Battery powered/Radio controlled locos

[StuartM]

Looks like even the real railway thinks Battery power is a good idea

http://www.railtechnologymagazine.com/Rail-News/battery-powered-train-to-be-developed?utm_medium=email&utm_source=Rail+Technology+Magazine&utm_campaign=3002311_thedailyrailnews+Aug+2013+Week+4&dm_i=IJS,1SCLJ,4DFP52,6DS1A,1

[Robin2]

[Rant]

Why on earth do people wast money electrifying real railways when diesel power is readily and conveniently available. We are told there is likely to be a shortage of generating capacity, so why use the generating stations to provide electric power for applications where it's not actually essential?

[/Rant]

 

... and, no, I'm not investigating NGauge diesel power

 

...R

[Graham_M]

Thanks for the clarification

So not really battery powered or remote control then, more wireless contol

~Yes, I suppose you could call it wireless control. I remember when wireless and radio meant the same thing! However, I find it convenient in the absence of a workable on-board battery system which will fit in a tank loco, even in 7mm.

[Robin2]

If it fits in an NGauge tank loco I can't imagine any problem fitting it in a 7mm tank

 

but we're not here to force anyone ...

 

...R

 

 

... in the absence of a workable on-board battery system which will fit in a tank loco, even in 7mm.

[dpbagley]

I've only today come across this forum, so apologies if I am repeating what others have already done or said. I have only returned to the hobby in the last couple of years, so things like DCC are new to me. I do remember Hornby's Zero 1 coming out!

I've been experimenting with battery powered/radio control over the last few months and have recently got a prototype running in a OO Lima class 47 bought from ebay.

My system has a controller PCB of my own design with a a PIC micro, a miniature 2.4GHz radio tranceiver module, some LED outputs for head/tail lights, and a H-bridge motor IC driven by a PWM output from the PIC to drive the motor. An on-board battery overcomes any problems with intermittent track power. The steel weight has been replaced with a few strips of lead as this takes up less space.

 

Rather than using a back emf technique, the motor speed is measured digitally. The motor has been modified so that a LED shines through the armature and a phototransistor produces a signal which is modulated by the rotation of the motor.

 

This pulse train is fed back to the PIC which measures the motor speed and adjusts the PWM drive according to the speed demanded over the radio link.

 

THEREFORE, the loco goes (within the limits of the motor power) at the speed you demand, whatever the load behind it or the gradient or curve of the track. This allows for a high degree of control even at slow speeds.

In theory, the battery is large enough to run the loco on its own for the best part of an hour, and it is trickle charged from the track, when available. Power is sent via a DCDC converter to the motor via the controller PCB.

 

The reason for the DCDC converter is that the track voltage is higher than the battery voltage so that the battery can be charged. Without the DCDC converter, any sudden changes between the battery/track voltage on the motor as the wheels turn will cause the loco to judder as the PIC adjusts the PWM drive to achieve the demanded speed. The DCDC converter is very quick to correct for changes to its input voltage, so it provides a stable output voltage for the motor. Aditionally, Since it has a wide input range, it allows the battery to discharge right down to a voltage where without it, the motor would probably stall, extending the operating time in the absence of track power.

Commands are currently sent via another radio module from a PC to set direction, speed, which end the driver is sitting (ie define which is forwards and backwards), and day/night headlight and tail light controls.

 

Since the radio module is bidirectional, the loco can also report data back to the PC, eg battery level ie "fuel", or even "amps" as on a real diesel electric loco to show how hard it is working.

As you can imagine, the electronics and batteries take up quite a bit of room, so while it fits (just) inside OO gauge diesel locos, it is probably not suitable for shunters or OO steam locos.

It is still very much work-in-progress, when my very limited spare time permits. There is still lots to do, and while the system works OK with my Lima "Duff", I do need to see if it still fits in other classes of locos with similar motors. There may be more design work to get it to work in locos from other manufacturers which may not allow the same optical technique for measuring the motor speed, or where space is more limited.

 

I also want to use a Rasbperry Pi instead of a PC to control everything, including points and signals, making it possible in theory to handle everything on a layout with just two wires (eg the rails).

 

Any feedback would be appreciated!

David.

[fallen]

Hi David, and welcome to the forum.

