2015-03-26 13:55 GMT-03:00 Jon Elson <el...@pico-systems.com>: > No, I don't think we are talking exactly about the same > thing. Common velocity servo amplifiers have an analog > velocity error amp, which takes in a velocity command from > the CNC control and a measured velocity, usually from a DC > tachometer mounted on (or IN) the motor. If there is not > tachometer, then some controls, especially Fanuc, synthesize > the tach signal using a chip such as the ST Micro L290 > (sadly, no longer available). A few people who have big > servo amplifiers like this have made LinuxCNC do the same as > the Fanuc control, and it works. Assuming a 1 KHz servo > cycle, there is inevitably a 1 ms delay in providing the > synthetic velocity output, but it seems to work fine. > Probably these old velocity amps from the 1970s don't have a > very high bandwidth, so it is OK. >
I see. I think this is how the servo drives are working on our Mazak. They are Meldas TRA-31A and TRA-41A if I remember correctly. They are taking the velocity from the motors using tachos and the only thing they do is to close the velocity loop. Then the CNC closes the position loop with the resolvers mounted on the screws. After we finish this machine the idea is to put hands on the Mazak to upgrade the CNC to LinuxCNC because we need to improve it's capabilities and also, everytime something on that lathe fails we're praying for the solution to be easy. In case of a CPU fail that's going to be almost impossible to solve taking the easy way, so LinuxCNC it's a much more logical solution. -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
