Week 4

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

• • We have currently hit a wall of sorts in determining the most accurate yet cost effective way to measure the forces in the knee joint.

  • Two designs are being worked in parallel the 4bar and the slider crank, both feature forms of actuation that only require motor input in one direction.

Accomplishments from Previous Week

• • We learned that the load pins will not be a feasible way to measure the forces in the knee.

  • However, moving forward from that we have found numerous other way to measure the forces such as strain gauges or force sensing resistors.

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

• • Begin ordering parts! - Randy

  • Final design concept CAD. Meagan/Chris/Brian

  • Frame/Casing research/CAD - Randy

  • Covering update CAD, full range of motion. - Chase

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments

• • Sponsor provided anthropomorphic data so w can begin designing the cycle tester to actual human standards.

  • Sponsor suggested using force sensing resistors to measure the effects of the brace.

Instructor Comments from Last Meeting and Actions Taken to Address these Comments

• • Add milestones for sensor:  Sensor milestones added, we really hope to have this wrapped up by the end of this week!

  • Complete model of expected torque:  We are working on an in depth analysis of both the slider method and the 4 bar linkage method.  By the end of this week we will know exactly which design we will be following through on.

Student Comments from Presentation and Actions Taken to Address these Comments

• • Strength concerns about 3D printing material for the covering:  We are comparing the strength of 3D printing a covering, molding it or just creating another shell with a foam covering.

  • Cost concerns of various components all adding up quickly:  We are trying to find the most cost effective way to assemble our design.

  • Bearings were not mentioned much in the presentation:  We are looking into linear rail bearings for the slider mechanism and roller bearings for the joint assembly.

  • Size variability of the leg:  As of now we do not plan to have the leg vary in size other than to represent the average male.  We have anthropomorphic data for the leg dimensions for men and women from the military which we are using to design the KCT.

  • Silicon as a skin replacement: We do not have to accurately model the effects of human skin on the system, and we are concerned with the durability of making our fatigue tester too biologically accurate.

  • Load pin concerns: The load pins are already out of consideration for this project.  The lead time on them is 10-14 weeks and the cost is not within our desirable range.

  • Slider crank bind concerns:  As of now our simplistic design has a major flaw in that it fails by binding or over rotating pas 0 degrees.  The final design will require a stop or spring to limit those motions.

Risks and Areas of Concern

• • The bind of the various components of the system in the slider crank method.

  • The variability of the 4 bar linkage method.

  • Sensor methods

  • Quick release mechanism for brace removal.

Resources or Information Required but not Available

• • Expected maximum torque/force output of a DJO bracing product.

Schedule

• • Upcoming milestone: finalized design concept

  • Update Gantt chart.

Budget (list amount spent and amount remaining)

• • $9.14 spent

  • ~$2490 remaining.

Progress on Report and Webpage

• • Webpage is currently up to date.