Introducing Pneumatic Actuators in Haptic Training Simulators and Medical Tools

Abstract

Simulators have been traditionally used for centuries during medical training as the trainees have to improve their skills before practicing on a real patient. Nowadays mechatronic technology has open the way to more evolved solutions enabling objective assessment and dedicated pedagogic scenarios. Trainees can now practice in virtual environments on various body parts, with current and rare pathologies, for any kind of patient (slim, elderly..). But medical students need kinesthetic feedback in order to get significant learning. Gestures to acquire vary according to medical specialties: needle insertion in rheumatology or anesthesia, forceps installation during difficult births.. Simulators reproducing such gestures require haptic interfaces with a variable rendered stiffness, featuring commonly called Variable Stiffness Actuators (VSA) which are difficult to embed with off-the-shelf devices. Existing solutions do not always fit the requirements because of their significant size. In contrast, pneumatic technology is low-cost, available off-the-shelf and has a better mass-power ratio. Its main drawback is its non-linear dynamics, which implies more complex control laws than with electrical motors. It also requires a compressed air supply. Ampère research laboratory has developed during the last decade haptic solutions based on pneumatic actuation, applied on a birth simulator, an epidural needle insertion simulator, a pneumatic master for remote ultrasonography, and more recently a needle insertion under ultrasonography simulator. This paper recalls the scientific approaches in the literature about pneumatic actuation for simulation and tools in the medical context. It is illustrated with the aforementioned applications to highlight the benefits of this technology as a replacement or for an hybrid use with classical electric actuators.