Is it possible to add Cruise Control to a LionChief Engine? Yes it is!

Looks like another interesting project. If you end up making it small enough to fit in the LC items and as easy to install as it sounds I think you might have a hit. The design part is above my level, I will stay aout of the way and let the folks in the know work on that part. I will be following along trying to learn a thing or two though. Thanks for posting this, I really enjoy all the projects the folks here come up with! Good luck with it all.

BRILLIANT!!!

That's fantastic John!  It'll be interesting to see if you can condense this to a smaller board.

It has definitely overcome the first two problems - the 8 driver bind on O36 and the need for a second power feed when extending the starter track.

Nice project!

PLCProf posted:

Very good!

I'd be interested in seeing a sketch of the H-bridge and the means you use to get the back-EMF into the Arduino, if you are inclined to disclose that.

The H-bridge in use is very similar to this one:

which is explained quite well in this video: https://youtu.be/PT0f6CRUnOQ

The code that actually runs the motor is astonishingly simple:  

void moveForward() {
 digitalWrite(reverseTIP125pin, LOW);
 digitalWrite(reverseTIP120pin, LOW);
 analogWrite(forwardTIP125pin, outputPWMspeed);
 digitalWrite(forwardTIP120pin, HIGH);
}

void moveReverse() {
 digitalWrite(forwardTIP125pin, LOW);
 digitalWrite(forwardTIP120pin, LOW);
 analogWrite(reverseTIP125pin, outputPWMspeed);
 digitalWrite(reverseTIP120pin, HIGH);
}

void moveNetural() {
 digitalWrite(forwardTIP125pin, LOW);
 digitalWrite(forwardTIP120pin, LOW);
 digitalWrite(reverseTIP125pin, LOW);
 digitalWrite(reverseTIP120pin, LOW);
}

Where the program calls upon the needed direction routine.  I thought that I might need to add some delay to prevent the chance of a brief short between sides of the H bridge, but in practice it doesn't seem to be an issue, especially as the LionChief electronics add a built in delay of about 1 second between stopping in one direction, and starting in the other.  

As for reading the BEMF, this turned out to be easier than I thought it would be when I started.  The circuit consists of a a diode from each side of the motor, to prevent negative voltage from reaching the Arduino, a voltage divider to lower the working voltage down to a 0-5v scale (actually more like 1-3v), and a zener diode used as a snubber in case there are any odd spikes, to protect the input pin.  The programing turned out to be fairly complex to get the timing right and a usable reading in, but the basics are that the H bridge is turned off every 20 milliseconds, the BEMF is read, then the H bridge is turned back on.  The BEMF voltage that is read is then sent to the input of a PID algorithm, which does it's best to match the motor speed to whatever speed setting it is given.  

I wouldn't mind looking for a higher resolution ADC, but the 10 bit one built into the ProMini does the job well enough.  I also think I might be able to squeeze a bit more low end out of the thing by using schottky diodes instead of the 1n4001's I had on hand.  

JGL

I spent a couple hours this evening pouring over data sheets and looking at pricing on various parts that would be needed to shrink down the board here to a useable size, and I think I have most of it figured out at this point.  Before I order some parts I thought I'd see what folks think on a couple topics; some for the electronics minded people, and others for the average Joe sorts:

Tech question 1:
I'm considering using TO-220 package power mosfets for the H-Bridge output here, mostly because it is much easier to add heat sinks to them to allow for higher current do you all think this is needed or will things work out fine using just PCB copper as the sink on a SMD mosfet?  The cost is about the same for the mosfets either way, and you don't really save a lot, if any, board space when all is said and done.  

Tech question 2:  
Should I install a TVS right on the board?  This would obviously help prevent damage from outside spikes and such, but is it a problem waiting to happen if the TVS fails?

Tech question 3:  
Do you think it worth while to add a thermal sensor to shut down the board if the drivers become too hot, and/or a second sensor to monitor motor temp?

