moving the robot (six axes) with laptop (3D software) to PLC to robot

    Dear all,
    Hello. I learned many thing from this forum in this 1 month. Thank you every one :icon_smile: .
    Is it possible to move robot sending the output from the PLC(or from the 3d software to PLC to robot)?
    As I am new to this robotic field I have no idea about the automated package.And i am not sure if my KSS version can support even if i buy it. I read some other related topics in this forum but that were for KRC4 mostly. I have no idea how to send command or write to robot via plc. If I am able to send the command to move to axes from 3d model to PLC, can PLC send to robot so that robot moves in reality?

    I would like to know your all opinions and advises to achieve this mission.

    Thank you everyone.

    Edited once, last by Captain (March 27, 2018 at 1:32 PM).

    Let me ask my question in little bit different way. Is it possible to program in Kuka control panel to move the robot according to received input? For example lets say if I send axis 1 angle from PLC as output to the robot, can we make program in kcp to move robot to that angle?

    Thanks

    Edited once, last by Captain (March 27, 2018 at 1:30 PM).

    It is entirely possible, with certain caveats.

    As a VERY simple bare-bones example:

    Code
    SIGNAL A1_Input $IN[1] TO $IN[32] ; 32-bit signed integer
DECL E6AXIS NextPose
WHILE NOT (A1_Input < -999) ; exit condition
  NextPose = $AXIS_ACT ; initialize to robot current pose
  NextPose.A1 = A1_Input
  PTP NextPose C_PTP
ENDWHILE

    The thing to understand here is that this is not realtime control. That is, once a motion command has started, you cannot change the trajectory until that motion has completed execution. So smooth, constant control is not fully possible at this level, unless you are feeding the robot a string of poses pre-calculated to create a smooth constant motion.

    There's also the effects of the advance pointer to take into account, which needs some careful study.

    Thank you SkyeFire
    your reply gave me motivation to work further :coeuranime:. I understand what you mean. But moving the axis can be risky in the sense that robot might get defeat (broken). So I want to get more knowledge before i implement the command. So with basic

    1. The signal declaration can be made again at $config right (or .dat)? is it good to do global?

    2. Can we make new .src and .dat program to program like as you showed or should we need to use some system file like cell.src?

    3. DECL E6AXIS NextPose , what are the array of it? is it DECL E6AXIS NextPose = {a1 0.0, a2 0.0, .........,a6 0.0}? Can we make global dec ?

    4.Will you please explain what do u mean by this? There's also the effects of the advance pointer to take into account, which needs some careful study

    5. So smooth, constant control is not fully possible at this level, unless you are feeding the robot a string of poses pre-calculated to create a smooth constant motion. Will you please tell how to feed robot with pre calculated string? Is it like what i have put in attachment??

    Thank u again

    Edited once, last by Captain (March 27, 2018 at 1:29 PM).

    I generally avoid creating Global variables unless absolutely necessary, but that is a personal choice.

    I would recommend creating a new program. Definitely do NOT tamper with CELL.SRC for this, that program has very specific functions that have nothing to do with moving the robot about.

    E6AXIS is a joint-defined position. PTP motion commands cannot access input signals directly, so it is necessary to create an E6AXIS variable, initialize it, then set its internal values for each axis from the input signals, before passing the E6AXIS variable to the PTP command.

    Read the Expert Programming Manual section on the Advance Run, and on continuous motion.

    Your attachment has a list of motions created and saved on the pendant. Which is completely different from sending axis motion commands to the robot from the PLC.

    Thank you skyefire.

    Firstly i sent my six axes from plc to kuka as input word (INW20 to INW30) 16 bits signal. I might need to send the negative angle so before sending the value I first add the highest constant (example for axis 6, my angle limit is lets say 180 to -119 so I add 120 for axis 6) and multiplied by 100.

