On 19 April 2011 08:12, Viesturs Lācis <[email protected]> wrote:
>From my readings about DH parameters, I understand that in prismatic > joints the D is the joint variable. D is measured along Z axis of > joint's coordinate system. So for joint 0 to be prismatic in X, I just > need to rotate it's coordinate frame so that joint's Z matches base's > X. It is done with Theta and Alpha parameters: > 1) Theta rotates around "old Z" - that is base's Z. So I should rotate > it by 90 degrees so that "new X" point along "old Y"; Rotating a vector parallel to Z around Z leaves it parallel to Z. > 2) Alpha rotates along "new X" - so I should rotate by the same 90 > degrees in the same direction so that "new Z" matches "old X" And a rotation about X leaves it perpendicular to X. (Alpha then theta would work, theta then alpha can't). Is it possible to call your linear axis "Y" and just live with it? Otherwise you could create a 7-joint kins with Alpha-0 = 90 and THETA-1 = 90. >> There is a spurious conversion from linear mm to radians. You need to >> move the joint 360mm to move Y or Z by pi mm. >> line 444 in genserkins looks like one likely culprit. > > Line 521 converts them back to degrees. But the linear axes should never be converted, nor be converted back. -- atp "Torque wrenches are for the obedience of fools and the guidance of wise men" ------------------------------------------------------------------------------ Benefiting from Server Virtualization: Beyond Initial Workload Consolidation -- Increasing the use of server virtualization is a top priority.Virtualization can reduce costs, simplify management, and improve application availability and disaster protection. Learn more about boosting the value of server virtualization. http://p.sf.net/sfu/vmware-sfdev2dev _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