General Question 1:
Is a minimum speed of 10 Scale miles per hour acceptable for an engine?  I can get this speed very reliable, but below 10 SMPH tuning the speed control becomes very complex.  I've gotten it down to about 5 SMPH, but the tuning only works with that exact motor/drivetrain.  I think to get reliable, and easy to use, operation below 10 SMPH would require moving away from back EMF as speed detection method.

General Question 2:
Is it important to have an actual scale MPH speed assigned to each speed step of the engine, or is it acceptable for each step to be some percentage faster than the last, in the way that LionChief Plus engines currently handle speed steps?  

General Question 3:  
Is it worth while to add additional features to the design?   There is plenty of space remaining for additional programing on the micro-controler and I'm wondering if additional features would be worthwhile to add.  Features that I can come up with so far include rule 17 lighting, cab light lighting (on stopped, off when moving), Fire box glow lighting, support for back-up light on tender, Support for fan driven smoke units, and support for 4 chuff/revolution.  I'm sure there are other things I missed that could be added as well.  I'm curious if any or all of these features would be worth while to people, or if they would just make things more complex for no reason?

General Question 4:  
Are people opposed to having to unsolder wires from the motor and/or splice up to half a dozen wires to install the board?  My original intention was to use the same plugs  to make installs require no soldering or cutting of wires, however as it turns out, bigL uses several different sized connectors in different engines for power and motor connections.  I could locate each of these connectors and offer whatever one is needed, but it seems simpler to have the installer unsolder the wires from the motor terminals 

General Question 5:  
Would you be interested in adding cruise control to your LC engines in the first place?

JGL

JohnGaltLine posted:

I spent a couple hours this evening pouring over data sheets and looking at pricing on various parts that would be needed to shrink down the board here to a useable size, and I think I have most of it figured out at this point.  Before I order some parts I thought I'd see what folks think on a couple topics; some for the electronics minded people, and others for the average Joe sorts:

Tech question 1:
I'm considering using TO-220 package power mosfets for the H-Bridge output here, mostly because it is much easier to add heat sinks to them to allow for higher current do you all think this is needed or will things work out fine using just PCB copper as the sink on a SMD mosfet?  The cost is about the same for the mosfets either way, and you don't really save a lot, if any, board space when all is said and done.  

Electronic Novice: I have only used this package a few times and the heat generated really surprised me. perhaps what I used was too small. (19vdc to 12vdc)

Tech question 2:  
Should I install a TVS right on the board?  This would obviously help prevent damage from outside spikes and such, but is it a problem waiting to happen if the TVS fails?

I say yes. The mathematical failure rates are low enough considering the voltages that the toy train environment operates.

Tech question 3:  
Do you think it worth while to add a thermal sensor to shut down the board if the drivers become too hot, and/or a second sensor to monitor motor temp?

General Question 1:
Is a minimum speed of 10 Scale miles per hour acceptable for an engine?  I can get this speed very reliable, but below 10 SMPH tuning the speed control becomes very complex.  I've gotten it down to about 5 SMPH, but the tuning only works with that exact motor/drivetrain.  I think to get reliable, and easy to use, operation below 10 SMPH would require moving away from back EMF as speed detection method.

The ability to crawl 5 smph or less of the LionChief starter sets is a plus versus a lot of engines. Speed control at 10 smph is acceptable if there is no loss of the crawl, only loss of speed control.

General Question 2:
Is it important to have an actual scale MPH speed assigned to each speed step of the engine, or is it acceptable for each step to be some percentage faster than the last, in the way that LionChief Plus engines currently handle speed steps?  

Doesn't matter to me.

General Question 3:  
Is it worth while to add additional features to the design?   There is plenty of space remaining for additional programing on the micro-controler and I'm wondering if additional features would be worthwhile to add.  Features that I can come up with so far include rule 17 lighting, cab light lighting (on stopped, off when moving), Fire box glow lighting, support for back-up light on tender, Support for fan driven smoke units, and support for 4 chuff/revolution.  I'm sure there are other things I missed that could be added as well.  I'm curious if any or all of these features would be worth while to people, or if they would just make things more complex for no reason?

