Removing Digestive Tumors With a Therapeutic Endoscopy Teleoperation Robot Controlled by LabVIEW

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"The new solution is much better than our previous prototypes. We now have a safe, reliable, efficient system and NI products played a big role in this success for several reasons."

- Martin Hiernaux, Endo Tools Therapeutics s.a.

The Challenge:
Developing the first flexible digestive teleoperation system linking the movements of two motorized tools to be used on the patient and the movements of two haptic joysticks to be controlled by the surgeon. This system needs to be responsive, compact, strong, and safe.

The Solution:
Using NI real-time hardware and NI LabVIEW software to communicate with all interfaces and to link the movements in a safe and timely manner, as well as to create an easy–to-use user interface on a touch panel.

Author(s):
Martin Hiernaux - Endo Tools Therapeutics s.a.

NI Silver Alliance Partner Endo Tools Therapeutics (ETT) is a medical device company based in Brussels, Belgium that was established in 2008. The company was formed after an innovative research project started in 2004 at Erasme hospital (Université Libre de Bruxelles) and the faculty of engineering (Beams department, Université Libre de Bruxelles) based on the need for gastroenterologists to have more degrees of freedom when maneuvering an endoscope. The researchers focused on developing robotized flexible arms anchored on an endoscope to insert into the digestive tract. Those arms would move independently from the endoscope and would enable surgery from within the digestive tract. This would give surgeons and gastroenterologists a whole set of new “scarless” therapies like those used in obesity treatment and tumor resection.

The first part of the system is called Endomina and consists of flexible arms that are inserted into the patient’s digestive tract. Endomina has multiple wires, which are pulled or pushed to move the arms like a puppet. The second part of the system, called Endofix, is a motorized medical station that connects to Endomina. Besides NI computational hardware, Endofix has several motors, two haptic joysticks, and a touch panel. Endofix motors move Endomina wires according to a calculation done on the movements performed by the gastroenterologist with the two haptic joysticks. Endofix has a visual human interface on the touch screen panel that gives information to the user about the status of the operation and also provides additional user controls. The gastroenterologist becomes a puppet master of what happens at the end of Endomina’s arms inside the digestive tract of the patient.   

We prototyped our device with commercial off-the-shelf (COTS) industrial controllers using text-based programming and sensors interfaced via an industrial controller area network (CAN). When we started developing the final product, we evaluated four options for the job. We considered using a custom route because we had the capabilities and there would be no major technical challenges, but this option was rapidly discarded because of production, safety, delay, and reliability concerns. The second option was to continue using the COTS controller from the motor vendor, but it was not powerful enough and the text-based programming had shown too many limitations. The third option was to use The MathWorks, Inc. MATLAB® or Simulink® rapid prototyping route, with an xPc target, but we discarded those options because they can’t support a turnkey operation, they are expensive, and most importantly, going into production involves multiple operations and often a platform switch to reduce costs. The fourth option was an NI solution, applying an embedded PXI system with a real-time operating system.
The NI hardware consists of a 4 slot PXI-1031 chassis, containing a PXI-8101 2 GHz embedded real-time controller a PXI-8512 one- port CAN interface and a PXI-7811R reconfigurable FPGA board with 160 digital I/O. The CAN interface is used to control the motor controllers for the Endofix medical motorized station.

Even though we were not familiar with NI products and had no LabVIEW programming experience, we chose NI products for several reasons, including the following:
• Relative ease of graphical programming
• Real-time hardware and software
• Development and production with the same hardware and software at a reasonable price
• Turnkey operation of many hardware modules and no need to worry about drivers
• Hardware reliability
• Responsiveness and knowledge of the NI staff

Developing the Endofix Software With LabVIEW

Endofix consists of two separate sets of VIs. The first set is a visual human interface developed in LabVIEW on a Windows XP-based touch panel. It provides the user information about the status of the entire system during the operation, as well as additional controls. There is also a set of real-time VIs, developed with the LabVIEW Real-Time Module running on the PXI platform. These VIs handle the communication with all the actuators and sensors, perform all the movement calculations, and take care of safety measures. Almost all communication is done via the CAN modules using the CANopen standard, which was particularly easy to implement with an additional library. All the VIs were managed in the same LabVIEW project under Source Control, a feature we used every day. Switching from HMI development to real-time system development yet staying in the same programming environment with almost all the same features was particularly useful and productive.

The Benefits of Using the NI Platform

The new solution is much better than our previous prototypes. We now have a safe, reliable, efficient system and NI products played a big role in this success for several reasons. NI gave us turnkey operation of all the hardware modules. For example, plugging in the modules and having direct access with an easy to use driver could not have been easier or more efficient. We could port the software to multiple hardware platforms and many subVIs in the project run on both Windows and in a LabVIEW Real-Time platforms. Because the VIs are hardware independent, we can maintain a single version and deploy it on many targets. Moreover, this means we can choose another less powerful platform for commercialization. The PXI system we are currently using is clearly oversized, so we will use a smaller NI CompactRIO or NI Single-Board RIO platform in the future, and we can leave the software almost untouched.

The modular architecture made it easy to add new functionalities throughout the project without having to redesign the entire system. Additionally, it was easier to meet regulations (currently CE mark, but we are working on FDA approval as well) with graphical programming. The software architecture translates almost immediately into block diagrams. Moreover, the LabVIEW VI Analyzer Toolkit, the LabVIEW Unit Test Framework Toolkit, and the source code control tools were extremely useful to ensure good programming practices, VI validation, and a detailed development history, respectively. All these criteria were essential to meet regulatory requirements for medical devices development.

The interaction with NI sales staff was very important. We received precise advice tailored to our specific project. The staff took the necessary time to understand our project and requirements before proposing configurations that would meet our criteria, as well as our budget. Throughout the project, NI staff cared about our progress and offered helpful suggestions.

NI technical support was also very impressive. Whenever we called tech support, they did not try to answer our question immediately, which can rapidly lead to a series of long conversations with different people. Instead, they made sure to understand our request, then someone extremely knowledgeable would get back to us in a timely manner and respond precisely to what we needed, saving both sides a valuable amount of time.

NI products also saved us a lot of valuable time. NI products were particularly helpful in meeting regulatory requirements in a cost-effective and scalable manner. Finally, NI software portability is helping us manufacture a product with the least expensive yet most efficient NI hardware without having to rewrite a single piece of software once development is finished.

Author Information:
Martin Hiernaux
Endo Tools Therapeutics s.a.
Rue de l’industrie 241400
Nivelles
Belgium
info@endotools.be

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