    1. I declared the global REAL A1_Input to GLOBAL REAL A6_Input (and DECL E6AXIS NextPose) in .dat file.

    2. I declared my signal in $config as signal A1_Input IN$[161] TO $IN[176] ..................signal A6_Input $IN[241] TO $[256]

    3.I need to convert my value at kuka side by dividing by 100 and subtracting by constant. for example lets say for axis6, A6_Input =(A6_Input/100.0)-120 . Normally i used to do this at SPU.SPS but this time it gave me error saying error 1388 A6_Input variable write protected in module sps line 52. So I planned to convert this step in my own program of .src. Is it good idea? or how can i make conversion at kuka side and which at which file?

    When I tried to pull my value at main window by >monitor>variable>Signal>A1_Input . It showed me right value for all six axis (with constant *100 example if i send 80 for axis 6 then it is 20000). But when i pull these variable after opening my program .src the value is not shown why? Please see the attachment

    4. I made my .src as
    ;just to test axis6 first

    While NOT (A6_Input <-999 ) ; How can i make boolean like While (A6_Input == true)?
    A6_Input= (A6_Input/100)-120
    IF (A6_Input<=180) AND (A6_Input>=-140) then ; just to limit my axis 6 as angle between 180 to -120
    Nextpose=$AXIS_ACT
    NextPose.A6=A6_Input
    PTP NextPose C_PTP
    ENDIF
    ENDWHILE

    but it gave me error saying a6 input invalid value...may be because the axes value is not shown inside .src. So why in the main window the value is correct and inside the .src file the value is not shown?
    I also tried declaring the signal in .dat file, but it didn't work.

    Any idea how to solve this problem and error? What did i do wrong?

    Thank you.

    Edited once, last by Captain (March 27, 2018 at 1:29 PM).

    Thank you for the reply SkyeFire

    Quote from SkyeFire


    Wait... you have REAL A1_INPUT and SIGNAL A1_INPUT? You can't do that. Your REAL variable, which you do math on before passing to the PTP command, must have a distinct name from the SIGNAL input. You cannot perform any kind of "write" on an Input Signal.

    Will you please tell me who can i achieve that. Lets say I have 21000 received at robot side. If i need to divide it by 100 and substract 120 from it before giving command to robot then how can i do it? ???

    Quote from SkyeFire


    a distinct name from the SIGNAL input. You cannot perform any kind of "write" on an Input Signal.

    will you please tell me, how to make distinct name for input signal? and how and where to alter write signal(divide or subtract)?

    [size=small]well...cannot have duplicate names.... [/size]
    [size=small]just rename [/size][size=small]one of them... for example. [/size]

    [size=medium]SIGNAL A1_Input_Val $IN[1] TO $IN[32] ; 32-bit signed integer[/size][size=small]


    then you read manual or existing programs to figure out how to do some math in KRL...
    [/size][size=medium]Something = (A1_Input_Val/100.0)-120 [/size]

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

    Thank u Panic mode and Skyefire. :flower:
    I have been able to move the robot (all six axes) via the angles sent from PLC. I have gone through the expert programming (all section of Motion programming).
    I have few question hope you will help me.

    1. In expert programming it says "point--to--point movements is dependent on the robot’s kinematic system and cannot,therefore, be accurately predicted. Common to both these types of motion is that
    programming takes place from the current position to a new position. For this reason, amotion instruction generally only requires the specification of the end position
    "    . Lets say If the current axes position of axis 1 is 90 degree. If i enter the command move to 5 degree, is it possible to see how it moves from the 90 degree to 5 degree(like 90...89....87...so on 4...5)? Or how robot takes 90....89...87...up to 5? I know $Axis_Act will show current robot position but isn't the axes show by $Axis_ACT is feedback? or am i wrong? And what is $Pos_Act (what can it do)?


    2.

    Quote from SkyeFire


    So smooth, constant control is not fully possible at this level, unless you are feeding the robot a string of poses pre-calculated to create a smooth constant motion.
    There's also the effects of the advance pointer to take into account, which needs some careful study.

    How can we do this?? how to send robot pre calculated position to create smooth constant motion? what is advance pointer & its effect? :waffen100:


    3. Expert programming made me more confuse about the velocity and acceleration things. . Lets say i want to move all 6 axis and i have define acceleration and velocity for all 6 axes like example $Acc_Axis[1]=100 & $VEL_Axis[1]=100 and same for other axes. Is is only the longest one will move fast i.e 100 in this case?