Keep it to the speed control. Like I said in my original comment, it overcomes two problems with the starter set and the 8 wheel driver engine. It would be very nice for the mountain up and downs that many design into their Polar Express layouts.

General Question 4:  
Are people opposed to having to unsolder wires from the motor and/or splice up to half a dozen wires to install the board?  My original intention was to use the same plugs  to make installs require no soldering or cutting of wires, however as it turns out, bigL uses several different sized connectors in different engines for power and motor connections.  I could locate each of these connectors and offer whatever one is needed, but it seems simpler to have the installer unsolder the wires from the motor terminals 

Not a problem for me to solder, but most would like the connectors. Make this a Polar Express upgrade to start and ride the popularity and quantity of those engines. The metrics won't work with other engines, in my opinion.

General Question 5:  
Would you be interested in adding cruise control to your LC engines in the first place?

I would for the Berk Jr. Polar Express. It's a staple in my trains and many others, too.

JGL

Thanks, Carl 

John,

I don't have the technical expertise to advise on the technical questions but regarding your general questions I offer this advice:

General Question 1 - Likely most folks will expect your upgrade to function with the same parameters that the LionChief Plus steam engines do and not noticeably less than that.

General question 3 - considering this is primarily designed for LionChief steam engines, support for rule 17 isn't needed but 4 chuffs is. Since some folks have already added firebox glow like those from Dan's Drumheads, Evans Designs, etc., I"d say add support for that plus also for fan driven smoke, cab lighting, and a tender back up light.

General question 4 - Since novices purchase the majority of starter sets, my advice is  keep it as simple as possible for those folks with as little splicing and soldering of wires as necessary and since it's targeted for Polar Express people, use connectors only if all LC versions of the PE LC have the same motor connectors.

General question 5 -I would be inclined to add this to my 10th Anniversary LC PE but if it works equally well and reliably for 0-8-0 LC rtr starter sets with their small flat motor, I'd most definitely add it to those too, albeit dependent that the price is in line with the PE add-on.

Hope my feedback helps you.

Answers Embedded below...

JohnGaltLine posted:

I spent a couple hours this evening pouring over data sheets and looking at pricing on various parts that would be needed to shrink down the board here to a useable size, and I think I have most of it figured out at this point.  Before I order some parts I thought I'd see what folks think on a couple topics; some for the electronics minded people, and others for the average Joe sorts:

Tech question 1:
I'm considering using TO-220 package power mosfets for the H-Bridge output here, mostly because it is much easier to add heat sinks to them to allow for higher current do you all think this is needed or will things work out fine using just PCB copper as the sink on a SMD mosfet?  The cost is about the same for the mosfets either way, and you don't really save a lot, if any, board space when all is said and done.  

Since Lionel manages to use SMT FET's on the RCMC board to run some pretty hefty motors, I'd think there's no reason to need the TO-220 package and any heatsink.  MTH also has their FET as an SMT package on the PS2/PS3 boards.

Tech question 2:  
Should I install a TVS right on the board?  This would obviously help prevent damage from outside spikes and such, but is it a problem waiting to happen if the TVS fails?

I'd certainly consider perhaps a 600W TVS on the board, they're not too big and may indeed help.  The only "problem" if the TVS fails is either you don't have any protection, or you have a dead short.  They don't fail so often as to make me omit the protection.

Tech question 3:  
Do you think it worth while to add a thermal sensor to shut down the board if the drivers become too hot, and/or a second sensor to monitor motor temp?

IMO, no.  This is unneeded complexity, at least that's what I feel.  If you want to add a sensor, consider sensing the current in the motor drivers and shutting down if it exceeds a predetermined value.

