Guy Macon wrote:> Tim Wescott wrote: > > >>Guy Macon wrote: >> >> >>> "Why do some controller boards have an option to reverse the >>> phase of the D? What is that good for?" >> >>OK, I'll bite -- what _is_ it good for? I've never done closed-loop >>control with prepackaged controllers and I've never seen that done >>elsewhere. I can certainly see reversing the phase of the whole thing, >>or reversing the phase of the D term if it's coming from some other >>feedback source (which would imply a second input) but I _can't_ see the >>point in intentionally establishing an unstable zero in your controlsystem.> > > My experience is more hands-on than theory, but here is the answer > I gave my classes: > > In N years of setting up servos, I have never once found a use for > it, nor have I found any literature that explains when it might be > of some use. I think that somewhere back in the early days someone > was told to put in a jumper that reverses the phase of the entire > servo (quite handy when someone miswired a section that is really > hard to get to), got it wrong, and some other manufacturers have > been copying the "feature" ever since. > > If one of the theory boys has a better answer, I am all ears.Shortly after VJ day, Japanese military electronic software began turning up in the surplus stores on Cortland Street (razed to make way for the World Trade Center). I bought a small panel meter, probably out of an airplane cockpit, that had Japanese markings molded into the inside of the case. The design itself had been blindly copied. Prominent in the inside center of the back cover were the letters, "Simpson". Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Shameless Plug
Started by ●November 29, 2004
Reply by ●November 30, 20042004-11-30
Reply by ●November 30, 20042004-11-30
"Jim Thompson" <thegreatone@example.com> wrote in message news:abepq0tt82o05fqiiikdq60v0bl3mvlpce@4ax.com...> On Tue, 30 Nov 2004 13:07:37 -0500, Jerry Avins <jya@ieee.org> wrote: > > [snip] > > > >It's simple: the level of literacy, even among "college boys", is > >appallingly low. Consider how many write "there" when they mean "their" > >or "they're". > > > [snip] > >Jerry > > Engineers, as a class, are notoriously bad spellers/grammarians. > > ...Jim ThompsonHardwired!
Reply by ●November 30, 20042004-11-30
Guy Macon wrote...> > I tend to agree, but the "wrong way" hinders communication if it is > *too* different from the "right way." If one decides to use a few > non-standard fleemishes and the reader can still gloork the meaning > from the context, but there ix a limit; If too many ot the vleeps > are changed, it becomes harder and qixer to fllf what the wethcz > is blorping, and evenually izs is bkb longer possible to ghilred > frok at wifx. Dnighth? Ngfipht yk ur! Uvq the hhvd or hnnngh. > Blorgk? Blorgk! Blorgkity-blorgk!!!!ROFLOL, LOL-LMAOXD, ROXCGHRKFITR! YUREBDH! -- Thanks, - Win
Reply by ●November 30, 20042004-11-30
Guy Macon <http://www.guymacon.com> wrote in news:10qpg6de3pksn56@corp.supernews.com:> > Tim Wescott wrote: > >>Guy Macon wrote: >> >>> "Why do some controller boards have an option to reverse the >>> phase of the D? What is that good for?" >> >>OK, I'll bite -- what _is_ it good for? I've never done closed-loop >>control with prepackaged controllers and I've never seen that done >>elsewhere. I can certainly see reversing the phase of the whole >>thing, or reversing the phase of the D term if it's coming from some >>other feedback source (which would imply a second input) but I _can't_ >>see the point in intentionally establishing an unstable zero in your >>control system. > > My experience is more hands-on than theory, but here is the answer > I gave my classes: > > In N years of setting up servos, I have never once found a use for > it, nor have I found any literature that explains when it might be > of some use. I think that somewhere back in the early days someone > was told to put in a jumper that reverses the phase of the entire > servo (quite handy when someone miswired a section that is really > hard to get to), got it wrong, and some other manufacturers have > been copying the "feature" ever since. > > If one of the theory boys has a better answer, I am all ears. >Could it just be because tachs have no polarization standard? If your system runs away, flick the switch! Scott
Reply by ●November 30, 20042004-11-30
Jerry Avins wrote:> Guy Macon wrote: > > >>Tim Wescott wrote: >> >> >> >>>Guy Macon wrote: >>> >>> >>> >>>>"Why do some controller boards have an option to reverse the >>>>phase of the D? What is that good for?" >>> >>>OK, I'll bite -- what _is_ it good for? I've never done closed-loop >>>control with prepackaged controllers and I've never seen that done >>>elsewhere. I can certainly see reversing the phase of the whole thing, >>>or reversing the phase of the D term if it's coming from some other >>>feedback source (which would imply a second input) but I _can't_ see the >>>point in intentionally establishing an unstable zero in your control > > system. > >> >>My experience is more hands-on than theory, but here is the answer >>I gave my classes: >> >>In N years of setting up servos, I have never once found a use for >>it, nor have I found any literature that explains when it might be >>of some use. I think that somewhere back in the early days someone >>was told to put in a jumper that reverses the phase of the entire >>servo (quite handy when someone miswired a section that is really >>hard to get to), got it wrong, and some other manufacturers have >>been copying the "feature" ever since. >> >>If one of the theory boys has a better answer, I am all ears. > > > Shortly after VJ day, Japanese military electronic software beganWah! Hardware! Hardware!> turning up in the surplus stores on Cortland Street (razed to make way > for the World Trade Center). I bought a small panel meter, probably out > of an airplane cockpit, that had Japanese markings molded into the > inside of the case. The design itself had been blindly copied. Prominent > in the inside center of the back cover were the letters, "Simpson". > > Jerry-- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●November 30, 20042004-11-30
