Newbie Troubleshooting

Hexy Questions, Problems and Suggestions
#1

Hi there,

I am having an issue getting my Hexy going and I think it might be related to the power adaptor I’m using (5V 3.8A adaptor that I had laying around). When I power on the hexy with PoMoCo most of the movements work fine however when I try to make more complex movements that involve more servos (forward, backwards, etc.) the motions become jerky and the servos start to shake. I’ve placed an order for a more powerful adaptor that I saw posted in another thread and I’m hoping that it will solve the problem.

http://www.mouser.com/Search/ProductDetail.aspx?R=GS40A05-P1Jvirtualkey63430000virtualkey709-GS40A05-P1J

Can anyone else confirm that this is likely the issue? Currently I do not have the rechargable batteries to test out that were also recommended in another thread.

Thanks.

#2

Hexy has been reported to pull up to 5 amps when doing more complex maneuvers. I am waiting on a couple of 5 amp sbec that I will run in parallel off a 3 cell lipo that can handle the current.

Yay for open source. :slight_smile:

#3

So I just got the new power supply (5V, 5 amps) in the mail but it looks like it doesn’t solve the problem with the more complex movements (moving forward, backward, turning left, right). The servos seem to vibrate and shake throughout the movements. When I hit setZero in PoMoCo all the servos center without a problem. I also made sure to upgrade Servotor with the latest arduino sketch and I made sure all the servos were centered. I’m wondering if this has something to do with my software on the computer side. I am using a Macbook Pro but PoMoCo was hanging in OS X Mountain Lion (not sure why yet) so I am running it in my Windows XP partition instead without a problem.

Are there any other tests I can run or any ideas on what to check next?

#4

We fixed the OSX serial hangup problem with an update a few days ago, see if that helps:
github.com/ArcBotics/PoMoCo

The hangup was caused by differences in how windows and OSX handle serial.

We should have another software update for both the firmware and PoMoCo out later this week, stay tuned. We have a demo Firmware 1.6 that solves all the shaking problems caused by the controller (timer0 interrupts used for delay() were messing with our servo timer interrupts, causing some skips, thus inconsistent signals, thus jittering). We’re packaging it up nicer in our own library though, so you can actually start writing your own code ontop of it.

We’re also working on a PoMoCo update that’ll export arduino code for moves that you can copy-paste. We’ve got a lot of cutting/bagging/shipping to do right now, but we should be able to get something in between runs.

#5

Great news, can’t wait to try the 1.6 version. I just tried running the updated PoMoCo in my Mac OS but I am still having the same issue with it hanging once I click anything. It might be something I’m doing (or not doing) since I’m new to using Python. I don’t have a problem when I connect to the hexy via serial within the arduino program.

My current config:
OS X 10.8.2
Python 2.7.3
pyserial 2.6
Servotor 1.5

Thanks again.

#6

I’m also looking forward to firmware v1.6 :wink:

I’m on 64bit windows 7 and I’m also seeing lots of shaking joints and disconnects. I tried backing out to v 1.4 and 1.3 and get frequent curlups with fresh new batteries. I’m also seeing this from PoMoCo when a disconnect happens:

Exception in thread Thread-1:
Traceback (most recent call last):
File “c:\Python26\lib\threading.py”, line 525, in __bootstrap_inner
self.run()
File “C:\Robotstuff\Hexy\PoMoCo-master\servotorComm.py”, line 63, in run
self.ser.write(str(toSend))
File “c:\Python26\lib\site-packages\serial\serialwin32.py”, line 270, in write
raise writeTimeoutError
SerialTimeoutException: Write timeout

#7

I didn’t read the original posts very well… and I know nothing about batteries… after getting a little more educated on the topic it sounds like 4 AA Alkaline batteries in the servo power will supply enough volts, but not enough amps? Is that right? I’m going to the store now to pick up some AA NiCd batteries!

I’m curious how Circuit’s experiment turns out with the UBEC.

#8

Hello All,

I am also experiencing a lot of shaking issues on my servos. I am using a 64-bit windows 7 PC and the latest firmware.
SERVOTOR32 is being powered using a AC to DC wall power jack, It supplies 5V 1A. I thought the issue might be that not enough current is being supplied so I decided to move one leg limb at a time. All is well until I test the servo that controls the walking movement of hexy, the servo that swings hexy’s legs left and right. After that I was a bit confused if it was really a power issue because the servo shakes erratically, maybe it is was a serial issue. On a side note I also notice that the servos get hot if i kept making the leg “walk” using Pomoco.

