knt@cbnews.ATT.COM (kirk.n.trost) (06/05/89)
Does anyone know the basics for stepper motor operation. I've got
a stepper motor with the following data sheet:
----------- SW1 -------
| |
--------- |
| |--- SW2 -------|
-----| motor | |------O +5v
| | |--- SW3 -------|
| --------- |
__|__ | |
___ ----------- SW4 -------
_
Four-Step Input Sequence
------------------------
Step SW1 SW2 SW3 SW4
---- --- --- --- ---
1 on off on off
2 on off off on
3 off on off on
4 off on on off
1 on off on off
What is the meaning of this 'four-step input sequence'?
The data sheet also has an 'eight-step input sequence'.
Is there an easy way to get the motor to step using a single
TTL pulse? Why all the different wires?
Thanks,
Kirk ...psfales@cbnewsc.ATT.COM (Peter Fales) (06/06/89)
In article <7137@cbnews.ATT.COM>, knt@cbnews.ATT.COM (kirk.n.trost) writes: > > Does anyone know the basics for stepper motor operation. I've got > a stepper motor with the following data sheet: > > I am far from an expert in this area, but I know driving steppers is much more complex than applying a single TTL pulse. Steve Ciarcia's "Circuit Cellar Ink" magazine a few months back had a whole article targeted toward hobbyists with surplus steppers describing the various types and how to make them work. -- Peter Fales AT&T, Room 5B-420 2000 N. Naperville Rd. UUCP: ...att!ihlpb!psfales Naperville, IL 60566 Domain: psfales@ihlpb.att.com work: (312) 979-8031
irwin@m.cs.uiuc.edu (06/06/89)
/* Written 7:53 am Jun 5, 1989 by knt@cbnews.ATT.COM in m.cs.uiuc.edu:sci.electronics */
/* ---------- "Stepper Motor" ---------- */
Does anyone know the basics for stepper motor operation. I've got
a stepper motor with the following data sheet:
----------- SW1 -------
| |
--------- |
| |--- SW2 -------|
-----| motor | |------O +5v
| | |--- SW3 -------|
| --------- |
__|__ | |
___ ----------- SW4 -------
_
Four-Step Input Sequence
------------------------
Step SW1 SW2 SW3 SW4
---- --- --- --- ---
1 on off on off
2 on off off on
3 off on off on
4 off on on off
1 on off on off
What is the meaning of this 'four-step input sequence'?
The data sheet also has an 'eight-step input sequence'.
Is there an easy way to get the motor to step using a single
TTL pulse? Why all the different wires?
Thanks,
Kirk ...
/* End of text from m.cs.uiuc.edu:sci.electronics */
A stepping motor, as its name implies, advances a given number of
degrees of rotation and will stop there until the next step is
requested. The numerious wires activate given poles within the
motor, to move it from one position to the next. What is lacking
here is a count decoder and step encoder, with motor drivers at
the output.
Some motors will require possibly 24 volts, and driver transistors
at the output of the "stepping motor drive logic". You indicate
yours runs on 5 volts, so drivers would not be subject to quite
as high voltage spikes.
A "motor controller" is needed, to convert the 5 volt logic pulse
that you referred to, to a "step control sequence". The control
logic would decode the logic input pulses into a count and set up
the wires of the motor to be energized for a 4 step full rotation,
or a 8 step rotation, as desired. The sequence given that you
mentioned, tells you what is required to achieve that number of
steps.