Tim Wescott <tim@wescottnospamdesign.com> wrote in message news:<10qngi1gmp7pr14@corp.supernews.com>...> I will be presenting two topics at the 2005 Embedded Systems Conference > San Francisco next March -- see http://www.esconline.com/sf/ for show > details. > > "Basic Control Theory for the Software Engineer" is as much information > on the z-transform as I can fit into 90 minutes. It gives a > high-altitude overview of designing software control loops in a > systematic manner. > > "PID Without a PhD" is a primer on developing PID controllers in > software, tuning them without using higher math, and avoiding some of > the common pitfalls for this popular controller form.I have the new issue and plan to read it on the plane tomorrow. Congratulations. BTW, why is ESP so thin now? Embedded Systems Pamphlet ????? I remember when it used to be 3 or 4 times longer, consistently. John
Reply by ●November 30, 20042004-11-30
>>>...I did a Google search... >>> Winfield Hill > >...The quotation marks are important... > Guy MaconWith few exceptions, hyphens are equally effective--perhaps more so, because e.g., it finds things with 'online' when you enter 'on-line'. When posting a link, hyphenated search strings are superior. (A double-quote mark tacks a '%A' onto the front of a search term making it difficult to search the Google archive for that term.)
Reply by ●November 30, 20042004-11-30
John Sampson wrote:> Tim Wescott <tim@wescottnospamdesign.com> wrote in message news:<10qngi1gmp7pr14@corp.supernews.com>... > >>I will be presenting two topics at the 2005 Embedded Systems Conference >>San Francisco next March -- see http://www.esconline.com/sf/ for show >>details. >> >>"Basic Control Theory for the Software Engineer" is as much information >>on the z-transform as I can fit into 90 minutes. It gives a >>high-altitude overview of designing software control loops in a >>systematic manner. >> >>"PID Without a PhD" is a primer on developing PID controllers in >>software, tuning them without using higher math, and avoiding some of >>the common pitfalls for this popular controller form. > > > I have the new issue and plan to read it on the plane tomorrow. Congratulations. > > BTW, why is ESP so thin now? Embedded Systems Pamphlet ????? > > I remember when it used to be 3 or 4 times longer, consistently. > > JohnI tried to sell them an article a couple of months after the dot-com bubble burst. The word then was that advertising revenue was down, so they had to thin it out. The reduced page-count plus all the suddenly unemployed engineers writing stuff nixed my article for a while (but I have published there recently). -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●November 30, 20042004-11-30
"Guy Macon" <http://www.guymacon.com> wrote in message news:10qpfh0mn84pve3@corp.supernews.com...> Tim Wescott wrote: > > >I fear that my mind was poisoned long ago by a German instructor who > >pointed out that modern linguistic theory doesn't much recognize a > >"right way" and a "wrong way" -- it just records prevalent usage, and > >tries to keep out of the way of the steamroller. > > I tend to agree, but the "wrong way" hinders communication if it is > *too* different from the "right way." If one decides to use a few > non-standard fleemishes and the reader can still gloork the meaning > from the context, but there ix a limit; If too many ot the vleeps > are changed, it becomes harder and qixer to fllf what the wethcz > is blorping, and evenually izs is bkb longer possible to ghilred > frok at wifx. Dnighth? Ngfipht yk ur! Uvq the hhvd or hnnngh. > Blorgk? Blorgk! Blorgkity-blorgk!!!! > >Finally someone who speaks my language! The first clear, concise, and lucid post in quite a while! A little off track at first, but you wrapped it up nicely towards the end! :o) Louis-- ********************************************* Remove the two fish in address to respond
Reply by ●November 30, 20042004-11-30
On Tue, 30 Nov 2004 21:12:10 GMT, "Clarence" <no@No.com> wrote:> >"Jim Thompson" <thegreatone@example.com> wrote in message >news:abepq0tt82o05fqiiikdq60v0bl3mvlpce@4ax.com... >> On Tue, 30 Nov 2004 13:07:37 -0500, Jerry Avins <jya@ieee.org> wrote: >> >> [snip] >> > >> >It's simple: the level of literacy, even among "college boys", is >> >appallingly low. Consider how many write "there" when they mean "their" >> >or "they're". >> > >> [snip] >> >Jerry >> >> Engineers, as a class, are notoriously bad spellers/grammarians. >> >> ...Jim Thompson > >Hardwired! >Probably. Though I'm a good speller myself... I just have right-hand-index-finger-gets-out-of-sync-with-left-hand-index-finger typing problems, so I religiously use a spell-checker ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