#9

I received my order the other day. I haven’t had time to do much with them yet but I did rig up one of them to run off a 3S1P 2200 mah Lipo. One SBEC couldn’t keep up with the current draw fast enough. They are cheap so they may not work as intended. When I have more time again I will try my original idea and run two in parallel. That should be 10 amps total allowable current and should be enough. Although my problem may not be enough power. I also have the twitchy servo issue and am really looking forward to the new library. For now I have been messing with the ultrasonic sensor and starting to plan out the programming for autonomous travel with object avoidance. I just need to nail down the power and shaky servo movement first. The servos try but can’t life the robot’s body to recover from any kind of leaning/bowing/dancing.

I am confident we will be able to figure all these things out. As people get their orders there will be more and more of us working on these excellent beginner platforms. I have already learned much and it has only just begun.

#10

Update: So I got 4 AA NiMH batteries, not NiCd (I guess these are hard to find these days :slight_smile: ). They are Energizer 1300mAh. I don’t see any curlups anymore, but I do still get lots of shaking. I also occasionally get disconnects which look like it has something to do with “setZero” in PoMoCo, so I’ve learned to not push that button anymore for now.

#11

They look ridiculous, but these are honestly the best batteries we’ve found so far:
amazon.com/Powerex-2700mAh-R … 9H5VVM/ref

put 4-5x of these in a pack and it’ll last for 30min+

Shaking is part the servo’s problem, part our controller. We have a 1.6 update that fixes the issues caused by the controller, but we’re looking to get it wrapped up into a nice 2.0 library that makes it easy to write extra arduino code. (i.e. not have to have 200 other lines of code in your arduino code to get it to work :wink:

#12

Another power supply option might be the 5V 10A power supply from Adafruit
adafruit.com/products/658

I’ve used it on a number of other projects with great success. Although it has a 2.5 mm barrel, it seems to
work well with 2.1 mm jacks because it’s the “springy” type.

I only suggest it because it’s a little cheaper than the one that Mouser carries. Haven’t had a chance to try it
out with the Hexy as I’m waiting for a replacement part for the Hexy body. :frowning:

#13

So where do I get my hands on this 1.6 update you speak of? I’ll beta test it for you. :smiley:

#14

It would be nice to see the 1.6 work-in-progress. Perhaps you could create a 1.6 branch and post it to Github.

It would also be nice to see some comments in the the Servotor and PoMoCo code. :slight_smile:

#15

Noted, we’ll at least be posting more comments! I’d love to be able to do a beta/release branch thing, I’ll try and figure out how to do it. Github/GIT is kind of a new thing to me, I’m more of a SVN guy, but github is what all the OSHW projects are using nowadays, so I figured I’d give it a shot.

#16

Yeah, DVCS’s like Git take a little getting use to, but the beauty of the model is that it encourages branching. I’m not an expert on the matter and you’ve probably read up on this, but for simple projects, the basic workflow is one where you create and check out a “feature” or “topic” branch such as via:

The.start coding and push working builds to that same branch on Github every so often if you want others to track your progress. Once you’re done, you can merge your changes into the main code line and check out a new feature branch.

It’s best not to think of publishing your branches as “releasing a beta”, I see it as more of a “look over my shoulder and check out what I’m working on” understanding, of course, that its most definitely a “use at your own peril” situation.

Some food for thought…

I’m looking forward to reading those comments!

#17

[quote=“roboalchemist”]They look ridiculous, but these are honestly the best batteries we’ve found so far:
amazon.com/Powerex-2700mAh-R … 9H5VVM/ref

We have a 1.6 update that fixes the issues caused by the controller[/quote]

I too have spastic servos. I ordered the batteries and will try a wall wart during dev and tweaking sessions.
That said…
Sadly I did not read the packaging on mine (got it few days ago) and did not realize it had 1.6 on it already. I followed the online instructions and put 1.5 over the top of it.
How would I go about getting 1.6 back on the board?

Thanks!

#18

I have the Powerex batteries, but they don’t seem to make a difference with Servotor 1.5.

#19

I snagged the Powerex batteries too.

Seemed to give Hexy a little more umph but he struggles to hold his own weight it seems.

** This seems to be fixed in the new firmware. He does better at holding himself up. I only need to manually help him once or twice a run now.**

#20

Any ideas on when this will be around? I would be interested in working with the Arduino end of things a bit more soon as this will allow me to get closer to making Hexy remote. Thanks for all your hard work!