Motions
Wall boundary particles can be moved during a simulation with a prescribed motion. Depending on the type of the imposed motion, different values must be defined.
Background
The principal concept is to define a motion for a specific phase and apply this motion within a given time-frame. Similar to the phases, different motions are defined consecutively. Using this approach it is possible to combine different motions for one and the same phase at different times. Thus, it is possible to realize more complex motions with a combination of existing motion types. However, if a special motion is required it is worth it to contact the nanoFluidX support. It might be easier/faster to improve the available motion types for special customer requests.
Before proceeding with the glossary of related commands for the motion setup, there is an important disclaimer that has to be made. Given the current structure of nanoFluidX, there are clear rules regarding which motions can be combined, executed in sequence or modified upon restart.
Motion combinations that are well-behaved and accounted for:
- A - impose_vel+impose_vel (allowed for all)
- C - rotate_axis+rotate_axis (allowed if only different in time and freq, other differences may cause unknown behavior)
- D - planetary+planetary (allowed if only different in time and freq)
- E - conrod+conrod (allowed if only different in time and freq)
- F - position_file+position_file (not allowed)
- G - trn_osc+trn_osc (allowed if only different in time and freq)
- H - passive_rigid_body+passive_rigid_body (not allowed)
- K - C+A (allowed)
- L - D+A (allowed)
- M - E+A (not allowed, unknown behavior)
- N - C+D or D+C (not allowed, unknown behavior)
- O - A+C (allowed, A is discarded)
- P - A+D (allowed, A is discarded)
- Q - F+Others or Others+F (not allowed, A+F/F+A may behave correctly though)
- R - G+Others or Others+G (not allowed, unknown behavior)
- S - H+Others or Others+H (not allowed)
Restart/continue (recon) clarifications:
- Motions should not be removed from a restart/continue
- Motions may be added to the restart/continue
- If a motion has to have a transition at the restart time, one may modify the ending of the first motion and add the second one from the start of the restart/continue time.
- Example for restart/continue, clean run:
- motion1{ROTATE_AXIS; start 0; end 10}
- Example for restart/continue from 5, add a second motion:
- motion1{ROTATE_AXIS; start 0; end 5}
Commands
motions
{
motion
{
phase_motion 1
motion_type IMPOSE_VEL
impose_vel "0. 0. 1."
tstart_prescribe 0.
tend_prescribe 2.
t_damping 0.5
}
motion
{
phase_motion 2
motion_type ROTATE
freq_unit RPM
rot_freq "50. 0. 0."
rot_freq_init "0. 0. 0."
rot_cntr "0. 0. 0."
tstart_prescribe 0.
tend_prescribe 3.
t_damping 0.5
max_dist 0.1
}
motion
{
phase_motion 2
motion_type ROTATE_AXIS
freq_unit Hz
rot_axis "1. 0. 0."
rot_axis_freq 50.0
rot_axis_freq_init 0.0
rot_cntr "0. 0. 0."
tstart_prescribe 0.
tend_prescribe 3.
t_damping 0.5
max_dist 0.1
}
motion
{
phase_motion 1
motion_type POSITION_FILE
positionFile motionfile.txt
rot_cntr "0. 0. 0."
isOrientation false
tstart_prescribe 0.
tend_prescribe 1.