    4.Is it possible to write (control) to system velocity/ acceleration from PLC for 6 axes?

    Note: I am using Kr3 robot, controller Krc3 and KSS V4.1.5

    Thank you.

    Edited once, last by Captain (March 28, 2018 at 4:17 PM).

    1. What this means is that PTP motions do not control the trajectory of the robot -- only the start and end points. So the path the arm will follow is not generally predictable. In your case, if you move a single axis at a time, the arc the TCP follows is much more predictable, but that's a rare case. In the more typical usage, large motions are carried out by all axes moving at the same time, but at different speeds, so that their start/stop times are synchronized, even if one axis is moving 180deg but another is only moving 15deg.
    When you command an axis to move X degrees, the motion planner plots that motion as an acceleration/cruise/deceleration trapezoid over time, and executes that pre-planned motion.

    $AXIS_ACT is the realtime value of each axis. $POS_ACT_MES is the realtime equivalent in Cartesian space, but only generates valid data if you have activated valid Base and Tool settings.

    The advance pointer, and its effect on approximated motion, is covered in great detail in the programming manual, and in many, many posts in the Forum archives.

    If you command all 6 axes to move at the same time, the path planner will plot out the require velocity/time trapezoid for each axis. Since each axis has different maxima for acceleration and speed, and may be commanded to move a different number of degrees, the path planner calculates which axis will need the most time to carry out the commanded motion, then slows all the other axes down, such that all axes begin and end the commanded motion at the same time.

    For PTP motions, $AXIS_ACC and $VEL_AXIS are % of maximum (1-100). PTP motions are not about deterministic motion over time, but rather allowing maximum optimization of motion over time -- PTP motions are used to get the robot from point A to point B in the fastest time possible, while LIN motions are used for deterministic motion paths at exact velocities.

    $VEL_AXIS and $ACC_AXIS are simply variables, and can be written to from your program, just like any other variable. So you could receive their values as inputs, just as you do your axis positions. Simply keep in mind that, once $VEL_AXIS and $ACC_AXIS are set and a motion begins, you cannot change their values until that motion is complete. So you cannot change the speed/accel profile of a motion in mid-flight.

    Thank u skyefire . I went through expert programming and system variables manuals again.
    but for beginners the manuals know how to confuse more :uglyhammer2:

    Quote from SkyeFire


    1. What this means is that PTP motions do not control the trajectory of the robot -- only the start and end points. So the path the arm will follow is not generally predictable. In your case, if you move a single axis at a time, the arc the TCP follows is much more predictable, but that's a rare case. In the more typical usage, large motions are carried out by all axes moving at the same time, but at different speeds, so that their start/stop times are synchronized, even if one axis is moving 180deg but another is only moving 15deg.
    When you command an axis to move X degrees, the motion planner plots that motion as an acceleration/cruise/deceleration trapezoid over time, and executes that pre-planned motion.

    1. So in simple language, does this means in PTP motion it is not possible to control the velocity of the axis according to the desire of programmer? And lets say if I want to move axis1 from 180 to 0 degree. But during this motion, if I want to say that example from 180 to 45 degree move fast then rest of it move slow. Is this possible? It this mean approximate positioning + advance run?

    2.For E6Axis , the fastest motion is PTP but the LIN movement is not suitable for this case right for joint(axes specification)?
    Since the path planner calculates its velocity for each axis then what is the use of writing $VEL_AXIS, $Acc_Axis and $APO.CPTP ? and what is use of all predefined values ($Vel_axis_act, $Vel_axis_C, $APO_DIS_PTP[1]=90.0 ) in $machine.dat?

    3. In manual it says "$AXIS_ACT_MEAS = Unlike $AXIS_ACT, which contains the setpoint positions, this variable always delivers the current actual axis angles of the drive. " what does that mean ? :fine:


    Sorry in case if I have asked same question, but still some things is confusing.

    Thankyou.

