2012/11/17 Martin Lederhilger <martin.lederhil...@gmx.at>: > Hello, > > I have upgraded my 3-axis cartesian machine with a 4th rotatory axis, > which looks along the X-axis. In my g-code programs I want to use X, Y > and Z for the position of the tool's tip on the workpiece and A for the > angle between the z-axis and the axis of the tool - which is always in > the yz-plane. > > Therefore I have written a kinematics module, but it seems that I have > problems with the tool length compensation. Now I have the following > questions:
AFAIK currently there is no 5 axis tool length compensation in LinuxCNC. I hope that I am wrong :) Could You, please, share Your kinematics module? The way I have been compensating for the tool length from tool tip to pivot point (in 5 axis plasma and waterjet machine kinematics), is: 1) create a HAL pin in kinematics module to feed in the tool length value (which can be changed during the operation and machine will adjust to that, just limit the rate of the change for this value so that machine can move accordingly); 2) in inverse and forward kinematics add calculations of the offset along Y and Z as the tool is tilted. For Y that would be "tool_length * sin(A)", for Z that would be "tool_length*(1-cos(A))" note that the difference between inverse and forward kins is the sign before these new additions, for example: joints[1] = tran.pos->y + tool_length*sin(A); tran.pos->y = joints[1] - tool_length*sin(A); 3) since pos->a is in degrees, but all the angle calculations need radians, You simply need to define a new variable, in this example this is A, to get from degrees to radians: A = pos->a*PM_PI/180; see pumakins module for examples, how that is done. -- Viesturs If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
