You're reading ...
Traincontroller

Traincontroller 16 – Speed Profiling

When a new engine is brought to our layout and we ‘throttle it up’, the speed at which it moves at every DCC speed step is unknown. To know the engine speeds, they need to be measured. This is done by measuring the time at takes to travel a given distance. This results in a scale speed in m/s. Given the layout scale (N, HO, O, …), this is then translated to ‘real world’ speed in km/hr. Traincontroller has a built in function to automatically perform these measurements at different DCC speed steps. This is called Speed Profiling.

What is the use of speed profiling our engines?

Well … first of course to have our on screen speed gauges show the correct km/hr values.

But more important, to have accurate brake- and stop distances, in cm. One and the same engine, with the same block entry speed, will repeatable stop at the same spot. But it’s probably not the point that we specified in cm. Also, different engines, and different block run in speeds, will give different stop positions. Absolute accuracy can only be accomplished when engine speeds have been measured.

After my engines were profiled, the stop accuracy, measured over different engines and over different speeds with which they drove into the block (20, 40, 60 km/hr), was well within +/- 2 cm, as the image shows.

The video shows how to prepare the engine’s CV values, how to prepare the mearurement track, how to perform the speed profiling and finally, how to do measurements to fine tune the ‘brake compensation’.

A PDF with a step by step ‘cook book’ explanation is available via this link: Traincontroller_Speed_Profiling

 

TC_Brake_Accuracy

 

Advertisements

About RudyB

Hobbyist

Discussion

10 thoughts on “Traincontroller 16 – Speed Profiling

  1. Hi

    And thanks for some great videos.

    Have done my speed profiling, only 1 thing

    I use n scale and in speed 120 brake in 50 cm works within 1/2 a cm
    But if i test with 60 then the brake is in 25cm (and it stops way early on the station)

    the marker is on 70 but the stop is after 44 cm. the train have speed limit of 60 in the station.

    Do you have any ide ?.

    All the bedst

    Erik Loeth

    Like

    Posted by Erik Loeth | August 15, 2015, 15:03
  2. Likewise Rudy, your videos have been inspirational to me taking up the TC mantle for myself (over the iTrain setup I have spent last 5 years mastering)…………….
    One thing I would like to expand on a bit is with speed profiling I have adopted technique of profiling my locos on their own (not with any coaches/wagons attached), simply because for some of my ‘trainsets’ I will eventually be swapping engines and rolling stock around and I assumed that one had to profile just the locos, and once you makeup the trainsets within TC the software would adjust the stopping distances taking into account the loco speed, block brake/stop markers assigned, and length/weight of wagons/coaches that one creates within the trainset option? I note you have chosen to profile the complete trainset Rudy? I know you have a direct line to Mr Freiwald – is this the way I should have done my profiling?

    Or have I got all of this wrong??……

    Like

    Posted by Alf King | July 28, 2015, 12:16
    • Hi Alf. I profiled the Intercity trains with their wagons on, cause they will not change over time.

      The cargo loco’s are profiled with an ‘average’ load. When later different trainsets are created with those loco’s, TC will indeed know the proper train length and weight and will adapt stop positions (when ‘middle’ or ‘end’ is in use) and acceleration and deceleration accordingly.

      The unknown factor is that with a heavy load the loco may have a lower speed than TC expects, or with less load a higher speed. When you turn on ‘load compensation’ in your DCC decoder, the effect will be minimal, but probably not zero. With a test I did, a loco without load stopped a few cm further down the track than the same loco with a heavy load. Speed profiling with an ‘average’ load minimizes this.

      Like

      Posted by RudyB | July 28, 2015, 13:33
      • Hi Rudy,

        By ‘average load’ do you mean actual wagons physically attached, or some software loading? ( I have seen in TC that you can apply some ‘virtual’ power and weight settings, although I have not been putting any values in these sections because I thought it too complicated for me at my stage of learning!

        Also by load compensation on my DCC decoder turning on I do not understand what you mean?…………….

        Regards,

        Alf King.

        Like

        Posted by Alf King | July 28, 2015, 14:18
      • Alf, I indeed meant the average amount of wagons. If in your future model railway operations a certain loco will pull between 3 and 10 wagons, I’d do the profiling with 6.

        DCC decoder ‘load compensation’ is used to keep the loco speed constant with different loads, or when running uphill. It also helps to run smooth at very low speeds. Please refer to your decoder’s user manual how to set it up. It may be switched on by default, but this may differ per decoder brand. It may also require some fine tuning of the PID control values on a per engine basis.

        Like

        Posted by RudyB | July 28, 2015, 15:44
      • I see where you are coming from with attaching half a load of coaches/wagons before profiling, however it is my desire to be able to uncouple about 3/4 of my locos from their ‘load’ in a reception sidings scenario, and then run the loco into engine facilities for coaling/watering after which it will be stabled in a multiple loco per siding shed where the blocks are very tight and thus will need centimetre precise stopping – hence my idea of loco only speed profiling…………..am I therefore going to have to put up with 4-5 cms. of inaccuracy when stopping on the mainline signals/platforms under normal full loads?

        Regards,

        Alf King.

        Like

        Posted by Alf King | July 28, 2015, 16:34
      • Hi Alf. In this scenario I’d opt to profile them with the full amount of wagons they will usually pull. Well profiled, and with their ‘brake correction’ tuned, their stop accuracy will be fine in all blocks on the main line. Without wagons, at the service / shelter blocks, they may now have a bit of overshoot. This is easily corrected by changing the brake ramp and stop position of those blocks a bit. Speeds will probably be low here so the differences will be little anyhow. And their reproduceability will still be great.

        Of course they can also be profiled with zero wagons. You’ll probably still need to fine tune the stop positions in the shelter, because of the narrow space. But now you may also need to check all blocks on the main line.

        Anyhow … in both cases I’d still feel comfortable using just one sensor per block.

        Like

        Posted by RudyB | July 28, 2015, 19:04
      • Okay thanks Rudy I will need to do a bit more ‘playing around’ with speed profiling my locos/train sets so I get the setup I desire!

        Regards,

        Alf King.

        Like

        Posted by Alf King | July 29, 2015, 15:42
  3. it is always a great pleasure to follow your videos – lots of inspiration! Keep it up, please!

    Like

    Posted by Michael Schønwandt | July 26, 2015, 14:45

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: