Development of Multipoint Haptic Device for Spatial Palpation

Abstract

This thesis deals with the development of novel haptic array system that can render distributed pressure pattern. The haptic devices are force feedback interfaces, which are widely seen from consumer products to tele-surgical systems, such as vibration feedback in game console, mobile phones, virtual reality applications, and daVinci robots in minimally invasive surgery. Telemedicine and computer-enabled medical training system are modern medical infrastructures where the former provides health care services to people especially in rural and remote places while the latter is meant for training the next generation of doctors and medical students. In telemedicine, a patient at a remote location consults the physician at a distant place through the telecommunication media whereas in computer enabled medical training system, physician and medical students interact with the virtual patient. The experience of physical presence of the remote patient in telemedicine and immersive interaction with virtual patient on the computer-enabled training system can be attained through haptic devices. In this work we focus on palpation simulation in telemedicine and medical training systems. Palpation is a primary diagnostic method which involves multi-finger, multi-contact interaction between the patient and physician. During palpation, a distributed pressure pattern rather than point load is perceived by the physician. The commercially available haptic devices are single and five point devices, which lack the face validity in rendering distributed pressure pattern; there are only a few works reported in literatures that deal with palpation simulation. There is a strong need of a haptic device which provide distributed force pattern with multipoint feedback which can be applied for palpation simulation in telemedicine and medical training purposes. The haptic device should be a multipoint device to simulate palpation process, an array device to render distributed force pattern, light weight to move from one place to another and finally it has to cover hand portion of physician. We are proposing a novel under-actuated haptic array device, called taut cable haptic array system (TCHAS), which in general is a m x n system, consist of m+n actuators to obtain m.nhaptels, that are multiple end effectors. A prototype of 3 x 3 TCHAS is developed during this work and detailed study on its characterisation is explored. The performance of device is validated with elaborate user study and it establishes that the device has promising capability in rendering distributed spatio-temporal pressure pattern.