Robotic Camera Mount

Project Objective

Improve the surgical vision of ENT surgeons during pediatric tonsillectomy and adenoidectomy procedures through the creation of a robotic camera mount

This project is a portion of my senior design capstone project. This page was done to display the hardware portion of the project which I am leading. The device will work in combination with a VR headset for the larger project objective. 

Robotic Mount Progress

Self-clamped mount with panel-mounted electronics featuring pan/tilt servo motors, a vertical axis movement stepper, and a manual linear sliding and locking mechanism for position camera using multiple degrees of freedom

Design Inputs

USB camera chosen for mount

Ideation

I wanted to incorporate motors to make the camera adjustment as precise and hands-free as possible.

This first sketch includes a lead screw-stepper motor system with a gantry for vertical motion, a rack and pinion system for horizontal motion, and a positioning hinge at the end of the rail for tilt control. 

This revision eliminated the vertical axis motion. The rack and pinion were replaced with a belt drive, with two servos at the end of the rail for pan and tilt functionality on the camera. 

Initial CAD Model

Prototyping

The drawer slides were replaced with a linear slide, which had to be inverted to use the full range of motion. The linear slide carriage connects to a servo motor mount which includes a clamping system I designed as a locking mechanism for the carriage.

The NEMA8 motor was not strong enough to lift the entire assembly, so I had to redesign the mount to house the stronger NEMA11 motor, which meant the gears had to be tweaked as well. The redesigned mount + gears worked great on the first iteration!

I replaced the original camera with a smaller camera capable of autofocusing. This video also shows the printed base design, the work-in-progress 3D printed clamps, and the camera stream view. 

Due to the amount of wires, I opted to create dedicated spots on the base for each main component and to pseudo-panel mount the connections. Also, having moving parts on display would not be optimal for an operating room environment so I created a tight-fighting cover with vents and ports.

Updated base with organized electronics CAD model

Box cover CAD model

The C-Clamps were constructed using M14 nuts and bolts superglued to 3D-printed knobs and heads. I also added a cut rubber piece to each bolt head piece to give the clamp more grip. 

This image also shows the updated base with the electronics secured and the unit cover in the back

Challenges

Problem: NEMA8 Stepper Motor kept stalling when trying to move the mount vertically

Solution: Modified gear ratios but determined that the motor had insufficient torque, so I redesigned the mount to house a larger NEMA11 motor with an increased gear ratio to provide more torque

Problem: C-Clamps only clamped the front half of the base in place

Solution: Extended the clamp design and repositioned the nut to clamp past the approximate center of mass to keep the base level and stationary

Problem: Electronics were scattered and interfered with device movement

Solution: Redesigned the base to include holders that I measured to fit each component, and zip tied and clipped wire bundles into place