Servos twitch when powered

Question

hi all am new to this,and am building a inmoov ,the problem is when I first put power to the ez-bv4 my servo outputs are powered up,which causes problems.when I have connected to my pc all is well and I can run my program ok,i am most proberly missing something but I don't know what? thanks walter

DJ Sures · Accepted Answer

Some servos will do that when power is applied to them - mostly it’s analog servos I’ve noticed have that behavior

wfairall · Answer

I was wondering if there is anyway I could stop power going to outputs when I first put power on the ez-bv4,because all my servos turn to the left 45 degrees when I do ?

DJ Sures · Answer

It's the servos - not the EZ-B. Soon as the signal line on some analog servos is held high or low, they begin measuring the pwm and causes it to move on the 20ms timeout. You can "try" to power the ez-b first and THEN power the servos a second later and see if the servos have a moment to sort them selves out. And keep the signal connected to the EZB the whole time

wfairall · Answer

Thanks for that looks like I will have to put a switch between inmoov and ez-b .will try that cheers walter

3dGuy · Answer

Comment deleted

DJ Sures · Answer

wfairall - you might want to try it first because I don't know if it'll work. The analog servos that I had experience with will ALWAYS twitch when powered on - no matter what the signal wire is connected to (or not connected to) So try it first with one servo before moving your system over to a switch

wfairall · Answer

Will try that tommorrow and let you know how I get on thanks

wfairall · Answer

hi yes just put a switch to neg on servo,powered up ez_bv4 then connected to wifi,and program ,then switched on all fine  thanks walter,also could you tell me if I can update software for my ez_bv4 ,I have tried with no luck,its about 4yrs old ,not sure which version it is cheers again

DJ Sures · Answer

You can check the ez-robot website (manufacturer of the ez-b product). They have a hardware upgrade for the real old version. I'm actually in that video - I believe there's a portion about identifying the version: https://www.ez-robot.com/Shop/AccessoriesDetails.aspx?prevCat=101&productNumber=51

You can contact EZ-Robot for more information about their product if there's product specific questions. Here's details and instructions for the EZ-B v4 controller from ez-robot website: https://synthiam.com/Community/Tutorials/72?courseId=4

DJ Sures · Answer

Also - it's good to know about the power being applied. It seems the analog servos need a bit of time to initialize their pwm capture on the signal wire. So what you're doing by powering the servos on after the EZ-B is giving the servos time to initialize.

Because when the power is applied to the analog servos AND ezb - there's a sudden rush of voltage across everything. Which is being interpreted as a pwm by the analog servos.

One of the things you can do is have the servos only engage when there is a connected client. There's a feature in the latest ezb's for that. Here's a previous question I found for you using the search feature on this website: https://synthiam.com/Community/Questions/How-do-I-set-an-output-to-reflect-the-status-led-of-IoTiny-or-19491

Looks like you can use that to turn on a relay which powers the servos only when there's an active connection. Good news about that setup, is if there's ever a disconnect, the robot would shut down.

wfairall

Servos Twitch When Powered

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