To use this, you will have to find, or design and build, a controller
for it.dmt@PacBell.COM (Dave Turner) (06/07/89)
In article <7137@cbnews.ATT.COM> knt@cbnews.ATT.COM (kirk.n.trost) writes: >Does anyone know the basics for stepper motor operation. I've got >a stepper motor with the following data sheet: Sky & Telescope magazine has printed several articles about stepper motors. The first one told how to identify and use surplus motors; the others have circuits that have been used to drive telescopes. Back issues are available for $3.00 if you can't find them in a library. Jul, 1986 p. 82 Jan, 1988 p. 80 correction: Apr, 1988 p. 418 Jul, 1988 p. 92 May, 1989 p. 89 Howard Sams publishes a book on robotics that describes stepper motors: Basic Robotics Concepts John M. Holland Sams 21952 -- Dave Turner 415/542-1299 {att,bellcore,sun,ames,decwrl}!pacbell!dmt
byron@pyr.gatech.EDU (Byron A Jeff) (06/07/89)
In article <21000026@m.cs.uiuc.edu> irwin@m.cs.uiuc.edu writes: - -/* Written 7:53 am Jun 5, 1989 by knt@cbnews.ATT.COM in m.cs.uiuc.edu:sci.electronics */ -/* ---------- "Stepper Motor" ---------- */ - -Does anyone know the basics for stepper motor operation. I've got -a stepper motor with the following data sheet: -[deleted for brevity - BAJ] - - Four-Step Input Sequence - ------------------------ - - Step SW1 SW2 SW3 SW4 - ---- --- --- --- --- - - 1 on off on off - 2 on off off on - 3 off on off on - 4 off on on off - 1 on off on off - - -What is the meaning of this 'four-step input sequence'? -The data sheet also has an 'eight-step input sequence'. -Is there an easy way to get the motor to step using a single -TTL pulse? Why all the different wires? - - -Thanks, - - -Kirk ... -/* End of text from m.cs.uiuc.edu:sci.electronics */ - -A stepping motor, as its name implies, advances a given number of -degrees of rotation and will stop there until the next step is -requested. The numerious wires activate given poles within the -motor, to move it from one position to the next. What is lacking -here is a count decoder and step encoder, with motor drivers at -the output. - - -A "motor controller" is needed, to convert the 5 volt logic pulse -that you referred to, to a "step control sequence". The control -logic would decode the logic input pulses into a count and set up -the wires of the motor to be energized for a 4 step full rotation, -or a 8 step rotation, as desired. The sequence given that you -mentioned, tells you what is required to achieve that number of -steps. - -To use this, you will have to find, or design and build, a controller -for it. If you have access to an eprom programmer a really quick solution comes to mind. Program the eprom with the step sequence and use a counter to pick the step. By using a up-down counter it's possible to get the motor to rotate in both directions (by presenting the sequence backward). So something like this: |---------|--------|---------|-------|---------|------|-------| | |--------| |-------| |------| | Step Pulse---| Counter |--------| EPROM |-------| Drivers |------| Motor | | |--------| |-------| |------| | |---------| |---------| |---------| |-------| Would be a sufficient driver to make it go. Does anyone know about drivers for these motors? BAJ -- Another random extraction from the mental bit stream of... Byron A. Jeff Georgia Tech, Atlanta GA 30332 Internet: byron@pyr.gatech.edu uucp: ...!gatech!pyr!byron
jack@csccat.UUCP (Jack Hudler) (06/08/89)
In article <8462@pyr.gatech.EDU> byron@pyr.UUCP (Byron A Jeff) writes: > >If you have access to an eprom programmer a really quick solution >comes to mind. Program the eprom with the step sequence and use >a counter to pick the step. By using a up-down counter it's possible >to get the motor to rotate in both directions (by presenting the sequence >backward). So something like this: > > > > |---------|--------|---------|-------|---------|------|-------| > | |--------| |-------| |------| | >Step Pulse---| Counter |--------| EPROM |-------| Drivers |------| Motor | > | |--------| |-------| |------| | > |---------| |---------| |---------| |-------| > >Would be a sufficient driver to make it go. ^^^^^ | Insert an 8-bit AC and some PWM curcuitry and you would have a microstepper. Although in it's most basic since. Now someone is going to ask what micro-stepping is... -- Classic Quotes from STNG: "Pen Pals" Picard: Her society is aware .. that there is intersteller life? Data: No Sir. Picard: Oooops..