 

That seems a really impressive system you have there.

 

As you may have noticed, there are a few of us here who are trying out radio control battery powered locos in small scales. We tend to use modified model aircraft technology, LiPo batteries, and the modified radio systems from DelTang are typically what we are using.

 

You look to have gone a different route. What sort of batteries are you using? The LiPos tend to impose constraints on motor voltage and charging systems which you look to have avoided.

 

The speed control system sounds fascinating too.

 

More details please!

 

Frank

[StuartM]

Hi David and welcome to this thread.

Your model is very impressive, especially the optical feedback.

I have a couple of questions if you don't mind.

1. The pcb is looks to me, to be of a professional standard, is electronics part of the day job or are you a talented hobbyist?

2. Why not use a proper rectifier rather than the 4 diodes soldered together?

3. What language did you program the pic with?

4. Any chance of a circuit diagram

 

From your description and the photo, it seems to me like you've cracked it, now all it needs is for Hornby or Bachman to approach you, have you considered sending them an email with a link?, the more people who can prove to them that BP/RC is the future the more likely they are to finally take notice.

Rgds,

Stuart

[Robin2]

Very impressive, David, and welcome.

 

As far as I know the DelTang (DelTino) modules could be programmed for a similar motor RPM detection system. I would like to get more information about how you detect motor speed. I presume you are just "counting" interruptions to the light? What exactly is interfering with the light? Is it important to position the led and photo transistor carefully? I presume your loco has an open-frame motor? Have you given any thought about how to apply the system with a can motor?

 

...R

[dpbagley]

Hello all and thanks for the comments. I will try to answer the questions.

 

- The batteries are 2 x 7.2V NimH by Varta. I have avoided LiPos because of the difficulties in charging them. This application requires the battery to be trickle charged, not fully cycled which I understand Lipos prefer. Super capacitors may be a future alternative to batteries.

 

- The PCB is of my own work, and yes I do this kind of thing for a living as well. I am not from a r/c modelling background, but I could see that whilst it was possible to buy r/c planes, gliders, helicopters, boats, cars, etc, it was not possible to buy r/c trains, so I started looking (as an electronics engineer) into what could be done.

 

- The 4 diodes were used as I didn't have a bridge rectifier to hand.

 

- The PIC is programmed in C.

 

- I may well be in a position to publish the circuit diagrams in due course, but at the moment, there are still changes which need to be done and bugs to iron out. In any case, most of the work is done in software! The PIC is a PIC18F4620, the motor drive IC is a BD6221 and the RF module is a RFM70. Apart from the LED driver, there's not much more on the PCB anyway.

 

- Obtaining the motor speed is simply a matter of counting pulses from the optical detector over time. The light beam shines through the motor past the armature windings which interrupt the beam as it turns. The motor is not open frame - I simply made a couple of holes in the plastic, one in each side! The alignment is not all that critical, but it does need to be fairly dark inside the loco body. I've not looked at any other kind of motor yet, and there may be difficulties in using this optical technique with other types. It is possible to obtain motors with encoders built in, but this will require some major changes to the drive mechanism. I was just trying to keep it simple.

 

At this stage it is just a "proof of concept" design, for my own interest. The prototype is currently at a stage where it does work. I will need to spend more of my limited spare time in testing it, and solving any problems that are found. The next major step is to develop the controller software on a Raspberry Pi. There will also be some work needed on the radio protocol so that more than one loco can share the same controller, avoiding collisions - not of trains but of radio messages!

 

I think that this is a step in the right direction, and time will tell if it is a viable solution for the manufacturers to take on.

 

David

[rodshaw]

David

 

Would your system be adaptable at all to link to an onboard sound module? I know it's not DCC - just wondering if there are other ways to skin a cat.

[dpbagley]

The PCB I have made does have a expansion port which could be used, but I don't know enough about how sound modules are powered and controlled to say for sure whether it would work or not.

 

David

[Robin2]

Rod, if you haven't read all the earlier replies in this Thread post #211 be of interest http://www.rmweb.co.uk/community/index.php?/topic/64616-battery-poweredradio-controlled-locos/page-9&do=findComment&comment=1085385

 

...R

 

David

 

Would your system be adaptable at all to link to an onboard sound module? I know it's not DCC - just wondering if there are other ways to skin a cat.