}
motion
{
phase_motion 3
motion_type PLANETARY
freq_unit Rad/s
orbit_cntr "0.0 0.0 0.0"
orbit_radius 0.06
year_rotationVec "1.0 0.0 0.0"
year_frequency 1.73
year_frequency_init 0.0
day_rotationVec "1.0 0.0 0.0"
day_frequency 6.11
day_frequency_init 0.0
initial_centerOfDayRotation "0.58 0.22 0.34"
tstart_prescribe 0.0
tend_prescribe 1.0
max_dist 0.1
}
motion
{
phase_motion 3
motion_type OSCILLATE
freq_unit Hz
oscill_ampl "0.0 0.07 0.0"
oscill_freq_init "0.0 0.0 0.0"
oscill_freq "0.0 50.0 0.0"
oscill_phaseshift "0.0 90.0 0.0"
tstart_prescribe 0.0
tend_prescribe 0.0
t_damping 0.0
}
motion
{
motion_type CONROD
phase_piston 5
phase_conrod 7
freq_unit Rad/min
crankshaft_rot_freq -100.0
crankshaft_rot_freq_init 0.0
crankshaft_axis "0.0 1.0 0.0"
crankshaft_cntr "1.15 0.11 0.6"
crankshaft_normal "0.2 0.0 -0.9"
crankshaft_phaseshift 0.0
crankshaft_rad 0.12
conrod_length 0.15
piston_offset 0.01
tstart_prescribe 0.0
tend_prescribe 1.0
t_damping 0.1
}
motion
{
phase_motion 1
motion_type PASSIVE_RIGID_BODY
freq_unit Rad/s
init_CoM "1.0 1.0 1.0"
mom_inert_diag "1.0 1.0 1.0"
mom_inert_offdiag "0.0 1.0 0.0"
body_mass 10
init_vel "0.0 0.0 1.0"
init_angvel "0.0 0.0 0.5"
mom_principal_ax_x_i "1.0 0.0 0.0"
mom_principal_ax_y_i "0.0 1.0 0.0"
mom_principal_ax_z_i "0.0 0.0 1.0"
prbcon_ax_x_i "1.0 0.0 0.0"
prbcon_ax_y_i "1.0 0.0 0.0"
prbcon_ax_z_i "1.0 0.0 0.0"
prbcon_linlck_c "1.0 1.0 0.0"
prbcon_anglck_c "1.0 1.0 1.0"
prbcon_linspr_k_c "5.0 0.0 0.0"
prbcon_linspr_p_c "0.0 0.0 0.0"
prbcon_angspr_k_c "0.0 0.0 8.0"
prbcon_lindmp_c_c "0.0 0.0 0.0"
prbcon_angdmp_c_c "0.0 0.0 0.0"
prbcon_angspr_p_c "0.0 0.0 0.0"
prbcon_linlim_pls_c "2.0 0.0 -3.0"
prbcon_linlim_mns_c "1.0 0.0 -2.0"
prbcon_anglim_pls_c "2.0 0.0 -3.0"
prbcon_anglim_mns_c "1.0 0.0 -2.0"
prbcon_pt_i "0.0 0.0 0.0"
prbcon_ax_hinge_c "0.0 1.0 0.0"
prbcon_cnstfrc_c "3.0 -1.0 0.0"
prbcon_cnsttrq_c "1.0 5.0 -2.0"
prbcon_linvel_ctoi true
prbcon_linvel_a_c "1.0 0.0 0.0"
prbcon_linvel_f_c "prb_tlvs.txt"
prbcon_angvel_ctoi true
prbcon_angvel_a_c "1.0 0.0 0.0"
prbcon_angvel_f_c "prb_alvs.txt"
}
motion
{
motion_type DOUBLE_ROLLER_1DOF
dr1dof_bod_phs "1 2 3"
dr1dof_frw_phs "4 5 6 7"
dr1dof_bck_phs "8 9"
dr1dof_drvr_frwbck reardrive
dr1dof_bod_cgpnt "5.0 1.0 2.0"
dr1dof_frw_axpnt "0.0 1.0 2.0"
dr1dof_bck_axpnt "0.0 2.0 3.0"
dr1dof_whl_rd 5.0
dr1dof_vel_init 0.0
dr1dof_vel 0.0
dr1dof_time_start 0.0
dr1dof_time_rampup 0.0
dr1dof_time_rampdn 0.0
dr1dof_time_end 0.0
dr1dof_rd_pth_ply 2.0
dr1dof_rd_pth_file somefile.someextension
dr1dof_tvs_file /path/to/tvsfile.txt
}
motion
{
motion_type DOUBLE_ROLLER_3DOF
dr3dof_bod_phs "1 2 3"
dr3dof_frw_phs "4 5 6 7"
dr3dof_bck_phs "8 9"
dr3dof_drvr_frwbck reardrive
dr3dof_bod_cgpnt "5.0 1.0 2.0"
dr3dof_bod_ms 730
dr3dof_bod_iyy 2460
dr3dof_frw_ms 46
dr3dof_bck_ms 46
dr3dof_frw_ks 17500
dr3dof_bck_ks 17500
dr3dof_frw_cs 1000
dr3dof_bck_cs 1000
dr3dof_frw_axpnt "0.0 1.0 2.0"
dr3dof_bck_axpnt "0.0 2.0 3.0"
dr3dof_whl_rd 5.0
dr3dof_bod_eqlb "0.0 0.0"
dr3dof_bod_reffrm false
dr3dof_ptch_mod false
dr3dof_bod_z_1dofcon "0 0.04 -0.04"
dr3dof_bod_a_1dofcon "0 0.001 -0.001"
dr3dof_fld_react_freq 1
dr3dof_vel_init 0.0
dr3dof_vel 0.0
dr3dof_tvs_file tvs_file.txt
dr3dof_time_start 0.0
dr3dof_time_rampup 0.0
dr3dof_time_rampdn 0.0
dr3dof_time_end 0.0
dr3dof_rd_pth_ply 2.0
dr3dof_rd_pth_file rd_pth_file.txt
}
...
