One very nice point of encoder connected to a stepper motor (the encoder has much high resolution than the motor) is that you can guess the load and load change in the difference between the actual and commanded position. Of course this will be different for different speeds already and will wildly change with acceleration and deceleration. For acceleration there is a rule that it has to rise or fall LINEARLY up to the maximum point useful for a movement. This was the tension rise will be fueln, positively affecting machining accuracy. In other words: the derivation of the of the acceleration should be linear, the derivation of derivation of acceleration should be a constant. (derivation of a constant is zero.) The tricky part is how to make the proper assumptions from a given set of variables.
On Dec 19, 2007 9:45 PM, Jeff Epler <[EMAIL PROTECTED]> wrote: > In emc2, you would make the HAL driver for your hardware step generator > work similar to the 'stepgen' component. It would probably include at > least include the following inputs and outputs: > .enable > .position-cmd OR .frequency-cmd > .position-fb > .counts > and the following parameters: > .maxvel > .maxaccel > .position-scale > .steplen > .stepspace > .dirsetup > .dirhold > and one or two functions: > .capture-position > .update-freq > (or combine both into a single HAL function) > > the meaning of each of these items in the software step generation > component is explained in 'man stepgen' or at > http://linuxcnc.org/docs/2.2/html/man/man9/stepgen.9.html > or > http://linuxcnc.org/docs/2.2/html/hal_rtcomps.html#sec:Stepgen > > then in a typical configuration, the .hal files create signals to link > e.g., > axis.0.enable => yourhardwarestepgen.0.enable > axis.0.position-cmd => yourhardwarestepgen.0.position-cmd > axis.0.potition-fb -> yourhardwarestepgen.0.position-fb > (but of course other position or velocity command sources can be used > instead, according to the needs of the integrator) > > The existing ppmc driver (which is nice and stable) and pluto_step > driver (which is buggy) are existing examples of HAL interfaces to step > generator hardware. > > Jeff > > > ------------------------------------------------------------------------- > SF.Net email is sponsored by: > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services > for just about anything Open Source. > http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > ------------------------------------------------------------------------- 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-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
