tag:blogger.com,1999:blog-1592992209402300549.post8165064579174160174..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: The Least You Should Know - Stepper Motors pt. 2SiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1592992209402300549.post-32749467764266464202012-06-02T12:23:31.986-04:002012-06-02T12:23:31.986-04:00Yeah, the ability to change speeds and acceleratio...Yeah, the ability to change speeds and accelerations is a strong advantage to steppers. <br /><br />A reciprocating drive is a common need in mechanical design and was solved ages ago: a rotating shaft with a cam to push and pull pistons is an example. With a stepper, command a phase reversal and you reverse; you can do that so fast the momentum change will tear your system apart. Do it with an acceleration ramp and you get reciprocating motion.SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-75431419666842269702012-06-02T07:02:04.177-04:002012-06-02T07:02:04.177-04:00SG - Back in the mid '80s I worked on a chip s...SG - Back in the mid '80s I worked on a chip sorter project that replaced mechanical activation & controls with steppers; we used generic 1.8 motors and Compumotor controllers, which changed the 200 step/rev motors to 5K step/rev. If you used their motors you could get 25K step/rev. One neat result was the ability to control ramp up/ramp down speeds and stepping speed differently on each motor, rather than accept the unchangeable speed factors on an induction motor-driven mechanical drive. That alone, by replacing one slotted cam drive, increased throughput about 20%. One challenge we faced - that you mentioned - and never solved completely, was tracking executed steps. If you sent an 1800 step command to stepper D, did the leadscrew actually complete the result of 1800 steps, or only 1792? We were able to incorporate a single LED between two perforated wheels bracketed by a pair of sensors that had an accuracy of +/- 5 steps, which was about 4 minutes either way, and that worked OK within in our tolerances (more closely tracking the accuracy of one step command/step execution would have been nice, but cumulative error over several step commands was more accurate and told us what we needed to know). <br /><br />Been out of it since early '90s, but looking at CNC developments since then both motors, controllers and sensors have gotten a whole lot better.Bobnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-38769118774100323122012-06-01T22:54:41.041-04:002012-06-01T22:54:41.041-04:00Glad you like, LA, and good to see you again.
You...Glad you like, LA, and good to see you again.<br /><br />You could certainly do it that way, and it's probably a good skill set to have, but the modern chips make it so convenient. Follow the rules of layout and use, and they just plain work. Do all the fancy stuff for you. I was reading a product announcement today at work, for a controller that will microstep in 128th steps, instead of 8th! <br /><br />Just keeps getting better and better.SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-66405527853976406982012-06-01T19:51:04.313-04:002012-06-01T19:51:04.313-04:00These last two posts are great stuff! I've ne...These last two posts are great stuff! I've never taken the time to research steppers (because I haven't yet had the need), but I love learning about new stuff. Last time I did anything with motors was back in design lab courses in college, and that time we had to build our own H-bridges and drive it with the PWM outputs from a microcontroller. I might just be referring back to this one before too long... Thanks!LeverActionhttp://leveraction.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-40334047454025219962012-06-01T17:04:48.390-04:002012-06-01T17:04:48.390-04:00I don't think I remember that. But me not rem...I don't think I remember that. But me not remembering things doesn't mean as much as it used to.SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-49677140588427464732012-06-01T00:47:16.079-04:002012-06-01T00:47:16.079-04:00I seem to recall some steppers w/position feedback...I seem to recall some steppers w/position feedback available, but fell short of servo system performance and cost - or does my memory miss steps?<br /><br />itorAnonymousnoreply@blogger.com