The sigma.7 haptic interface for MiroSurge: A new bi-manual surgical console

Abstract

This paper presents the design and control of the Sigma.7 haptic device and the new surgical console of the MiroSurge system. The console and the haptic devices are designed with respect to requirements in minimally invasive robotic surgery. A dedicated left and right handed device is mounted on an operator console in an ergonomic configuration. The height of the whole console is adjustable, allowing the surgeon seated and standed operation. Each of the devices is fully actuated in seven degrees of freedom (DoF). A parallel mechanism with 3 DoF actuates the translational motion and an attached serial kinematic structure with another 3 DoF drives the rotations of the handle. The latter integrates a 7th motor for grasping. Cartesian forces are 20 N within the translational workspace, which is a sphere of about 120 mm diameter for each device. The rotations of the device are not limited within the workspace of the human hand. Maximum torques of the rotations and the grasping are 0.4 Nm. A force/torque sensor is integrated in the device and used to reduce inertia and friction to improve the ability to discriminate fine stiffness variations, e.g. for localizing tumors. It is theoretically shown that the non-linear closed loop system behaves like a passive system and experimental results validate the approach. The haptic devices, Sigma.7, are designed by Force Dimension in cooperation with DLR and are integrated into the operator console of the DLR MiroSurge system.