Haptic interface for endoscopy simulation

Abstract

Various haptic devices have been developed to provide haptic feedback in gastrointestinal endoscopic simulation. The previously developed haptic feedback device satisfied the required force and torque, but the haptic interface was large and the haptic bandwidth was under 20Hz, or the size and inertia were reduced, but the required torque and reaction were not satisfied. In this paper, an interface that reduces the size and inertia of the device is designed while satisfying the required torque and forces. To satisfy the required torque, the eccentric rotational mechanism is used to maintain low friction force. To maintain low friction force, contact between endoscope and eccentric guide was modelled as of flexible and rigid body to calculate friction force. The path of the guide was optimized considering the friction caused by the resiliency of the endoscope. The contact of the endoscope with the rollers was modelled as contact between the rigid and the elastomer to determine the optimum number and the shape of the rollers. In the case of translational force, the existing device has been improved. The mechanism implemented using six pins and one bush has been modified to enable one pin to be actuated. Design parameters are specified to minimize resistance due to friction with the cam. Rotational resist torque is minimized by optimizing the position and size of the rollers. Experiments have shown that for eccentric rotational device can provide 0.28 Nm. Analyze the cause of no torque amplification is not available. The torque bandwidth of an eccentric rotational device meets the requirements at 30 Hz. In the case of translational part, 40 pins and 8 bushes were reduced compared to conventional devices. Overall rotational inertia was reduced by 30%. Force bandwidth is 58 Hz, which is about twice as much as conventional devices. For translational friction force is 1.2 N, down 0.4 N from the conventional devices. Rotational resist torque is 0.12 Nm a similar to the conventional devices.