New Frame Design for the Morph: Back to a Single Tube. The Bike Look is Back, But We Kept all the Good Stuff.

Just received this concept model from Alan Ball. Rory, Bill and Alan will have an online design meeting tomorrow to discuss this new approach. We have moved back to a more "planar" and more bike-like frame with single tubes. One wheel is hidden to reveal the frame.

Here you can see the "fork" apprach to what we used to call "twin flanking members." These forks let the frame overlap, and allow the morphing to go lower, for good distance riding stability and cornering.

Low rider mode. Not sure about the curved sections. They could be hard to fabricate. But this is just a concept model.

Wheel and seat removed, and you can see how the fork allows the main tube to morph lower without interference.

Here's a look at the previous design, which spead the frame members out to the sides. Better for strength, but many more parts, more metal, and it loses the bike look. That's way we went to this design, that combines the single tube look with the forks that give us our flanking members.

Click here: http://www.edrawingsviewer.com/ to download the viewer for Mac or PC. You'll need it to see the files below: Note that this concept design doesn't show the handcranks or any of the front end.

.

More on the Low-Cost Wooden Model That Moves: Designing a Morphing Handcycle By Seeing It In Action

Alan Ball sent along an e-Drawings file of the 3D Solidworks model that he used to cut out the wooden pieces to make the 1/8 scale model of the most recent design of the Morphing Handcycle.  An overview of the project is at www.movewithfreedom.org. This technique of using CNC-routed wood parts is very significant, because it lets us understand a design in "real life" at very low cost.

Note that our next design is going to take some of the concepts in this model, but will go back to a more planar frame, which will have more of a "bike" look. We may use this style of design on a future morphing wheelchair.

Click here: http://www.edrawingsviewer.com/ to download the viewer for Mac or PC. You'll need it to see the files below

Below is another output of the Powerpoint file that shows animations using the wooden model. The previous version used a PDF output, but I worry that the PDF takes a long time to load. Below are JPEGs from that same file. Just click through the images to see the frame animate.

A Wood Model Reveals: How to Understand the Self-Adjusting Seat on the Morphing Handcycle (choose full screen, and set view mode to "slide")

(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)

Morphing Handcycle Design Meeting in Cambridge - Morph 2.5; A Cool Wooden Model; Bungee Lift System

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.

A New Look at the Morphing Handcycle - Space Frame for Rigidity and No Gas Springs



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)

The cords are not shown in this early mock up.


Here is the e-Drawings file for the SolidWorks model:  You'll need the free e-Drawings Viewer (for Mac or PC)

Morphing Handcycle - Important Breakthroughs - See the uncut video

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)

Photos of the Morphing Handcycle Test Rig

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.

How Smart Can a Mechanical System Be? Pretty Smart. Variable Rider Weight and Automatic Seat Adjust.

John Baron sent along this e-Drawings file of the test rig showing an adjustable mechanism to compensate for a variety of rider weights. On Morph II, we calibrated the shocks to work for Rory's weight. This worked very well, but doesn't work well for showing other riders. And its not practical for production.

So, one of the goals of the new morph is that it handle a range of rider weights with a simple adjustment. That's what John is testing here.

While Morph II had the frame as a single member, and had two gas shocks, the new design puts two frame members on the outside and a single shock in the middle.

Here's a bunch more photos.


By the way, the gold-colored mechanism is the automatic seat adjuster. As you morph up, it tilts the seat back by droppiing the rear of the seat. This corrects for the forward tilt that morphing up causes.

Here is the e-Drawings file for the SolidWorks model:  You'll need the free e-Drawings Viewer (for Mac or PC)