Fanuc slows down on a straight line with large number of points

    Hi, all!

    I have 2 linear paths: with 2 points and with 100 points. Start and goal points are equal. Velocity is 800 mm/sec. Distance between start and goal - 800 mm.

    1-th path. 2 points (start and goal). Time is 1.0 - 1.1 sec. It's normal because of acceleration / deceleration.
    2-nd path. 100 points - (start and goal are the same as in previous path) + intermediate points on a straight line with const orientation. Distance between points is 800 / 100 ~= 8 mm. Time of program execution is 1.55 sec. It is 1.5 time slower. Why? 8 mm between points is not very big distance. Smoothing is CNT100.

    Fragment from program:

    Do not think calculation is the reason of slower motion. Calculating the pass consider total distance to calculate acceleration/deceleration. With many points even with CNT100 total distance for calculation is one extra point ahead and so on. So the acceleration/deceleration curve is different and so the speed over all. My thinking...

    Quote from sborchshev

    Do not think calculation is the reason of slower motion. Calculating the pass consider total distance to calculate acceleration/deceleration. With many points even with CNT100 total distance for calculation is one extra point ahead and so on. So the acceleration/deceleration curve is different and so the speed over all. My thinking...

    I think it is more a thing of the motion planner, think about this... what would happen if you put a condition betwheen two of these points like wait DI[1]=ON while moving at 800mm/s (assuming it reached that speed) seperated 8mm each point?

    It would not be able to stop in case that input was off. If the read ahead instructions are set to 3 instructions, this will limit the processing speed as it needs to also take into account the program pointer being stopped mid motion.

    I know, someone would say that if you need to check a signal, you should put a fine behind it, but this is not really needed and slows down the robot a lot if you do that for every condition.

    As a rule of thumb, I always avoid adding more points than needed on paths, as since a lot of time some other guy demonstrated me that if you want the robots to run and be fast, the less points, the better, and this applies to abb, fanuc, kuka and more brands.

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