I am looking to build a larger hexapod for a current project. I am considering using the Futaba S3306 1/5 Scale Hi-Torque/Speed Servos (over 300 oz/in of torque) with an “upscaled” CH3-R leg design.
As I am interested in minimizing the amount of code to write, and parts to design/build – I was hoping to use the CH3-R controller and geometry setup including as many purchased parts / software as I can.
Does anyone know which CH3-R or other “off the shelf” parts I could use. Would starting with a full CH3-R or AH3-R kit prove valuable?
FWIW, for this project I have full access to a 4-axis CNC mill, water-jet CNC router, lots of aluminum stock and several thousand dollars for parts (which seems to be eaten up quickly on a project like this).
What’s that supposed to mean? A guy disappears for 3 months and everyone turns on him.
I got your PM bud. I’ll answer your questions tonight. If you like, I can post them here and we can discuss it in public so it benefits everyone. Your call.
Probably the difference in the dynamics of a larger walking robot. The smaller a hexapod is, the easier it is to make the walking functional. A Larger hexapod has more mass and the accuracy of the placement of each foot and compensation for weight shifting and load, becomes very important.
There is no replacement for the SSC-32. It rocks. Easy, cheap, and very functional. And the MiniAtom Botboard with an Atom Pro 28 was perfect. If you are looking for a chip with more free codes and ease of modifying other’s hexapod codes, I would recommend the Basic Atom 28. There are more codes out there for it. I had a few nice members here modify the Basic Atom code for my Atom Pro.
Other than the servos and electronics, everything was custom made. There are no large scale hexapods readily available to the public right now. And very little information, if any, on attempts to build a large scale one with 1/4 Scale “hobby” servos.
Not yet. My hexapod is based on an experimental design. So I only sell the brackets and parts at the moment. Anyone can build their own version. The huge size and weight of mine is pushing the servos abilities to the limit. Even overvolting them to 7.0 Volts and pulling 400 oz/in out of them is just enough to have torque to spare. At 300+ oz/in, it’s just enough to walk on it’s own. I have since added load bearing springs on the joints to help free some torque out of the servos. It has made a huge improvement.
I would do it again in a heartbeat. In fact, I’m planing on it. I used aluminum to be sure my design was strong and functional. The key to improving the performance of a 1/4 scale hex is to lighten the chassis and components. I plan to made a second version of the Hexapod Explorer out of Sandwiched Carbon Fiber components and reduce it’s weight by 40%. I also plan to mold my own Carbon replacement servo cases for the HS-805 that have aluminum heatsinks built in to surround the motor and mosfets.
The lightened AUW will give the hex torque to spare and an even faster gait.
If I was you, I would start with as light a material as possible. Carbon Fiber is expensive if you don’t make your own but will get you way ahead of the game. Lexan or aluminum is another good choice.
Bearings all around. A big Hexapod has a surprising amount of deflection in the joints and it will bend all over the place without solid joints. And solid joints without friction means you need bearings.
Be reasonable with your scaling of size. I ended up with the maximum size the servos could support. If I did it again, I’d scale everything down about 5%. Not enough to redo mine, but I would definitely do it with the Carbon Version.
Also be sure everything is very strong. You may be surprised how much the legs try to bend and flex all over the place with a Hexapod this size. It’s alot worse than the side loads on a standard sized servo hexapod.
Alot. But not as much money as time. ALOT of time. Designing anything from scratch is very time consuming. Especially when you don’t have any previous attempts to learn from.
Money wise, I had a great supplier for HS-805s at less than $20 a pop. So I lucked out there. Overall I spend about $600 on electronics and $400 on materials and a new bending brake to form my brackets.
The best way to increase your chances of success, is to buy one of lynxmotions Hexapod kits and learn to program the gaits for them and get familiar with how they work, and the dynamics involved. Without previous hands-on experience with a hexapod, you will find it very difficult to properly design one.
Building one from scratch and buying all the parts and materials new, you’ll be looking at $1500+ for sure.
I hope that helps. And be sure to keep us posted on your progress.
A guy disappears for 3 months and everyone turns on him.