irwin@m.cs.uiuc.edu (06/08/89)
/* Written 10:11 am Jun 7, 1989 by byron@pyr.gatech.EDU in m.cs.uiuc.edu:sci.electronics */ >If you have access to an eprom programmer a really quick solution >comes to mind. Program the eprom with the step sequence and use >a counter to pick the step. By using a up-down counter it's possible >to get the motor to rotate in both directions (by presenting the sequence >backward). So something like this: |---------|--------|---------|-------|---------|------|-------| | |--------| |-------| |------| | >Step Pulse--| Counter |--------| EPROM |-------| Drivers |------| Motor | Fwd/Bkwd-----| |--------| |-------| |------| | ^ |---------| |---------| |---------| |-------| | | -------Add this for forward/reverse, logic looks good. >Would be a sufficient driver to make it go. >Does anyone know about drivers for these motors? If the current required is known, and the voltage, I would think that power transistors in the T-036 case style could be found to drive it. A fudge factor could be added to the total wattage so that the transistor selected was not working at 100% of its power rating. Clamp diodes would be required across the driver transistors so that "punch through" did not kill the drivers as the transistor turned off and a reverse voltage spike got generated by the collapse of the field. >BAJ -- >Another random extraction from the mental bit stream of... >Byron A. Jeff >Georgia Tech, Atlanta GA 30332 >Internet: byron@pyr.gatech.edu uucp: ...!gatech!pyr!byron /* End of text from m.cs.uiuc.edu:sci.electronics */ Al Irwin Univ of Illinois Dept of Comp Sci irwin@m.cs.uiuc.edu
jbm@eos.UUCP (Jeffrey Mulligan) (06/10/89)
From article <21000031@m.cs.uiuc.edu>, by irwin@m.cs.uiuc.edu: > If the current required is known, and the voltage, I would think that > power transistors in the T-036 case style could be found to drive it. > A fudge factor could be added to the total wattage so that the transistor > selected was not working at 100% of its power rating. Clamp diodes would > be required across the driver transistors so that "punch through" did > not kill the drivers as the transistor turned off and a reverse voltage > spike got generated by the collapse of the field. I have worked with a number of stepper drivers including commercial ones, and one common feature is the presence of large wire wound hi power resistors, presumably to prevent the drive transistor from taking the voltage drop. I don't remember the package designations, but the (old) commercial units used those flat round metal packages about the size of a quarter with two little ears for mounting, while some replacement units designed and constructed by our department technician used drive transistors in smaller rectangular plastic packages (like 8 x 10 mm) with a metal tab for heat sinking (which was not necessary). -- Jeff Mulligan (jbm@aurora.arc.nasa.gov) NASA/Ames Research Ctr., Mail Stop 239-3, Moffet Field CA, 94035 (415) 694-6290
hobbit@topaz.rutgers.edu (*Hobbit*) (06/12/89)
The easiest stepper to deal with is one with coil center taps, aka "4-phase".
+V
o
|
_________ ---__-------__--------
( |
( |
+---*
( |
(_________ -----__-------__------
|
_________ -------__-------__----
( |
( |
+---'
(
(_________ ---------__-------__--
_H*mmm@cup.portal.com (Mark Robert Thorson) (06/18/89)
You can get a really good book on designing stepper motor drive circuits for free from Warner Electric. I lost my copy, so I don't have their address or phone. (Perhaps someone on the net could provide it?) BTW, today I got a newsletter from a maker of drive units (Anthem Automation, I believe) which had an interesting tidbit of information. It says that most modern high-torque step motors are rated for case temperatures of 100 degrees C. Mighty toasty, eh? They also note that steppers generate excess heat even when the shaft is not moving (i.e. when they are exerting holding torque). BTW.2, a friend of mine who is a machinist doesn't know how steppers and servos work, but he sure knows which ones he likes. He says steppers are crap. Eventually they go bad, while servos last forever. His exposure to motion control systems comes from CNC (computerized numerical control) systems used to run machine tools. I suppose the mechanism of failure is the gradual de-magnetization of the magnets in the step motors. BTW.3, there are two main types of step motors: permanent magnet steppers, which have numerous small magnets embedded in the periphery of the rotor, and variable reluctance step motors, which have an iron core with notches cut in it. Only PM step motors are subject to demagnetization, but they are smaller and more efficient than the VR type. Most vendors only offer PM steppers, but Warner Electric specializes in the VR type. BTW.4, an engineer at Allen-Bradley developed an interesting new use for PM step motors. He uses them as the transducers in control knobs on a console. When someone twists a knob, the passage of the magnets over the coils creates small magnetic pulses which can be amplified and converted into digital signals. Advantages of this technique include the ability to set knobs to desired locations (by driving the motor as a motor) and a slight detent action when the knob is turned by hand.