 

[NorthHighlander]

It's good to see that battery powered/radio control is developing in all sorts of ways, and I'm writing this to let members who have asked how we are getting on know that we are very near finishing all our testing and our products will be available in the very near future. Exact dates will depend on the results of EMC testing which will be happening later this month.
RM Web members who have asked when we are exhibiting Protocab, we are at ExpoEM North on 14/15 September and at Scaleforum on 28/29 September.
We have just issued a newsletter to Club Protocab members, so if you would like a copy and would like to be kept informed of progress, please email club@protocab.com.
Our new website, www.protocab.com should be up and running just before ExpoEM North.

Best regards
Tony Hagon
Director
Acc+Ess Ltd
 

[billbedford]

My system has a controller PCB of my own design with a a PIC micro, a miniature 2.4GHz radio tranceiver module, some LED outputs for head/tail lights, and a H-bridge motor IC driven by a PWM output from the PIC to drive the motor. An on-board battery overcomes any problems with intermittent track power. The steel weight has been replaced with a few strips of lead as this takes up less space.

 

Rather than using a back emf technique, the motor speed is measured digitally. The motor has been modified so that a LED shines through the armature and a phototransistor produces a signal which is modulated by the rotation of the motor.

 

This pulse train is fed back to the PIC which measures the motor speed and adjusts the PWM drive according to the speed demanded over the radio link.

 

THEREFORE, the loco goes (within the limits of the motor power) at the speed you demand, whatever the load behind it or the gradient or curve of the track. This allows for a high degree of control even at slow speeds.

 

This is exactly the way real trains don't move. Full sized trains are load sensitive, that is the acceleration is dependent on the load on the drawbar. Heavy trains take a long time to reach line speeds and take an equally long time to come to a stop. OTOH light engines only need a touch of regulator/throttle to get moving but there can coast a surprisingly long way. Unfortunately there are very few controllers that come near being able to reproduce the acceleration of real trains, and the idea that a model should move at the speed set by the control knob is just one to those model railwayisms that detract from realistic model operation.

[dpbagley]

At the moment, the prototype loco does go at the speed demanded, but the eventual idea is to "drive" the train in as realistic a way as possible where the speed of the motor is calculated by the onboard controller using various feedback factors, including throttle, brake, wind resistance and load.

 

This will always be an approximation as it won't be possible for the loco to know every factor to use in its calculation, eg the gradient or curvature of the line, but it will be much more realistic than just turning a knob.

 

In my workshop, I have a simple loop of track which is 7.5m in circumference. On the slowest speed setting, the modified class 47 loco took 8 minutes to go around, a scale speed of about 2.6mph, ie walking pace! If the software is altered to go slower than this, then it is a bit jumpy as there are rather too few pulses from the optical detector on the motor to count.

 

I have now started modifying a Lima class 66 and will post some pictures in due course.

 

David

[Robin2]

If the electronics in the loco makes the motor run at a speed dictated by a wireless signal received from the controller then, in my opinion, the acceleration/deceleration should be calculated in the controller and not in the loco. That makes the software in the loco much simpler and makes the whole system more flexible.

 

I experimented briefly with acceleration/deceleration on my little NGauge layout and I found it totally impractical because there wasn't sufficient distance for it to work and not being able to instantly control the loco meant that it crashed all the time.

 

...R

Edited September 12, 2013 by Robin2

[davetheroad]

I just noticed this RC section a week ago and have followed the links provided and avidly read everything, even if a lot of it is way too technical for me. Even so the idea of radio control really intrigues me, especially as I have just spent a considerable time track cleaning!. I think converting my DMU fleet might be worth it as they do a lot of stopping and starting in contrast to the big through trains which can thunder trough the station at speed.

 

Maybe the downside is it is all in n-gauge and where do you fit in the batteries. I presume for DMU's the battery or batteries can go in the trailer coach and the control chip as well.

 

I have three  questions

 

1. If using a Deltang transmitter I can control 12 reciever chips but what if i need more?. Can you have say 3 transmitters and that way control 36 trains?

 

2. If my batteries are round cells can i wire them in series to get extra voltage and charge them seperately to avoid these mysterious balancing problems?

