I’ve been having problems with defective servos.
Five of the servos are not working and all I get out of them is alot of noise and no movement.
I originally thought that the hub was not seated properly and took apart and rebuilt that part of the leg.
Also, there is no control coming from pin set 31 where the head movement servo plugs in.
Now inspite of having followed the instructions twice once with the old set atear down and rebuild with the new set, some of the legs are returning to thier zero set position and others are either not moving or hitting some random positions.
There doesn’t seem to be any rhyme or reason to the preset movements in PoMoCo and they do not repeat thrmselves from run to run.
Any thought anyone?
Before anyone suggests that I change the batteries for fresh I have tried that and although Hexy was more responsive it didn’t fix the issues.
I thought of the power supply route, but in reviewing the posts here it doesn’t appear that there are any concrete recomendations on getting a proper working unit, and it appears that Arcbotics is actively looking for a solution.
I had two duds in my batch, so I had to resort to using the spare and scavenge a servo from an old RC plane which used for the head.
I realized this while on my 3rd leg, so I proceeded to test all the servos individually by running PoMoCo, connecting the servo to servo pin 4 and sliding left-right to verify full range of motion.
One of the dead servos makes a constant whirring noise but doesn’t move, which sounds similar to your problem, the other doesn’t do anything at all. These are cheap $5 servos, so I have low expectations, but I still would want them to be a bit more stable than they are.
Aside from all that, I do have a few servos that are very shaky and find that, even with fresh batteries, Hexy seems unable to recover when the legs slip such that they’re no longer in the “reset” position.
I’ve gone through the exercise of calibrating the servos through PoMoCo by leveraging the “offsets” feature. To do this, zero out the hexy using the Zero preset and then use the + and - buttons to the right of the servo sliders to align all your leg servos nice and straight. You can save the presets to the PoMoCo directory through the File and they’ll get automatically reloaded when next you run the app. I did some additional fine-tuning from the “Reset” preset to ensure the feet all touch the floor and they angle slightly outward. Doing these things mitigated some, but not all of the shaking.
I realize I’m not answering your question, but hopefully these tips will help you and others make the best of things while we wait for improved software and further tips from Joseph.
I have also done the zeroing and created an off set file.
I found that on a PC if you start PoMoCo from the start menu that it doesn’t run the iffset file, probably something to do with paths.
It does run it when I run PoMoCo from within the sub directory both files sit in.
So far Hexy has been a bust for me, after a build and rebuild sitting the servos setting the zero, which wasn’t truely zero because the splines on the pinion and the hubs rarely lined up (pretty standard I expect with servos and hubs).
Even with rthe reset preset ssome legs go up others go down.
I’m hoping that when the full documents get out all these issues will be fixed.
Maybe that’s why it’s twice the price to buy a prebuilt one now rather than the U-build kit.
Bummer…
You’re correct about the paths, the Python code will open the first .cfg file it finds in whichever directory you run it from (the “current” directory).
I would imagine ArcBotics would happily replace the busted servos and you should do some debugging of the Servotor to confirm that pin 31 is truly dead because that would justify exchanging the board. I recall reading some boards were manually soldered somewhere, so maybe the header pins aren’t properly seated, visual inspection may confirm that and some re-soldering might be warranted.
Now… I’m curious about this comment:
I imagine you’ve already done this, but double-check the wiring against what’s illustrated here:
Also make sure the brown ground wires are always facing the nearest outside edge of the board.
Finally, since losing 5 servos kills two of your legs (or 1 leg and the head), this might be a good time to experiment with implementing a 4-legged walking gait in Python. 
it is a curiosity what happens with the presets.
You can only assume what should happen by the names but it’s hard to tell what to really expect.
I’ve checked the plug orientation, would have been nice to have had some kind of document or statement that assured us that
things were plugged in right, in this case a picture is not worth a thousand words, or even a hundred.
I have tried one of the working servos in port 31 but nothing happens from PoMoCo.
I like the suggestion to try and create a four legged walk, it would be easier if I could get any actions that made sense.
I tried to get PoMoCo running on my Mac at home, I’ve been using the windows PC in my office, but it keeps crashing when I run it because it can’t find serial.py.
