[From Alan Ball May 11, 2010]
Attached is an e-drawing of the CAD model that Graham has created. This is what Graham intends to build. The only thing missing is the lock mechanism that will need to be implemented for use with non locking shocks.
Graham Butler sent along a series of screen images in advance of todays online meeting of the minds between Morph inventor Rory McCarthy, design and manufacturing engineering from Graham Butler, industrial designer Alan Ball, and design consultant and project manager Bill Warner.
Above is the initial frame design for Morph 4. Wow, that is looking great!
This image shows the metal frame model on the left. The red members provide the flanking design needed for Morph 4. The green area just shows the chain path...there won't be any "green thing" on the chains!
Rear view of the initial Morph 4 frame design.
Side view of Morph 4 initial frame design. Note that some of the wood structure is still shown for comparison on the front.
Wireframe shows the wood model.
The new frame will use an SNS coupler so the frame can be taken apart to fit in a car. This coupler requires steel or titanium, so this means the main tube will likely be thin wall chrome molly steel tubing. (Graham already uses this on his current handcycles.)
A closeup of the morphing arms. Not sure what these will be made of...probably aluminum. We're taking a cue from suspension mountain bikes, and we plan to use bearings on all the morphing joints, rather than bushings. Mountain bikes have moved away from bushings as they have been unreliable.
A closeup of the assembled morphing joint. I think there is a single bearing on each side, since there is a thru-axel.
Graham proposes using tie-rods for the automatic seat adjusters. This allows us to adjust their length to suit the user's preferences, and they already take care of 8 points of rotation at very low cost.
Tie rods under the rear portion of the seat bottom. These linkage cause the seat to move not with the main tube, but with the lower morphing arm. This provides the self-adjusting magic that make the Morph work just right.
How many joints? How many bearings?
Upper and Lower Link Arms : 4 joints, 8 bearings total
Forward seat tilt hinge, similar bearings to morphing joints? Thru axel? Probably 2 bearings.
Forward Seat Tilt Hinge: 1 joint, 2 bearings
Seat back articulation: Just above red link arm on the bottom is a rotation point for automatic seat tilt.
Seat Bottom Pivot: 1 joint (maybe this one is a bushing.) Just above red link arm on the bottom is a rotation point.
Total joints and bearings:
Upper and Lower Link Arms : 4 joints, 8 bearings total
Forward Seat Tilt Hinge: 1 joint, 2 bearings
Seat Bottom Pivot: 1 joint (maybe this one is a bushing.) Just above red link arm on the bottom is a rotation point.
Automatic Seat Tilt Tie Rods - 8 joints, 8 bearings
TOTALS: Joints: 14 joints total (sounds like a lot, but suspended mountain bikes have many also.)
Bearings: 18 (wow), 8 are in the tie rods, 10 outside of tie rods
Here is the e-Drawings file for the SolidWorks model: You'll need the free e-Drawings Viewer (for Mac or PC)
[Fram Alan Ball January 19, 2010]
We talked about a footrest design that would be from carbon fiber, and woudl also serve as a guard - the bike hits walls often.
[From Alan Ball - January 12, 2010]
Attached to this email message is a pack 'n go of the solidworks model. Please note that I built this in SW 2009, so you may not be able to open it. With this in Mind I am sending you some edrawings, and also a step file and an IGES file( in the zip file). I hope this is sufficient for you to see what we have been up to.
We are heading towards a "Reference Design" for Morph 4, which we hope will the the configuration that we build six prototypes. This SolidWorks model shows a colored model of a wood model that we will use to finalize the design. The finished bike will not be made of flat sections like this!
This model is deceptive, because it looks so simple. But in fact, it encapsulates almost a year of work to figure out how to get everything we want in the Morph to all be possible in a single design:
- A good, very low rider height in the Low Rider Position
- A full High Rider position
- Self-adjusting seat bottom so you don't tilt too far forward when you morph up.
- Self-adjusting seat back to you are comfortable in both positions. (looks a little vertical in the high mode here, but its adjustable.
- Narrow, bike-like frame
- Single gas spring (not shown). It will be mounted between the arms. This will be nice and strong.
- Slug seat bottom and seat back. (Not shown, but the room is there to do it.)
- Capability for main tube to have a coupler so you can break the bike apart for travel by car, plane, etc.
- Light weight
- Simplified construction
- Proper steering trail in high and low modes (not easy to get right!)
- Easy to build. (ie simple parts, no fancy construction needed.) (after all, this one will be made out of wood as a scale model)
High mode. Back is a bit vertical, but we can adjust based on length of the green and yellow arms.
Low mode. Note that the dowels are not shown. These will hold the wood model together and let it morph.
High mode.Notice that the seat is tilted more towards the blue tube now. This corrects the tilt that occurs when you morph up.
High Mode Isometric for wood model.
High mode iso. Remember, this is a wood model. Next step is to decide on materials, and on other items, like foot rests, locking mechanisms.
Here is the list of what remains to be figured out after this reference model and wood model:
1. Main tube materials selection - chrome molly steel most likely for main tube. (Coupler not possible in aluminum.)
2. Other members materials - probably many will be aluminum.
3. Design for the morphing joints - how to make it light, strong, reliable, easy to build, easy to repair.
4. Slung seat bottom.
5. Seat bottom adjust mechanism - we show the mechanics, but not the design itself.
6. Slung seat back
7. Seat back adjust mechanism - again, we have the mechanics, not the design.
8. Bike component selections
9. Foot rest design (this always gets too little attention!)
10. How to lock in high and low mode. (and with high reliability! Our current latch design has had its reliability issues.)
11. Desired: a way to lock the bike in intermediate positions and even ride in that mode. (Harder than it sounds!)
And then some things that may seem like minor add-ons, but they matter:
12. How to hold crutches, and make it fast and easy to get them on and off.
13. Storage space - how do you carry groceries, for example?
14. Water bottles
Additional design issues:
15. How to make it easy to get on and off. This relates to how often people will use it.
16. Design care to be sure the high mode stays short and turning radius is good.
17. Design of pedals so rider can (ideally) turn 90 degrees in high mode)
18. Design of foot rests so rider can turn as sharply as possible in low mode. (ie avoid footrests hitting ground, or maybe they have movement)
Input to Alan for finalizing the wood model:
1. Look at verticality of seat back in high mode. Seems too vertical. Fix before we cut wood!
2. Make the steering work. (Right now its fixed.) Key design issues relate to turning at the steerer tube.
Otherwise, look good to go to wood. The nice thing is that it's very inexpensive to make a wooden model with the technique you've worked out.
Here is the e-Drawings file for the SolidWorks model: You'll need the free e-Drawings Viewer (for Mac or PC)
(Note: this model is a little tricky because it is set to a small scale. But if you're careful you can get the views that I showed.)
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.
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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.
