Zenta

I’ve just made a new video of MorpHex for demonstrating the rolling feature. One thing you may notice is that MorpHex rolls more or less in a curved direction instead of a straight forward direction. This is caused by the asymmetric design; the upper sphere section vs. the lower section. I’m about to get my hands on some more of those high torque servos and I’m thinking of making MorpHex more symmetrical again. Actually, that was my original plan:

I’ve found a way around the wiring issue but I might want to go for a totally different leg design too. At this moment I’m not sure.

Anyway, here is the new video:

I hope you enjoyed it! I’m also using this video to promote my April contest entry at the Boca Bearings 2012 Innovation Competition. The video with the most votes will be announced winner at the beginning of the following month. Out of all monthly winners the jury of Boca Bearings will select a grant prize winner who will receive $10000 in cash. The two follow up winners will receive their own Makerbot 3D printer.

To be the monthly winner I need your vote.

If you want to see more advanced robots coming out of my hands leave your vote here. Thanks a lot, its highly appreciated!

To day I got some time to take some new photos of MorpHex.

After my last post I found it necessary to some additional improvements, like strengthen the ribs on the lower sphere sections:

The solution was pretty simple; just a little piece of PC glued to the rib and a 3mm nylon screw for extra strength:

I’ve also done some small changes to the battery holder, relocated the main switch and mounted a plastic band to keep the battery wire as close to the body as possible:

Also pay attention to the main fuse. When dealing with LiPo’s directly connected to the main board its always a good idea  to use fuse for limiting the max current in case of an accidental shortcut. In this case we don’t want a great ball of fire..

For replacing a battery I need to remove a 3mm hex screw. Then just slide out the battery and replace it:

The battery are fixed in place by a 3mm hex screw mounted on each end of the bottom plate. I don’t want a loose battery in “rolling mode”..

These two pictures demonstrate the effect of having an expanding body.

Closed body:

Expanded body:

Some more pictures of MorpHex in different poses:

A strange form of attack pose?

“Sphere mode”:

Some standing poses:

Standard pose with closed body:

Standard pose with fully expanded body and upper sphere sections:

In the future I plan to mount about 36 RGB Starlite LED’s as background lighting. The Starlites are made by Basic Micro:

My next post will include a new video of MorpHex.. !

When I posted the MorpHex part II video I cheated a little to make the upper sphere sections to operate as intended. The “cheat” was to use some kitchen rubber bands. As you can see from the pictures below the 5990 servo push the upper section out/upward. The rubber-band work like a spring and simply make the sphere section move inward.

As you probably can imagine, this isn’t a very stable solution. Since my goal is to make MorpHex able to roll, the upper sphere sections will be needing some additional support. I’m solving this by making six special brackets.

Some details behind the process of making the brackets:

The brackets are made of PC (Poly Carbonate). All handmade using a band-saw to cut them out. I’m using a simple technique by cutting six at ones:

Using two long 3mm screws for clamping the parts together. By making six in one cut you save time and its easier to make several duplicates.

I do wish I had a CNC machine though! Would be so much easier to make even more complex parts. The next step is to mill out a track/slot. I’m using a manual XYZ milling/drilling machine:

A simple table made of rubber coated aluminium holds the parts in place:

I’m using a guidance template of aluminium to hold the PC part in place:

Milling out the guidance track:

So far so good, only 11 more to go..

I didn’t take any photos of the next process. But I had to repeat it one more time to make an additional slot and also make a little part that hold a pair of the main parts together. The final result of the brackets looks like this:

The parts are glued together. Mounting the brackets to each sphere section was relative easy. I’m using only one nylon 4mm inset screw for mounting the bracket. As you can see the brackets makes the upper sphere section much more stable and no need for rubber bands:

So far I’m very satisfied with the result. Without even doing any changes to the code I’ve managed to make MorpHex roll! So far the rolling motion is not very controllable, more like a proof of concept. But when I’m finished writing the “roll code” it will perform much better and hopefully be easier to control in “roll mode” too.

