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Scaled TeleRobotics for EnhAnced Microsurgery

Periodic Report Summary 2 - STREAM (Scaled telerobotics for enhanced microsurgery)

STREAM developed a framework to design robot controllers for 'bilateral control', thus including force feedback, teleoperation focusing on microsurgical minimally invasive applications, with intraocular interventions taken as a case study. The control methods developed in STREAM allow variable and high scaling of forces and motions between surgeon console (joystick) and robotic slave, paving the way towards interventions with superhuman positioning / manipulation precision. In order to realise the required precision it was necessary to design a surgical robot that can actually achieve such ultra-precise motions. Based on an innovative robot mechanism a novel surgical slave robot was designed and built. A patent application to protect this invention is under preparation. The novel robot can be employed 'hands-on'. The surgeon can directly hold the robot and co-manipulate the device to position instruments in a precise manner. Different co-manipulation strategies were investigated and some first results were reported. Micro surgeons participating in the experiments evaluated the system very positively and managed to achieve accuracies in the order of 5 microns when performing positioning tasks. Some teleoperation experiments with a commercial haptic joystick (PHANToM haptic display by Sensable Technologies) as master robot were performed. Currently a dedicated haptic master joystick with geometric / dynamic properties that lie closer to those of the slave robot is under development.

STREAM further developed methods to improve human-robot collaborative tasks by exploiting prior or online obtained environmental knowledge:

- Image-processing techniques are being developed to interpret the surgical scene and help steering instrument motion, keeping it away from dangerous regions and allowing automatic adjustment of scale factors.
- In collaboration with the project SCATH which was funded under the European Union (EU)'s Seventh Framework Programme (FP7), the feasibility of bilateral teleoperation to steer catheters inside the vascular system is being investigated. Catheter steering is complicated by the presence of slack between catheter and vessel which complicates accurate tip position control dramatically. From STREAM activities out, a new approach to perform intra-operative SLAM in the vessel for catheter steering was formulated. After approval of the SCATH project the fellow continued to guide this research.
- It is shown how, by incorporating prior knowledge about the dynamic properties of the environment that is interacted with, bilateral controllers can be tuned to provide better performance in the envisioned working range. These findings are described in a series of publications that can be gathered under the denominator of the new concept of 'bounded environment passivity'. Some first steps are also made to translate geometric environmental knowledge towards a constrained-based robot programming method. This approach could complement passivity-based methods and improve operational safety by simplifying the formulation of static or dynamic geometric constraints, safety zones and program haptic guidance techniques.
- Experiments with novel guidance techniques providing 'haptic environmental feedback' for navigation tasks were conducted, submitted and accepted for publication. This research took place jointly under the scope of the FP7 project RADHAR. A novel compact and powerful 2-d.o.f haptic joystick was designed for these experiments. The new haptic display system is extremely compact, yet capable of delivering output forces up to 30 Newton. The device has shown to be very robust in use, gracefully surviving occasions where controller instability occurred and requiring no adjustments whatsoever ever since. A series of user trials are planned shortly. First, trials will take place in a simulation environment to allow further tuning of controller parameters to the specific users. Through further experiments and in collaboration with industrial partners it will be decided how further exploitation of this device could take place.

Current efforts are dedicated to transfer the developed guidance techniques towards surgical interventions. Also, here the importance of user trials cannot be overestimated as the motion of the surgical instrument will result from a combination of system (guidance) and user input. The question on how to share control in such manner is highly application- and likely person-dependent.

In short, STREAM investigated and developed a number of control strategies to enable reliable-scaled teleoperation. Special attention was paid to methods to ensure safe operation, embedding safety and simplifying operation through varies sorts of haptic guidance. Novel hardware was designed to support the targeted research. Protection of the internet protocol (IP) following from STREAM research is still under way. Obviously, more experiments with actual users will help to evaluate and tune the developments and understand the impact of the developments.

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