Evaluation of User Interfaces for Actuated Control of Endoscopes During Flexible Endoscopy

Flexible endoscopy is a valuable tool in diagnostic procedures, enabling examination of internal areas via natural orifices. An actuation system tends to improve the procedural outcomes by enabling controlled movements of the endoscope and offering a stable view of the operative field. A user interface is used to issue actuation commands to these systems. Thus, selection of an ideal user interface is vital to improve the ergonomics for the endoscopist and to ensure efficient endoscope navigation. The objective of this work is to perform an in-depth comparative analysis of various user interfaces to optimize endoscope maneuverability.

A custom-built actuation system was used to maneuver a flexible endoscope. The actuation system enabled translational and rotational movement of the endoscope's shaft as well as supported left/right and up/down steering of the endoscope's distal end. Four user interfaces (head-motion based device, eye-gaze based device, a stylus, and a joystick) working under three interaction modes (continuous, discrete, threshold) along with a clutching mechanism were used to issue commands to the actuation system. A user study was conducted to assess the effectiveness of the user interfaces for two scenarios: Scenario-A, which involved maneuvering the endoscope's distal end to focus on a localized operative field, and Scenario-B, which required targeting polyps during the withdrawal phase of a simulated colonoscopy.

In Scenario-A, the head motion-based device and stylus, when used in continuous interaction mode, resulted in the shorter task duration and fewer clutches. The joystick, operating under threshold interaction mode, also demonstrated a reduced task duration. Additionally, the joystick led to fewer instances of the endoscope's focus shifting outside the localized operative field. In Scenario-B, eye gaze-based device under discrete interaction mode took the longest duration for task completion. The continuous mode of the stylus took the shortest duration to target polyps, once visualized in the operating field. However, it also required the highest number of clutches compared to other user interface and interaction modes.

The joystick consistently outperformed other interfaces across all interaction modes. Performance among the other user interfaces varied based on the parameters of the scenarios. Head motion-based and eye-based user interfaces enabled hands-free manipulation of the endoscope. This study establishes a benchmark for enhancing both user interfaces and interaction modes in actuated flexible endoscopy.