}Definitions
Important: ROTATE and ROTATE_AXIS motion
types have the same function, albeit slightly different definitions. In
ROTATE_AXIS the rotational frequency is separated from the
rotational axis definition, while in ROTATE the axis vector
definition is multiplied by the frequency scalar. Both functions can be used. You
can choose which one is more convenient.
| Command | Contents | SI Unit Example |
|---|---|---|
| phase_motion | The following motion is applied to this phase number Options
Note: The type of these phases needs to be
MOVINGWALL or WALL. The
WALL phase types can only be assigned
IMPOSE_VEL and ROTATE_AXIS
motion types, in which case the velocities on these
WALL phases will be set as a velocity
boundary condition, in accordance with the specified
motion.
|
|
| motion_type | The type of the imposed motion Options
|
|
| freq_unit | Defines which unit will be used to specify rotational frequencies
for this motion Options
Default = Hz (same as rotations per second) except for PASSIVE_RIGID_BODY (Rad/s). |
|
| impose_vel | For motion_type = IMPOSE_VEL.
This is the imposed velocity of the moving wall particles defined as
a vector in X, Y and directions. Default = “0. 0. 0” |
|
| tstart_prescribe / tend_prescribe | Within the time-frame tstart_prescribe and
tend_prescribe, the velocity of the moving
wall particles is set to
impose_vel. Note: tend_prescribe
should be greater than or equal to
tstart_prescribe.
Default = 0.0 |
|
| t_damping | In SPH, impulsively started motions always cause pressure
oscillations since in a weakly-compressible method disturbances can
only travel at the numerical speed of sound. To alleviate this
effect it is possible to slowly increase the imposed motion starting
at tstart_prescribe for an interval of
t_damping. Tip: For example:
Default = 0.0
Note: t_damping
will be renamed to t_ramping in the
future, as it describes better the effect it has in the
simulation. The exact version wherein this switch will take
place is unknown, but will be appropriately announced via
Release Notes.
|
|
| rot_freq | For motion_type= ROTATE.
Rotational frequency vector [rot/s] specified as a vector with x, y,
and z-axis components. Default = “0. 0. 0” |
|
| rot_freq_init | For motion_type= ROTATE. This
case is a restart and you can specify initial frequency of rotation.
With this command you can start from, for example, 1000 RPM to an
arbitrary RPM. Default = “0. 0. 0” |
|
| rot_cntr | For motion_type= ROTATE and
ROTATE_AXIS. Center-of-rotation for the
rotational motion. Note: For a body that is rotating around its axis
of symmetry such as a gear, the center of rotation needs to lie
anywhere along the specified direction of the rotation vector.
For example, on the axis of the gear.
Default = “0. 0. 0” |
|
| rot_axis | For motion_type= ROTATE_AXIS.
Defines the axis of rotation of a body. Default = “0. 0. 0” |
|
| rot_axis_freq | For motion_type= ROTATE_AXIS.
Defines the frequency of rotation of the body. Default = “0. 0. 0.” or 0.0 (depending on the motion type) |
|
| rot_axis_freq_init | For motion_type= ROTATE_AXIS.
In case it is a restart, you can specify initial frequency of
rotation. This allows you to start from 1000 RPM to an arbitrary
RPM, for example. Default = 0.0 |
|
| positionFile | The name of the file that contains the prescribed motion
information Note: For more information, refer to the POSITION_FILE
section.
Related Commands
|
|
| rot_cntr | If this command is defined in the configuration file, it will use
this point as the center of rotation and it will move it as
specified by the position text file. Attention: If this
command is not specified, the code will rotate the body around
the calculated center of mass.