 

3. Are there problems with interference from light and electrical equipment like fan heaters etc?

 

It looks as if i have found a nice winter project to put me off building scenery, I hate building scenery.

[dpbagley]

I was planning on putting the speed calculation in the loco and not in the controller since this minimises the amount of data which needs sending over the radio link to the loco. All that needs sending is the few parameters needed to calculate the required speed (throttle, brake and load) and once received by the loco, no further communication is needed until required. There is plenty of processing time to perform the actual speed calculations in the loco.

 

Also, it's best to keep the volume of radio traffic to a minimum, as this is reduces the chances of data errors over the air, and it allows the same radio frequency to be shared by other locos and/or controllers. Radio interference caused by the proximity of the radio receiver to the motor may be a problem, which is one of the things I am keeping in mind.

 

There is an "emergency stop" which will stop all locos immediately and (hopefully) reduce the risks of crashing!

 

The Deltang system looks interesting, but there seems to be no facility to trickle charge the onboard batteries from the track, nor is there any speed control by using feedback from a sensor on the motor (or even back emf).

 

D.

[SHMD]

I was planning on putting the speed calculation in the loco and not in the controller since this minimises the amount of data which needs sending over the radio link to the loco. All that needs sending is the few parameters needed to calculate the required speed (throttle, brake and load) and once received by the loco, no further communication is needed until required. There is plenty of processing time to perform the actual speed calculations in the loco.

 

Also, it's best to keep the volume of radio traffic to a minimum, as this is reduces the chances of data errors over the air, and it allows the same radio frequency to be shared by other locos and/or controllers. Radio interference caused by the proximity of the radio receiver to the motor may be a problem, which is one of the things I am keeping in mind.

 

There is an "emergency stop" which will stop all locos immediately and (hopefully) reduce the risks of crashing!

 

The Deltang system looks interesting, but there seems to be no facility to trickle charge the onboard batteries from the track, nor is there any speed control by using feedback from a sensor on the motor (or even back emf).

 

D.

 

Hi D.

 

I agree with your assement.

As sending parameters would be quicker, easier and thus more reliable but it does require a lot more processing power in the target system.

Interpolation is not easy in a micro controller. It may be easier to send a "speed curve"/"look up table" instead.

 

Kev.

[SHMD]

I just noticed this RC section a week ago and have followed the links provided and avidly read everything, even if a lot of it is way too technical for me. Even so the idea of radio control really intrigues me, especially as I have just spent a considerable time track cleaning!. I think converting my DMU fleet might be worth it as they do a lot of stopping and starting in contrast to the big through trains which can thunder trough the station at speed.

 

Maybe the downside is it is all in n-gauge and where do you fit in the batteries. I presume for DMU's the battery or batteries can go in the trailer coach and the control chip as well.

 

I have three  questions

 

1. If using a Deltang transmitter I can control 12 reciever chips but what if i need more?. Can you have say 3 transmitters and that way control 36 trains?

 

2. If my batteries are round cells can i wire them in series to get extra voltage and charge them seperately to avoid these mysterious balancing problems?

 

 

3. Are there problems with interference from light and electrical equipment like fan heaters etc?

 

It looks as if i have found a nice winter project to put me off building scenery, I hate building scenery.

 

The removal of the rail/wheel interface unreliability problem is the goal of most of us here.

 

I work in oo and so is biased that way. 

Does n gauge dmus have blacked out Windows? If so then batteries may be easier. OO require a below Windows height and, I'm assuming, o gauge is not a problem.

 

Sorry but I have no experience of deltang and so I can't answer your questions, but good luck with your winter project.

Might I request updates as we are interested with progress.

 

Kev.

[Robin2]

Welcome to the wonderful world of BPR/C Dave.

 

I started by converting a Farish NGauge large prairie to BPR/C using a 6v? motor from a servo and a single 3.6vLipo cell. I have an onboard rectifier so I can charge from fiddle-yard tracks while the loco is waiting its turn. I found by accident that the same servo motor is a direct drop-in replacement for the 12v motor in my Class 101 DMU.

 

My large prairie was converted with a Deltang Rx41 but I have since discovered that the Rx6x modules use an Atmega 328 chip and can be programmed like an Arduino device so I will be changing over to that system. With it I expect that one "transmitter" will be able to drive about 15 or 20 trains simultaneously from a fleet of a hundred or so. And if that's not enough you could have a second or third transmitter.