larry@kitty.UUCP (Larry Lippman) (06/18/89)
In article <19588@cup.portal.com>, mmm@cup.portal.com (Mark Robert Thorson) writes: > It says that > most modern high-torque step motors are rated for case temperatures of > 100 degrees C. Mighty toasty, eh? Many of the newer high-torque stepping motors and servo motors are rated for even higher temperatures. I have used DC servo motors made by Vernitron that are rated at 180 degrees C maximum winding temperature. That is indeed toasty, and is also the reason why these motors all have teflon wire leads (so do many stepper motors). Also, there are heat sinks available which surround stepping motors to dissipate this heat. > They also note that steppers generate > excess heat even when the shaft is not moving (i.e. when they are exerting > holding torque). Everything has a price. An electromagnetic brake used with a DC servo motor will dissipate about the same amount of heat. While a stepping motor keeps the heat in one place, it generally simplifies a mechanical design since no external brake is required. While it is comparatively easy to implement dynamic braking of DC servo motors while they are in motion, it is rather difficult to implement an effective static brake without resulting in undesireable hunt and chatter conditions. > BTW.2, a friend of mine who is a machinist doesn't know how steppers and > servos work, but he sure knows which ones he likes. He says steppers are > crap. Eventually they go bad, while servos last forever. His exposure > to motion control systems comes from CNC (computerized numerical control) > systems used to run machine tools. I suspect your friend has not seen a large enough cross-section of CNC equipment. At worst, stepper motor versus DC servo drive motor systems will show equal reliability; at best, stepper motors will show significantly greater reliability. Why? Because stepper motor systems are fundamentally simpler and have vastly reduced analog circuitry requirements. A stepper motor design will typically just contain the stepper motor, plus a simple one-point optical encoder for position reference. The position and direction of the stepper motor becomes a purely digital function, along with speed, which is a simple function of step rate. Not so simple with a DC servo motor, which in exacting applications not only requires a tachometer for speed control feedback, but requires a resolver or optical shaft encoder for accurate position sensing and to provide a step increment function. While it is possible to obtain the speed feedback from the position encoder, it is usually simpler to keep the motor control circuit analog by using a voltage obtained from a tachometer. > I suppose the mechanism of failure is > the gradual de-magnetization of the magnets in the step motors. This problem is no less prevalent than in DC servo motors with permanent magnet field. > BTW.4, an engineer at Allen-Bradley developed an interesting new use for > PM step motors. He uses them as transducers in control knobs on a console. > When someone twists a knob, the passage of the magnets over the coils creates > small magnetic pulses which can be amplified and converted into digital > signals. Advantages of this technique include the ability to set knobs > to desired locations (by driving the motor as a motor) and a slight detent > action when the knob is turned by hand. This technique has been used since before World War II in fire control systems. Instead of a stepping motor, however, the control knob is attached to a "control transformer", which is a servo component that is AC-operated, and which contains a 3-phase three-winding stator, and a single-winding rotor. A variation of this device is a "differential control transformer", which also has a 3-phase three-winding rotor. Control transformers (a _very_ misleading term for anyone without servo exeperience!) can be used as both position sensors and motors in the same application. Control transformers are similar to "synchros" and "selsyns", but are generally designed for lesser torque applications. Control transformers are still used in current fire control systems, and many solid-state support circuits are available from the various analog "building block" manufacturers. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
jad@dayton.UUCP (J. Deters) (06/20/89)
In article <3242@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: >In article <19588@cup.portal.com>, mmm@cup.portal.com (Mark Robert Thorson) writes: >> BTW.2, a friend of mine who is a machinist doesn't know how steppers and >> servos work, but he sure knows which ones he likes. He says steppers are >> crap. Eventually they go bad, while servos last forever. His exposure >> to motion control systems comes from CNC (computerized numerical control) >> systems used to run machine tools. [ net.bandwidth saved by deleting much of argument, thereby pleasing the net.cabal* ] >> I suppose the mechanism of failure is >> the gradual de-magnetization of the magnets in the step motors. The typical failure mode is bearing failure. Most servo motors are used in spindle applications whereas most stepper motors are used as axis positioners. The servo motors are typically running at higher speeds, then, and the steppers are swinging back and forth. The frequent start-and-stop of an axis-controller plays hell with the bearings, whereas the (relatively) constant and smooth speed of a spindle is the least damaging to the bearings. Actually, the most frequent failure I saw on our CNC gear was seal leakage. Most coolants used in the newer CNC equipment are water-based. When the seals fail, _BZZZT_. (This happened mostly to the turrets.) -john * there is no secret cabal. -- "Captain's log: Stardate 2734.3. 'I am nailed to the hull.'"
