Serge NOEL
264 lines
16 KiB
Plaintext
264 lines
16 KiB
Plaintext
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<title>JMRI: Warrant Speeds Help</title>
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<meta name="author" content="Pete Cressman">
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<meta name="keywords" content="JMRI help Modifying Warrant Speeds">
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<h1>Warrants: When Warrant Speeds Are Modified</h1>
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<p>Regardless of the throttle setting and intended track speed in the command script of a
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Warrant, track conditions may occur that require a restriction of the track speed. "Stop"
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aspects of signals, occupancy or allocation to another Warrant will deny permission to
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proceed. Other aspects of signals or block limits may require a reduction of speed. For an
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overview discussion of Warrants, see <a href="Warrant.shtml">Warrants</a>.</p>
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<h2>Warrants and Speed Restrictions</h2>
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<p>A train running under a Warrant must be aware of track conditions ahead. Signals may
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indicate reduced speed or permission to return to normal speed. Blocks may impose yard limit
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speed restrictions. Rogue trains may show up unexpectedly in the route. In our imagination,
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we can presume their detection means our warrant "engineer" sees a fuss. For each of these
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cases the warrant must look ahead, detect the need for a speed change and schedule the right
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time to do it - all the while making the change smoothly and completing it in prototypical
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fashion.</p>
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<h3>Configuring Speed Restrictions</h3>
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<p>For a warrant to detect a <strong>signaled speed change</strong> the signal must be
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configured in the Occupancy Block Tables. The Signal Table there configures the entrance
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Portal to the OBlock that the signal protects. The warrant then uses the signal system
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configured for the signal to define the aspect speed.<br>
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Likewise, <strong>Block Speeds</strong> are configured in the Occupancy Block Tables. A
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column in the OBlock Table allows you to choose an aspect speed that the Warrant will enforce
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before entering the block.</p>
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<p>When an <strong>occupancy</strong> sensor is activated ahead of the train on its route,
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the warrant will take note of it and bring the train to a stop before entering the block.</p>
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<p>Finally, you can manually instruct the Warrant to ramp down to a stop using the
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<strong>Halt</strong> control command. - or issue an emergency stop with the
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<strong>E-Stop</strong> command, Also, you can ramp up from a stop and resume the train's
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former speed with a <strong>Resume</strong> command. With the exception of E-Stop, all these
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unscripted speed changes are made smoothly.</p>
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<p>When a warrant ramps down a speed change due to a signal, block or rouge occupancy
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condition, That speed change remains in effect until the condition is removed. At that time
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the speed is ramped up to the previous "normal" speed. The precedence order is: rouge
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occupancy, signal aspect, block speed.</p>
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<h2>How Signal Aspects and Block Speeds Modify a Train's Speed</h2>
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When a speed restriction is required before entering a block, the speed change needs to begin
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at some point before entry.
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<p>When a Warrant is running and its train enters a block, it looks ahead to see if any speed
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changes are coming up. The look ahead distance must be adequate for the train to be able to
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stop should that be needed. The warrant calculates the look ahead distance to be what is
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needed to stop from its present speed. This distance may include several blocks. If a signal
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or block is encountered within this look ahead distance, and the aspect protecting the block
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indicates the speed must be restricted, then the warrant performs a "ramp down".</p>
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<p>When a speed restriction is lifted, the problem is much simpler. The warrant can
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immediately begin a "ramp up" upon entering the block.</p>
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<h3>A Note about Ramps</h3>
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When a warrant ramps up or down, it does it stepwise. In order for it to done smoothly in
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prototypical fashion, it depends on the following parameters:
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<ul>
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<li><strong>Ramp Step Time</strong> The number of milliseconds between making throttle
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setting changes.</li>
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<li><strong>Ramp Step Throttle Increment</strong> The initial throttle increment when
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increasing speed, or last increment when decreasing speed.</li>
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</ul>
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These are configured in Warrant Preferences. See <a href=
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"../../../apps/TabbedPreferences.shtml#Warrants">Warrant Preferences</a> for information
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about configuration of Warrant parameters.
