MWF Morphing Handcycle Project Blog

Alan Ball, Rory McCarthy, and Bill Warner got on the phone today to go over the latest design. Here it is, with a simplified tubular frame. Easy to build

Low rider mode. Not that seat back and many other parts are not shown in this simplified model.

High Rider side view

High Rider iso

Low rider side view. We added some color to make it clearer. Main tube looks like it wants a bend.

Low rider top view

Low rider front view

Low rider iso.

High rider iso with coloring.

High rider side view with coloring

High rider to view

High rider front view

Lets curve the main tube. Try 6" radius.

Curved tube at 6" radius.

Higher radius -- 10 "?

Higher radis - 12". This looks nice.

Iso with curved tube 12" radius.

Curved.

Curved.

Curved.

Curved.

We agreed that the function looks good, and now we just need to talk about some more asthetics.

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We started the session by looking at the issue of curved vs. straight tubes. Alan turned on the layer that shows where the main joints are.

Just in case you want some dimensions and angles.

Curvy Morph in upright mode. Bill expresses concerns about curved tubes. One concern is how it looks...not as angular as our earlier designs, and also the difficulty in fabrication. Discussion moves to what would a design with straight tubes look like. Alan made some screen captures and we did some overlay drawings.

Here we straighten some of the tubes.

Now the upper tube has once joint, rather than two.

Lower member also now has one joint.

Now we look at straightening the main tube. But it bangs into the seat, which can change angles.

Now the main straight tube is below the seat joints.

Adding the gusset tube to the head tube.

Another design for the main tube. One little weld, and then it hits the head tube in the middle.

How it looks in low rider mode.

Now exploring how to make the members look good in low rider. Want them to be parallel.

The upper, blue member now has an angle that causes the tube to be parallel to the green one on the bottom.

Same design in high rider mode.

We discussed that there are 6 places where we have a fork. (oh my!). Need to figure out something that is lightweight, low cost, and looks good, and then gets repeated six times.

The center upper drawing shows a very short fork at #6.

We agreed that Alan should take another pass at the frame design, and we'll get back on the phone to refine further. Note that the initial curvy frame that he designed was about 3 hours of work! We are getting very fast at being able to make new morph designs in very minimal time.

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Click here to download:

Morphing Handcycle - Learning from the wooden model.pdf (9343 KB)

(Set viewer to "SLIDE" mode shown on lower left so animations will work)

This Powerpoint presentation and animation uses Alan Ball's clever and low-cost 1/8 scale wooden model to let us see how the seat bottom and seat back magically change angles to correct for tilt when the bike morphs up and down. Very cool, and it really works! (Note: this is a re-post using a PDF format from the the original Powerpoint)

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Rory, Alan and Bill met to discuss next steps for Move With Freedom and the Morphing Handcycle and the Morphing Wheelchair. Alan brought along an important breakthrough: A low cost 1/8th scale model of the latest handcycle design. This working (it morphs!) model was made using a CNC router, cutting out thin plywood. Alan's friend did it for $100! Wow, that is amazing, and so useful. This model shows a new version of the design that includes automatic adjustment of the seat bottom and the seat back.

I'm holding up the single sheet of plywood that supplied all the parts for the model. It's really amazing that a fully working, accurate scale model can be made so quickly, easily, and cheaply.

This is what we're calling "Morph 2.5" Morph 2 weighed almost 60 pounds, while Morph 3 was about 40. But Morph 2 worked better, and had better steering. At the recent MassTLC Innovation 2000 unConference, Rory wanted to come with an improved vehicle. I a period of just a week, George Reynolds and Rory combined Morph 2 and Morph 3. They took the aluminum front end from Morph 3, and fixed the footrest design, and put that on Morph 2. Then George removed the vestigial angle adjust mechanism that didn't work out on Morph 2. That also removed one morphing joint. Voila. We cut some 13 pounds from the weight! (Background has been hastily Photoshopped to remove clutter.)

Here's Morph II as stood during our marathon measuring session last summer. Notice that the struts are gone, one morphing joint is gone, the steel footrests are gone, the steel front end is gone.

The main tube is crumpling. Oops. Too much force, all piling up in one spot. We'll have to fix that. Rory was noticing that the pedals seemed to be getting closer to him as he rode.

Closeup. The tube had too much force on its surface. Can't do that!

