I have a UR5 robot that, during its cycle, has to reach down below its base and drop of a part into a basket. On every other stop this machine has, it stops smoothly and the radius blends just fine. On this particular stop however it jerk to a sudden stop every time. I added a “slowdown” waypoint with barely any speed to try and give it the chance to get there slowly and smoothly but it still jerks to a sudden standstill.
Had to replace some joints for this robot due to this kind of issue.
Anyone know how to make it slow down and stop gently?
Its on a MoveJ movement, speed is 20 degrees/s before it reaches the stop. Radius is blended. Acceleration is also 20. I’ve heard someone mention a stopJ function but i havent found it anywhere.
Try turning off the blended radius.
I’ve seen that cause the jerky motion before.
You shouldn’t have a blended waypoint before any type of stop/wait/delay. 
That will indeed cause the abrubt stop and unwanted wear on the joints.
not sure who your distributor is but if they are letting you buy new joints instead of helping analyze your program, i think it’s time for a new distributor… like efn said, if you have any type of decision making happening at that waypoint, you should not have a blend. also, if you are using subprograms, try not to blend the last waypoint in it as it will jerk like this when entering back into main program.
They offered to do so, but you know how some management can be about slowing things down in production.. So i tried removing blends and it helped somewhat, so that seemed to be the issue.
However, trying the exact same on a different robot running the same program did no difference at all. Same abrupt stop
The UR will read its program sequentially. So whatever command is before the stop will be executed. I have never heard of it not doing this right.
Check the blend again. And the acceleration settings of the waypoint.
If it’s a MoveJ, stay below 400 deg/s^2. If it’s a MoveL, stay below 2500mm/s^2.
I added a new waypoint to the 2nd robot and it completely ignored it. After a reboot it read the program correctly, so something odd happened. The robots are fairly old so i am not surprised that some gremlins appear with age.
Speed and acceleration is well within those values, i think it was 160 deg/s^2 and 250mm/s^2 at maximum, for both MoveJ and MoveL.
I went ahead and sent the program to my distributor so we’ll see if he can figure it out. Thanks for the help!