Tuesday, 14 July 2020 19:50

Speed Matching Locomotives

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using JMRI, Android Mobile Phone or Tablet & DCC++ Command Station

By Gary Broom

A step by step instruction for speed matching locomotives on the club speed matching PC and track.

Disclaimer:

This document has been produced to assist model train enthusiasts using dcc-enabled locomotives to fine-tune (speed match) their locomotives for consisting purposes.  The document is by no means exhaustive as different decoders have different settings that require differing approaches.  It is highly recommended that the current settings on each locomotive are recorded before making any changes so that the decoder can be restored to its previous state should it be necessary.

Requirements

1. 

Test track isolated from main layout

2. 

JMRI

3. 

DCC++ Command Station[1]

4. 

Android Mobile Phone/Tablet[2]

System Preparation

1. 

DCC++ Command Station

POWERED

2. 

Laptop

BOOTED

3. 

Decoder Pro App

STARTED

 

a. DCC++ Configuration Profile

SELECTED

 

b. Actions/Start WiThrottle Server

(note Server Settings e.g. 10.0.0.5:12090)

SELECTED

 

c. Actions/Start Web Server

SELECTED

4. 

Phone/Tablet

BOOTED

 

a. Engine Driver App

STARTED

 

b. Either

i. Connect to Discovered Servers; or

ii. Select from Recent Connections; or

iii. Enter settings from 7.b. above

CONNECT

Locomotives Preparation

Best results are achieved when:

1. 

Locomotives are identical[3]:

 

·       Manufacturer

·       Model

·       Decoder

2. 

Track is clean

3. 

For each Locomotive:

 
 

3.1 Locomotive wheels are clean

 
 

3.2 Clear Momentum:

See step 6.1

 

3.3. Clear Kick/Kick Start:

See step 6.2

 

3.4 Clear Dither:

See step 6.3

 

3.5 Clear BEMF:

See step 6.4

 

3.6 Clear Consist Addresses:

See step 7

 

3.7 Run each locomotive in forward and reverse for at least 5 minutes

Basic Speed Matching

Set DCC++ to Program Mode

In JMRI, Select Programming Track

For each Locomotive

4. 

In JMRI:

 

4.1.  Create a Roster Entry in JMRI

 

Save

Set DCC++ to Operate Mode

In JMRI, Select Programming on Main

  • Select each locomotive to be speed matched

Select the locomotive in the Roster

Select Program

5. 

Read the following full sheets for the locomotive

 

·       Basic

·       Motor

·       Basic Speed Control

·       Consist

 

5.1.  Record all the current settings

Clear Settings on Each Locomotive

6. 

On the Motor sheet, reset the following as available

 

6.1. 

Momentum

   

6.1.1 Set the Acceleration Rate to: 0

   

6.1.2 Set the Deceleration Rate to: 0

   

Note: Momentum will not be applied in speed matching

 

6.2.  Kick/Kick Start

   

6.2.1 Set the Torque Compensating Kick Rate to: 0

   

6.2.2 Set the Torque Compensating Kick Strength to: 0

   

6.2.3 Set Kick Rate to: 0

   

6.2.4 Kick Strength to: 0

   

6.2.5 Kick Start to: 0

   

6.2.6 Motor Drive Frequency to: 0

 

6.3. 

Dither

   

6.3.1 Set the Dither Frequency to: 0

   

6.3.2 Set Dither Amplitude to: 0

 

6.4. 

Back EMF

   

6.4.1 Set the Back EMF to: 0

This can be called a number of different names e.g.
- BEMF
- ‘… compensation for speed stabilization’

   

Note: Back EMF will not be applied in speed matching

 

6.5. 

Write changes on sheet

   

 

7. 

On the Consist page

 

7.1. 

Consist

   

7.1.1 Set the Advanced Consist Address to: 0

   

7.1.2 Write changes on sheet

Apply New Settings to Each Locomotive

8. 

On the Basic Speed Control & Motor sheets

 
 

The settings required on each sheet are trial and error

 

As you move between the Basic Speed Control and Motor sheets to change settings Write changes on sheet

 

Basic Speed Control sheet

 

Start Voltage (VStart)

 

8.1.  Adjust the VStart so that the locomotive starts moving at about 4%

   

or at least make all the locomotives start at about the same percentage)

   

Used to ensure smooth starting in conjunction with Kick/Kick Start and Dither

 

8.2.  Write changes on sheet

     
 

EITHER (if available)

 
 

Motor sheet

 
 

Kick/Kick Start/Torque Kick Rate (Kick Start)

 

8.3. 

Adjust the settings to make the locomotive start consistently

   

Kick Start helps to overcome motor and drivetrain friction (stiction) and can provide a little extra burst of power to get the locomotive started when speed step 1 is selected

   

Either

   

8.3.1 Kick Start from 1 to 8 (typically 2 to 4)

   

and

   

8.3.2 Total PWM Period/Motor Drive Frequency from 0 to 50 (typically 4 to 25)

   

or

   

8.3.3 Kick Strength/Torque Kick Strength from 0 to 50 (typically 4 to 25)

   

8.3.4 Write changes on sheet

     
 

OR (if available)

 

Dither

 

8.4. 

