Hello, gentlemen! I have created a module for a puma arm on a linear slide. I have customized scarakins module to handle all the kinematics of the arm. And I have encountered strange behavior. The wrist has 2 rotary joints - one (joint[3]) is attached to lower arm and revolutes around A axis. This joint has adjustments in the kinematics module so that tool (basically everything that is attached to this joint) does not rotate as arm moves and upper and lower arms change their angles (the same what joint [3] does in original scarakins, where it revolutes around C axis) The second joint (joint[4]) revolutes around B axis is attached to previous joint. In kinematics module I have following lines for forward and inverse kinematics for this joint: world->b = joint[4] joint[4] = world->b
I had some difficulties with joint[3], because of those adjustments - EMC was showing A position to be 180 or -180, when it had to be 0, but I finally got that right. But I cannot figure out, what is wrong with joint[4]. It homes correctly, switching to world mode shows position 0, which is ok, jogging by hand keeps the tool tip in place and everything is fine. The problem is, when I am running a g-code. Command B0 in the code will lead to EMC changing B position to 90, and joint[4] also will go to 90. So if I want B to do this: G0 B0 G0 B20 G0 B0 G0 B-20 I have to apply -90 offset in the g-code and write it this way: G0 B-90 G0 B-70 G0 B-90 G0 B-110 The thing is that EMC in DRO shows the actual position, it just somehow adds 90 degrees to what is stated in the g-code. Since forward and inverse kinematics for this joint are trivial, I am out of ideas, where should I look for solution. Has anyone ever encountered something similar? I would appreciate, if someone could point me a direction, where to search for a clue. Thanks! Viesturs ------------------------------------------------------------------------------ Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand malware threats, the impact they can have on your business, and how you can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