I had hoped that the issues were with the PC and wanted to give the Mac a crack at Hexy.
Perhaps the final manual will resolve the issues I’m having.
At least Hexy looks cool sitting on my desk.
From your Mac terminal, type:
sudo easy_install pyserialThat will take care of installing it for you.
There’s a post that covers a minor tweak that you might need to make to PoMoCo on the Mac here:
BTW, I just contributed the beginnings of a getting started guide to:
github.com/ArcBotics/Hexy/wiki
Anyone with a Github account can edit, so feel free to add to it.
Good luck!
Thank you for the Mac hint, worked great.
PoMoCo locks up but I think there is a post about that, I’ll look it up and see what the fix is.
Arcbotics responded on th Kickstarter site about the bad servos.
I also thought of looking into metal gear servos, the plastic ones might be what is breaking.
Size might be an issue, but I’ll see, there is an RC shop local to my area.
It is all a learning experience, one I’m having a blast with.
Correct, that’s the post I linked to above. Additionally, PoMoCo needs to scan through your different serial devices and can therefore take a minute or two to connect to your board.
Use this to see how many serial devices you have on your mac:
Here’s my list, yours will be different:
$ ls -al /dev/tty.*
crw-rw-rw- 1 root wheel 18, 28 Dec 21 12:42 /dev/tty.ArcBotics-DevB
crw-rw-rw- 1 root wheel 18, 0 Dec 21 08:29 /dev/tty.Ardy-SPP
crw-rw-rw- 1 root wheel 18, 4 Dec 21 08:29 /dev/tty.Bluetooth-Modem
crw-rw-rw- 1 root wheel 18, 8 Dec 23 09:06 /dev/tty.Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 18, 6 Dec 21 08:29 /dev/tty.LuissJAMBOX-SPPDev
crw-rw-rw- 1 root wheel 18, 2 Dec 21 08:29 /dev/tty.X-Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 18, 106 Dec 23 09:19 /dev/tty.usbmodemfa1311I’ve had it take up to 3 minutes to connect, particularly because one of the devices (/dev/tty.X-Bluetooth-PDA-Sync) takes a long time to timeout.
It crossed my mind to consider getting different servos, I’m no expert, but my research indicates metal gear servos can actually wear out faster than nylon and you still need something with a decent amount of torque. For example, the Tower Pro SG92R’s that are included in the kit are rated at 2.5kg/cm.
Agreed, the holes on the horn side of the legs have near-zero margin for differently sized servos; a millimeter or two difference might prove too much and prevent a proper fit. That said, the pivot end might offer a bit more leeway where the height of the servo is concerned.
I noticed on the Kickstarter video that the demo Hexy there uses Hextronik XHT900 servos whose dimensions look to be a dead-match for the Tower Pros. That makes me think that Hextronik OEMs them from Tower Pro, perhaps roboalchemist can confirm.
I’m enjoying myself as well, and am looking forward to the promised updates to the firmware which promises to alleviate the shaking somewhat.
Despite having fun, I worry because my Hexy is completely unable to tilt or lower itself without falling flat. About the best it can do is walk, and it does so quite shakily, not nearly as cleanly as the video shows.
It fares marginally better when it’s not burdened by the weight of the 5-battery pack, but that kind-of defeats the purpose. 
Anyway, I’ll wait for the 1.6 (or 2.0) update before allowing myself come to any conclusions.
I have another question about the MAC and the usb serial port, if I can.
How do I select the Baud rate it uses, another post refers to ensuring that the rate should be 115200.
It is easy to change on the PC but I can’t find anywhere to adjust it on the MAC.
Any suggestions?
I very much respect that this is a work in progress, I can only see good things ahead as we all learn what Hexy is capable of and I’m confident that the Hexy team will get all the bugs out.
who knows what 1.6 or 2.0 will bring.
Thanks for the Hexy Wiki, it answered some questions about the sensor hook up.
The baud rate is set in line 94 of servotorComm.py and you’ll find it’s set correctly.
Gosh, all this serial port and baud rate talk is giving me flashbacks of the BBS days.