I bought a Johnny5 robot a few months ago, and have had success setting it up and coding etc, the problem is that I keep burning up servos and am constantly needing to repair instead of move on with the project.
It was bought used and I have added several new arm joints to take it in the direction I intended but its just not working out.
Here are the major components:
J5 kit
SSC-32
Eight - HS-645MG servos
Two - HS-485HB servos
Six - HS-422 servos
Two - HS-475HB servos
Two Logitec QuickCams
Pico PC, WinXP
Two 2200mAh Lipo 11.1V batteries in parallel for PC
One 2200mAh lipo 11.1V for drive motors
One 3600mAh lipo 7.4V battery for servos
One NiCad for logic
Dimension Engineering 2x10 motor driver
I can upgrade servos and keep going with this current project, it will cost a fair amount I think though to get the needed high torque metal gear digital servos. Or, move on and build another BOT using as many of these parts as possible and hopefully have greater success
Here is a link to an earlier test of the bot, after only several runs I tend to fry servos, I’m very careful not to over drive them so I know it is because of the stress on them.
Any particular servos failing (shoulder, etc.) or do they seem to be random. Do the servos get hot when operating? What is failing in the servo (H-bridge on the circuit board, the motor, etc.). The arms seem to be somewhat long to be supported by regular servos.
I’ve read the standard Hitec servos can handle up to 12v until ther burn, but I’m sure under no load. they all run cool except the 2 shoulder 645MG’s that get warm, this is one that burned the other day.
Any thoughts on a new build? I’m leaning toward putting a 6"x8" plate on the J5 base and tracks and then putting the arms on shortened to reduce load on the servos and still be able to pick up objects which was my plan to start with
12v standard… wow! now that would be fun to watch. no!
6v!
using the J5 base to work on a new project sound like a good place to start. look about on this forum for more ideas intill you see something you like. we properbly cant tell you what to build as we dont know all the parts you have. best to just have a think at what you want the robot to do and then think about how to build it.
I know 12v is too much rather I read it was a burning point for standard size Hitec servos, in other words running them at 7.4v is not usually going to kill them but only shorten their lives somewhat.
I think I will go with the platform on my J5 base and build up something unique, this will be an interesting project, i will make a thread about it in the tracked bot thread :mrgreen:
I’m certain it is the motor failing, the heat is on the backplate of the servos. The failing servos are always the shoulder, all others run cool. I think your right, the arms are heavy and likely causing the servos to burn up on me.
Hey wow what a cool build! Yes the arms are too long for 645 servos. You would be ok with 5980 or 5990 but they are pricey. You could shorten the arms back to stock and significantly reduce the load on the servos.
If you use a LPA for the shoulders, it would help out since the gears provide more of a mechanical atvantage. I saw Tyberius do it this way and it seemed to work well, he also used stronger servos. You might want to look into adding 2 LPA’s and at least 2 HS5645MG servos. The ball bearings will also help with the weight of the arms and put the stress on the bearings instead of the servo shaft.
This is what I came up with, simple design that meets my goal of a bot that is able to reach the surface it is on and pick up or move objects. I have not yet begun to code yet, what you see is simply a sequence I generated for testing movement and if the servos ran warm.
I added a voltage step down for the servos so they run at 5.1V instead of 7.4 all seemes well now All servos are hs645mg except for the hands that are hs422. I look forward to making this project an autonomous robot with voice recognition, wish me luck
Thanks for the comments guys, here’s a few pictures to show some of the setup. All of the components are listed on the opening post of this thread. I’m really torn between MS robotics studeo express or Webotlib or VB as the IDE to build with, I have no prior experience with programming so none of the above will be of an advantage to me. I just need to coose one and begin the proccess of getting informed I’m leaning towards Visual Basic as it plays well with RoboRealm which I use for the cameras
now that would be fun to watch. no!
rather I read it was a burning point for standard size Hitec servos, in other words running them at 7.4v is not usually going to kill them but only shorten their lives somewhat.
