea is that we exploit gravity to let the object fall from one pressure nodal node to one at a lower position. This is achieved by amplitude modulation of the transducers driving signal with varying gap times in order to match the free-fall time of the levitated object from one nodal plane to one of the nodal planes below. The levitator is able to generate sound pressure levels of up to 163 dB SPL, and, thus, capable of levitating lightweight objects over longer distances of several centimeters and high density samples such as water drops, glass or steel spheres over shorter distances. Our results prove that the levitated objects can be precisely and reproducibly transported from a higher pressure nodal plane to the next lower nodal plane position.

Miniaturized Haptic User-Interface for Heart Catheterizations – Concept and Design

During heart catheterization the cardiologist controls the direction of the guide wire mainly by visual x-ray information. In this paper a haptic display is presented, which generates an amplified force feedback of the contact force measured at the distal tip of a guide wire. A network model is elaborated and a concept for miniaturization and integration into a haemostasis valve is proposed.

Measurement setup to evaluate haptic interaction in catheterization procedures for training purposes

Recanalization of chronic total occlusions (CTO) of coronary vessels is a catheter intervention with proven benefit for the patient. However, it incorporates a risk of penetrating the vessel as well as increasing patients exposure to radiation and contrast agent. The physicians expertise is a key to successful interventions. In this work, we present a system to assess haptic interaction of medical professionals in an CTO intervention. As a test scenario, a silicone model with comparable mechanic properties of a CTO, including fibrous caps and microchannels is used. A special guide wire with a diameter of 360 μιη and an integrated force sensor at the tip can measure intracorporal forces. Additionally, a torquer with an integrated single-axis force sensor is used to measure the forces executed by the cardiologist during the procedure. The guide wire motion is measured by two encoders (translational and rotatory) in order to assess motion-based quality criteria. A camera setup with software filtering is used to obtain an x-raylike image of the training scenario. Applied x-ray and contrast agent doses can be measured as well. The setup is intended to develop new training schemes based on interactions exerted by experts.