the discreet spline teeth are also an approximation. in fact, anything made out of atoms is flexible and grainy. why not construct mechanisms from massless rigid rods and such?
--- On Mon, 5/14/12, Viesturs Lācis <viesturs.la...@gmail.com> wrote: > From: Viesturs Lācis <viesturs.la...@gmail.com> > Subject: Re: [Emc-users] Some advice needed > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Date: Monday, May 14, 2012, 11:29 PM > 2012/5/14 charles green <xxzzb...@yahoo.com>: > > well, there's your spline form right there in the > video. screen capture. the eliptical bearing is nice, > but you can get away with a diametrically opposed pair of > rollers for that function. > > > > No, diametrically opposed rollers is bad idea. Rollers > determine only > the large diameter of elipse and makes some teeth of > flexible gear to > engage the stiff gear. The remaining profile of elipse is > not > determined - it is free to flex as it wants under external > load, so > the stiffness of the reducer is considerably lower. > Flexible bearing determines the shape of elipse thus > flexible gear > cannot take different shape under external load, so the > reducer is > much stiffer. > > For robotic arms the stiffness is crucial. > > Another problem with diametrically opposed rollers is that > they > require relatively low input speed, because of the same > reason that > they do not maintain overall shape of the elipse and at > higher input > speeds the flexible gear is not elipse any more, but > something else, > thus it hurts not only precision, but also the service life > of the > wave reducer. > > If I cannot get the flexible bearings, then there is option > of > eccentric discs as a wave generator. > > Viesturs > > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's > security and > threat landscape has changed and how IT managers can > respond. Discussions > will include endpoint security, mobile security and the > latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
