Beyond the manual touch: situational-aware force control for increased safety in robot-assisted skullbase surgery

PURPOSE

Skullbase surgery demands exceptional precision when removing bone in the lateral skull base. Robotic assistance can alleviate the effect of human sensory-motor limitations. However, the stiffness and inertia of the robot can significantly impact the surgeon's perception and control of the tool-to-tissue interaction forces.

METHODS

We present a situational-aware, force control technique aimed at regulating interaction forces during robot-assisted skullbase drilling. The contextual interaction information derived from the digital twin environment is used to enhance sensory perception and suppress undesired high forces.

RESULTS

To validate our approach, we conducted initial feasibility experiments involving a medical and two engineering students. The experiment focused on further drilling around critical structures following cortical mastoidectomy. The experiment results demonstrate that robotic assistance coupled with our proposed control scheme effectively limited undesired interaction forces when compared to robotic assistance without the proposed force control.

CONCLUSIONS

The proposed force control techniques show promise in significantly reducing undesired interaction forces during robot-assisted skullbase surgery. These findings contribute to the ongoing efforts to enhance surgical precision and safety in complex procedures involving the lateral skull base.

A force-sensing surgical drill for real-time force feedback in robotic mastoidectomy

PURPOSE

Robotic assistance in otologic surgery can reduce the task load of operating surgeons during the removal of bone around the critical structures in the lateral skull base. However, safe deployment into the anatomical passageways necessitates the development of advanced sensing capabilities to actively limit the interaction forces between the surgical tools and critical anatomy.

METHODS

We introduce a surgical drill equipped with a force sensor that is capable of measuring accurate tool-tissue interaction forces to enable force control and feedback to surgeons. The design, calibration and validation of the force-sensing surgical drill mounted on a cooperatively controlled surgical robot are described in this work.

RESULTS

The force measurements on the tip of the surgical drill are validated with raw-egg drilling experiments, where a force sensor mounted below the egg serves as ground truth. The average root mean square error for points and path drilling experiments is 41.7 (± 12.2) mN and 48.3 (± 13.7) mN, respectively.

CONCLUSION

The force-sensing prototype measures forces with sub-millinewton resolution and the results demonstrate that the calibrated force-sensing drill generates accurate force measurements with minimal error compared to the measured drill forces. The development of such sensing capabilities is crucial for the safe use of robotic systems in a clinical context.

Haptic feedback in the da Vinci Research Kit (dVRK): A user study based on grasping, palpation, and incision tasks

BACKGROUND

It was suggested that the lack of haptic feedback, formerly considered a limitation for the da Vinci robotic system, does not affect robotic surgeons because of training and compensation based on visual feedback. However, conclusive studies are still missing, and the interest in force reflection is rising again.

METHODS

We integrated a seven-DoF master into the da Vinci Research Kit. We designed tissue grasping, palpation, and incision tasks with robotic surgeons, to be performed by three groups of users (expert surgeons, medical residents, and nonsurgeons, five users/group), either with or without haptic feedback. Task-specific quantitative metrics and a questionnaire were used for assessment.

RESULTS

Force reflection made a statistically significant difference for both palpation (improved inclusion detection rate) and incision (decreased tissue damage).

CONCLUSIONS

Haptic feedback can improve key surgical outcomes for tasks requiring a pronounced cognitive burden for the surgeon, to be possibly negotiated with longer completion times.

Experimental Study of Thrust Force and Torque for Drilling Cortical Bone

Excessive drilling forces can result in drill breakage, bone breakthrough, and thermal necrosis during bone drilling process. However, the effect of drilling process parameters, drill geometry parameters, and bone material type on drilling forces have not been fully investigated. Three designs of experiments are introduced separately to study single factor's effect on drilling forces, identify significant geometry parameters and possible interactions for drilling forces, and formulate direct relationship between drilling forces and process parameters. The results show that thrust force and torque are increased with feed rate, drill diameter or web thickness. The effect of spindle speed, point angle, helix angle, and chisel edge angle on drilling forces is complex. The results also show that the drilling forces are affected by bone type significantly, which are highest for bovine cortical bone, and lowest for Sawbones 3401. The levels of significance of geometry parameters are identified and different for thrust force and torque, which can assist new surgical drill development. Quadratic regression equations obtained by response surface methodology can predict thrust force and torque accurately in a wide range of process parameters, which can be used to control drilling conditions for robot assisted surgeries to realize safe drilling.