156B Week 7

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

    After several trials of cranking the mechanism using an oscilloscope/power-supply in Dr. Steve Roberts laboratory with the DC motor,

    we concluded upon Steve's suggestion that a stepper motor may be more effective and easier to use.

    This assumption was confirmed by running trials with a readily available stepper motor from the component room, and resulted in 

    a re-design of the crank-mechanism, improving its overall performance and simplifying the programming/control process.

Accomplishments from Previous Week

• • DC Motor replaced by a Stepper Motor for better low-end torque and simpler control

  • A photo-sensor has been mounted in order to control the crank-position (home-position)

  • The two shafts at the front-end of the carriage have been replaced by one long shaft

  • One large link placed in the center of this long shaft replaced the two links cranking the carriage

  • A coupler has been added to the motor shaft

  • Telephone wires for each activity monitor were cut to length and hubs were attached on the rear end of the carriage

  • The accelerometer has been embedded in acrylic and attached to the carriage

  • Following Isaiah's advice, additional support triangles have been glued to the front and rear walls of the carriage

  • Overall, the crank motion is now much smoother and reliable (less jamming and friction, jolt-free motion etc.)

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

• • Fabricate acrylic guides for the telephone wires along the sides of the carriage, and finalize the wiring (Chris)

  • Begin development of the GUI in Matlab. The sponsor will help with the programming (Shannon)

  • Begin programming and control with the new Stepper-motor & photosensor configuration (Roque)

  • Fabricate new baseplate to mount all components (Mark)

  • Create powerpoint slides and prepare for Final Design Review (All)

  • Make corrections according to comments on 1st draft, and complete 2nd Draft of Report (All)

  • Finalize 2nd Draft of Team Website (All)

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

• • No significant comments, other than that sponsor is willing to help with programming GUI in Matlab (in person, 5/10/12)

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

• • A coupler has been added to the motor shaft, and a photosensor is used to set the home position of the crank mechanism (in person, 5/9/12)

  • A central link on one long shaft has replaced the two side links with side shafts on carriage to eliminate misalignment issues and jamming (in person, 5/9/12) 

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

• • none

Risks and Areas of Concern

• • Taking all components off the "temporary" base plate and re-mounting everything on a clean, new base plate:

    • Will there be alignment issues or i.o.w. can we achieve the same smooth motion as we currently have?

    • Can the locations of the holes drilled on the base plate simply be measured (coordinates),

    • or is it better to place & align components before marking and drilling holes? 

Resources or Information Required but not Available

• • none

Schedule

    Now that the mechanical key aspects of our design have been finalized for the most part, more emphasis will be put on:

        - Programming of the controller and user-interface development (Week 8)

        - Extensive testing of the apparatus in conjunction with continued programming (Week 8/9)

        - Documentation and reporting of results (Week 9/10)

Budget (list amount spent and amount remaining)

• $213.52 spent, $786.48 remaining

Progress on Report and Webpage

• • no notable updates (Budget and this Progress Report aside)