![]() Steiner equation for "shifting": I = I CM + M * r 2įor palett inertia around $NULLFRAME (tool0) coordinate:įor this we need distances from palett center of gravity coordinates to $nullframe coordinates: J Palett.zz=(M*(a 2+b 2))/12=4,6127 kg*m 2 -> Same as in SW, other axis little difference, but it's OKįor the empty gripper if i use "Taken at the output coordinate system."!!:Ĭoordinate system located at $NULLFRAME (tool0) coordinate. It doesn't matter there i am using the "Taken at the center of mass and aligned with the output coordinate system" OR just "Taken at the output coordinate system", if my coordinate system located in the palett center of gravity.(calculate here the 3 inertia for xx,yy,zz) I calculated the robot inertia around palett center of gravity. I can't decide if I calculated correctly then It does not matter if the different tools are mounted directly or using tool changer. This also need to be done when robot has more than one tool that can handle the same object. When "output coordinate system" is parallel both does not match robot flange, obtained inertia value must be corrected using parallel axis theorem. When "output coordinate system" matches robot flange, but order of axes is different, inertia value components need to be swapped accordingly. In this case inertia values are Lxx,Lxx,Lzz. When inertia value is taken at the center of the mass, X,Y,Z of CM need to be entered (they are not zeroes). When inertia value is taken at the "output coordinate system" that matches robot flange, X,Y,Z of CM are zeroes and inertia values are Ixx,Iyy,Izz When "output coordinate system" matches robot flange, A,B,C are zeroes. One just need to be careful, pay attention, pick the correct one and ensure that orientation of coordinates matches. So it is more practical to use report result that does match robot coordinates. This is the only report result that does not refer to robot frame, but obtaining rotation angles A,B,C can be a problem - this may not be orthonormal (all three vectors perpendicular to each other or orthogonal). Also user can choose which coordinate system results refer to.įirst result in report is for "Principal axes of inertia" which solidworks takes at the center of the the mass with principal axes of inertia oriented to match eigenvectors of the object. Solid works offers several results and export windows show coordinate systems of each. ![]() If you are using load principal moments of inertia, taken at output (robot flange), thenĪgain do not forget the correct decimal place. (Btw SolidWorks representation of the matrix is transposed, not conventional, see here) You also have to determine which rotation angles A,B,C produce rotation matrix shown next to Px,Py,Pz. Those would be values for KUKA tool EOAT inertia JX, JY and JZ. If you are using load principal moments of inertia, taken at CoG, then inertia values are Px,Py,Pz (do not forget to adjust decimal point if units do not match). The next part is to choose inertia values. that is when robot is at cannon position then flange and robroot are parallel. Orientation depends on place where load is mounted.ĮOAT and shoulder (A3) mounted loads are relative to robot flange.īut to figure out correct flange orientation and specify correct CoG of the EOAT, robot need to be moved into correct position. So you just need to move decimal place correct number of places.įor example if you see in CAD output that load is computed in g*cm 2 thenĪlso note that KUKA expect Inertia values about CoG of the load. KUKA robots expect load data that is expressed in proper units:ĬAD may use different units but in metric system conversion is easy.īut note that for inertia values, distance is squared. Refer to Figure for the moments of inertia for the individual objects. In both cases, the moment of inertia of the rod is about an axis at one end. In (b), the center of mass of the sphere is located a distance R from the axis of rotation. ![]() In (a), the center of mass of the sphere is located at a distance L+R from the axis of rotation. Since we have a compound object in both cases, we can use the parallel-axis theorem to find the moment of inertia about each axis. The radius of the sphere is 20.0 cm and has mass 1.0 kg. The rod has length 0.5 m and mass 2.0 kg. ![]() Find the moment of inertia of the rod and solid sphere combination about the two axes as shown below. ![]()
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