Safety stop on loss of Serial Connection

Questions about using encoders with the Roboclaw product line
SouthernAtHeart
Posts: 31
Joined: Fri Jan 29, 2016 4:00 pm

Safety stop on loss of Serial Connection

Postby SouthernAtHeart » Mon Feb 15, 2016 9:11 am

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.

User avatar
Basicmicro Support
Posts: 1135
Joined: Thu Feb 26, 2015 9:45 pm

Re: Safety stop on loss of Serial Connection

Postby Basicmicro Support » Mon Feb 15, 2016 9:15 am

Correct, there is currently no automatic motor stop on a timeout in packet serial mode.

SouthernAtHeart
Posts: 31
Joined: Fri Jan 29, 2016 4:00 pm

Re: Safety stop on loss of Serial Connection

Postby SouthernAtHeart » Mon Feb 15, 2016 9:32 am

Ok, thanks. That might be something to consider in future firmwares...

User avatar
Basicmicro Support
Posts: 1135
Joined: Thu Feb 26, 2015 9:45 pm

Re: Safety stop on loss of Serial Connection

Postby Basicmicro Support » Mon Feb 15, 2016 9:49 am

Yes,we are already considering it.

jwatte
Posts: 45
Joined: Thu Apr 02, 2015 11:55 am

Re: Safety stop on loss of Serial Connection

Postby jwatte » Wed Feb 24, 2016 3:00 pm

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.

User avatar
Basicmicro Support
Posts: 1135
Joined: Thu Feb 26, 2015 9:45 pm

Re: Safety stop on loss of Serial Connection

Postby Basicmicro Support » Thu Feb 25, 2016 9:27 am

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
Posts: 10
Joined: Sun Oct 08, 2017 3:41 am

Re: Safety stop on loss of Serial Connection

Postby cyberdemon » Sun Oct 08, 2017 3:52 am

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!

User avatar
Basicmicro Support
Posts: 1135
Joined: Thu Feb 26, 2015 9:45 pm

Re: Safety stop on loss of Serial Connection

Postby Basicmicro Support » Mon Oct 23, 2017 10:11 am

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
Posts: 10
Joined: Sun Oct 08, 2017 3:41 am

Re: Safety stop on loss of Serial Connection

Postby cyberdemon » Tue May 29, 2018 9:03 am

Hello again :)

Any update on this?

User avatar
Basicmicro Support
Posts: 1135
Joined: Thu Feb 26, 2015 9:45 pm

Re: Safety stop on loss of Serial Connection

Postby Basicmicro Support » Tue May 29, 2018 9:52 am

None yet. It is still in our todo.


Return to “Velocity and Position Control”

Who is online

Users browsing this forum: No registered users and 1 guest

cron