/SENSOR/DIST

Block Format Keyword Describes a sensor which is used to activate or deactivate an object according to distance.

Format

Field	Contents	SI Unit Example
`sens_ID`	Sensor identifier. (Integer, maximum 10 digits)
`unit_ID`	Optional unit identifier. (Integer, maximum 10 digits)
`sens_title`	Sensor title. (Character, maximum 100 characters)
`T`_delay	Time delay. (Real)	$[s]$
`node_ID`₁	Node identifier 1. (Integer)
`node_ID`₂	Node identifier 2. (Integer)
`D`_min	Distance minimum. Default = -1E30 (Real)	$[m]$
`D`_max	Distance maximum. Default = 1E30 (Real)	$[m]$
`T`_min	Minimum time duration to satisfy criterion. (Real)	$[s]$
`Dflag`	(Optional) Deactivation flag. (Integer)

Sensors can be used to activate airbags, imposed forces, pressures, and fixed velocities.
Sensors can be used to activate or deactivate these elements: brick, quad, shell, truss, beam, spring or 3N Shell with /ACTIV.
For Sensor type DIST, nodal distance N₁N₂ between node_ID₁ and node_ID₂ is defined as:(1)
$D_{\min} < |N_{1} N_{2}| < D_{\max}$

Activation criterion is reached if $|N_{1} N_{2}| > D_{\max}$ or $|N_{1} N_{2}| < D_{\min}$ and sensor timer is set (T_crit). The criterion must be satisfied for the duration of time interval T_min, otherwise the sensor time counter T_crit is reset once again. Then the sensor is activated after an additional time delay.(2)
$T_{a c t i v a t i o n} = T_{c r i t} + T_{m i n} + T_{d e l a y}$
If deactivation flag Dflag = 1, the sensor may be deactivated once again when the nodal distance falls again between the values $D_{\min} < |N_{1} N_{2}| < D_{\max}$ . Further reactivations and deactivations become possible depending on the same criteria.