Related Commands
|
|
| isOrientation | Options
Related Commands
|
|
| orbit_cntr | Defines the planetary carrier center location. It is sufficient that it lies on the year rotation axis, since the year rotation axis is specified separately. | |
| orbit_radius | Distance between the orbit_cntr and the planet gear center (initial_centerOfDayRotation). | |
| year_rotationVec | Axis of year rotation. Can be defined as an arbitrary vector (it will be normalized automatically). | |
| year_frequency | Frequency of the year rotation | [rot/s] |
| year_frequency_init | In case it is a restart, you can specify initial year frequency
of rotation. This allows you to start from 1000 RPM to an arbitrary
RPM, for example. Default = “0. 0. 0.” or 0.0 (depending on the motion type) |
|
| day_rotationVec | Axis of day rotation. Can be defined as an arbitrary vector (it will be normalized automatically). | |
| day_frequency | Frequency of the day rotation | [rot/s] |
| day_frequency_init | In case it is a restart you can specify initial day frequency of
rotation. This allows you to start from 1000 RPM to an arbitrary
RPM, for example. Default = “0. 0. 0.” or 0.0 (depending on the motion type) |
|
| initial_centerOfDayRotation | Initial coordinates of the planetary gear for which the motion is defined. |
Oscillatory motion is based on a cosine trigonometric function and it is defined by
three parameters: oscillation amplitude, frequency and initial phase shift. It is
only translatory oscillating motion, for example, piston motion, not rotational, for
example, wiper motion.
| Command | Contents | SI Unit Example |
|---|---|---|
| oscill_ampl | Amplitude of the oscillatory motion | [m] |
| oscill_freq_init | Initial frequency of the oscillating motion. When the case is a restart, you can specify initial frequency of oscillation. For example, you can start from 1000 Hz and go to an arbitrary oscillation frequency. | |
| oscill_freq | Frequency of the oscillating motion | |
| oscill_phaseshift | Initial phase shift along the cosine function, for example, which defines the initial piston position. | [deg] |
CONROD Commands
The commands below are related to the CONROD type of motion. Given that the motion is
rather complex, refer to the CONROD section for
more information.
| Command | Contents | SI Unit Example |
|---|---|---|
| phase_piston | Defines which piston phase belongs to a particular
conrod Note: CONROD motion is the only motion that defines
the motion for two phases at a time – the piston and the
conrod phase.
|
|
| phase_conrod | Defines which conrod phase belongs to a particular
piston Note: CONROD motion is the only motion that defines
the motion for two phases at a time – the piston and the
conrod phase.
|
|
| crankshaft_rot_freq | Rotational frequency of the crankshaft (needed for proper
conrod/piston motion definition) Note: The actual crankshaft
motion is defined separately by ROTATE or
ROTATE_AXIS.
|
[rot/s] |
| crankshaft_rot_freq_init | Initial rotational frequency of the crankshaft in case of a restart | [rot/s] |
| crankshaft_axis | Defines the axis of the crankshaft (necessary for proper conrod/piston motion definition) | |
| crankshaft_cntr | Point belonging to the crankshaft axis (lying on the crankshaft axis) | |
| crankshaft_normal | Cylinder-parallel vector in a direction pointing closer to
the crankshaft axis unit vector. In other words, this is a
vector parallel to the piston's line of movement and pointing in
the direction of piston movement when moving away from
TDC. Tip: Be aware of the sign, try the opposite direction
if it is not working.
|
|
| crankshaft_phaseshift | Defines the initial angular position (phaseshift) of the
particular conrod/piston pair with respect to the
crankshaft_normal direction. The reference point for this angle is when the crankshaft is parallel to the cylinder and the piston is closer to TDC. The sign is with respect to crankshaft axis. |
[deg] |
| crankshaft_rad | Defines the radius of the crankshaft; the distance between the crankshaft axis and the conrod-crankshaft connection center. | [m] |
| conrod_length | Defines the length of the conrod; the distance between the conrod-crankshaft and conrod-piston connections. | [m] |
| piston_offset | Positive or negative offset in the direction of crankshaft_axis x crankshaft_normal (cross product). | [m] |
| max_dist | Provides a maximum radius of the geometry with the center of
the circle being on the rotation axis. In combination with the
other motion definitions, this helps calculate the reference
velocity. This value is automatically exported by the SimLab pre-processor. Tip: It is recommended that
you specify ref_vel explicitly and avoid
using the fall back option of automatic
ref_vel calculation.
|
[m] |
PASSIVE_RIGID_BODY Commands
The options below pertain only to the PASSIVE_RIGID_BODY motion. Use
these options to add linear and torsional spring forces to the rigid body, as well
as linear and angular constraints on the motion, which enables a number of new
applications. For more information, refer to the PASSIVE_RIGID_BODY section.
