Anders Wallin wrote: > Brushless is not much more expensive so you could look at those too. > I don't know much about servos at all, but I was under the impression that brushless servos had less angular position accuracy then brushed dc servos? It looked like the brushless dc motors had more power for the same size package and were a little cheaper, but I'm not sure what the tradeoffs are. > >> The next part is where I am confused. I was looking at the Gecko Drive >> G320X. Is it correct in thinking this would be used just like a stepper >> driver with the step, dir inputs and emc would know nothing about the >> encoder positions on the servos? >> > > If you have fast encoder inputs to emc (mesa or similar card), you > could wire the encoder signals to emc also. The gecko-drive would > still close the loop, but emc would be aware of the position (or > position error) of the machine. > This is the way most professional big machines do it (I think). The > drive is closely matched/tuned to the motor and closes the loop. The > motioncontroller just outputs step/dir signals and just to make sure > also reads the encoder signals. > > >> Instead of the G320X, if i got a mesa FPGA card, could I use any generic >> h-bridge with the mesa card to control the servo and have the servo >> encoders read by the mesa fpga card? >> > > This is the cool thing about emc, it can close loops in real-time. On > my mill I used a mesa card with pico-systems pwm-input amplifiers for > brushed motors. Now I'm converting a lathe and the plan is to use a > mesa card+ pwm-input brushless amps. > This is roughly how my mill setup looks like: > http://www.anderswallin.net/wp-content/uploads/2008/09/dc_servo_schematic_2008jan19.pdf > Nice diagram! Did you use a special program to draw that or just a paint program?
Since you have a mesa card, maybe you or anyone else that has a mesa card can explain how the servo PID works with the mesa in EMC. Does EMC do the PID calculations and just send a command to the mesa board or does the mesa board do the PID calculations and just tell EMC where the servo currently is? I guess another way to rephrase that is, is the mesa board closing the loop or does it need EMC to close the loop? Thanks! FlyingElectron > > Anders > > ------------------------------------------------------------------------------ > This SF.Net email is sponsored by the Verizon Developer Community > Take advantage of Verizon's best-in-class app development support > A streamlined, 14 day to market process makes app distribution fast and easy > Join now and get one step closer to millions of Verizon customers > http://p.sf.net/sfu/verizon-dev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
