Safety stop on loss of Serial Connection

Questions about using encoders with the Roboclaw product line
SouthernAtHeart
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Joined: Fri Jan 29, 2016 4:00 pm
Safety stop on loss of Serial Connection

Post by SouthernAtHeart »

Some controllers I've used have a watchdog timer you can set to something like 1 second. If the controller receives no Serial command for that duration, it will stop the motors. This safety feature is to prevent runaway motors in the event of a connection failure between the roboclaw and the MCu controlling it. I'm not seeing anything like this on the roboclaw. Am I missing it somewhere? I see the packet timeout, but that doesn't seem to stop the motors in the event of serial com failure.
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Basicmicro Support
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Re: Safety stop on loss of Serial Connection

Post by Basicmicro Support »

Correct, there is currently no automatic motor stop on a timeout in packet serial mode.
SouthernAtHeart
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Joined: Fri Jan 29, 2016 4:00 pm
Re: Safety stop on loss of Serial Connection

Post by SouthernAtHeart »

Ok, thanks. That might be something to consider in future firmwares...
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Basicmicro Support
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Re: Safety stop on loss of Serial Connection

Post by Basicmicro Support »

Yes,we are already considering it.
jwatte
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Joined: Thu Apr 02, 2015 11:55 am
Re: Safety stop on loss of Serial Connection

Post by jwatte »

there is currently no automatic motor stop on a timeout in packet serial mode
Isn't it possible to use the "drive distance at velocity" command?

If you make the distance slightly further than you intend to go in the next command interval, and then overwrite that buffered command with a new command before you get to the target distance, then the motor will keep running, until you don't send more commands, and then it will stop at that distance.

Edit: Fixed "position" -> "distance"
Last edited by jwatte on Thu Feb 25, 2016 6:24 pm, edited 1 time in total.
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Basicmicro Support
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Re: Safety stop on loss of Serial Connection

Post by Basicmicro Support »

I think you meant the Velocity commands with Distance, not Position. Yes, with the Distance commands you could do as you suggest. Then if no new command was given the motor would just stop at the end of the distance.
cyberdemon
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Joined: Sun Oct 08, 2017 3:41 am
Re: Safety stop on loss of Serial Connection

Post by cyberdemon »

Hello,

I was wondering if you had finished considering this yet?

I was quite surprised and disappointed to find that the RoboClaw controllers don't have this safety feature.

Given that these drives also don't have any gross error limit setting, then all of the closed-loop commands, including 'distance' are not very safe either, because a loss of feedback will cause the motor to run away!
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Basicmicro Support
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Re: Safety stop on loss of Serial Connection

Post by Basicmicro Support »

Sorry about the delay in getting your post approve. Some of the recent posts have not show up in our control panel and didnt show in the forums to the admins even though they should have.

We did add this in our todo list for the controllers shortl after our last post. Unfortunately time has been in short supply. We will be adding this as well as a number of other updates soon. We estimate by the end of the year(about 2 months).
cyberdemon
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Re: Safety stop on loss of Serial Connection

Post by cyberdemon »

Hello again :)

Any update on this?
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Basicmicro Support
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Re: Safety stop on loss of Serial Connection

Post by Basicmicro Support »

None yet. It is still in our todo.

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