Project Updates: February

Scroll down to see weekly updates regarding the current
status of the project, and any other interesting news.

February 1 - 7

The Raspberry Pi and Pi Camera were set up to takes photos of the laceration and suturing pad. The image is then normalized and converted to grayscale. A binary inverse threshold was used to create a gradient mask. Erode and dilate filters were found to work well to mitigate unwanted noise. A median blur filter and canny edge detection algorithms were applied. Logic was necessary to isolate the desired contour from any extraneous information. Entry and exit points were identified, and the coordinate system data was successfully sent to the Arduino.

Images: Suturing Pad (Bottom Left), Edge Detection (Bottom Center), Contour Mapping (Bottom Right).

February 8 - 14

A second robotic arm, whose purpose is to handle the suturing threads, was implemented with six degrees of freedom. During the knot-tying step of a suturing procedure, the arm will be manipulated such that its gripper is within reach of the loose thread near a wound. The gripper will hold the thread while the suturing mechanism creates a loop. To fasten the loop into a knot, both the suturing mechanism (its position being controlled by the gantry robot) and the articulated arm will move in opposing directions. To be able to easily manipulate the gripper to a specific coordinate, the articulated arm was modelled using algebraic inverse kinematics to resolve the x, y, and z positions in terms of specific joint angles.

Image (Left): Newly Designed CAD Assembly of the Articulated Secondary Arm.

February 15 - 21

After conducting several tests with the mechanical suturing arm, it was identified that the solenoid being used is simply not strong enough to be able to push down on the end of the slider mechanism to open the clamp. As a consequence, the needle was unable to be properly released during the suturing process. The possibilty of a stronger solenoid was considered, but eventually discarded due to size and weight constraints. In the end, the mechanism was redesigned with an elliptical shaft passing throught the center of the slider. A stepper motor can thus be used to rotate the elliptical shaft and thereby open the clamp enough to release the needle. The same process applies to grasp the needle.

Image (Right): Final CAD Assembly of the Mechanical Suturing Arm.

February 22 - 28

This week was dedicated towards comprehensively testing all of the mechanical and electrical components of our medical device. The Gantry Workspace was calibrated using a reference datum and trials were conducted to ensure that the mechanical arm could reliably be moved back to a "home" position. The accuracy of the Gantry Workspace was found to be approximately 1.0 millimeter, limited only by the step size of the NEMA stepper motors and the thread spacing of the guiding rods. We carried out our first proper suture this week! The results were exciting, and suggestive of the fact that our device has the core mechanics implemented properly. The secondary arm's ability to hold a thread was validated.

Images (Above): Various Phases of the Testing Process.

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