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Laryngoscopy Robotic Training Simulator

University of California, San Diego 

Spring 2017 

MAE 156B Sponsored Project

Background:

Laryngoscopy is a technique used to visualize the larynx during intubation, a procedure in which a tube is placed into the trachea of a patient to assist with breathing. This procedure occurs prior to many surgeries and during resuscitation following a cardiac arrest. It must be executed quickly and precisely as errors can easily lead to patient harm or death. Traditionally intubation is learned directly on patients, however, manikins have recently been adapted to provide simulated practice with the hopes of reducing patient risk and enabling optimization of technique prior to patient contact. The main drawbacks of manikin platforms include their lack of feedback due to the difficultly supervisors have of visualizing the laryngoscope's position once inside the manikin and the limited number of experienced supervisors able to oversee multiple trainees at once. More information on the laryngoscopy procedure can be found here while information on one of the leading manikin platforms can be found here.

  Laryngoscopy Overview1                                 Example of Manikin Training Platform2

Objective:

To develop a laryngoscopy training simulation platform using two WoodenHaptics open source haptic arms that is able to track and guide a laryngoscope while practicing the procedure on a manikin. The system will detect the position of the laryngoscope and constrain it to a region defined by data collected from the trajectories of multiple experts performing the procedure. Resistance, in the form of forces generated by the arms and applied to the laryngoscope, that is proportional to the deviation of the laryngoscope from the defined region will assist the trainees in developing a knowledge of the proper trajectory for a laryngoscopy procedure. The goal of developing such a system is to increase the success rate and efficiency of laryngoscopy training and to create a platform with a relatively low financial footprint that can be extended to other procedures and virtual reality in the future.

WoodenHaptics Open Source Haptic Arm3

Final Design:

Our final design consists of a 3D printed laryngoscope attached to two WoodenHaptics arms via universal joints on the tip of the terminal linkage of each arm, allowing movement of the laryngoscope in the five degrees of freedom used in a laryngoscopy procedure. This system is then controlled via the Chai3D open source software framework. Haptic feedback is provided to the user via forces translated from the arms to the laryngoscope in proportion to the laryngoscope's deviation from a defined region. This region is created using data collected from an expert's laryngoscope position as they perform the procedure.

Overview of Hardware Platform

Actual WoodenHaptics Arm

Components of Final Design

(From left to right: 3D printed laryngoscope with actual blade, laryngoscope with motor-driven rotary joint and extension piece, universal joint)

Final Design 

Performance Results:

Thus far we have developed a MATLAB simulation that uses the Jacobian matrix of the system and a combination of forces and torques we wish to be exerted on the laryngoscope to determine the magnitude and direction of the forces the arms must each output to achieve these desired forces and torques. The simulation allows us to calculate these required forces for any laryngoscope dimensions and orientation. Furthermore, it has proven to be a useful tool in justifying our hardware modifications by being able to predict how a change in physical parameters will affect the behavior of our system.

Required output forces for 5 randomly generated desired force and torque combinations with laryngoscope dimensions and orientation held constant

Magnitude of compensatory forces necessary to counteract the induced rotation from a force applied along the handle axis (x-axis) with an off-axis center of mass