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- Added passive forces plugins

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- Added new `cable` composite type:
  * The `initial` parameter specifies the joint at the starting boundary: `free`, `ball`, or `none`.
  * The boundary bodies are exposed with the names:`B_left` and `B_right`.
  * The vertex initial positions can be specified directly in the XML with the parameter `vertex`.
  * The orientation of the body frame **is** the orientation of the material frame of the curve.

- Added new `cable` passive force plugin:
  * Twist and bending stiffness can be set separately with the parameters `twist` and `bend`.
  * The stress-free configuration can be set to be the initial one or flat with the flag `flat`.
  * New cable example showing the formation of plectoneme.
  * New coil example.
  * New belt example showing interaction between twist and anisotropy.
  * Added test using cantilever exact solution.

PiperOrigin-RevId: 480033694
Change-Id: I491271bce8fccb185961477e903e5a72d172c8a3
This commit is contained in:
Alessio Quaglino
2022-10-10 02:45:59 -07:00
committed by Copybara-Service
parent 794ef0b771
commit e250ff0d5a
34 changed files with 1564 additions and 72 deletions
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doc/APIreference.rst
+18
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@@ -1403,6 +1403,8 @@ mjModel
int ntupledata; // number of objects in all tuple fields
int nkey; // number of keyframes
int nmocap; // number of mocap bodies
int nplugin; // number of plugin instances
int npluginattr; // number of chars in all plugin config attributes
int nuser_body; // number of mjtNums in body_user
int nuser_jnt; // number of mjtNums in jnt_user
int nuser_geom; // number of mjtNums in geom_user
@@ -1415,12 +1417,14 @@ mjModel
// sizes set after mjModel construction (only affect mjData)
int nM; // number of non-zeros in sparse inertia matrix
int nD; // number of non-zeros in sparse derivative matrix
int nemax; // number of potential equality-constraint rows
int njmax; // number of available rows in constraint Jacobian
int nconmax; // number of potential contacts in contact list
int nstack; // number of fields in mjData stack
int nuserdata; // number of extra fields in mjData
int nsensordata; // number of fields in sensor data vector
int npluginstate; // number of fields in the plugin state vector
int nbuffer; // number of bytes in buffer
@@ -1461,6 +1465,7 @@ mjModel
mjtNum* body_inertia; // diagonal inertia in ipos/iquat frame (nbody x 3)
mjtNum* body_invweight0; // mean inv inert in qpos0 (trn, rot) (nbody x 2)
mjtNum* body_user; // user data (nbody x nuser_body)
int* body_plugin; // plugin instance id (-1 if not in use) (nbody x 1)
// joints
int* jnt_type; // type of joint (mjtJoint) (njnt x 1)
@@ -1576,6 +1581,7 @@ mjModel
// skins
int* skin_matid; // skin material id; -1: none (nskin x 1)
int* skin_group; // group for visibility (nskin x 1)
float* skin_rgba; // skin rgba (nskin x 4)
float* skin_inflate; // inflate skin in normal direction (nskin x 1)
int* skin_vertadr; // first vertex address (nskin x 1)
@@ -1679,17 +1685,20 @@ mjModel
int* actuator_group; // group for visibility (nu x 1)
mjtByte* actuator_ctrllimited; // is control limited (nu x 1)
mjtByte* actuator_forcelimited;// is force limited (nu x 1)
mjtByte* actuator_actlimited; // is activation limited (nu x 1)
mjtNum* actuator_dynprm; // dynamics parameters (nu x mjNDYN)
mjtNum* actuator_gainprm; // gain parameters (nu x mjNGAIN)
mjtNum* actuator_biasprm; // bias parameters (nu x mjNBIAS)
mjtNum* actuator_ctrlrange; // range of controls (nu x 2)
mjtNum* actuator_forcerange; // range of forces (nu x 2)
mjtNum* actuator_actrange; // range of activations (nu x 2)
mjtNum* actuator_gear; // scale length and transmitted force (nu x 6)
mjtNum* actuator_cranklength; // crank length for slider-crank (nu x 1)
mjtNum* actuator_acc0; // acceleration from unit force in qpos0 (nu x 1)
mjtNum* actuator_length0; // actuator length in qpos0 (nu x 1)
mjtNum* actuator_lengthrange; // feasible actuator length range (nu x 2)
mjtNum* actuator_user; // user data (nu x nuser_actuator)
int* actuator_plugin; // plugin instance id; -1: not a plugin (nu x 1)
// sensors
int* sensor_type; // sensor type (mjtSensor) (nsensor x 1)
@@ -1704,6 +1713,14 @@ mjModel
mjtNum* sensor_cutoff; // cutoff for real and positive; 0: ignore (nsensor x 1)
mjtNum* sensor_noise; // noise standard deviation (nsensor x 1)
mjtNum* sensor_user; // user data (nsensor x nuser_sensor)
int* sensor_plugin; // plugin instance id; -1: not a plugin (nsensor x 1)
// plugin instances
int* plugin; // globally registered plugin slot number (nplugin x 1)
int* plugin_stateadr; // address in the plugin state array (nplugin x 1)
int* plugin_statenum; // number of states in the plugin instance (nplugin x 1)
char* plugin_attr; // config attributes of plugin instances (npluginattr x 1)
int* plugin_attradr; // address to each instance's config attrib (nplugin x 1)
// custom numeric fields