Note: There are no
rigid-rigid body interactions or rigid-wall interactions in nanoFluidX, therefore collisions and impacts among
multiple bodies is not possible.
| Command | Contents | SI Unit Example |
|---|---|---|
| body_mass | If the MOVINGWALL phase is a passive rigid
body, you need to prescribe the mass of the body, as the
discretized geometry based on particles that may not reflect the
real geometry. For example, you can create just the hull of a ship and assign specific masses to the body, as if the geometry was a full ship. Note: This option recalculates
the density of each particle, and the rho_0 of this phase is
ignored.
|
|
| init_CoM | Initial location of the center of mass Related Commands
|
|
| init_vel | Initial linear velocity of the rigid body Note: This is a
vector value.
|
[m/s] |
| init_angvel | Initial angular velocity of the rigid body Note: This is a
vector value.
|
[rad/s] |
| mom_inert_diag | Diagonal components of the moment of inertia around the
global X, Y and Z axes. Tip: For more information,
refer to the PASSIVE_RIGID_BODY
section).
The corresponding values refer to XX, YY and
ZZ components. |
[kg*m2] |
| mom_inert_offdiag | Off-diagonal components of the moment of inertia around the
global X, Y and Z axes. Tip: For more information,
refer to the PASSIVE_RIGID_BODY
section).
The corresponding values refer to XY, XZ and
YZ components. |
[kg*m2] |
|
Important: For the following commands, if the
inertial reference frame does not align with the global
axes, for example, if the moment of inertia needs to be
defined around the principal axes of the body, then
additional information must be supplied to define the
principal axes. To do this you must define any two unit
vectors of the principal axes and a third vector is
calculated by the code. The coordinates must be specified
with respect to the global axes.
|
||
| mom_principal_ax_x_i | Unit vector in the X-direction of the principal axis. This is a vector value, for example “1.0 0 0” implies the principal axis is aligned with the global X-axis in this case. | |
| mom_principal_ax_y_i | Unit vector in the Y-direction of the principal axis. This is a vector value, for example “0.0 1.0 0” implies the principal axis is aligned with the global Y-axis in this case. | |
| mom_principal_ax_z_i | Unit vector in the Z-direction of the principal axis. This is a vector value, for example “0 0 1.0” implies the principal axis is aligned with the global Z-axis in this case. | |
|
Important: With the above rigid body related
commands, you can simulate a freely moving rigid body that
is interacting with the fluid. However, additional options
are available to constrain motion and add linear or
torsional springs with the following commands. Unless
another coordinate system is defined for the constraints
(constraint reference frame), the code assumes constraint
alignment with the global axes. If this is not the case, if
some of the constraints are under angles, then the
constraint reference frame must be defined by specifying any
two unit vectors. The coordinates must be specified with
respect to the global axes.
|
||
| prbcon_ax_x_i | Unit vector in the X-direction of the constraint axis. This is a vector value, for example “1.0 0 0” implies the X-axis of the constraint frame is aligned with the global X-axis in this case. | |
| prbcon_ax_y_i | Unit vector in the Y-direction of the constraint axis. This is a vector value, for example “0.0 1.0 0” implies the Y-axis of the constraint frame is aligned with the global Y-axis in this case. | |
| prbcon_ax_z_i | Unit vector in the Z-direction of the constraint axis. This is a vector value, for example “0 0 1.0” implies the Z-axis of the constraint frame is aligned with the global Z-axis in this case. | |
|
Important: Once the constraint reference frame has
been defined, you can proceed to defining the constraints
themselves. If you want to lock linear or angular
degrees-of-freedom you can use the following.
|
||
| prbcon_linlck_c | This is a vector value that defines which of the linear
motions will be locked. Options
Tip: For example, “1.0 0 0” locks the
linear motion in the X-direction of the constraint
frame.
|
|
| prbcon_anglck_c | This is a vector value that defines which of the angular
motions will be locked. Options
Tip: For example, “1.0 0 0” locks the
angular motion around the X-direction of the constraint
frame.
|
|
|
Important: Define linear and torsional springs using
the following commands.
|
||
| prbcon_linspr_k_c | Linear spring stiffness coefficient. This is a vector value. | [N/m] |
| prbcon_linspr_p_c | Pre-deformation distance with respect to the initial (equilibrium) position. This is a vector value. | [m] |
| prbcon_angspr_k_c | Torsional spring stiffness coefficient. This is a vector value. | [Nm/rad] |
| prbcon_angspr_p_c | Pre-deformation angle with respect to the initial (equilibrium) position. This is a vector value. | [rad] |
| prbcon_lindmp_c_c | Linear damping coefficients along the corresponding constraint axis. Inactive when pinned. | [Ns/m] |
| prbcon_angdmp_c_c | Torsional damping coefficients around the corresponding constraint axis. | [Nms/rad] |
|
Important: It is often necessary to set the limits
of motion, such that the constrained body would not go
beyond a certain distance or beyond a certain angle value.
