Hi,

I hope you all are having a nice Christmas!

For a long time I've been thinking about some new projects to work on. Since 2006 I've made a few more and some less successful robots, mostly hexapods but also an octopod, a biped and a quad. For me this hobby has been incredible fun and I've learned a lot from people like Kurt Eckhardt and Jeroen Janssen. Until now all my custom made robots has been RC servo based, mostly using the popular SSC-32 servo controller combined with the Basic Atom Pro 28 (BAP28) mcu.


I think I was pushing the limits (payload capacity and complexity) when using RC-servos on my last project MorpHex. Using some sort of serial bus controlled servos would certainly make the wire work a lot easier.


From now on I've decided to go dark.. Lately I've invested in several MX-106T and MX-64T servos.

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At first I'm going to make a rather simple 3 DOF hexapod. I'm thinking more "Back to the basics". I want a good platform for experimenting on new code, terrain adaptation and learning new stuff, especially C++ and the Teensy.. My plan is to make a rather light weight hexapod with large leg segments and a relative small body. Since the cost is so high I'll probably reuse the servos for several future projects.

When I'm done with the hardware I'll study what others like KevinO and KurtE has done. I probably need to pick up some books about kinematics again.

Until now I've not used any form of CAD when designing my robots. So I'm a total noob when it comes to that part. So far I've peeked at almost every free CAD solutions. At first I ended up with Autodesk 123D, but I find it a bit limiting and a bit frustrating to work on. I've also tried freeCAD but found it a bit overwhelming at first, but I might give it a second try. Any other suggestions for a good low cost CAD solution is appreciated.

Like I said I'm going for a simple design at first. I decided to go for the MX-106T for both femur and tibia. The MX-106T has a much better weight/torque ratio than the MX-64T. For only 26 gram additional weight (158 gram vs. 132 gram) you get a lot by upgrading from the 64's to the 106's. Here is a picture of how I plan to design the leg:

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The femur are going to be made of 4,76mm Delrin and the length is 18cm (servo center to servo center) and the tibia (3,15mm Delrin) is about 27cm (servo center to tars/foot). I've not completely designed the tars (foot) section yet. But it will be relative simple at first, I'll later replace it with a foot with sensors/switches. A while ago Tyberius (Andrew) was very kind to laser cut some test parts for me so that I could get the feeling of the Delrin plastic. My first attempt on the femur got very solid and rather heavy. After the test I removed more material and made it slightly slimmer. A Picture of my first attempt:
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My progress is very slow, due to life.. Little free time. But today I'm home alone, lol. Giving me time to finally make a post on the forum and making a simple and relative small body for the hexapod. I'm not finished with the body section yet. I'll probably add a smaller top section for covering electronics. The 5000 mAh 3S LiPo takes most of the space inside the body.

Some pics of the hexapod:
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In this picture I've just lifted the battery for illustrating the battery size vs body size:
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Again, I find Autodesk 123D terrible to work with when the model gets more complex.
My plan is to bend the tibia sections slightly closer at the foot section. I've no idea how to bend them in Autodesk 123D though, lol.

Let me know what you think. Any suggestions is highly appreciated!

(Btw, my blog is down. Hopefully I'll find a solution next year.)