Compact teleoperated laparoendoscopic single-site robotic surgical system: Kinematics, control, and operation

Suture Breakage Warning System for Robotic Surgery

As robotic surgery has increased in popularity, the lack of haptic feedback has become a growing issue due to the application of excessive forces that may lead to clinical problems such as intraoperative and postoperative suture breakage. Previous suture breakage warning systems have largely depended on visual and/or auditory feedback modalities, which have been shown to increase cognitive load and reduce operator performance. This work catalogues a new sensing technology and haptic feedback system (HFS) that can reduce instances of suture failure without negatively impacting performance outcomes including knot quality. Suture breakage is common in knot-tying as the pulling motion introduces prominent shear forces. A shear sensor mountable on the da Vinci robotic surgical system's Cadiere grasper detects forces that correlate to the suture's internal tension. HFS then provides vibration feedback to the operator as forces near a particular material's failure load. To validate the system, subjects tightened a total of four knots, two with the Haptic Feedback System (HFS) and two without feedback. The number of suture breakages were recorded and knot fidelity was evaluated by measuring knot slippage. Results showed that instances of suture failure were significantly reduced when HFS was enabled (p = 0.0078). Notably, knots tied with HFS also showed improved quality compared to those tied without feedback (p = 0.010). The results highlight the value of HFS in improving robotic procedure outcomes by reducing instances of suture failures, producing better knots, and reducing the need for corrective measures.

A gesture-based design tool: Assessing 2DOF vs. 4DOF steerable instrument control

Iterative prototyping is costly and time-consuming. Particularly when designing medical instruments, human factors related design choices significantly impact performance and safety. A tool is presented that allows for the evaluation of steerable instrument controls before the onset of the prototyping stage. The design tool couples gestural input to virtually simulated instrument motions using hand motion tracking. We performed a human-subject evaluation of two manual control strategies that differed in their degrees of freedom (DOF). 2DOF thumb control was compared to 4DOF thumb-index finger control. Results identified regions within the instrument workspace that are difficult to reach and showed participants to favor using the thumb for gross and fine-tuning motions at both control strategies. Index finger ab/adduction was found to be least functional. A strong learning effect was observed at 4DOF control. Based on the results, gesture-based instrument design is a viable design tool.

Torque Contribution to Haptic Rendering of Virtual Textures

Despite the fact that conventional haptic interfaces and rendering algorithms commonly approximate interactions with force only, the dynamic effects of even simple tasks, e.g., writing on a paper, involve both forces and torques. To extend previous algorithms as well as to investigate the effects of torque feedback on human roughness perception, we deployed a novel haptic platform with two probes, fingertip and penhandle. Three torque conditions were examined: 1) Slope Torque, which orients the probe perpendicular to the surface, 2) No Torque, where no active torque is provided by the device, and 3) Stiff Torque, where torque feedback is provided to keep the probe upright. A conventional magnitude estimation experiment was performed. The results indicated that both the torque signals and grasp type mediate human perception of virtual textures. Slope Torque led to greater perceived roughness when the fingertip was used, and the fingertip led to higher roughness ratings than the penhandle with the Slope Torque condition. The Slope Torque algorithm appears to be advantageous for generating rougher surfaces compared to the force-based algorithms which are typically limited by the system stability and actuator saturation.