Posts by MOM

    now I got it

    You are using a s type load cell (range probably up to 750 N) and the module HX711 as amplifier and for higher resolution for the input voltage(s).

    The robot should not monitor (or display) the values on the way to reach the required force. A threshold is set (maybe changeable) which activates an output to the robot control and via interrupt the robot motion will stop.

    If you want to reach 500 N then you probably want to set the threshold to 490 N so when the interrupt is executed and the robot came to a stop the 500 N are reached.

    As an arduino output I just want to mention, that are EtherCAT modules for arduino available wich may be used as well

    I just followed the rules of DH.

    for FK:

    1. draw kinematic model of the robot with all axes set to zero

    2. get the coordinate system for every axis

    3. get the DH Parameter for every axis (as introduced by Denavit Hartenberg - A1, A4 und A6 are inverted)

    4. calculate the transformation matrices (as introduced by Denavit Hartenberg)

    5. calculate flange frame (T06 by multpliying T01*T12*T23*T34*T45*T56)

    for IK:

    1. calculate wrist center point (wcp)

    2. using wcp to calculate axis position for A1, A2 and A3 (which gives 4 sets of angles)

    3. calculate R36

    4. Using R36 to calculate A4, A5 and A6 (which gives either 2 more choices (+/- 180°) or eight more choices (A4 and A6 +/- 360.0°)

    so I had a closer look to your post #8

    draw the kinematic model of your robot with all joints set to 0.0 (A1 thru A6, some robot could move to this position, but it is easier to calculate!)

    I gave you an example for axes A1 and A2 (see post #5)

    A1, A2 and A3 (Z-axis) pointing in the opposite direction (see also post #7 for that)

    (this is the reason why my axis 2 is pointing up and your A2 is pointing down)

    Where you got the number 0.6709 from - you are not allowed to make any orientation change besides theta or alpha

    (this part of the drawing is wrong - your first guess was correct - post #8)

    To me you are not 5 cm off, you are 800 mm in Z off

    let's go thru the posts:

    Hello, we have kr15 / 2 robot that we are driving with krc1 controls that we actively use, we cannot make backups on this robot, we can see the usb we plugged in on the Windows side, the USB in krcconfigator is selected but it gives a path error, it gives the same error when we want to get to the d directory. Thank you

    he wants to make a backup (archive) and can not do it!

    (at this moment we do not know the KSS version and we do not know the type of main board; all we know: it is a kr c1!)

    Just a guess: On old KUKA controllers USB was deactivated in BIOS. The reason being that USB violated realtime conditions in VxWorks. As long as you do not use USB while robot is running you can activate it in BIOS.

    I would not recommand this for one reason:

    in order to make a backup you would need to shut the pc down to activate USB in BIOS?

    Sometimes you want/have to make a backup while the system is running

    KSS Version and Name of main board would be helpful

    We still do not have this information yet!

    And how do you take it from d to some external medium? if you dont have floppy and you can't use USB? It is not helpfull if the archive is only on D disk in the controller and you can't transfer it to PC...

    I can show you pictures of kr c1 with floppy drives

    or you simply change the path to d:\\ as shown in post #6

    this is the local HDD and follow panic mode

    archiving to local HDD works if controller is accessible from other machine (through network or laplink)

    where is the problem?

    Case :

    DH Matrix introduced by Denavit and Hartenberg and Craig

    A1 inversed

    Comparison of the transformation matrices (symbolic vs. calculated)

    Test case 1 (introduced by Denavit Hartenberg):


    s11 = c11 = 1 => theta = 0.0° (multiplied by $AXIS_DIR[1])


    s32 = c32 = -1=> alpha = -90.0°


    s14 = c14 = cos(0)*260.0 => 260.0

    s24 = c24 = sin(0)*260.0 => 0.0


    s34 = c34 => 675.0

    result: theta = (-)0.0; d = 675.0; a = 260.0; alpha = -90.0;

    Home work: do the same thing with DH Transformation introduced by Craig

    (the indinces of the symbolic DH Transformation is not alway correct - the rest is ok)


    you are talking all the time about voltages.

    Start with the sensor. What is the sensor outputting (force and torque given in voltages, or just voltage and you have to calculate the forces and torques by yourself)?

    Or are you looking for a simple sensor only supplying one force value? The same question as above




    concerning DH Paramter:

    You need the DH Parameter in order to create you DH transformation for each axis.

    Unfortunately there are two ways doing the DH Transformation

    1. DH Transformation introduced by Denavit Hartenberg (rot.z(theta) * trans.z(d) * trans.x(a) * rot.x(alpha))

    2. DH Transformation introduced by Craig (rot.x(alpha) * trans.x(a) * trans.z(d) * rot.z(theta))

    Which DH Paramter you looking for?

    as a first step you should draw the kinematic model of a robot in xz-plane

    given coordinate systems:

    K0 Base coordinate system (your K0 is wrong - you draw yz-plane, K1, K2 and K3 as well)

    K6 Flange Coordinate System

    Send a corrected version of you kinematic model, please

    You also should not forget, that A1, A4 and A6 are rotating mathematical negative and A2, A3 and A5 mathematical positive.

    On Github searching for KR210 you will find some examples on the DH paramter (Craig). You just need the dimensions for your robot in



    just send picture of how the wiring is done (or how they looks like)

    There are actually a few sets of the cable (40 and 80 - 80 is preferred)

    Cable with some prongs are converted

    A lot of things which can be made wrong (Type of cable or jumper settings)

    Results unpredicable


    I am just wondering

    Normally HDD is at IDE Primary Master (IDE Drive 1) Jumper set to single and DVD at IDE Secondary Master (IDE Drive 3) Jumper set to single

    As seen at Picture DVD is at Primary Master (IDE Drive 1) and HDD at Secondary Slave (IDE Drive 4)

    What are the Jumpers settings for DVD and HDD?