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<h3>Parameters Needed for Look Ahead</h3>
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<p>Both the look ahead distance and the time when to begin the speed change require knowing
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the track speed. Thus to get the train to begin and end its speed changes at the proper
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points, and relating the throttle settings to the actual track speed, some crucial
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information is needed. Without such information a fast running engine may overrun the point
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where a speed change expects to be completed, or a slow running train may stop too far short
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of where it is expected.</p>
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<ul>
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<li>
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<strong>Distance</strong> the train must travel. <em>Your wild guess is better than any
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default.</em> <strong>Block Lengths</strong> are needed for distances. There is a length
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column in the OBlock Table. (Use menu <strong>Add Items -> Occupancy Blocks</strong>).
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Also the <strong>Paths</strong> column in the table opens its path tables. Each Path
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Table has a length column as well.
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<p>Likewise the menus <strong>Circuit Builder -> Add/Edit Circuit OBlock</strong> and
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<strong>Circuit Builder -> Add/Edit Circuit OPaths</strong> in Circuit Builder have
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text fields to enter lengths.</p>
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<p>Inches or centimeters may be used for all of these fields.</p>
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<p>When no block length is specified error messages are written to the console and you
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may have trains over-running their stopping points. It is <strong><em>highly
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recommended</em></strong> that path lengths be specified. If the paths within a block
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vary widely, path lengths should be set. Otherwise, path lengths are inherited from the
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block length.</p>
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</li>
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<li><strong>Layout Scale</strong> is needed for distances when speed is expressed as Mph or
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Kmph. This is set from a drop down box at the
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<strong>Edit->Preferences->Warrants</strong> menu of the main PanelPro window</li>
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<li>
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<strong>Track Speed</strong> of the train. A correlation of the throttle settings to the
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actual speed of the train on the layout must be known. For this two methods are used.
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<ul>
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<li>A first approximation is the <strong>"Throttle Setting/Speed Factor"</strong> value
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at Edit->Preferences->Warrants. When used, this factor is a linear multiplier to
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relate throttle setting to track speed. <strong>Note</strong> this is a global value
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for all of the locomotives in your fleet and over the entire speed range of each.
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Obviously this may not function optimally. However, it could be satisfactory for your
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tastes.</li>
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<li>For more precision a <strong>Speed Profile</strong> can be used for each
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locomotive. These provide track speed values that give more accurate calculations for
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time and distances. The Speed Profiler is found at <strong>Roster->Speed
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Profiling</strong> is used to create a speed profilr for each locomotive or
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consist.</li>
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</ul>
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</li>
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</ul>
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<h3>Getting Speed Profiles for your Trains</h3>
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<p>Speed Profiles are maintained in the Roster and there is a tool that will create them at
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<strong>Roster->Speed Profiling</strong> The tool can measure a track speed for each step
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in the throttle. However, interpolation and extrapolation have been implemented so it is not
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necessary to go to such detail. Five or six data points well distributed over the throttle's
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range is quite sufficient.</p>
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<h2 id="autoSpeedProfile">Automatic Speed Profiling</h2>
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<p>Since <strong><em>Release 4.9.2</em></strong> track speed of an engine/consist is measured
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when that address is used for running a Warrant. A data point is recorded whenever a path
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with known length is traversed with a known throttle setting. The data is kept for the layout
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session and when the session ends this Session Speed Profile can be merged into the Roster
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Speed Profile. Warrant Preferences provides choices for how you may want to manage the
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merging of Roster Speed Profiles. See <a href=
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"../../../apps/TabbedPreferences.shtml#Warrants">Warrant Preferences</a> for how you want to
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manage the end of session behavior. The default is you are prompted for how you want to treat
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each Session Speed Profile.</p>
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<h3>Track Speeds for Throttle Settings</h3>
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<p>If you used the Roster Speed Profiling tool most likely you ran an engine running light
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over a straight level track. With Warrant dynamic speed profiling, measurements are made over
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straight level track, but also upgrade, down grade, curved gently or severely, running light
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or pulling 30+ cars. <em>The track speeds are not going to be all the same for a given
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throttle setting.</em> When merging, new values are averaged with the old, with the intention
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of a composite speed profile that reflects average use.</p>
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<p>At some point, merging this data may make a speed profile that is not monotonic
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increasing. (Certainly increasing throttle setting increases speed). When this anomaly occurs
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the speed profile is displayed and the cells where the profile is not monotonic are marked in
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red. You may edit the table to correct it. Whether to do this editing is your choice. Perhaps
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it is best to let the anomalies remain and have the profile resolve itself - or do the
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editing after letting more values accumulate. Of course, a value resulting when the train was
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shorted or was dragging a derailed car should be deleted.</p>
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<h4>Editing a Speed Profile</h4>
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<p>When given the opportunity to edit, either the value of a single cell can be changed or an
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entire row deleted. Replacing a value with 0.0, causes that speed step to be ignored. When a
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track speed is needed for a throttle setting there, an interpolated value is used. If values
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in both directions are 0.0, the row might as well be deleted.</p>
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<h2>Aspect Speed Table and its Interpretation</h2>
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<p>Speeds are named in the aspects.xml files that signal masts use in the Signal Mast System.
