Test Rig: Update 2

[From Graham Butler April 9, 2010]

We have changed the geometry to be as close to the new design as possible (as close as possible without having to rebuild the whole fixture.  The results are awesome.  We got the fixture lifting 250 - 130 lbs with out changing the shocks.  The adjustment is fairly quick (30 seconds or less) The morphing action is smooth, and relatively easy.  I have a couple of comments on it:

Initiating an upwards morph is not at seamless as it was in morph 2.  I think the reason is that you are now down lower than you were in morph 2, so it takes more to get the morph started.  This said, it doesn't take much, and it feels great.

Morphing down is awesome.  It feels smooth, and natural both for the heavy guy (josey) and me.  The shocks that we used were 250 lb shocks.

I have attached pictures of the test including the new geometry, I have also taken some video which I will upload to the FTP site over the weekend for you to check out.

In other news.... I talked with easy lift this afternoon, and they indicated that they could get the locking gas shocks to us faster than their usual lead time of 5 weeks.  I explained the problem of not being able to test the product and they said that we should be able to get a single pair fairly quickly to test.

I will send an email tomorrow as soon as I have had a change to get the videos off of the camera onto the FTP site

Photos of Test Rig: Morph lift system update

[From Graham Butler April 9, 2010]

I have modified the test fixture and done some initial testing with non-locking gas springs (because that is what we can get quickly)

I have attached a series of pictures showing the current state. With 2 riders.... me at 130lbs and Josey at 245 lbs.   It turns out the the adjustment system works pretty well.  It allows us to adjust the force without changing the shock; but the lift characteristics are not ideal.  There are several reasons for this..... the geometry of the test fixture is slightly different from the CAD model.  What this means is that we are loosing mechanical advantage in low rider mode, so it is hard to morph up.

Josey in low rider mode.

Note that gas shocks meet the upper linkage arm about 2 1/2 inches from the upper rear joint. Notice later that the meeting position is changed for Graham.

The tester uses two separate adjusters, one for each gas shock. On the finished machine, a single adjuster will move both shocks.

Graham in high rider. Notice how much further back the gas shocks hit the upper linkage arm.

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.

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)

A First Look at the Morph Test Rig In Action - Heavy Steel With Lots of Holes So We Can Test Anything

I took Lucas and a friend to Water Country in Portsmouth, NH (lots of fun) and on the way back, I stopped at John Baron's shop to see the new test frame in action.

 While 3D CAD is amazing, it's hard to beat RL (real life)

 This sequence shows the new morphing configuration in action. Alan Ball realized that in order to get the low riding mode we want, we should have a frame that has "dual flanking members." Which means that the part of the bike that goes up and down (the wheel to seat part) will fit in between two outer support members. This means that when the bike morphs down, it can go much lower because you eliminate the interference that stops the downward Morph in Morph II.. (Actually that was done on purpose in Morph II...so it would be rigid once you got down.)

 Now, as you watch this sequence, you can see the benefits. The bike practically folds on itself in the up position (we probably can't do that once the gas spring is installed). And in the low position, you'll see that it can go REALLY LOW. (also not practical, but hey, fun to see.)

 Note that right now we only plan to use the middle set of pictures as a real range. The very first ones and very last ones are outside the usable range of the full design with gas springs. (We think)

Here is a brief video showing John moving the test rig.

Note the automatic seat leveling device. Here in the low mode, it is tilting the seat forward. Note the angle between the left strut, and the small upper strut.

Now notice that the upper strut is almost parallel to the lower one. This tilts the seat back in the up mode, thus reducing the forward seat tilt that occurs with the morphing up.
 
Discussion: There is a lot of new ideas in this frame design. John has figured out a lot of details already in building the unit. He is also planning to use one gas shock rather than the two found on Morph II. This will save cost, and save weight.
 
In early discussion of the Morph, Rory talked about a "Super Tight" mode where you could make the bike even shorter than you might normally use, say for really tight spaces. This frame can do that, when going all the way up and when the morphing arms nest completely.

This picture shows the arm positions (roughly) in the high rider mode.

Now check this out. The twin flanking members are fully nested, and the bike will get a good 3" shorter.

Designs for a Test Rig to Determine if a Morph Has the "Magic"

When the Morph is working right, it is truly magic. You float on the gas springs, and with virtually no effort, you can make yourself float up to talk to people, and then glide down to high-speed riding position. Morph II, our 60-lb steel prototype had the magic. But Morph III, which had the benefit of weighing in at only 40 pounds, lacked the magic. Why? Well, there are lots of reasons that we know, and maybe some we don't know. Morph III used locking gas springs, and they didn't have the same amount of force. We didn't get as much float. But the mechanism was different also.

So we went back to the Morph II design, and carried that forward into the MorphOut design. And we decided to make a flexible tester so we can try out designs in the morphing frame easily and see how they work when we sit on them.

This is the first version of a text rig to work out geometry for the MorphOut design. (We call it MorphOut as in getting out to users. Goal is to build five bikes and put them in people's hands soon!)

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


This is the CAD for an improved version of the test rig. This rig includes the ability to overlap the morphing arms, which we believe will be crucial for the eventual finished design. This added complexity to the test rig, but we thought it would be worth it to have a more complete view of how the design will work.

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


Below are progress photos from John Baron as of July 19th. The Telestrut tubing will allow us to bolt on anything we need as we proceed with our tests.