Morphing Handcycle Lift System: Decision to Use Dual Gas Shocks & Adjustable Shock Cord

Rory, Graham, Alan and Bill met on Tueday, Feb 2 by screen share. This post will review the decisions made.

Decision 1: Pursue dual gas springs, mounted inside of the two upper morphing arms

There were three choices for the gas shock (we also call it a gas spring.) Choice 1 was a single shock that didn't protrude, but that requires a custom shock. Choice 2 is dual shocks (the choice we picked) and choice 3 was a single off-the shelf shock that would be longer and would have an extension that would hold it down

This sequence will let you create your own animation of the morph up/down sequence showing the action of the gas shock.

This animation shows Choice 3 - a single, longer shock, mounted further along the morphing arm. The good news here is that the total force from the shock can be lower, because the mechanical advantage for lifting is higher. But we didn't like the look of the shock protruding out of the mechanism. Also, Morph 2 uses two shocks, and it has that "magic." We don't know what a single shock would be like.

Custom Shock Side View.

Custom shock top view.

Here we have the custom shock solution. One big, powerful shock mounted at a partial distance along the morphing link arm. But here's the shocker: due to the longer range of Morph 4 compared to Morph 2, this shock needs about 1000 lbs of force for a 250 lb rider. Wow! We don't want a single shock with this much force, and we don't want a custom solution.

Rear view of the dual shock approach. We're going to see if the two shocks can be mounted inboard of the struts, rather than with the small extension. With 500 lbs on each shock, that' creates a lot of moment a the mounting points.

Side 3D view of the dual shocks.

Adjustable Lift System

Adjustable Lift System - This side view shows the idea of some of the lifting force being supplied by an elastomer (shock cord). The cord is shown in red. In the low mode, the cord is stretched, and it is providing significant lifting force. By changing the where the cord is attached to the forward frame, we can instantly adjust the up force. This adjustment will be done when in high mode, where the cord is slack.

An idea for the upper morphing arm. Teardrop shaped tubing with a machined end that is welded on. Not sure this is an ideal design.

Bearings are captured in the clamp?

What Makes a Morph Go Up and Down Like Magic? Animations and Lots of Details Here

This is a big post that will review a wide range of design choices on Morph 4.

First up is the design for the "lift system" - the gas spring and any other elements that make the Morph...well... morph. Here we see a design that uses a single long-stroke gas spring that fits in between the dual arms of the upper and lower link arms. This spring would be rated at about 500 lbs of force. It is an off-the shelf shock from McMaster Carr:

Details on the single shock. Click here to see the gas spring online.

Morph 2 (and its modified version, Morph 2.5) uses two gas springs. We're debating right now which is better. With two gas springs, we can have more force, and the place the springs closer to the hinge point. This means a smaller shock, and maybe a neater look.

Side view animation. Gee, the single gas spring seems like it's hanging out in low rider mode. Is that cool? Or wrong? Note the "extension" that holds it to the upper morphing arm. This member is only in tension. It is like the vertical cables on a suspension bridge.

Rear view animation. Note that the big shock "pokes up" in Morph 4, but in Morph 2/2.5, the gas springs protrude downward and are handled by an extension from the axle tube.

Note the two thin extensions welded to the axle tube. These welds actually failed on Morph 2 because there is about 250 lbs of force acting at a distance on these extensions. But they do serve to allow a longer gas spring to fit into the system. I believe  we could use a similar approach on Morph 4.

We decided to look into this some more, and scheduled another online meeting for Tuesday, Feb 2, 2010. Or calls uses www.yuuguu.com for screen visuals, and we are in Bath, Maine, Cambridge, MA, Somerville, MA, and Santee, CA.

Adjustable Lift System

Let's say you weigh 170 lbs, and the gas shock is sized just for you. You want to show a guy who's 200 lbs exactly how cool the Morph is. Well, it won't work that well, because the 200 lb person is 30 pounds over the design weight. This means that he will sink down fast to low rider mode, and will need to work a bit to get up. He won't have that wonderful "float" that makes the Morph so amazing.

We would like to have a fast, easy way to adjust the lift system. One idea is to have the gas spring handle part of the weight, and have an adjustable elastomer system handle the rest. Those are the red cords in the picture above.