General Question 1:
Is a minimum speed of 10 Scale miles per hour acceptable for an engine?  I can get this speed very reliable, but below 10 SMPH tuning the speed control becomes very complex.  I've gotten it down to about 5 SMPH, but the tuning only works with that exact motor/drivetrain.  I think to get reliable, and easy to use, operation below 10 SMPH would require moving away from back EMF as speed detection method.

Interesting question.  This one is a bit harder to quantify as some will value great low speed performance, and others will be more interested in maintaining speed on curves and grades.  I believe this is why Jon Z. stated that at low speeds the Cruise Commander uses commutator segment sensing, the back-EMF at low speeds is very small.  I'd probably lean to simplicity, at least for the first cut.

General Question 2:
Is it important to have an actual scale MPH speed assigned to each speed step of the engine, or is it acceptable for each step to be some percentage faster than the last, in the way that LionChief Plus engines currently handle speed steps?  

This is an inexpensive set locomotive, I don't see any need for true scale steps,  The speed control is far more important in my mind.  In point of fact, MTH has a patent on remote controls with scale MPH which may come up, I haven't looked at that patent to see if what you would do would infringe on their patent.

General Question 3:  
Is it worth while to add additional features to the design?   There is plenty of space remaining for additional programing on the micro-controler and I'm wondering if additional features would be worthwhile to add.  Features that I can come up with so far include rule 17 lighting, cab light lighting (on stopped, off when moving), Fire box glow lighting, support for back-up light on tender, Support for fan driven smoke units, and support for 4 chuff/revolution.  I'm sure there are other things I missed that could be added as well.  I'm curious if any or all of these features would be worth while to people, or if they would just make things more complex for no reason?

I'd say yes to most of these features.  You don't have to wire up cab lights, firebox lighting, or the backup light if you don't want them.  The Rule-17 lighting would be a no-effort installation as you already have the headlight.  I'd probably include a small jumper for 2-chuffs/4-chuffs if you add this feature, some folks think four chuffs on small locomotives like this sound like a machine gun at any speed above dead slow.

The fan driven smoke is a really nice option, but I must say I don't know how many people would go to the trouble of installing the smoke unit.  If the only thing you were doing is toggling the fan with the chuffs, that would probably be fairly easy.  You could keep the control of the smoke heater the way it currently works.

General Question 4:  
Are people opposed to having to unsolder wires from the motor and/or splice up to half a dozen wires to install the board?  My original intention was to use the same plugs  to make installs require no soldering or cutting of wires, however as it turns out, bigL uses several different sized connectors in different engines for power and motor connections.  I could locate each of these connectors and offer whatever one is needed, but it seems simpler to have the installer unsolder the wires from the motor terminals 

Obviously, that would not be an issue for me.   I wonder if you could have a small connector on the board for motor and power, then offer jumper cables that have the various connectors or that solder direct to the source?  Since the jumper cables with the various connectors wouldn't be part of the basic package (and price), you could have your cake and eat it too.

General Question 5:  
Would you be interested in adding cruise control to your LC engines in the first place?

I currently don't have any plain LC locomotives, one of the reasons is no cruise and lack of fan driven smoke.  I'd probably be one of those people that would add fan driven smoke.

JGL

Obviously, many of these features being added may run up the cost where it isn't that attractive, that's a danger that you have to evaluate.

Another point to consider is the size of the board and how it fits into the locomotive.  I haven't had enough of them apart to know if there's a huge size constraint as far as adding a board.

As one who has no LC or LC+ items and doesn't really see having any in the near future (never say never), I think a couple of considerations may apply here. I will leave the technical stuff to those that know much more than I do about these things. Also consider that I have only been back in the hobby a few years and am still learning myself, it was like starting all over again for me, only with a lot more to choose from and all kinds of neat, new features. I am just throwing out some thoughts here.