    Edited once, last by Captain (March 30, 2018 at 2:31 PM).

    1. No you can't change an already started motion. so your summary is correct. There is a way around this if you need it. during a motion you can change the general PTP velocity like you can on the pendant. this a variable you can write to and set the speed to for example to 50% of the current planned motion. if i am not mistaken this is the variable $OV_PRO.

    2. E6Axis positions is only for ptp movements, lin movement require coordinates in Cartesian space.

    3.$AXIS_ACT are the axis positions where the robot is moving towards. $AXIS_ACT_MEAS contains the current axis positions

    Every problem has a solution, that isn't the problem. The problem is the solution.

    Thank you Leon.

    My aim now is just to control velocity (acc/deacceleration) of the robot (not by pendant) but something with program. The video

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    (you can watch only between 1 minute to 2 minute only) so something like this. Slowing the speed or increasing some where during the motion. I hope something like this is possible with out buying the packaged from kuka?

    My code looks like this
    LOOP
    A1_Input= ((A1_Input_Val*100)-141) ;A1_Input_Val is signal from PLC & A1_Input is real
    A2_Input= ((A2_Input_Val*100)-4)
    A3_Input= ((A3_Input_Val*100)-101)
    A4_Input= ((A4_Input_Val*100)-101)
    A5_Input= ((A5_Input_Val*100)-101)
    A6_Input = ((A6_Input_Val/100.0)-119) ;//back to real


    NextPose=$AXIS_ACT ;// current value of axis act is copied to Nextpose


    NextPose.A1=A1_Input ;//change nextposition to input position
    NextPose.A2=A2_Input ;//change nextposition to input position
    NextPose.A3=A3_Input ;//change nextposition to input position
    NextPose.A4=A4_Input ;//change nextposition to input position
    NextPose.A5=A5_Input ;//change nextposition to input position
    NextPose.A6=A6_Input ;//change nextposition to input position


    PTP NExtPose C_PTP
    ENDLOOP

    So it can basically move all the 6 axes (E6Axis)according to the input feed from the PLC(both +ve or -ve angle). It will wait at PTP line and wait the input from PLC and move axes accroding to recieved input. I can decrease/increase the speed from pendant but that is not what I want. And $VEL_AXIS[] is controlled by controller and not programmer.

    So how can I implement $OV_PRO to control the velocity of axes (lets say for example current position of robot is a1 0, a2 4, a3 42, a4 1, a5 25, a6 -85 and I want to move to new position a1 -120, a2 -33, a3 29, a4 -30, a5 0, a6 0 ). Let say increasing the speed at when it reach near to end position? Any one can please give example suitable for my case? :help:

    I looked at system variable manual & expert programming but there is not syntax (and example in this forum are little bit complex to understand). IS it good to use OV_pro in SPU or in .src file? And do we also need to consider the deceleration if we increase speed? I have attached machine.dat if needed.

    Thank you.

    For example by doing this:


    vel_ptp() is a routine from bas.src.
    You can also use something like
    $vel_axis[1]=vel_input
    $vel_axis[2]=vel_input
    $vel_axis[3]=vel_input
    ....
    if vel_input is limited to values between 0 and 100.

    Or declare variable inside sps,

    $ov_pro = speed_input (or whatever input you have available)

    When you change the input is automatically changes the speed of the robot. In your program you would have to use the maxium speed you want to achieve and then you could change that speed between 0 and 100%.
    Slight drawback is that the speed override button on the pendant does not work anymore because the variable is constantly overwritten by the sps.
    You could ad a if statement so i only executes when the robot is in auto, or when it is not in T1 or something.

    Every problem has a solution, that isn't the problem. The problem is the solution.

    Thank you hermann and leon

    Quote from Leon


    Or declare variable inside sps,
    $ov_pro = speed_input (or whatever input you have available)


    1. Just $ov-pro= speed_input, enough ?? I mean no need to write any thing in .src?
    Can this be used for 6 different velocity? something like $ov_pro1= speed_input1 ............ $ov_pro2= speed input2??? Just curious although i might use same velocity but just for knowledge in case someone ask for 6 different velocity? :dance:

    2. But my new problem is now is it possible to decrease pendant velocity when it is set to 100%. So my robot moves very rapidly which look likes it is going to crash when the pendant velocity is 100%. I can decrease the pendant velocity from controller. Around 20%the movement looks nice(safe/medium speed).