X-ray view.

You can see the elastomer cord bisecting the "diamond" of the frame, and then going inside the main tube, then emerging to a hook. What hook you set it on determines how much supplemental force you get for the lift system. Want to change it? just move the hook when you are in high rider mode and the cord is slack.

This is one proposed supplemental lift system. Just hook it to get the lift you want. We're still working on other ideas. The silver item below the cord is the coupler that lets the front and back of the bike come apart for getting the Morph in a car.

We're debating aesthetics vs ease of construction. Here is an upper link arm with straight tubes. Much easier to make, but will it have that "cool" look that gets people excited? Other arm has the cuts/and welds shown.

Aye, she's a beauty, but oh, the work to make this part. Cuts, welds, and precision machining for the bearing races that mate at either end.

This design avoids having to seat bearings at each end. Uses ball joints. Hmmm.

Here's another way to complete the tube. A machine insert that is welded on. We're also thinking about teardrop tubes which would look much better than rectangular.

In the previous post, we had an issue with seat clearance to the main tube. The new design moves the cross-member further forward, so the horizontal supports can straddle the main tube.

A look at an assembled version using ball joints. I like the ball joints for the little seat adjusters. Not sure they're great for the main morphing joints.

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

Do You Love Seeing the Details?: Two Years of Morphing Handcycle Photos and Videos Examine Every Moment, Every Measurement

CONFUSION ALERT! What looks like image galleries below are really SCREEN GRABS of the Picasa Web Albums galleries! So no, you can't click on the little images to see it bigger. Instead, you need to click on the ORANGE links to see Picasa Web Album it is associated with (and alas doesn't go to if you click on the photo itself!

Note: When you play a video, you can choose "View HQ Video" on the upper right of the screen. This will make all subsequent videos at the higher (much better!) resolution. The original videos were shot at 800x600 with a Panasonic TZ1 camera, and later videos are shot at 1200x800 with a Panasonic TZ5 camera. Find this video to learn why popcorn is so important to the Morphing Handcycle project.

A Christmas Morph! Alan Ball Delivers a Scale Model of Morph 4 on Christmas Day. It's beautiful, sexy, and sleek.

On Chrismas Day, Alan Ball brought over a wonderful present - a working, 1/4 scale model of the Morph 4 prototype. Jake, our dog, is check Alan out. The wonder of this design is in how simple it looks, but how much it does. I believe we are now ready to design in metal, and build five or six prototypes so people can really experience what its like to ride a morph. What it's like to "get back the Z", meaning that you can go up and down, and not just ride around at 18-21" off the ground in a wheelchair. The Morph goes from bar-stool height in the high mode to a low and fast 13" off the ground for speed in low rider. Both modes are a thrill, but you just can't explain to people what it's like to be riding at bar stool height. You see everything in a new way compared to a wheelchair. So we need to make some prototypes and let people try it for themselves. More details about Move With Freedom, our non-profit, is at www.movewithfreedom.org.

Our previous iteration of the Morphing Handcycle wood model was much more complex in look and form, although all the joints are actually in the same place. The goal of bringing the Morph back to its "planar" and more "bike like" form has been achieve in the new red and black model. Nicely done, Alan.


Watch as Alan move the morph and his daughter does a little narration.

Our previous design sought to move the rider load closer to the rear wheels, so the frame members moved to the outside. Nice idea, but the bike ended up with a wheelchair look, and it felt more complex. It also lost that "I've gotta have that" look and feel. So we want back to the drawing boards. (Well, Alan did.)

Ah, what a difference a day makes. Okay, many days. But now we have that beautiful look again, and the Morph has all the features and range that we're seeking.

Cool wheels, huh? That's plexiglass with a notch machined on the outer edge to hold O-rings. Hey, I get credit for that one.

Again, for contrast.

The magic of the blue joints. These are the magic links that make the seat bottom and the seat back adjust their angle as you morph up and down.

Note how far above the red main tube the back of the seat bottom is.

Now look at the red main tube. It rises almost to the bottom of the seat. But it doesn't tilt directly with the red main tube, which is how things used to work.


In this very brief, video, you can see how the joints work. The seat bottom is mainly tied to the red tube on the front of the seat, and to the lower (black) link arm for the rear of the seat.

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)