Set limits with the following commands.
|
||
| prbcon_linlim_pls_c | Allowed upper limit coordinate of the linear motion with respect to the init_CoM. This is a vector value (to specify all three directions in the constraint reference frame). | [m] |
| prbcon_linlim_mns_c | Allowed lower limit coordinate of the linear motion with respect to the init_CoM. This is a vector value (to specify all three directions in the constraint reference frame). | [m] |
| prbcon_anglim_pls_c | Allowed upper limit angle of the rotational motion with respect to the initial position. This is a vector value (to specify all three directions in the constraint reference frame). | [rad] |
| prbcon_anglim_mns_c | Allowed lower limit angle of the rotational motion with respect to the initial position. This is a vector value (to specify all three directions in the constraint reference frame). | [rad] |
|
Important: A special case of limited motion is a
hinge whose center of rotation is not the center of mass
(axis of rotation does not pass through the center of mass).
In this situation the axis of rotation needs to be
specified, which can be done by translating the constraint
reference frame to a new position and by modifying the
rotational lock command.
|
||
| prbcon_pt_i | Specified by the new origin of the constraint frame and defined in the global coordinate system. This is a vector value. | |
| prbcon_ax_hinge_c | Since the rotations are now moved away from the center of
mass, new rotational constraints must be set in place. This is a
vector value that defines which of the angular motions will be locked. Options
Tip: For example, “1.0 0 0” unlocks
only the angular motion around the x direction of the
constraint frame. By setting all three values to zero, one
enables a spherical joint behavior.
CAUTION: Overrides the
prbcon_anglck_c
command.
|
|
| prbcon_cnstfrc_c | A constant force applied in constraint frame. Note: Inactive if the motion is pinned in the given
direction.
|
[N] |
| prbcon_cnsttrq_c | A constant torque applied in constraint frame around a X, Y
and Z axes. Note: Inactive if the motion is pinned in
the given rotation.
|
[Nm] |
| prbcon_linvel_ctoi | Set this command to true to keep constraint frame stationary,
set to false to rotate constraint frame with body frame. Note: Applies only to the
prbcon_linvel
constraint.
|
|
| prbcon_linvel_a_c | Set any element to a positive number to activate the preset time dependent linear velocity for that constraint axis. | [m/s] |
| prbcon_linvel_f_c | Name of a 4-column file (t,u,v,w) for preset time dependent
linear velocity applied in constraint frame. Note: Inactive for all pinned motion directions.
|
[m/s] |
| prbcon_angvel_ctoi | Options
Note: Applies only to
prbcon_angvel
constraint.
|
|
| prbcon_angvel_a_c | Set any element to a positive number to activate the preset time dependent linear velocity for that constraint axis. | [Rad/s] |
| prbcon_angvel_f_c | Name of a 4-column file (
) for preset time dependent
linear velocity applied in constraint frame. Note: Inactive for
all pinned motion directions.
|
[Rad/s] |
DOUBLE_ROLLER_1DOF Commands
| Command | Contents | SI Unit Example |
|---|---|---|
| dr1dof_bod_phs | List of phases associated with the body in form of a vector (space separated and under quotation marks). | |
| dr1dof_frw_phs | List of phases associated with the front wheels (space separated and under quotation marks). | |
| dr1dof_bck_phs | List of phases associated with the rear wheels (space separated and under quotation marks). | |
| dr1dof_drvr_frwbck | Optional command that specifies if the vehicle is rear drive
or front drive Options
|
|
| dr1dof_bod_cgpnt | Optional command that defines a reference point on the
vehicle body which would later be used for post-processing. This
does not have any impact on the motion definition. Default = "0.0 0.0 0.0" |
[m] |
| dr1dof_frw_axpnt | A reference point on the line passing through the front wheel axle and parallel to Y-axis | [m] |
| dr1dof_bck_axpnt | A reference point on the line passing through the rear wheel axle and parallel to Y-axis | [m] |
| dr1dof_whl_rd | Defines the wheel radius. It must be a positive number | [m] |
| dr1dof_vel_init | Initial velocity of the center of the driving wheel Note: This
command is optional.
Default = 0.0 |
[m/s] |
| dr1dof_vel | Determines the velocity of the vehicle. Set this command to false to rotate constraint frame with body frame. | [Rad/s] |
| dr1dof_time_start | Starting time of the motion Note: This command is
optional.
