Are there more than one possible solution to the kinematics equations you are using here. I remember years ago when K&T showed a Hexapod at IMTS. Every so often the control would pick the wrong solution and rip the ballscrew out of a nut.
I know that the NIST Hexapod software picked the solution closest to current position. Rayh On Wed, 2007-09-19 at 09:49 -0400, Kenneth Lerman wrote: > 100,000 iterations sounds like way too many. I suggst that you use a > variable number of iterations based on some convergence criterion. > > Also, if you save the answer from the previously calculated forward > kinematics and use that as the initial value of the new calculation you > will be able to save a considerable amount of time. That takes advantage of > the fact that the motion at each iteration is a relatively small distance. > > Ken > > [EMAIL PROTECTED] > Mark Kenny Products Company, LLC > 55 Main Street Voice: (888)ISO-SEVO (888)476-7386 > Newtown, CT 06470 Fax: (203)426-9138 > http://www.MarkKenny.com > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of jros > Sent: Monday, September 17, 2007 12:56 PM > To: Enhanced Machine Controller (EMC) > Subject: [Emc-users] Debugging parallel kinematics: how to printf in > dmesg? > > > Hello!. > > We are implementing a 6 dgf kinematics for a parallel manipulator. > > (see http://imac/parallel/images/argazkiak/img_4336.jpg for a photograph > of the machine without the head) > > We are using as a template genhexkins.c file so that compiling and > launching is not a problem. > > We have provided new implementations for forward and inverse kinematics. > > And we are continuously hanging ./scripts/emc hexapod-sim. Well, the > computers gets frozen, and we have to reset it!!!!!. > > I've compiled the kinematics outside emc providing a main, and it seems > that we have done a correct programing. > > Forwardkinematics requires a newton raphson iteration, much longer to > compute compared with Inverse kinematics. > > A 9 newton raphson iteration calculation requires on a 100000 iteration > average a calculation time of 0.000797 secs > in our computer. > > As emc hangs we've tried to use trivkins to replace the forward and > inverse kins in genhexkins.c and it works ok, it does not hangs. > > As a last try, we have forced our kinematics to output the trivkins > kinematics, but forcing it to internaly deal with all the computations > of our model (we are forcing 9 newton-raphson iterations), in order to > see if it is a "too time consuming subrutine" problem. > > It works, it seems it works slower that with the surplus of > computations. > > But we are eye blinded to to see what is happening in fact within our > subrutine, how many iterations? output values? and input values?. > > Being the kinematics a real time module, I presume that printf debuging > will not work, more if the aplication freezes the computer. > > I presume the only posibility is to use dmesg, but I don't know how to > send output so that I can see what is happening with dmesg > > What can I do?, or where can I read about dealing with this type of real > time subrutine debugging?. > > I think I can try to debug using dmesg approach, using a working > kinematics -so the computer does not get freezed- (as the trivkins > approach mentioned before) to see what are the subrutines called and the > values of the variables passed to them, and hopefully discover what is > going on. > > Thanks in advance > > Javier Ros & Aitor Plaza > > > > > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2005. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2005. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