 

There has been an extensive discussion about multi-cell Lipos here http://freerails.com/view_forum.php?id=45. I couldn't fit more than one cell in my large prairie so I decided to use 3.6v in all my locos for convenience. Two LiPos (7.2v) is probably enough to drive a 12v motor. 

 

@dpbagley - I know the onboard microprocessor can do it. I just don't see the point of the complexity. Also I don't think there is likely to be any shortage of data transmission capacity. If you feel like changing something it takes a few minutes on a PC with no need to upload anything to the loco.

 

...R

[fallen]

Hi Dave and welcome!

 

The Deltang TX 22 will control up to 12 RX 6 series receivers and I would expect that another TX 22 would control another 12 but I suggest you email David who makes them, he usually responds to queries pretty quickly. His email is on the DelTang website, or you can post a query on Freerails on the thread about his equipment.

 

I would not expect any interference problems with electrical equipment generally, the system uses quite high frequency at 2.4 GHz, the same as WiFi, and is fairly robust. The only problem I have ever had was when first binding the loco to the TX when working next to a PC running a WiFi link. Once bound the system is trouble free.

 

I guess you can wire the cells in series and use the RX 6 series which has higher power capability, and the charge the cells separately, but it will extend the time spent charging. Usually charging is quite quick at say 10 mins to half an hour depending on the charger setup, but then you would multiply that by the number of cells or have several chargers. I have found that loco motors need less voltage than you might think since you don't have the voltage drop in the connections, rails and wheel contacts. It might be worth doing some tests with the motor wired directly to the controller and a voltmeter reading the voltage, to see what it actually needs.

 

Have fun!

 

Frank

[davetheroad]

I emailed David at Deltang and yes additional Tx-22's will allow more trains to be controlled. You can also re-bind a Rx to a different tx-22 so i can go ahead with my initial single Tx-22 and a few Rx units for experimental and development purposes and subsequently move those receivers to another Tx if i decide to develop the system.

 

A 'full' system for my layout would need 3 Tx's controlling:

 

1st one - 9 DMu's of various types plus 3 spare slots.

 

2nd one - 8 passenger trains including loco hauled, HST, DEMU's and EMU's, plus 4 spare slots.

 

3rd one - 6 fixed formation freight trains and 6 more permutated as any 6 out of 12 (the layout fiddle yard can store 12 freight trains). the idea is to have 6 Rx's housed in small modules including switch and connectors. These can be moved between different types of 'battery wagon'.

 

I model modern image so there is no room for batteries in the loco. The DMU's etc are not a problem as the Rx and battery can go in the trailer car. My fixed formation Pretendolino and Virgin West Coast use either a Class 87 or Class 90 so a Rx plus battery in the Mk3 coach should work. The freights are more of a problem but lots of modern wagons have room for the RX and batteries. Double heading using a Dapol dummy Class 66 to house the bits and bobs should allow for more trains of funny shaped wagons.

 

This is all going to be an interesting learning experience and although i have done some initial concept planning i still have the initial equipment to buy plus learning all those new skills such as building lipo packs etc etc.

 

all this new stuff means building hills on Castlerock has ceased for now, never mind, i hate building hills!

[Simond]

Radio control sounds wonderful, except for the sounds.....

 

I just upgraded from DCC to DCC + Sound and I love it - and now you are showing me 009 loos driving silently on glass...

 

My initial attempts at "stay alive" capacitors seem somehow like wasted effort!

 

But I can't imagine not having onboard sound (ok, O gauge here, sorry) - I was planning on upgrading the fleet - which will cost the thick end of £100 per loco and there are 2 done and 9 to do, plus at least 3 to build, but the entirely glitch free running is gorgeous, so what should I do???

 

I'm well impressed, if you hadn't noticed

SD

[Robin2]

There are radio control systems that use DCC chips and I guess that would be the simplest way to get onboard sound - though not necessarily cheap, because you need the radio stuff and the DCC stuff.

 

There is no reason why on-board sound can't be provided by a non-DCC BPR/C system but I don't think anyone has done it yet. Go on, accept the challenge

 

...R