mmm@cup.portal.com (Mark Robert Thorson) (06/22/89)
I found that great stepper motor applications book I got for free! It's title is WARNER ELECTRIC'S GUIDE TO SELECTING AND CONTROLLING STEP MOTORS. There's a price of $5 listed on the inside cover, but I got it merely for the asking. The place to ask is: Warner Electric Beliot, WI 53511 (815) 389-3771 This book describes all types of step motors (even though Warner only seems to make the VR type). It also describes how to design the drive circuits, both the analog and the digital parts. It only lacks a discussion of micro- stepping. If you want to learn how to design with step motors, GET THIS BOOK!!
wiz@xroads.UUCP (Mike Carter) (06/27/89)
I was about to write about the guy who mentioned that an engineer "Discovered" a "NEW" way to make use of stepper motors....and tell the net about how the Fire Control System worked on the nuclear sub. The first thing that enetered my mind was that these so called engineers have absolutely no idea how old these "NEW" ideas of theirs really are until the dampness behind their ears starts to dry. The Mark 113, Mod 9 Fire Control System was a maze of resolvers, servos, selsyns and error voltage wires...not to mention travelling nut mechanical rods, pulleys, screws, twisters and 3-ton fish. But Larry beat me to it. ;-) -- ============================================================================= = Mike Carter N7GYX, Phoenix AZ| Q: Why did the Chicken cross the road ? = = hplabs!hp-sdd!crash!xroads!wiz| A: To ESCape the Main Menu . = =============================================================================
larry@kitty.UUCP (Larry Lippman) (06/28/89)
In article <736@xroads.UUCP>, wiz@xroads.UUCP (Mike Carter) writes: > I was about to write about the guy who mentioned that an engineer > "Discovered" a "NEW" way to make use of stepper motors....and tell the net > about how the Fire Control System worked on the nuclear sub. > The first thing that enetered my mind was that these so called engineers have > absolutely no idea how old these "NEW" ideas of theirs really are until > the dampness behind their ears starts to dry. > The Mark 113, Mod 9 Fire Control System was a maze of resolvers, servos, > selsyns and error voltage wires...not to mention travelling nut mechanical > rods, pulleys, screws, twisters and 3-ton fish. > > But Larry beat me to it. I have personally utilized and "rediscovered" old technology on several occasions. Many readers on the Net would be truly amazed at the non-digital logic (for lack of a better term) "computing" technology which existed during the 1940's and 1950's. For those of you who may be interested, I highly recommend spending a few hours in the library some day just casually perusing the 27-volume "Rad Lab" series, more properly known as the "Massachusetts Institute of Technology Radiation Laboratory Series". These volumes were published during 1947 and 1948, and summarize an amazing amount of the radar and fire control system work performed during World War II. My organization has a full set of these volumes in our library, and Net readers would be amazed how many times I have found useful information for current projects. As an example, we have recently been developing a specialized analytical method and test instrument which utilizes phosphorescence as part of its operating principle. Volume 22 of the Rad Lab series, which is entitled "Cathode Ray Tube Displays" provided some highly useful information on CRT phosphor formulations and characteristics which I could not find elsewhere. A volume of particular interest is entitled "Computing Linkages and Servomechanisms", and covers many aspects of fire control system operation, including the control transformers which I mentioned in a previous article. An example of an interesting technique used in these fire control systems is the use of a "ball and disk" as a means of integrating. While I admit that this technique probably has no application in our microprocessor age, this volume can nevertheless facilitate the birth of new ideas and applications for "old" technology. Also, at one time (and they may still be available), Dover Books reprinted several of the Rad Lab volumes in softcover. <> Larry Lippman @ Recognition Research Corp. - Uniquex Corp. - Viatran Corp. <> UUCP {allegra|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> TEL 716/688-1231 | 716/773-1700 {hplabs|utzoo|uunet}!/ \uniquex!larry <> FAX 716/741-9635 | 716/773-2488 "Have you hugged your cat today?"
