There is a trend towards miniaturization in surgical robotics with the objective of making surgeries less invasive [1]. There has also been increasing recent interest in hand-held robots because of their ability to maintain the current surgical workflow [2, 3]. We have previously presented a system that integrates small-diameter concentric tube robots [4, 5] into a hand-held robotic device [3], as shown in Figure 1. This robot was designed for transurethral laser surgery in the prostate. It provides the surgeon with two dexterous manipulators through a 5mm port in a traditional transurethral endoscope. This system enables the surgeon to retract tissue and aim a fiber optic laser simultaneously to resect prostate tissue.

This robot provides the surgeon with a total of ten degrees of freedom (DOF) that must be simultaneously coordinated, including endoscope orientation (3 DOF), endoscope insertion (1 DOF), as well as the tip position of each concentric tube manipulator (3 DOF per manipulator). In [3], a simple user interface was employed that involved thumb joysticks (which also had pushbutton capability) and a unidirectional index finger trigger, as shown in Figure 2 (Left). The thumb joysticks were mapped to manipulator tip motion in the plane of the endoscope image, and the trigger was used for motion perpendicular to the plane. Whether the finger trigger extended or retracted the tip of the concentric tube manipulator was toggled via the pushbutton capability of the thumb joystick. While surgeons could learn this mapping with some effort, and were able to use it to accomplish a cadaver study, the experiments made clear that further work was needed in creating an intuitive user interface — particularly with respect to how motion perpendicular to the image plane is controlled. This paper describes a first step toward improving the user interface; we integrate a bidirectional dial input in place of the unidirectional index finger trigger, so that extension and retraction perpendicular to the image plane can be controlled without the need for a pushbutton toggle. In this paper we describe the design of this dial input and present the results of a user study comparing it to the interface in [3].

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