Let's Make Robots!

InterbotiX PhantomX Hexapod


Hey guys,

(Full disclosure) I work for Trossen Robotics, and this is a prototype for an upcoming product we're making. But- I think it's a pretty cool bot, so I wanted to show off the prototype. This crawler features 18 AX-12+ Dynamixels, an 11.1v 2100mAh LiPo Batterie, a custom lasercut ABS frame, and ArbotiX Robocontroller w/ Xbee Wireless onboard!

I designed everything in Autodesk Inventor, it's actually pretty simple construction. Two flat pieces make up the torso, and two more flat pieces make up the tibia of each leg. The femurs consist of end to end Dynamixels. There are only 14 custom cut parts for this bot, 12 of which are the same (tibia pieces), the rest of the crawler is built using the stock brackets that come with the servos (but dyed black).

It runs a fully open source IK engine developed by Vanadium Labs, and has tons of I/O available for additional sensors. For now it's just remote controlled, but we're working on autonomous behaviors as well as experimenting with implementing a FitPC2 onboard running ROS. I'd be more than happy to post the code if anyone is interested in seeing it.

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In that first close up picture, is that a force senor in the foot?

Indeed it is =)

It's a 0.2" Force Sensitive Resistor from Interlink. A terrain adaptive gait is also in the works.

How are these extremely nice parts cut out? Can you show a picture of the machine that did it, perhap a video of it in function?

If you got drawings from an LMR member, would you be able to have the pieces cut out (of course for payment)?


Ask and you shall receive Frits! We own a Vytek FX2 Lasercutter CNC. It's a big machine, weighs about 300kg and is about the size of a very large deep freezer. It uses a 50w CO2 laser and can cut with some pretty ridiculous accuracy, and is capable of speeds of up to 150cm/second (when engraving, cutting requires slower speeds). It can cut most plastics, foam, wood, etc. No metal though, as metal just absorbs the heat of the laser. Here are some videos:

Here is the machine in action:


And here is some parts I've cut from it.


At this time, we're too busy with internal development to offer a cutting service, BUT, it may be something we open up in the future. That said, Pololu has an awesome and very reasonably priced lasercutting service. I've personally used it on a few occasions before we picked up our own machine.

Is femur the last link of the leg, the part actually touching ground?
I just wondered why it stick up above the servo/joint? Is it for aesthetic reasons or does it have a structural purpose?

Most hexapod legs are described by their insect companions' nomenclature. The femur is actually the part that is made up of the AX-12 servos mounted back to back, it's similar to your thigh. The end part you're talking about is the tibia, and the extensions above the servo are mostly aesthetic, but also to protect anything mounted on the top of the robot if it were to get flipped over. Also, the 'coxa' is more of less the 'hip' of the hexapod. 

I almost got excited about before I realised the servos alone would cost over $700 :-(

Yeah, the AX-12s run about $45 a pop. Thing is, given their feature set and strength, they are the best bang-for-buck in the market. Really no other servos that hold a candle to them around that price, I think the closest equivalent is the HS-5645MG from Hitec, and it's $5-10 more, nearly half the torque, and has none of the feedback features. Guess it's all relative though, my latest project uses $500 a piece servos, so AX-12s are DIIIIIRT cheap to me :P