156B Week 6

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

• • Parts have been ordered and are expected to arrive this week

  • Dynamics of system and working controller were shown in Working Model

Accomplishments from Previous Week

• • Brake was sent to sponsor and has been ordered by sponsor

  • Most parts for mechanical testing setup have been ordered

  • New SolidWorks model was created after input from Tom and Jack from machine shop and sponsor

    • Analysis was done on the original swinging rod with 115 lb loading, and we found that the rod would bend

    • New swinging arm will be made from a larger perimeter, hollow beam

  • Proof of Concept presentation, First Draft of Report and website

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

• • Work on MATLAB model of dynamics and controlller (Chris/Ky)

  • Create dimensioned drawings of each part to be machined (Derrick)

  • Finalize materials and rest of components and prepare order (Zhan)

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

• • 5/2/12 Sponsor Meeting:

  • Sponsor once again brought in Greg Anderson, and concerns were raised about lateral forces on system and strength of joints

    • Sheet metal plates will be added across the structure to improve lateral strength

    • Gussets will be added at joints

  • SPAWAR performed a similar test with the same one inch diameter rod with similar loading and experienced bending

    • Pendulum arm will be changed to a larger beam, which will also simplify fabrication

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

• • 5/2/12 After Proof of Concept Presentation:

  • Dynamics of buoy can be modeled by modeling buoy as two buoys with independent buoyancy forces

  • Control of system should be inverse of direction of velocity so that brake will not cause pendulum to get farther away from vertical

  • Need to use shear yield stress for shear stress analysis

  • FEA simulations from SolidWorks are not as reliable as calculations

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

• • 5/2/12 After Proof of Concept Presentation:

  • Concerns were raised about durability of materials at sea. However, system will not spend extended time at sea.

  • Friction of system might cause motion of pendulum to be coupled with motion of buoy

    • We will try to incorporate friction into equations of motion

Risks and Areas of Concern

• • Still do not have specific specs and modulation ability of brake until we can get it and test it

  • Small lead time with brake, so delivery must be close to on time

  • Control approach must be fully defined, but somewhat dependent on information about brakes

Resources or Information Required but not Available

• • As was the case in the previous week, information on modulation of braking force could still not be confirmed but brake has already been ordered so we will wait until brake arrives to confirm

Schedule

• • Begin machining and fabrication

  • Work on control code

Budget (list amount spent and amount remaining)

• • Spent: $1420

  • Remaining: $3480

Progress on Report and Webpage

• • First draft of report and webpage is completed