knudsen@ihlpl.ATT.COM (Knudsen) (07/06/89)
Ball and disk integrators are beautiful and the SMithsonian has a gorgeous Henrici Harmonic ANalyzer (19th centruy FFT box) on display with several of them working in parallel. But you probably have a B&D integrator on your desktop right now. The second most valuable "mouse" to come out of California. Open it up; you'll see two disks bearing on the ball, driving opto-encoders most likely. Same good old principle. [BTW, California's 1st most valuable mouse was created by Walt D.]. -- Mike Knudsen Bell Labs(AT&T) att!ihlpl!knudsen knudsen@ihlpl.att.com Round and round the while() loop goes; "Whether it stops," Turing says, "no one knows!" Shotguns -- just say PULL!
sukenick@ccnysci.UUCP (SYG) (07/22/89)
In article <8462@pyr.gatech.EDU> byron@pyr.UUCP (Byron A Jeff) writes: >-a stepper motor with the following data sheet: >- Four-Step Input Sequence [1 = on, 0= off step# c1 c2 c3 c4 >-step 1 1 0 1 0 >- 2 1 0 0 1 >- 3 0 1 0 1 >- 4 0 1 1 0 >- 1 1 0 1 0 ] >If you have access to an eprom programmer a really quick solution >Step Pulse---| Counter |--------| EPROM |-------| Drivers |------| Motor | My solution: Step Pulse---| data flip flop |-------| Drivers |------| Motor | (-: Ah, kids nowadays. `just grab an EPROM and program'. Back in my day, if we needed sdfgsatubesrewf we purified the silcon dgdgdwalked 10miles in snow Ok serious: The above looks like a problem in logic: how do you connect a bunch of flip flops to get the above output? Answer: use 4 data flip flops (74xx174 is a quad in one package with common clock) call each c1,c2,c3,c4 to correspond to the above table. Use Q outputs of c2 and c4; Q bar of c1 and c3. Now, at startup, you have step#1, 1010. Now, if you notice that the columns form the same pattern, but shifted from one another. ie: c1 is c3 shifted down one; c2 is c4 shifted once; etc. Final connection: data input connected to output of c1 Q c3 c2 Qbar c4 c3 Q c2 c4 Qbar c1 This will give the required output, without resorting to eproms. (Of course the advantage of EPROM is that if you get another motor with different specs, all you do is pop out the old chip. This method saves a chip, though.) To reverse direction, a 4pole DT switch may be used. Instead of feeding back Q Qbar Q Qbar, you feed back the opposite: Qbar C3 to c1 in; Q c3 to c2 in, etc. If it is desired to control up/down via computer, etc. then a quad 2->1 data selector is required and you lost the lower part count advantage. -george ccnysci!sukenick
pcf@galadriel.bt.co.uk (Pete French) (08/03/89)
From article <2293@ccnysci.UUCP>, by sukenick@ccnysci.UUCP (SYG): >>If you have access to an eprom programmer a really quick solution > >>Step Pulse---| Counter |--------| EPROM |-------| Drivers |------| Motor | > > My solution: > Step Pulse---| data flip flop |-------| Drivers |------| Motor | > Or even better... A0-3 D0-3 +--->| Eprom |>---+--------->| Drivers |>------->| Motor | | | | | | | +-<| Flip Flop |<-+ ^ | Step pulse ---------+ The advantage is that you can use spare lines on the EPROM to control such things as direction/full,half stepping. I built such a device that drove 2 3-pole steppers in full or half step mode in either directon totally independantly of one another. It also only uses 2 IC's and you dont have to wire up counters. -Pete French.