Abstract
Purpose :
Advancements in robotics and computing technology enabled robotic enhanced surgeries in many medical sectors and while such technologies yet have to be successfully adopted in ophthalmology, they are under active research.
Designing a user interface that enables the operator precise control while providing feedback in an adequate way is a key challenge. We built a prototype of an haptic input device that provides force feedback to the operator.
Methods :
We designed a haptic input device that mimics the kinematics of an instrument inserted through an incision by combining two rotary (yaw and pitch) and one linear axis (penetration). Both rotary axes are equipped with encoders (high quality potentiometers) to record the position as well as motors (Maxon S26 series) to apply force, acting as haptic feedback. The strength of the feedback force is controlled by a micro controller that also records the current orientation of all axes. The mechanical design ensures the forces applied to the two axes are independent. Further the device can be easily integrated into a modular control desk, with most of the hardware mounted below. Among other controls such a control desk would feature a 3D stereoscopic display. During development the usability of the device was evaluated using our robotic surgery setup that was presented at ARVO Anual Meeting 2023.
Results :
The arrangement proved more intuitive for guiding an instrument than controlling the position of the instruments tip directly (using a delta kinematic or 3D joystick for example). The force needed to move the handle when no force feedback is applied is sufficiently low (< 0.015 Nm) while the maximum force of the feedback mechanism is high enough to provide useful feedback (> 0.40 Nm). The device has an accuracy of +-0.2°, limited by the 10-bit ADC of the currently used micro controller.
Conclusions :
The feedback force could be used to mirror a force on the real world instrument as captured by sensors or simulate virtual forces. These virtual forces can guide the operator on an predefined instrument trajectory or keep them from entering areas that must be avoided.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.