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These speed names are also used in the Blocks tables. To control train speed, values must be
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assigned to these speed names. The Aspect Speed Map found at
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<em>>Edit->Preferences->Warrants</em> provides a value for each named speed. It is
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up to the user to assign a value to the name and a meaning to the value. On the Warrant
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Preferences Pane are four radio buttons to assign meaning to the values entered into the
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Speed Map Table.</p>
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<p>When a signal or block defines an aspect speed by name, the warrant looks up the name in
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the Aspect Speed Table and uses the value there tp modify the speed of the train.</p>
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<ul>
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<li><strong>Percent of Normal</strong> - The value is a percentage of the recorded
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("Normal") speed. <em>Any speed name that is restrictive must have a values less than
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100.</em> The warrant reduces the "Normal" scripted speed by this value as a
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percentage.</li>
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<li><strong>Percent of Full Throttle</strong> - The value is an absolute throttle setting
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expressed as a percentage of full throttle. <em>All speed names must be a number between 0
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and 100.</em> The warrant sets the modified speed to be the value as a percentage of the
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full throttle setting.</li>
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<li><strong>Miles per hour</strong> - The value is the scale speed expressed as miles per
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hour. <em>All speed names must be expressed as miles per hour.</em> The warrant, using
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layout scale, converts the value to track speed and finds the corresponding throttle
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setting for the modified speed.</li>
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<li><strong>Kilometers per Hour</strong> - The value is the scale speed expressed as
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Kilometers per hour. <em>All speed names must be expressed as kilometers per hour.</em> The
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warrant, using layout scale, converts the value to track speed and finds the corresponding
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throttle setting for the modified speed.</li>
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</ul>
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<p>To sum up; if you are not fussy about being prototypical and always want to see speed
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change when signals are passed, use "Percent of Normal". If you have calibrated a sufficient
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Speed Profile for each of your engines you can use either of the last two speed
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interpretations which express throttle setting in terms of scale speed.</p>
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<h3>The Signal Head Appearance Table</h3>
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<p>If signal heads are used on the layout, their appearances can be mapped to the speed names
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of signal masts in this table on the Warrant Preferences pane. For the above, the warrant
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maps appearance name to speed name to value.</p>
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<p>One use of this is to use Virtual Signal Heads to dynamically influence the behavior of
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warrants. The appearance of these Signal Heads can be set either by panel icons or Logix.
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Since there are 8 possible Signal Head appearances, additional speed names can be created so
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a unique speed can be made for each appearance.</p>
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<h3>Editing the Speed Map Table</h3>
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<p>Rows can be added or deleted. The default speed map has the names "Fifty" and "Sixty".
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These names only appear in signal mast systems for UP-2008 and BNSF-1996, so they can safely
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be deleted if you do use these signal systems. You only need but <em>must have</em> all the
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speed names that appear in the signal system you have configured for your layout.</p>
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<p>If you add a new speed name for a signal head appearance, then add a row for that name in
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the Signal Map Table.</p>
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<h2>Block Speed Names</h2>
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<p>A speed name can be set for each Block by selecting a name from the <strong>Speed
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Notch</strong> column of the OBlock Table. One use of this feature could be to enforce a yard
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limit speed. Unlike signal speed names, block speed names are bi-directional.
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<strong>NOTE:</strong> To return a Warrant's speed to normal when leaving a yard limit, the
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speed names of the OBlocks on either side of the yard block should set to "Normal". Use care
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when combining this feature with signals to avoid providing conflicting speed change
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messages.</p>
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<p>To unset an OBlock speed name, choose the blank setting from the <strong>Speed
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Limit</strong> column. As with the absence of a signal, when there is no speed name the
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Warrant continues at its current speed.</p>
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<p>Back to <a href="Warrant.shtml">Warrants Help</a>.</p>
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