IMO, many folks with the LC starter sets will probably be beginners with little or no knowledge of electric trains. They may not even know what Rule 17 lighting is or maybe some of the other features you mention? I think maintaining the speed would most likely be what they would like the most. They probably won't like the train slowing down on curves and grades etc. The folks wanting slow speed control for switching or things like that might be purchasing the LC+ engines in the first place and not the LC sets? I don't think having SMPH per speed step would matter, just basic speed control and the 10 SMPH at the low end would probably be fine. And if kids are running these they will probably be going 'fast' anyway?

However, whether they would even be interested an adding features to their sets is a very good question and I am not sure I have even a guess about that one? If I did, my guess would be that some would want to continue on in the hobby would be interested, but who knows how many? Then someone wanting to continue in the hobby might just be interested in the additional features you are considering as well. Maybe a couple of different boards? Say one for speed control only and then another with the additional features added? Using jumpers for some selections like GRJ suggests sounds like a good idea too. (As well as do many of the other suggestions above and those folks are probably much more in the know than I am.) 

I think a lot of folks do not like (or want) to have to solder anything. I think the plug in ideas are the best if at all possible. At least that is my impression from being on this forum for a few years now. I think this would also include some folks that have been running electric trains for quite some time and probably can fix many things on them, but just don't like soldering.

Of course, it would be nice to have some comments from some of the folks that are new to the hobby and just beginning with their first LC starter set. I think all the technically knowledgeable folks here will probably give their ideas on all those things. 

Anyway, just my thoughts and good luck with the project. Even though I don'e have any LC products, I will be following along to try and learn something myself. Good Luck!

Simple cruise control would work for me. At low speeds, my grandson's PE bogs down in one corner of an oval of O-54 Real Trax. I don't know why. The track is on a hardwood floor.

I would use it on my PE and 0-8-0 LC engines. I would like a simple plug in version for the PE and a pigtail to work on any engine. I would say no to any other features. I would look for it to control speed on inclines and curves and would not be too concerned about <10 smph.  I would not care about smph steps. 

Speed control(cruise) would be nice I think on my LC set just purchased. But my SpNeeds kid loves being tossed a remote, and having the train talk,whistle,clang and smoke on her control. She runs the thing pretty fast for the most part.  But me, having watched videos for a solid three weeks of your legacy engines and locomotives rounding bends with chuff and smoke of fan driven elements are absolutely the best. The realism of sound and visuals cant be beat. So I say I want it all, but I could be the only one.  Ted

John, while this is undoubtedly the most active and far reaching O gauge forum in terms of daily participants, you might nevertheless also consider posting your questionnaire from 15 hours ago on additional model train forums to maximize its feedback.

I would be interested in adding cruise to 10th PE.
If Lionel is reading this, I would be interested in a LC+ PE for the same reason.

Of course, simple connectors would be nice, but clear directions requiring soldering would be fine.
It is true that I am recently back to the hobby, but I am certainly capable of doing the electrical work.

I have some legacy engines, and have considered an upgrade of some sort to get the Legacy features in the PE engine.  However it looks like doing so means I lose the PE sounds, and that is part of what I like about the engine. 

The added features would be nice as well.  I would most likely add them over time.

An added added feature would be the ability to set a reduced max speed.

The interest in having cruise and setting a max speed comes from wanting to let it run, only lightly attended as a sort of decoration under the tree.  Without the cruise it is difficult to get to to run slow enough to not be loud without getting stuck.  The PE engine works great for this application becasue so many people recognize it from the movie.  When there are adults only I use a Legacy engine, which works great, but people do not respond to it quite the same way.  It is fun to see the look of recognition as a new visitor goes from "It is nice to have a train under the tree" to "Hey, that is the one in the movie!" 

So, here's what I'm gathering so far.  first it seems the target market is highly slanted toward Polar Express engines, which I pretty well expected.  As such, I think I may be best to put the most focus on making the best product for this particular engine, and going from there.  Anyway, on to where I'm at:

Tech question 1: TO220 vs SMD Fets:
Whatever is easier to work with here.  Don't need to provide for added heat sinks, and I might just save a couple pennies one way or the other.  

Tech question 2:  TVS on the board:  
May as well add it.

