Summary of My Current Research

Summary of My Current Research


Jitendra Prasad Khatait

Surgical robotic systems are revolutionizing healthcare and medical services. Minimally-Invasive-Surgery (MIS) has greatly reduced the unnecessary damage and trauma to healthy tissues, leading to faster recovery, reduced infection rate, and reduced post-operative complications. The state-of-the-art robotic surgery systems employ rigid instruments. However, with conventional colonoscopy and with the emergence of Natural Orifice Transluminal Endoscopic Surgery (NOTES) and Single Incision Laparoscopic Surgery (SILS) procedures, the use of flexible instruments is inevitable. These flexible instruments are fed through access channels provided in the endoscope or endoscopic platform. The instrument tip is remotely controlled. The inherent flexibility of the instrument, coupled with the friction inside the endoscope channel and the convoluted shape of the endoscope inside the body, makes the control of the instrument tip difficult and cumbersome. As the flexible endoscopy continues evolving more into a therapeutic tool and as the endoscopic procedures are becoming more invasive, the surgical instruments require complex manipulations. The motion and force fidelity of these instruments is critical for achieving good surgical outcomes.

The TeleFLEX project is the initiative of University of Twente to design, and develop a state-of-the-art surgical robotic system for endoscopic surgery, and carry out research on the enabling technologies. The master-slave concept can solve many of the technical challenges encountered in conventional flexible endoscopic surgery. The master side contains a master input device (e.g. a haptic device or a master manipulator) with a controller and other visual display devices. The slave side includes an endoscope/ endoscopic platform, which provides access channels for the flexible surgical instruments and other accessories required for the particular intervention, controller and drive system.

My current research focus is on the mechatronic design of a surgical telemanipulation system, especially to understand the dynamic behaviour of a flexible surgical instrument inside the access channel of the endoscope through modelling and simulation.

In a endoscope-like surgical system, the instrument is controlled from the proximal end. Nonlinearities are introduced in motion transmission by the friction forces between the instrument and the access channel. Moreover, the shape of the endoscope is not fixed. It changes depending on the location of the surgical site. There will be a change in the force/torque delivered which is dependent on the friction properties and the shape of the contacting surfaces. Since it is difficult to place the sensors at the distal end of the instrument, the actual position and the force delivered at the instrument tip are difficult to estimate and control. This makes the control of the instrument tip difficult and challenging.

A thorough understanding of the flexible instrument behaviour inside the access channel of the endoscope can lead to proper design of controller and eventually leads to automatic control of the instrument tip for desired motion or force. This also leads to design of the instruments not only for the functionality but also for the control.

Currently, I am looking at the sliding behaviour of the flexible instrument inside a curved endoscope in the presence of friction. The shape of the curve and the bending rigidity of the instrument can have large influence on the sliding behaviour of the instrument. I am using a computer program SPACAR for the modelling and simulation of the flexible surgical instrument inside a curved tube. SPACAR is a modelling and simulation tool based on finite element method (FEM) for multibody dynamic analysis of planar and spatial mechanisms and manipulators with flexible links. I studied the effect of friction on stick-slip behaviour of the instrument and motion hysteresis at the instrument tip.

I also designed an experimental set-up for measuring forces exerted by the instrument on the endoscope while in motion. The instrument can be actuated from the proximal end in both translation and rotation independently. The motion at the distal end can be measured using contactless sensors. This will be used to validate the modelling and simulation results.

I am also supporting TeleFLEX project. I am working closely with other PhD students from other departments in the university to achieve the deliverables defined under the TeleFLEX project. I, together with other PhD students involved in TeleFLEX project, defined the project scope, objectives, and deliverables, after consulting and interviewing surgeons and experts. I have designed functional models, actively engaged in various discussions, and shared my work and expertise. I completed survey on surgical robotics, state-of-the-art in endoscopic surgery and master manipulator.

I am also collaborating with overseas PhD students through my supervisor and sharing my work and helping them in their research. That also results into joint publication for a conference.

I am also working on various conference and journal articles to share my work and research results with other researchers working in the similar area. I plan to attend related conferences also.

I will be looking into various aspects of dynamic behaviour of the instrument, particularly the rotational behaviour in coming months through modelling and simulation. I will be also looking at the experimental validation.


Project Teleflex, 2008 – 2012

(funded by the Dutch Ministry of Economic Affairs, Pieken in de Delta 2007, BAS-number PID07038)

Project partners:







Overseas collaboration

Dr. Craig R. Forest

Asst. Professor

Woodruff School of Mechanical Engineering

Georgia Institute of Technology

Atlanta, Georgia, USA

Suhasa Kodandaramaiah

PhD student

Department of Mechanical Engineering

Georgia Institute of Technology

Atlanta, Georgia, USA


J.P. Khatait, M. Krijnen, J.P. Meijaard, R.G.K.M. Aarts, D.M. Brouwer, & J.L. Herder (2011). Modelling and simulation of a flexible endoscopic surgical instrument in a tube, ASME 2011 International Mechanical Engineering Congress & Exposition, November 11-17, 2011, Denver, CO, USA, accepted.

S. Kodandaramaiah, M. Krijnen, J. Go, S. Malik, J.P. Khatait, R.G.K.M. Aarts, D.M. Brouwer and C. Forest (2011). Characterization of translation of fused silica micropipettes in non-rectilinear trajectories, 26th Annual Meeting of the American Society for Precision Engineering, Sunday-Friday, November 13-18, 2011 Denver, CO, USA, accepted.