16   The ConstantSpeed Behavior


16.1 Configuration Parameters
16.2 Variables Published
16.3 The duration Parameter
16.4 The ConstantSpeed Objective Function


This behavior will drive the vehicle at a specified speed. This behavior merely expresses a preference for a particular speed. If other behaviors also have a speed preference, coordination/compromise will take place through the multi-objective optimization process. The following parameters are defined for this behavior:

16.1   Configuration Parameters    [top]


Listing 16.1 - Configuration Parameters Common to All Behaviors.

activeflag:A MOOS variable-value pair posted when the behavior is in the active state. Section 6.5.4.
condition:Specifies a condition that must be met for the behavior to be running. Section 6.5.1.
duration:Time in behavior will remain running before declaring completion. Section 7.2.6.
duration_idle_decay:When true, duration clock is running even when in the idle state. Section 7.2.6.
duration_reset:A variable-pair such as MY_RESET=true, that will trigger a duration reset. See Section 7.2.6.
duration_status:The name of a MOOS variable to which the vehicle duration status is published. Section 7.2.6.
endflag:A MOOS variable-value pair posted when the behavior has completed. Section 6.5.4.
idleflag:A MOOS variable-value pair posted when the behavior is in the idle state. Section 6.5.4.
inactiveflag:A MOOS variable-value posted when the behavior is not in the active state. Section 6.5.4.
name:The (unique) name of the behavior. Section 7.2.2.
nostarve:Allows a behavior to assert a maximum staleness for a MOOS variable Section 7.2.9.
perpetual:If true allows the behavior to to run even after it has completed. Section 7.2.7.
post_mapping:Re-direct behavior output normally to one MOOS variable to another instead. Section 7.2.4.
priority:The priority weight of the behavior. Section 7.2.3.
pwt:Same as priority.
runflag:A MOOS variable and a value posted when a behavior has met its conditions. Section 6.5.4.
spawnflag:A MOOS variable and a value posted when a behavior is spawned. Section 6.5.4.
templating:Turns a behavior into a template for spawning behaviors dynamically. Section 7.7.
updates:A MOOS variable from which behavior parameter updates are read dynamically. Section 7.2.5.

Listing 16.2 - Configuration Parameters for the ConstantSpeed Behavior.

ParameterDescription
basewidthThe width of the base, in meters per second, in the produced ZAIC-style IvP function. Section 16.4.
durationBehavior duration, in seconds. Mandatory configuration for this behavior. Section 16.3.
peakwidthThe width of the peak, in meters per second, in the produced ZAIC-style IvP function. Section 16.4.
speedThe desired speed of the vehicle, in meters per second.
summitdeltaThe height of the summit delta parameter in the produced ZAIC-style IvP function. Section 16.4.
speed_mismatch_varName of the MOOS variable indicating the present delta between the desired speed and the current speed. If left unspecified, no posting is made. Section 16.2.

Listing 16.3 - Example Configuration Block.

 Behavior = BHV_ConstantSpeed
 {
   // General Behavior Parameters
   // ---------------------------
   name         = const_spd_transit  // example
   pwt          = 100                // default
   condition    = MODE==TRANSITING   // example
   updates      = CONST_SPD_UPDATES  // example

   // Parameters specific to this behavior
   // ------------------------------------
            basewidth = 0.2          // default
             duration = 0            // default
                speed = 0            // default
   speed_mismatch_var = SPEED_DIFF   // example
            peakwidth = 0            // default
          summitdelta = 0            // default
 }

16.2   Variables Published    [top]


The behavior may be optionally configured to publish a variable indicating the discrepancy between the requested speed and the actual observed speed. The MOOS variable is named using the speed_mismatch_var parameter. This variable will only be published when the behavior is in the running state.

16.3   The duration Parameter    [top]


The duration parameter defined for all general behaviors, but for this behavior, specification is mandatory for safety reasons. The default if not specified is 0 seconds which will result in the behavior completing immediately. If no duration limit is desired, e.g., if the behavior is tied to another behavior or event via condition variables, then setting duration = no-time-limit will result in no time duration checks for this behavior.

16.4   The ConstantSpeed Objective Function    [top]


See Figure 8.1.

  • peakwidth: The width of the peak in meters/second in the produced objective function. The default is 0. See Figure 8.1 for more on the peak parameter used in the ZAIC tool for building IvP functions.
  • basewidth: The width of the base, in meters/second in the produced objective function. The default is 0.2. See Figure 8.1 for more on the basewidth parameter used in the ZAIC tool for building IvP functions.
  • summitdelta: The width of the base, in meters/second in the produced objective function. The default is 0. See Figure 8.1 for more on the summitdelta parameter used in the ZAIC tool for building IvP functions.

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