Modelica.Mechanics.Translational.Sources

Information

This package contains ideal sources to drive 1D mechanical translational drive trains.

Package Content

Name	Description
Position	Forced movement of a flange according to a reference position
Speed	Forced movement of a flange according to a reference speed
Accelerate	Forced movement of a flange according to an acceleration signal
Move	Forced movement of a flange according to a position, velocity and acceleration signal
Force	External force acting on a drive train element as input signal
Force2	Input signal acting as torque on two flanges
LinearSpeedDependentForce	Linear dependency of force versus speed
QuadraticSpeedDependentForce	Quadratic dependency of force versus speed
ConstantForce	Constant force, not dependent on speed
ConstantSpeed	Constant speed, not dependent on force
ForceStep	Constant force, not dependent on speed

Modelica.Mechanics.Translational.Sources.Position

Information

The input signal s_ref defines the reference position in [m]. Flange flange_b is forced to move relative to the support connector according to this reference motion. According to parameter exact (default = false), this is done in the following way:

1. exact=true
   The reference position is treated exactly. This is only possible, if the input signal is defined by an analytical function which can be differentiated at least twice. If this prerequisite is fulfilled, the Modelica translator will differentiate the input signal twice in order to compute the reference acceleration of the flange.
2. exact=false
   The reference position is filtered and the second derivative of the filtered curve is used to compute the reference acceleration of the flange. This second derivative is not computed by numerical differentiation but by an appropriate realization of the filter. For filtering, a second order Bessel filter is used. The critical frequency (also called cut-off frequency) of the filter is defined via parameter f_crit in [Hz]. This value should be selected in such a way that it is higher as the essential low frequencies in the signal.

The input signal can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
exact	true/false exact treatment/filtering the input signal
f_crit	if exact=false, critical frequency of filter to filter input signal [Hz]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component
s_ref	Reference position of flange as input signal [m]

Modelica.Mechanics.Translational.Sources.Speed

Information

The input signal v_ref defines the reference speed in [m/s]. Flange flange_b is forced to move relative to the support connector according to this reference motion. According to parameter exact (default = false), this is done in the following way:

1. exact=true
   The reference speed is treated exactly. This is only possible, if the input signal is defined by an analytical function which can be differentiated at least once. If this prerequisite is fulfilled, the Modelica translator will differentiate the input signal once in order to compute the reference acceleration of the flange.
2. exact=false
   The reference speed is filtered and the first derivative of the filtered curve is used to compute the reference acceleration of the flange. This first derivative is not computed by numerical differentiation but by an appropriate realization of the filter. For filtering, a first order filter is used. The critical frequency (also called cut-off frequency) of the filter is defined via parameter f_crit in [Hz]. This value should be selected in such a way that it is higher as the essential low frequencies in the signal.

The input signal can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
exact	true/false exact treatment/filtering the input signal
f_crit	if exact=false, critical frequency of filter to filter input signal [Hz]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component
v_ref	Reference speed of flange as input signal [m/s]

Modelica.Mechanics.Translational.Sources.Accelerate

Information

The input signal a in [m/s2] moves the 1D translational flange connector flange_b with a predefined acceleration, i.e., the flange is forced to move relative to the support connector with this acceleration. The velocity and the position of the flange are also predefined and are determined by integration of the acceleration.

The acceleration "a(t)" can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Source.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component
a_ref	Absolute acceleration of flange as input signal [m/s2]

Modelica.Mechanics.Translational.Sources.Move

Information

Flange flange_b is forced to move relative to the support connector with a predefined motion according to the input signals:

    u[1]: position of flange
    u[2]: velocity of flange
    u[3]: acceleration of flange

The user has to guarantee that the input signals are consistent to each other, i.e., that u[2] is the derivative of u[1] and that u[3] is the derivative of u. There are, however, also applications where by purpose these conditions do not hold. For example, if only the position dependent terms of a mechanical system shall be calculated, one may provide position = position(t) and set the velocity and the acceleration to zero.

The input signals can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Sources.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component
u[3]	Position, velocity and acceleration of flange as input signals

Modelica.Mechanics.Translational.Sources.Force

Information

The input signal "f" in [N] characterizes an external force which acts (with positive sign) at a flange, i.e., the component connected to the flange is driven by force f.

Input signal f can be provided from one of the signal generator blocks of Modelica.Blocks.Source.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component
f	Driving force as input signal [N]

Modelica.Mechanics.Translational.Sources.Force2

Information

The input signal "f" in [N] characterizes an external force which acts (with positive sign) at both flanges, i.e., the components connected to these flanges are driven by force f.

Input signal s can be provided from one of the signal generator blocks of Modelica.Blocks.Source.

Connectors

Name	Description
flange_a	(left) driving flange (flange axis directed in to cut plane, e. g. from left to right)
flange_b	(right) driven flange (flange axis directed out of cut plane)
f	Driving force as input signal [N]

Modelica.Mechanics.Translational.Sources.LinearSpeedDependentForce

Information

Model of force, linearly dependent on velocity of flange.
Parameter ForceDirection chooses whether direction of force is the same in both directions of movement or not.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
f_nominal	Nominal force (if negative, force is acting as load) [N]
ForceDirection	Same direction of force in both directions of movement
v_nominal	Nominal speed [m/s]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component

Modelica.Mechanics.Translational.Sources.QuadraticSpeedDependentForce

Information

Model of force, quadratic dependent on velocity of flange.
Parameter ForceDirection chooses whether direction of force is the same in both directions of movement or not.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
f_nominal	Nominal force (if negative, force is acting as load) [N]
ForceDirection	Same direction of force in both directions of movement
v_nominal	Nominal speed [m/s]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component

Modelica.Mechanics.Translational.Sources.ConstantForce

Information

Model of constant force, not dependent on velocity of flange.
Positive force acts accelerating.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
f_constant	Nominal force (if negative, force is acting as load) [N]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component

Modelica.Mechanics.Translational.Sources.ConstantSpeed

Information

Model of fixed velocity of flange, not dependent on force.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
v_fixed	Fixed speed (if negative, force is acting as load) [m/s]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component

Modelica.Mechanics.Translational.Sources.ForceStep

Information

Model of a force step at time .
Positive force acts accelerating.

Parameters

Name	Description
useSupport	= true, if support flange enabled, otherwise implicitly grounded
stepForce	Height of force step (if negative, force is acting as load) [N]
offsetForce	Offset of force [N]
startTime	Force = offset for time < startTime [s]

Connectors

Name	Description
flange	Flange of component
support	Support/housing of component