Tech question 3:  Thermal sensor protection:  
Use current sensing rather than thermal sensing, if it is practical to do so.  I'm going to have to look into this and see if it it is worth while.  The current sensing methods that come to mind all cost about a buck or so in parts, where as a thermistor  costs a Nickel, so I'm going to have to so some homework on this. 

General Question 1: Minium Speed:  
This one is still a little mixed.  I agree that 2-3 SMPH crawling would be amazing, but obtaining such speeds may not be worth the trouble.  I will put more research into this.  Still it seems that for many people even a 10 SMPH minimum speed would be acceptable, so long as the engine maintains the given speed at all times.  

General Question 2: Scale MPF speed steps:
Not needed, and possibly a lawsuit waiting to happen.  I'll go with a percentage based speed control here... which is actually much easier to program, and will work better across various models of engines.  

General Question 3:  Additional features:  
Hit or miss here.  My conclusion is, if it doesn't add to the cost, then go ahead and add as many options as possible, but make sure the installer can choose to use or not use whatever they like.  In general make the basic install as simple as possible.  

General Question 4:  Soldered connections:  
Direct plug-in is greatly preferred, but most folks seem ok with some straight-forward surgery if needed.  I'm liking the idea of having the Polar Express connectors pre-installed, then leaving the installer to cut off those plugs if the engine they have uses different plugs.  The second option that seems viable is to use the same single wire jumpers that I used in the mock-up, and have the installer secure them in place with hot-glue and shrink wrap.  

General Question 5:  Product Interest:  
As mentioned above, it seems the must-work here, target audience is for the Polar Express.  As such I'm going to focus on making the best possible speed control for this one engine... but still keep it functional for other engines as well.  While many(most?) of these engines are owned by casual model railroaders, I think that the people that would actually choose to modify their engine are going to be a bit more into the hobby.  As such, at this time I'm going to direct things toward what I would consider beyond entry level users, ex the vast majority of users of this forum.  

At this point I still have quite a way off from having a marketable product, but I do think that one is possible.  I'd like to discuss the idea of stocking such a product with any forum sponsors that might be interested, and may also discuss it with my LHS.  I expect that to get started the For Sale forum of this site is where the first actual product might appear, unless I find a partner.  

Additional suggestions:  
BWRR suggested adding a feature to limit the max speed.  I really like this idea and will incorporate it.  The issue here is where to mount the control?  It is quite simple to put a potentiometer on the board, but that would be a set-on-install type of feature.  I think it would be much more useful if the max speed could be adjusted without disassembling the engine.  What about having two speed adjustment pots on the board, and a switch that could be mounted in an accessible location to choose between them?  

GRJ mentioned the 2/4 chuff switch.  I can confirm that the engine sounds like complete garbage using the onboard sound system with 4 chuffs.  It is worth noting that the default of the polar express is just 1 chuff per revolution.  My thought is to provide a simple high/low chuff signal that could be used with a better sounding sound system... This is actually another project I've been fiddling with, a way to mix the built in sounds with a second sound set to improve the engine's sounds, without removing the original announcements and such.  For the moment I think it best to add support for four chuffs, but not to do anything else with it.  I'll make it compatible so that one could unplug the chuff sensor from the LC board, and plug in this input if they wanted to.  

Anyway, I'll keep folks up to date with any progress I make, but, as always, I welcome any suggestions, comments, or critiques from anyone that wants to give them.  I'm also still looking for as much data as possible from folks on the questions posted above.  

JGL
JohnGaltLine@comcast.net

P.S.  OGAUGEGUY, I agree that I could likely reach a larger group by joining other sites, but at this time I'm comfortable with just this one.  I don't know that I have the time to keep up with multiple threads, or groups of users, and for the small faults I find with this site from time to time, I do really enjoy it and feel like a part of the community here.  I don't mind if anyone that does participate in other forums wants to direct people that might be interested in this thread.  Again, I welcome any and all constructive comments.