The steel "test rig" set up with a bungee lift system. No gas springs. Also note the seat has the self-adjusting mechanism. so when you morph, the seat automatically corrects for added tilt. It works so well you don't know its there.

Note the big black shock cord bundle. It's helping me morph up.

Now I'm morphed down. Note the path of the cord. It goes between the two steel members. The bungee lift system works better with a clear center span, and with flanking support members. This frame design can also accommodate a single gas spring.

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Alan Ball sent along this concept that is based on our recent design meeting at John Baron's shop. This design separates two morphing arms to make the rear frame more 3D, instead of the earlier designs that essentially have the frame all in one vertical plane. The idea is to get better torsional rigidity and reduce weight. This design is based on using an NEMSHPEC gravity reduction system. (NEMSHPEC stands for Nylon Encased Multi-Strand High-Performance Elastic Cord ... or to most consumers "bungee" cord.) Instead of the gas springs of our earlier designs, this vehicle will actually use a multistrand shock cord to provide the morphing lift. We've tested it, and it works great. Its also much easier to adjust than a gas spring, and it will be lighter and less expensive. I also belive it will be more reliable. At New England Handcycles, we used shock cord for seat components, and for the centering spring. The cords are waterproof, tough, and seemed not to care about sun exposure, even over long periods of time. (years)

Click here to download:

mbungee 2.EASM (483 KB)

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2009-07-17 Morphing Handcycle Test Rig MOV small.mp4 (24733 KB)

This post shows the uncut video from our design session at Baron Engineering on Monday, August 17, with John Baron and Alan Ball. Bill Warner mans the camera.
 
This video tips the scales at a Titanic length of 8 minutes, which in the "dog minutes" of the Internet translates to a major time committment (is that 56 "Internet" minutes?)
 
But there's a lot of interesting stuff here, including how you can make a morphing handcycle using bungee cords. (no kidding. Shock cord works great)

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Here are all the photos from our August 17th meeting at John Baron's shop, with Alan Ball. Sorry, no time to do nice organizing.

 Here's what we were looking at:

 1. Can we replace the expensive, heavy gas spring with shock cord "spring".

 We tried this with a few bungee cords, and it worked rather well. See the videos in the next post. We will refine the approach this week by testing with shock cord set to balance John's weight. Note that without the gas spring in the way, flanking members on the frame work better, and the frame travel is much longer. The bike goes a little higher, but gets a lot shorter, and it can also go much lower, practically touching the ground if you let it. (we may have a removable stop for that)

 2. Could we get the damping and locking of the frame by using a standard bike brake hub?

 Again, we think the answer is yes. The internal drum hub would go on the joint under the seat and would allow firm locking of the morphing frame, at low weight, low cost. We think this control, along with some "end of travel" bumpers, may work well with the shock cord lift system.

 3. The seat bottom is from an office chair. Real seat won't be that big.

 4. The automatic seat adjusting system works like a charm. I didn't even realize it was happening. It just felt right.

 5. When you don't worry about weight, things really do get heavy. This test rig weighs about the same as a small refrigerator. (We knew that, but still interesting.)

 6. The adjustment mechanism for the gas spring didn't work the way we want. Turns out you have to adjust TWO attach points, not just one. This is because by changing only one point, you adjust travel AND pre-load at the same time, and they tend to cancel each other out. The shock cord lift system is actually much easier to adjust.

 7. As designed, the bike has a huge moment arm where the axle meets the morphing frame. If you ever hit one wheel and not the other, you'll twist the frame and it will be easy to make it go out of alignment.

 8. We discussed separating the rear flanking members to be closer to the wheel. This will triangulate the rear frame and will eliminate the moment arm. It will also let us use smaller tubes and save weight. Some of the sketches are related to this.

 9. John has a detailed spreadsheet that shows the calculations to maintain weightlessness at every angle of the frame, and for any rider weight.. (we should post it later)

 10. The pictures of Bill (in purple) on the test rig are meant to be a sequence, but they may be out of order in this post.

 11. Alan is going to make some very rough concepts for review next week when Rory returns.

 12. John is going to work on the shock cord lift system.

 13. The items we talked about could make the morph lighter, stronger, cheaper, more reliable, easier to adjust and easier to build.

                                                                             

Click here to download:

Photos_of_the_Morphing_Handcyc.zip (8987 KB)

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