Good Practice for acceleration and tool speed.

AZalmanov

Hi all,

In the process of tweaking the program to reduce cycle time a question arose in regard to good practice for setting accelerations and tool speeds in the program. In the interest of balancing joint longevity with cycle time what are some guidelines for determining this or a good place for me to look for reference? I appreciate your time answering my questions thank you. My installation is a UR5 with Robotic 2 finger 85 gripper.

JacobBom

In general, the accelerations are the ones, that has impact on joint health and longevity. 
The speed is not critical, but more the way you obtain this speed. 

I would recommend using accelerations at or less than:
Joint motions: 300 deg/sec^2
Linear motions: 2500 mm/sec^2

Also consider, if you have to stop a motion prematurely (e.g. included in an IF-statement, with "Check expression continuously") to use the script codes "stopj(a)" or "stopl(a)" to decellerate.

matthewd92

One of our recommendations practices is to use the position_deviation_warning() method to know when you are pushing any particular move to hard. We use a threshold of 0.8. This has definitely helped make our programs more robust and limit protective stops

AZalmanov

This is one aspect of it. I was leaning more towards the realm of joint health and longevity.

Alan_Jordan

If you are running the robot at speed for prolonged periods, tick the BLEND WITH RADIUS button for most waypoints. This allows the robot arm to move smoothly between waypoints and prevents jerking. Don't use this feature for the first & last waypoints. 

manjunath13

@matthewd92
how can i use position_deviation_warning() script in the program. I tried to insert it in before start sequence, i get an error

type error position_deviation_warning() takes exactly 1 arguments (0 given) 

did you find a way to use this as a variable value.

mkardasinski

You omitted the enabling argument. ie. "position_deviation_warning(true)" or "position_deviation_warning(false)" Take a look at the URscript manual for further information.

manjunath13

Thanks for the suggestion. it worked 

vickailiu

@matthewd92, any idea how can we get the log in realtime? As we want to control the robot in realtime and get the warning from PC asap.

matthewd92

It is being streamed on port 30001, you will need to be able to decode the message packets to find the logs.  There is more information on what is coming out of that port here

Using that data you would be able to get access to the log files, we do not decode that data today so not sure what you would be looking for in the message.  The log files are message type 20, text message I believe.  Look at the tab "3.0" for a list of all the messages that are being broadcast.

Would be interested to know if you are able to get this working.

vickailiu

matthewd92 said:

It is being streamed on port 30001, you will need to be able to decode the message packets to find the logs.  There is more information on what is coming out of that port here

Using that data you would be able to get access to the log files, we do not decode that data today so not sure what you would be looking for in the message.  The log files are message type 20, text message I believe.  Look at the tab "3.0" for a list of all the messages that are being broadcast.

Would be interested to know if you are able to get this working.

Hi Matthew, good to know. I let my engineer intern tried and we managed to get it working. We used the "ur_modern_driver" and here is the commit for the key message unpacking. It may not be optimized and need some tweak if anyone wants to use it. But the bottom line is that it works for us.

lakshmip001

@vickailiu , any idea how to monitor UR5 robot mode using ur_modern_driver. I see I can sent "set robot enable" through ur_driver/URScript. How can I monitor UR5 real-time robot status and when it reaches protective stop, disable protective stop and move back to home position and continue the process again?