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From: andy pugh <bodgesoc@gm...>  20130815 11:56:06

I seem to recall discussion of using the kinematics module to perform a discrete differentiation to determine the trajectory speed. (which would allow velocity limits to be respected in nontrivial multiaxis kins). Is this implemented anywhere?  atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto 
From: Jeff Epler <jepler@un...>  20130819 16:08:55

On Thu, Aug 15, 2013 at 12:55:38PM +0100, andy pugh wrote: > I seem to recall discussion of using the kinematics module to perform > a discrete differentiation to determine the trajectory speed. (which > would allow velocity limits to be respected in nontrivial multiaxis > kins). Is this implemented anywhere? I think this is the Inverse Jacobian, and is implemented in genhexkins but unused by linuxcnc. http://en.wikipedia.org/wiki/Jacobian_matrix_and_determinant The Jacobian at a point is not itself enough to figure out how to apply joint velocity constraints, because those constraints vary all along the course of the move. A single move, even a linear one, can take the machine from a place where joint J0 would require a velocity limit, into a region where the Fnumber gives the velocity limit, and then into a region where joint J1 gives the tighest velocity constraint (crossing the center of the work volume of a delta, for instance). However, computing the jacobian at many points along a planned move may be one ingredient of applying joint velocity constraints to trajectory planning. Jeff 
From: andy pugh <bodgesoc@gm...>  20130819 16:24:29

On 19 August 2013 16:52, Jeff Epler <jepler@...> wrote: > The Jacobian at a point is not itself enough to figure out how to apply > joint velocity constraints, because those constraints vary all along the > course of the move. A single move, even a linear one, can take the > machine from a place where joint J0 would require a velocity limit, into > a region where the Fnumber gives the velocity limit, and then into a > region where joint J1 gives the tighest velocity constraint This seems to imply that for a linear move the kins transformation is only applied at the end points, and that was not my understanding. Or is the assumption that the velocity limitation has to be on a movebymove basis not a pointbypoint basis? Does adaptivefeed take effect midmove?  atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto 
From: Michael Haberler <mail17@ma...>  20130819 16:27:19

see this project https://trac.lcsr.jhu.edu/cisst , it might be a cheat sheet in particular references here: https://trac.lcsr.jhu.edu/cisst/wiki/cisstRobotTutorial m Am 19.08.2013 um 18:23 schrieb andy pugh <bodgesoc@...>: > On 19 August 2013 16:52, Jeff Epler <jepler@...> wrote: > >> The Jacobian at a point is not itself enough to figure out how to apply >> joint velocity constraints, because those constraints vary all along the >> course of the move. A single move, even a linear one, can take the >> machine from a place where joint J0 would require a velocity limit, into >> a region where the Fnumber gives the velocity limit, and then into a >> region where joint J1 gives the tighest velocity constraint > > This seems to imply that for a linear move the kins transformation is > only applied at the end points, and that was not my understanding. > > Or is the assumption that the velocity limitation has to be on a > movebymove basis not a pointbypoint basis? > > Does adaptivefeed take effect midmove? > >  > atp > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > >  > Introducing Performance Central, a new site from SourceForge and > AppDynamics. Performance Central is your source for news, insights, > analysis and resources for efficient Application Performance Management. > Visit us today! > http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk > _______________________________________________ > Emcdevelopers mailing list > Emcdevelopers@... > https://lists.sourceforge.net/lists/listinfo/emcdevelopers 
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