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# Speed limits: does RoboDK know not to exceed robot joint speed limits?

Hi,

I am new to RoboDK, and am wondering whether RoboDK stores information about robot joint speed limits in its robot models, and whether it knows not to exceed them when planning robot motions.

For instance, I'm looking at milling a piece using the ABB IRB 6700, which lists maximum axis speed for axes 1-6 in deg/sec as [100, 90, 90, 170, 120, 190]. I'm using the robot machining functionality, which sets speed to say 1000 mm/s for a certain operation. I take it this is speed of the TCP. Does RoboDK calculate the resulting speeds at each axis and check that those are within limits?

Thanks!
Hi JCC,

It's a good question, but kind of a trick question.
RoboDK don't really need to know the speed limits of each joint, this is mostly the job of the robot controller.
It's especially true for machining projects.

Machining projects are composed of a high amount of MoveL packed together. Therefore the linear speed is more important than the angular speed.
Once the robot controller receive a TCP speed, let's say 1000 mm/s, it will TRY to reach that speed. I say TRY because it can possibly be limited by external factors like "acceleration and deceleration ramps" or by the speed limit of a joint. In other words, the controller will try to bring the TCP to a speed as close as 1000 mm/s, but won't go faster than that.

By the way, it's the exact same behavior as what you would get if you were to program your ABB robot manually.

Have a great day.
Jeremy
Hello, I'm beginning a project using a Fanuc R-2000iC-210F.
From Robot specs, I see joints speed have those limitation: [J1 J2 J3 J4 J5 J6] Maximum speed (°/s) [120 105 110 140 140 220].
Now I see that in the robot parameters panel I can assign only one generic joint speed limit, and I cannot assign a limit for every joint.

How to define a limit for every joint as per specifications ?

Or the Robot joint speed limits are respected anyway during a simulation ?
You can use one joint speed limit that applies to all axes. RoboDK doesn't know if you are exceeding the real robot joint limits. To be safe and calculate a cycle time accurately I recommend you to use the slowest joint limit. Keep in mind that these joint speed limits also vary depending on the position of the robot.

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