Default = 0.0 |
|
| dr1dof_time_rampup | Ramp-up duration of the motion (after which the vehicle
reaches desired velocity). Note: This command is
optional.
Default = 0.0 |
|
| dr1dof_time_rampdn | Ramp down duration of the motion (after which the vehicle
comes to a halt). Note: This command is
optional.
Default = 0.0 |
|
| dr1dof_time_end | Ending time of the motion Note: This command is
optional.
Default = End time of the simulation |
|
| dr1dof_rd_pth_ply | Arc length coefficient (arc length is equal to
dr1dof_rd_pth_ply*dx).
The arc is used to connect any two lines in the path
definition. Note: This command is optional.
Default = 2.0 |
|
| dr1dof_rd_pth_file | Relative or absolute path to the file containing the two-column (X Z) piecewise linear road path (the road path Z must be a function of road path X, that is, X values must be strictly increasing). The vehicle will follow the specified road. | |
| dr1dof_tvs_file | Relative or absolute path to the file containing
time-velocity series (.tvs) data. The
.tvs file has a two column space
delimited format with the first column specifying time values in
a strictly increasing order, while the second column specifies
the driving wheel axis signed velocity magnitude along the road.
It is possible to specify any positive or negative value as well
as zero in any order in the second column of the
.tvs file. Note:
|
Important additional notes regarding the 1DoF double roller motion can be found below:
- Only two axles are supported.
- All wheels must have the same radius.
- The wheels always follow the road.
- This motion is not stackable (no ability to super-pose double roller motion with any other motion).
- The wheel rotation axes must be parallel to Y-axis.
- Only constant driver wheel axis velocity is supported.
- Initial position of driver and driven wheels must be within the first line segment.
- Two consecutive road segments may not have the same normal (there has to be an angle between two segments).
This means only X-positive motion is supported and dr1dof_vel must
be positive and larger than dr1dof_vel_init. The road path is
defined through a file according to following conditions:
- Road path is a two column file of the X Z form.
- Road path must contain at least one line segment (two X Z pairs).
- Road path X-coordinates must be strictly increasing.
DOUBLE_ROLLER_3DOF Commands
| Command | Contents | SI Unit Example |
|---|---|---|
| dr3dof_bod_phs | Phase or list of phases that follow the body motion. If more
than one phase was specified, the list should be enclosed in
quotation marks, start with a number and end with a number. The
list separator is space. Tip: For example, "1 10 2 6
5".
No default (Multi element integer) |
|
| dr3dof_frw_phs | Phase or list of phases that follow the front wheel motion.
If more than one phase was specified, the list should be
enclosed in quotation marks, start with a number and end with a
number. The list separator is space. Tip: For
example, "4 7".
No default (Multi element integer) |
|
| dr3dof_bck_phs | Phase or list of phases that follow the rear wheel motion. If
more than one phase was specified, the list should be enclosed
in quotation marks, start with a number and end with a number.
The list separator is space. Tip: For example,
"8".
No default (Multi element integer) |
|
| dr3dof_drvr_frwbck | Options
Default = reardrive (Predefined) |
|
| dr3dof_bod_cgpnt | Center of mass of the body phases and reference point used
for calculating moments on the body phases. This is the internal
center of rotation though apparent center of rotation may be
different. Default = "0.0, 0.0, 0.0" (Three element float) |
|
| dr3dof_bod_ms | Total mass of the body phases No default (Float) |
|
| dr3dof_bod_iyy | Mass moment of inertial of combined body phases about Y No default (Float) |
|
| dr3dof_frw_ms | Combined front wheel mass. Only used when
dr3dof_ptch_mod is active and ignored
otherwise. Default = 0.0 (Float) |
|
| dr3dof_bck_ms | Combined rear wheel mass. Only used when
dr3dof_ptch_mod is active and ignored
otherwise. Default = 0.0 (Float) |
|
| dr3dof_frw_ks | Effective front wheel spring constant. A positive value is
recommended. No default (Float) |
|
| dr3dof_bck_ks | Effective rear wheel spring constant. A positive value is
recommended. No default (Float) |
|
| dr3dof_frw_cs | Effective front wheel damping coefficient. A positive value
is recommended. No default (Float) |
|
| dr3dof_bck_cs | Effective rear wheel damping coefficient. A positive value is
recommended. No default (Float) |
|
