156B Week 1

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• • Performed some vibrational analysis. Realized mass and tension wires increase frequency of the system.

  • CAD workup detailing the functionality of the 4 out of 5 DoFs. (3 translation, 1 rotation)

  • Discuss/conceptualize a method to add the final rotational DoF to our current CAD.

  • Developed additional tilting mechanisms for comparisons and debated pros/cons.

Accomplishments from Previous Week

• • Showed our sponsor preliminary design sketches as well as an update on our progress thus far.

  • Develop a preliminary CAD design for the 5 DoF system

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• • Source cheap and reliable linear rail or alternate component - Gio

  • Combine the ball joint design with the linear rail design (CAD) - Alex

  • Develop the cantilever design (CAD) - Chase

  • Create a prototype to test out the ball joint and linear rail - Everyone

  • Begin report writing - Ramzi

  • Think about other design - Everyone

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

Meeting with sponsor (14 December, 2018)

• • Alternate approach. Instead of a cantilever, a "bridge approach" could provide additional stability.

    • Response: This is true and would eliminate the need for a cantilever, as the microscope would be hanging from the middle of the bridge over the patients head. We will explore this concept further.

  • Consider an alternate approach for x & y translation. Current method may be too difficult to wheel into desired position relatively accurately.

    • Response: Agreed, we are currently looking into a linear carriage for these two DoFs to position the microscope itself as opposed to the entire apparatus. (Think of a claw machine, but hand actuated.)

  • Near effortless manipulation is key. Some sort of counterbalancing mechanism would help.

    • Response: We are planning on implementing some sort of spring counterbalance system. We're trying to see if a single counterbalance mechanism could be used to balance all three angular DoFs.

Instructor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

Meeting with instructor (13 December, 2018)

• • Vibration isolation of the patient. If the microscope is perfectly still, but the patient and bed are not, the problem has not been solved.

    • Response: This is true and we have been discussing ways to mitigate this with our sponsor. Currently we are looking into a viscoelastic pad that can be placed beneath the patient.

  • Measuring displacement with an accelerometer would result in integrating the error twice, which would probably invalidate all data collected considering the scale of our measurements.

    • Response: We’re considering a method that can measure displacement directly without integration. We are thinking of using some sort of optical sensor on the floor and shine a laser into it to measure displacement. This allows us to directly measure displacement of the bed and microscope relative to each other.

Comments from Other Students in the Class (indicate date of comments and if via email or in person)

• • None to report

Risks and Areas of Concern

• • Vibration Damping is a crucial concern for our final product. However, our sponsor has told us that we should first focus on a complete design as some of this damping can be “bought” by inserting fancier active damping devices.

  • Counterbalancing design

  • Budget and time

Resources or Information Required but not Available

• • Operating Room (OR) constraints are currently preventing us from finalizing any designs. We plan to schedule a meeting into the OR soon to gather the exact physical limitations.

  • The dimension and the exact weight of the microscope

Schedule

• • We are scheduling a visit to the OR soon with our sponsor and surgeons.

  • We hope to finalize a tilt design and begin purchasing equipment starting next week.

Budget (list amount spent and amount remaining)

• • None spent, $1600 remaining

  • Our first purchasing will likely be for our slider/tilting devices to test since these components require some manufacturing on our end and are cheap.

Progress on Report and Webpage

• • We are up to date with our weekly progress reports. We will begin working on other pages of this site (contact, multimedia, announcements, etc.)

  • We aim to get a jump start on the report writing within the next week.