1. Today’s Agenda Short (really short!) mini lecture & prelab description so you’re ready for lab next week Midterm: – Split into 2 groups: – D102 and D103: go to Room 3090 with Naghmi – D101, D104 and D105: stay here in 5280

2. Making Things Move Mini-Lecture: intro to 4Bar Lab SIAT = School for Interactive Arts and Technology Interact with a computer: buttons, touch Interact with the Physical World: mechanisms (& analog circuits)

3. Mechanisms Lots of different mechanisms: – Levers – Cams – Gears – Cranks – Linkages Today: intro a link type for this week’s lab – Will look at others next week

4. Mechanism examples http://www.engr.sjsu.edu/minicurric/images/lecture_powerpoints/mechanisms.pdf Watch mechanism

5. Mechanisms: Cranks Crank Shaft Crank Pin D Throw = 2 x D

6. Slider-Crank: a simple linkage mechanism (simplest?) Function: Transform rotation (of input link) into translation (of output link) Video: http://global.oup.com/us/companion.websites/fdscontent/uscompanion/us/st atic/companion.websites/9780195384086/DataFiles/Chapter-One/Videos- Movies/Video-1-5-SliderCrank.mp4 http://global.oup.com/us/companion.websites/fdscontent/uscompanion/us/st atic/companion.websites/9780195384086/DataFiles/Chapter-One/Videos- Movies/Video-1-5-SliderCrank.mp4 Q: how far does slider move along x-axis? A: think about the “throw” distance in the crank in slide 5

7. Four Bar Linkage http://en.wikipedia.org/wiki/Four-bar_linkage

8. Types of Four Bar Linkages Double-rocker - both side links rock http://engineering.union.edu/~tchakoa/mer312/Lectures/Fall08/LECTURE03.pdf http://robotics.mem.drexel.edu/mhsieh/Courses/E91_F07/notes/linkages2.pdf Double-crank (Drag Link) - both side links revolve Crank-rocker - shorter side link revolves, other rocks

9. SolidWorks Model of 4-Bar

10. Four Bar Linkage Simulator http://www.mekanizmalar.com/fourbar01.html

11. Four Bar Linkage Paths

12. Grashof’s Criterion Grashoff's condition for 4-bar linkage: shortest link can rotate fully if… length of shortest + longest < length of other 2 https://en.wikipedia.org/wiki/Four-bar_linkage Not all 4-bar configurations allow full rotation of crank!

13. Prelab (Week 7) Objective -- assist you to: Build understanding of mechanisms: how components of simple assemblies can interact in useful ways Preparation for the lab Pre-lab: Experiment with the 4-bar simulator at http://www.mekanizmalar.com/fourbar01.html, http://www.mekanizmalar.com/fourbar01.html Create a linkage whose output (path traced by “blue dot”) is close to circular. This is likely to be a crank-crank mechanism (see lecture slides for definition). Submit a screen-capture of your linkage image should include parameter values (at the top) and the Grashof’s Law numbers (at the bottom). DUE: beginning of next lab (Today 25 Feb, Mon 29 Feb)