| dr3dof_frw_axpnt | Coordinates of a point passing through the front axis of the
motion. This point is used as a reference point for calculating
moments on the front wheel phases. No default (Three element float) |
|
| dr3dof_bck_axpnt | Coordinates of a point passing through the rear axis of the
motion. This point is used as a reference point for calculating
moments on the rear wheel phases. No default (Three element float) |
|
| dr3dof_whl_rd | Wheel radius. Must be a positive number. No default (Float) |
|
| dr3dof_bod_eqlb | Adjustment of position and angle of the body by "Z ANG" in
case the initial configuration is not in equilibrium. This
adjustment does not introduce perturbation. The body is
translated by Z [m] in the Z-direction and is rotated by ANG
[deg] about the driver axis. Default = "0.0 0.0" (Two element float) |
|
| dr3dof_bod_reffrm | Options
Default - false (Boolean) |
|
| dr3dof_ptch_mod | Options
Default - false (Boolean) |
|
| dr3dof_bod_z_1dofcon | Constrain body Z-position by equivalent 1DoF motion in
meters. In combination with dr3dof_bod_a_1dofcon, it has a similar effect to limiting stretch/compression of the suspension. Set the first element to a positive number to activate, for example, "1 X Y". Or set to a non-positive number to deactivate, for example, "0 X Y". Once active, the second element is the allowed positive deviation and the third element is the allowed negative deviation. The body is not allowed beyond the deviation range. For example, when set to "1 0.02 -0.05", the body may go 0.02 m further up and 0.05 m further down compared to equivalent 1DoF motion in Z-direction. A positive number for the second element and a negative number for the third element is recommended, but is not necessary. Default = "0.0 0.0 0.0" (Three element float) |
|
| dr3dof_bod_a_1dofcon | Constrain body the Y-angle by equivalent 1DoF motion in
degrees. In combination with dr3dof_bod_z_1dofcon, it has a similar effect to limiting stretch/ compression of the suspension. Set the first element to a positive number to activate, for example, "1 X Y". Or set to a non-positive number to deactivate, for example, "0 X Y". Once active, the second element is the allowed positive deviation and the third element is the allowed negative deviation. The body is not allowed beyond the deviation range. For example, when set to "1 5 -2", the body may deviate by 5 degrees in positive Y (clockwise) and 2 degrees in negative Y (counter clockwise) direction from equivalent 1DoF motion. A positive number for the third element is recommended, but is not necessary. Default = "0.0 0.0 0.0" (Three element float) |
|
| dr3dof_fld_react_freq | Frequency of sampling fluid force and torque on the body
phases. The force and torque will remain constant in between
sampling points. Set to a non-positive value to
deactivate. Default = 0 (Integer) |
|
| dr3dof_tvs_file | Relative or absolute path to the file containing
time-velocity series data. When defined, takes precedence over
dr3dof_vel_init, dr3dof_vel,
dr3dof_time_rampup and/ or
dr3dof_time_rampdn. Note: Relative path is
preferred over absolute path due to
portability.
(String) |
|
| dr3dof_vel_init | Initial signed velocity magnitude of the driving wheel axis
along the road. Ignored when dr3dof_tvs_file is
present. Default = 0.0 (Float) |
|
| dr3dof_vel | Signed velocity magnitude of the driving wheel axis along the
road. Note: Ignored when dr3dof_tvs_file
is present.
Default = 0.0 (Float) |
|
| dr3dof_time_rampup | Time duration to ramp from dr3dof_vel_init
to dr3dof_vel. The ramp starts at
dr3dof_time_start and ends at
dr3dof_time_start +
dr3dof_time_rampup. Note: Ignored when
dr3dof_tvs_file is
present.
Default = 0.0 (Float) |
|
| dr3dof_time_start | Start time of the motion Default = 0.0 (Float) |
|
| dr3dof_time_end | End time of the motion Default = t_end (Float) |
|
| dr3dof_time_rampdn | Time duration to ramp from dr3dof_vel to
dr3dof_vel_init. The ramp starts at
dr3dof_time_end -
dr3dof_time_rampdn and ends at
dr3dof_time_end. Ignored when
dr3dof_tvs_file is present. Default = 0.0 (Float) |
|
| dr3dof_rd_pth_ply | A coefficient to determine the arc length as
dr3dof_rd_pth_ply*dx. An approximate arc length is then used to
construct a circular piece to connect the road pieces with a
topside angle of more than 180 degrees after
elevation. Default = 2.0 (Float) |
|
| dr3dof_rd_pth_file | Relative or absolute path to a file containing the two-column
(X Z) piecewise linear road path. The road path Z must be a
function of road path X, for example, X-values must be strictly
increasing. No default (String) |