int* numeric_adr; // address of field in numeric_data (nnumeric x 1)
@@ -1753,6 +1770,7 @@ mjModel
int* name_textadr; // text name pointers (ntext x 1)
int* name_tupleadr; // tuple name pointers (ntuple x 1)
int* name_keyadr; // keyframe name pointers (nkey x 1)
int* name_pluginadr; // plugin instance name pointers (nplugin x 1)
char* names; // names of all objects, 0-terminated (nnames x 1)
};
typedef struct _mjModel mjModel;
doc/XMLreference.rst
+17 -1
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@@ -2286,7 +2286,7 @@ coordinates results in compiler error. See :ref:`CComposite` in the modeling gui
All automatically generated model elements have names indicating the element type and index. For example, the body at
coordinates (2, 0) in a 2D grid is named "B2_0" by default. If prefix="C" is specified, the same body is named
"CB2_0". The prefix is needed when multiple composite objects are used in the same model, to avoid name conflicts.
:at:`type`: :at-val:`[particle, grid, rope, loop, cloth, box, cylinder, ellipsoid], required`
:at:`type`: :at-val:`[particle, grid, cable, rope, loop, cloth, box, cylinder, ellipsoid], required`
This attribute determines the type of composite object. The remaining attributes and sub-elements are then
interpreted according to the type. Default settings are also adjusted depending on the type.
@@ -2316,6 +2316,12 @@ coordinates results in compiler error. See :ref:`CComposite` in the modeling gui
elements are equality-constrained to remain connected (using the "connect" constraint type). The softness of this
equality constraint is adjusted with the attributes solrefsmooth and solimpsmooth.
The **cable** type creates a 1D chain of bodies connected with ball joints, each having a geom with user-defined type
(cylinder, capsule or box). The geometry can either be defined with an array of 3D vertex coordinates :at:`vertex`
or with prescribed functions with the option :at:`curve`. Currently, only linear and trigonometric functions are
supported. For example, an helix can be obtained with curve="cos(s) sin(s) s". The size is set with the option
:at:`size`, resulting in :math:`f(s)=(size[1]*\cos(2*\pi*size[2]), size[1]*\sin(2*\pi*size[2]), size[0]*s)`.
The **cloth** type is a different way to model cloth, beyond type="grid". Here the elements are connected with
universal joints and form a kinematic spanning tree. The root of the tree is the parent body, and its coordinates in
the grid are inferred from its name - similar to rope but here the naming format is "CB2_0". Neighboring bodies that
@@ -2370,6 +2376,16 @@ coordinates results in compiler error. See :ref:`CComposite` in the modeling gui
smoothness-preserving equality constraint for box, cylinder and ellipsoid types. For all other types they have no
effect. They obey the same rules as all other solref and solimp attributes in MJCF, except their defaults here are
adjusted depending on the composite type. See :ref:`CSolver`.
:at:`vertex`: :at-val:`real(3*nvert), optional`
Vertex 3D positions in global coordinates (cable only).
:at:`initial`: :at-val:`[free, ball, none], "0"`
Behavior of the first point (cable only). Free: free joint. Ball: ball joint. None: no dof.
:at:`curve`: :at-val:`string(3), optional`
Functions specifying the vertex positions (cable only). Available functions are `s`, `cos(s)`, and `sin(s)`, where
`s` is the arc length parameter.
:at:`size`: :at-val:`int(3), optional`
Scaling of the curve functions (cable only). `size[0]` is the scaling of `s`, `size[1]` is the radius of `\cos(s)`
and `\sin(s)`, and `size[2]` is the speed of the argument (i.e. `\cos(2*\pi*size[2]*s)`).
.. _composite-joint:
doc/changelog.rst
+18
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@@ -60,6 +60,24 @@ General
- Added :at:`realtime` option to :ref:`visual` for starting a simulation at a slower speed.
- Added new :at:`cable` composite type:
* Cable elements are connected with ball joints.
* The `initial` parameter specifies the joint at the starting boundary: :at:`free`, :at:`ball`, or :at:`none`.
* The boundary bodies are exposed with the names :at:`B_left` and :at:`B_right`.
* The vertex initial positions can be specified directly in the XML with the parameter :at:`vertex`.
* The orientation of the body frame **is** the orientation of the material frame of the curve.
- Added new :at:`cable` passive force plugin:
* Twist and bending stiffness can be set separately with the parameters :at:`twist` and :at:`bend`.
* The stress-free configuration can be set to be the initial one or flat with the flag :at:`flat`.
* New `cable.xml <https://github.com/deepmind/mujoco/tree/main/model/plugin/cable.xml>`_ example
showing the formation of plectoneme.
* New `coil.xml <https://github.com/deepmind/mujoco/tree/main/model/plugin/coil.xml>`_ example
showing a curved equilibrium configuration.
* New `belt.xml <https://github.com/deepmind/mujoco/tree/main/model/plugin/belt.xml>`_ example
showing interaction between twist and anisotropy.
* Added test using cantilever exact solution.
Python bindings
^^^^^^^^^^^^^^^