What about magnetic damping, where a strong magnet moves through a coil of wire? A shorted coil would be solidly damped, like a shorted generator. You would change the damping factor by varying the resistance across the coil. You could use a bridge rectifier and a MOSFET as the variable resistor. Better yet, two series connected MOSFETs with their gates and sources tied together. It would take almost no power to control the damping factor. You could run the controller for a long time on a 9 volt battery.
Just curious. What are the majors of the students who participated? Also, how did the idea for this project come about? What was the deciding factor in picking the Arduino board versus maybe a Beagleboard?
Keeping in mind that the temptation for students is to overreach what they are able to do in the course of a class because of all of the options that are available - I think they did a fantastic job and they kept the project achievable. While I agree that the placement perhaps needs to be redesigned, I view this as I would a working prototype and no doubt the students involved learned a lot about multiple disciplines during the course of their work. Bringing a project from design to completion is no small task and I applaud their efforts.
Unfortunately, that was my point. You will have a plethora of students who want to make the video, but very few who will want to work on the bike. However, as you state letting the students take ownership yields much more positive results.
When I was still teaching and I assigned a research paper, I never received near the quality as when it became an I-search paper for which the student could choose their own topic, do first-hand interviews and experiments and report their findings and failures. (That was hard to convince students that what did not work can sometimes be as valuable as what did work.) One of the best papers I got came from a very hard to motivate student who wrote an excellent paper, complete with illustrations, on the evolution of hockey sticks. He wrote a ton of letters, received enough responses from players from different eras that he gained sufficient knowledge to produce a quality paper.
What was really cool was that I seldom had to direct the students to get back on task as each was anxious to get to work on their project.
Tool_maker Thanks for the confirmation. Your correct about how social media has an impact on educational endeavors. Maybe the key to increasing active educational participation is to allow total student ownership of the video production. In addition to creating the product and engineering documentation, the students will be involved in the planning of the video recording/production. Hopefully, this hands-on involvement will promote active participation among the students. Hopefully!!!
mrdon: I completely agree about getting caught in the glitz etc. and no substitute for hands-on-experience. I would bet a majority of students would be more interested in producing a Zoom -Pow video with exploding bikes and a rock soundtrack rather than this straight forward: Here it is approach. Many would volunteer for the video, few will be willing to give up time for the bike. Just look at some of the elaborate pranks and tricks on various social media web sites.
Guys, the correct iron powder for MR systems is spherical and under 15 microns (even better under 7 microns). Two companies, BASF and Ashland make iron powder from a chemical process that meets these specs (these two companies also sell powder that is already annealed). It has excellent magnetic properties if the carbon is reduced (removed) by an annealing process. The spherical shape allows even a rare earth magnet to activate a shock. The MR shocks use nothing close to 10 amps. The small iron powder flows through very small orifices so the switching does not have to be great magnetic flux if your path is small.
Previous poster said it well, this is a combination of mechE, EE and chemistry among others.
Now, finding the right software control logic is your next big task!
Rob, Another reason for my students to submit their projects to the magazine. Gadget Freak provides hands-on, real world experience for the students base on their submitted designs to the magazine. Yes, it does provide a nice item to include on their resumes.
Festo's BionicKangaroo combines pneumatic and electrical drive technology, plus very precise controls and condition monitoring. Like a real kangaroo, the BionicKangaroo robot harvests the kinetic energy of each takeoff and immediately uses it to power the next jump.
Design News and Digi-Key presents: Creating & Testing Your First RTOS Application Using MQX, a crash course that will look at defining a project, selecting a target processor, blocking code, defining tasks, completing code, and debugging.
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