    So when i decrease velocity in my code .src with like lets say $VEL_AXIS[1] = 5 and $ACC_AXIS[1]=5 only then with 100 velocity of pendant, the robot moves little bit slowly.
    But what I want to do is, when pendant velocity is 100% I want robot to move slow(without lowering pendant speed/velocity) and with $ov_pro=100 or $VEL_ACXS=100, I want to increase velocity/speed of robot. I hope you understand what i mean?

    So will you please tell me how to decrease controller velocity from system when it is showing 100% ? May be something to do with machine.dat or bas or some system file?

    Thank you. :hmmm:

    If $vel_axis [ x ]=5 is too slow then use $vel_axis [ x ]=10 thats double of 5 and corresponds to 10% override on smartpad. Don't use $acc_axis.
    If You use the method with $ov_pro the speed of all axis is the same.
    If you want to change the speed of every axis seperate you have to declare six input values and set $vel_axis[ x ] according the example posted above. Don't know if makes sense to have different speeds on different axis with a movement that uses several axis. I'm wondering about the result of such a movement.

    Just a little background information.
    The variable $OV_PRO is a program override setting(Override Velocity PROgram. So for example if you set $vel_axis to 100% and $OV_PRO to 100%, all axis will move with the maximum speed they are capable of, which is a setting in machine.dat:

    Code
    REAL $VEL_AXIS_MA[12] ;NENNDREHZAHL DES MOTORS ACHSE[I] (I=1:A1,I=7:E1) [U/MIN]
$VEL_AXIS_MA[1]=4000.0
$VEL_AXIS_MA[2]=3500.0
$VEL_AXIS_MA[3]=4000.0
$VEL_AXIS_MA[4]=5000.0
$VEL_AXIS_MA[5]=4000.0
$VEL_AXIS_MA[6]=5000.0


    If you change $vel_axis to 50% and leave $OV_PRO on 100% the robot will move with 0.5 * 1 = 0.5 so half the programmed maximum speed
    last if you would keep $vel_axis on 50% and change $OV_PRO to 50% you would get 0.5 * 0.5 = 0.25 so 1/4 of the maximum speed.

    In your case i think it would be sufficient to just set $vel_axis to a speed you are comfortable with and use $OV_PRO to change speed during a move.
    I hope this clears it up a bit

    Every problem has a solution, that isn't the problem. The problem is the solution.

    Things to keep in mind:

    $VEL_AXIS[ x ] is only checked and applied between motions. That is to say, if running this code:

    Code
    VEL_AXIS[1] = 100
PTP P1
VEL_AXIS[1] = 50
PTP P2

    The velocity of Axis 1 will not change from 100% to 50% until the robot reaches P1.

    It's also important to recall that, if you slow one axis down, the rest of the robot will slow down to match it, if necessary.

    $OV_PRO, on the other hand, effects the robot velocity in (near) realtime. So altering $OV_PRO while the robot is in motion will affect the velocity of that motion, regardless of what $VEL_AXIS[ x ] is set to. However, to do this you either need to use Interrupts, or put code into the SPS to adjust $OV_PRO on the fly.
    And, of course, since $OV_PRO is a general override, it effects all axes equally.

    One thing I've done in the past to help make my lab robots less collision-prone is to put a limit on $OV_PRO in the SPS:

    Code
    IF $OV_PRO > 30 THEN
  $OV_PRO = 30
ENDIF


    This will block someone from increasing the playback speed value on the pendant past 30%. It is VITAL to keep in mind, however, that this is NOT a safety limitation -- it can help you avoid crashing the robot into things during testing, but it does not qualify as keeping humans safe within the reach of the robot. And anyone trying to use it that way is begging for a lawsuit and/or jail time.

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