Adjust the Dither settings to make the locomotive start consistently

   

Dither applies extra voltage spikes at early speed steps to assist getting the locomotive moving smoothly

   

8.4.1 Dither Frequency from 1 to 10 (start with 5)

   

8.4.2 Dither Amplitude from 5 to 50 (start with 25)

   

8.4.3 Write changes on sheet

     
 

AND

 

Basic Speed Control sheet

 

Maximum Voltage (VHigh) & Midpoint Voltage (VMid)

 

8.5. 

Adjust the VHigh to 255

   

Note: Some suggest that 255 is too high a value, as it produces an unrealistic top speed and suggest 180 is a good value to use

 

8.6. 

Adjust the VMid half way between VStart and VHigh

 

8.7. 

Write changes on sheet

9. 

Release the locomotive from Engine Driver on the phone/tablet

10. 

Repeat steps 5 to 9 for each locomotive to be speed matched

     
     
     
     
       
  • Consist the Locomotives

11. 

In Engine Driver on the phone/tablet

 

11.1. 

Select each locomotive in turn to create an on the fly consist

 

11.2. 

Run the consist at maximum speed with the locomotives separated and see which locomotive is the slowest

 

11.3. 

Record which locomotive is the slower and this will be the Master.

   

·       All other locomotives to be in the consist will have their settings adjusted to match the Master

·       You should avoid adjusting the Master from this point, or you may have to redo the other locos to match the change/s you make

 

11.4. 

If consisting more than 2 locomotives, release the second fastest locomotive from the consist and remove it from the track.  This locomotive will be speed matched with the Master later after completing steps 12 to 15 for the fastest locomotive.  If you are confident enough, this step can be bypassed and move to step 12 for all the locomotives to be in the consist

For each locomotive to be speed matched

Consist this locomotive with the Master

12. 

In the JMRI roster, select a locomotive other than the Master

 

12.1. 

Select Programming on Main

 

12.2. 

Select Program

13

Select the Basic Speed Control sheet

   

13.1.1 Read the sheet

   

13.1.2 In Engine Driver, run the consist separated to confirm they start approximately together

   

13.1.3 If they don’t go back and restart at step 8

     
 

Minimum Speed

 

13.2. 

In Engine Driver, Run the locomotives at minimum speed (~8%) to see if they maintain the same separation

 

13.3. 

If they don’t

   

13.3.1 In JMRI (the window for the locomotive you are adjusting (Not the Master))

   

13.3.2 Adjust the VMin slightly until they maintain the same separation

   

(This is a balancing act, as this may alter the start setting.  You may have to compromise, not have the same start speed to maintain a similar running speed.)

   

13.3.3 Write changes on sheet

   

13.3.4 Repeat step 13.3 until they maintain the same separation

     
 

Mid Speed

 

13.4. 

In Engine Driver, run the locomotives separated at mid speed (~50%) to see if they maintain the same separation

 

13.5. 

If they don’t

   

13.5.1 In JMRI (the window for the locomotive you are adjusting (Not the Master))

   

13.5.2 Adjust the VMid until they maintain the same separation

   

13.5.3 Write changes on sheet

   

13.5.4 Repeat step 13.5 until they maintain the same separation

     
 

Max Speed

 

13.6. 

In Engine Driver, run the locomotives separated at max speed (100%) to see if they maintain the same separation

 

13.7. 

If they don’t

   

13.7.1 In JMRI (the window for the locomotive you are adjusting (Not the Master))

   

13.7.2 Adjust the VHigh until they maintain the same separation

   

13.7.3 Write changes on sheet

   

13.7.4 Repeat step 13.7 until they maintain the same separation

14. 

In Engine Driver, run the locomotives at different speeds, separated by a few centimetres to confirm separation is maintained

 

14.1. 

If they don’t

   

14.1.1 Repeat from the appropriate step as needed (steps 13.2 to 13.7)

15. 

Run the locomotive and the Master coupled and listen for any pushing, shoving, grinding, etc.

   

·       If satisfied with the results for that locomotive, move to step 12 for the next locomotive to be speed matched with the Master

16. 

When satisfied with all results for all locomotives to be speed matched, consist all the locomotives and run coupled and listen for any pushing, shoving, grinding, etc.

     
     
     

References:

Useful documents used in the compilation of this document

https://www.digitrax.com/tsd/KB902/scaleable-speed-stabilization-back-emf-in-digitrax/

https://ncedcc.zendesk.com/hc/en-us/articles/202449995-Fine-tuning-locomotive-operation

http://cmrci.info/wp-content/uploads/2017/06/FINE-TUNING-DCC-LOCOS-3.pdf

https://dccwiki.com/Kick_Start

https://ncedcc.zendesk.com/hc/en-us/articles/204241665-Locomotive-Speed-Matching-for-consisting

https://ncedcc.zendesk.com/hc/en-us/articles/200876489-What-is-PWM-

 

[1] Any command station can be used, but these instructions are tailored for DCC++

[2] The Apple WiThrotle app can be used, but these instructions are tailored for Engine Driver on Android

[3] Not required, but advantageous

Read 77 times Last modified on Sunday, 19 July 2020 08:49
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