The kill-switch.

I did spend some time to figure out a good solution for operating the servo power switch. Its operated using a simple tool for turning it ON. As you also could see in the video turning it OFF is pretty easy (KISS).

Close-up of the switch:

I’m using a simple custom tool to operate the switch:

The little hole work as a hook for turning the switch ON:

That’s it for now. I’ll post some pictures of Morphex when its complete.

Then the most exciting part of this project begins.. 

Sadly I've not had much time for robotics this year. But yesterday I finally got some time for shooting a video of MorpHex. I'm still not finished so there are still some features missing, like rolling. Hopefully there will be a part III video too. I'll post more details later with some pictures.

In the meantime I hope you'll enjoy this video:

Hi,

A new update about my MorpHex project. I didn't have time to take some good quality pictures because I'm working with some gardening and renovating stuff that occupies my "photo studio". Some workshop pics with bad lighting was my only option last evening/night.

Anyway, I've been very eager to get the lower sphere sections mounted onto the legs. So eager that I selected a rather easy way by using some counter sink white nylon screws. I'm planning to use three screws on each sphere part and mount it to the ASB-04 tibia bracket. So far I'm using only two for testing. It was a bit tricky to align the hole for drilling, so I used a LED as a lamp behind the sphere part:

Already drilled and just plugged in the screws for holding it in place when doing the next leg (sorry for the blurry picture):

Btw, I'm also planning to reinforce each sphere part. I did just a simple test, the final result will be better. The plastic material is Poly Carbonate. By mounting ribs on each side the part gets more rigid, the rib also make sure that the neighbor leg/sphere part doesn't overlap each other in sphere mode.

Here are some pictures of MorpHex in action with all six sphere parts mounted.

Fully extended body:

Ready for transforming into sphere mode:

Transforming:

Sphere mode!   As you can see there are some small adjustments to do, and I've already done some improvements today to get them even better aligned. but so far, so good.

Normal body height for walking, the legs have very much free space for moving around without any conflict.

Still a lot of work left. I'll start on the upper sphere section when I'm satisfied with the lower section.

Recently I've had to make a hard decision. I'm not ending the project, but there are some issues that has bothered me for a while. The fact is that I'm afraid MorpHex is just a little bit to heavy while being in sphere mode. Another thing is the wires, a total of 36 (x3) servo wires gets a bit to crowded in the center of the body.  For reducing total weight I'm using a simple 3 DOF leg not the double femur/tibias. Instead I plan to mount 6 servos on the top deck for manipulating the six upper half spheres. At this moment I'm using 5990's on the femurs and 5645's on the tibias. The 5990's are directly power by the main 2S (7,4v) LiPo battery. The other 13 5645's are powered using one Turnigy 8amp (max 15 amp) switch regulator. I'm also planning to use 36 Starlites from BasicMicro as background light inside the sphere. The Starlites require an additional regulator, i'm using a 3 amp switch regulator (also Turnigy).

I've also decided to go for one single ARC-32 board from BasicMicro for commanding the servos. Also a XBee module and a Razor 9 DOF IMU running AHRS code for getting accurate orientation in sphere mode.

Here is a short teaser video of MorpHex (not yet completed). The main goal of this video was to demonstrate the morphing body part.

For making the hexapod work with a variable sized body there are some math to do, simple trig (law of cosine). The input value to the math algorithm is the angle of the inner body servo. Then you've to calc the new bodyradius and a new coxaoffset. When you have the body radius its pretty easy to find the new body dimensions (coordinates) for a circular body.

After that you need to adjust the positions of the feet corresponding to the new body radius. In the walking gait you can re-set the inital positions when the leg is lifted.

Next step is to work more on the code (sphere mode) and start mounting the actual sphere parts.

Its been awhile since I posted anything about MorpHex. I've not got much time for it either. Sadly this has to be a longterm project.

The power wires are going to be guide through these brass tubes. The tubes protects the wires from being crushed between all the gears. That would be very messy using LiPo power..