Universal Robots Forum

Possibility to lower the acceleration when resuming a program?

Hi everyone,

I made a very simple program : just a moveL between 2 points in which I specified a speed of 1000 mm/s and an acceleration of 500 mm/s.
If I pause the program when the robot is in the middle of the trajectory (at full speed), when I resume the program the robot does not apply the acceleration I specified. The robot applies a very high acceleration to recover the trajectory (position and velocity) as fast as possible.

Is it possible to make the robot apply the acceleration I specified in the program when resuming ?
And if so, how could I do that ?

Thanks,

Baptiste

PS : I am using a UR10 robot with Polyscope 3.5

If you update your robot to at least 3.7, you get the option to change how fast it changes speed. If I remember correct, that will affect all speeds when starting and stopping, except emergency and safety stops. It still isn’t the acceleration you set, but it is softer than the default/old hard one.

Hi,

Thanks for your help.

I updated my robot to Polyscope 3.7 and tested this smooth transition capacity.
Unfortunately it doesn’t change much things for me.
Indeed, this smooth transition does not affect the safety stopping time and distance. I understand that these safety limits are used for both pausing and resuming the movement. Thus, in my case, as I’d like a low acceleration, the movement is mostly constrained by the safety limits and cannot apply an acceleration as low as I’d like.

Is there a way to bypass the safety stopping time and distance only when resuming a program ?
I suppose no, because of safety reasons.

I don’t know your case, or how flexible it needs to be, but maybe you could have a daemon running in the background, checking program status. When the program status is detected to be paused, it sets the speed slider to 2% (dont set it to 0, that made our robots completely lock up).

When the daemon then detect the program has been started again, it can ramp the slider back up to 100%, in a way you control.

https://www.universal-robots.com/how-tos-and-faqs/how-to/ur-how-tos/setting-the-speed-slider-from-a-program-15293/

Hi
When Resuming, the robots will accelerate relatively hard to the speed of the motion of the program, If payload etc. is set correct, it should not lead protective stops.
Safety and the smooth decelleration due to Safegurad stops does not affect this.
So if you encounter problems with protective stops, and things are setup correctly, the workaround proposed by michael.andresen is probably necessary.

Hi,
In fact, I am not facing problems with protective stops. As you said, when resuming the robot will accelerate relatively hard. What I’d like is a soft acceleration.
I think the workaround proposed by michael.andresen might be a good solution, but I haven’t had time to try it yet.
I’ll let you know as soon as I try it.
Thanks.