mujoco_api

Socket-based client interface to the MuJoCo server backend.

This module defines the low-level communication layer used to exchange data with an external MuJoCo simulation server. It includes command and error constants, lightweight data containers for MuJoCo model and runtime state, and the mjInterface client class used to connect to the server, load models, control simulation execution, and get or set kinematic, dynamic, sensor, and visualization data.

class robotblockset.mujoco.mujoco_api.mjInfo(nq, nv, na, njnt, nbody, ngeom, nsite, ntendon, nu, neq, nkey, nmocap, nsensor, nsensordata, nmat, ncam, timestep, apirate, sensor_type=None, sensor_datatype=None, sensor_objtype=None, sensor_objid=None, sensor_dim=None, sensor_adr=None, sensor_noise=None, jnt_type=None, jnt_bodyid=None, jnt_qposadr=None, jnt_dofadr=None, jnt_range=None, geom_type=None, geom_bodyid=None, eq_type=None, eq_obj1id=None, eq_obj2id=None, actuator_trntype=None, actuator_trnid=None, actuator_ctrlrange=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjState(nq, nv, na, time, qpos=None, qvel=None, act=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjControl(nu=0, time=0.0, ctrl=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjApplied(nv=0, nbody=0, time=0, qfrc_applied=None, xfrc_applied=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjOneBody(bodyid=0, isfloating=0, time=0, linacc=0, angacc=0, contactforce=0, pos=None, quat=None, linvel=None, angvel=None, force=None, torque=None)

Bases: object

serialize()

deserialize(data)

class robotblockset.mujoco.mujoco_api.mjMocap(nmocap, time, pos=None, quat=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjDynamics(nv, na, time, qacc=None, actdot=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjSensor(nsensordata, time, sensordata=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjBody(nbody, time, pos=None, mat=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjGeom(ngeom, time, pos=None, mat=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjSite(nsite, time, pos=None, mat=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjTendon(ntendon, time, length=None, velocity=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjActuator(nu, time, length=None, velocity=None, force=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjForce(nv, time, nonconstraint=None, constraint=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjContact(ncon, time, dist=None, pos=None, frame=None, force=None, geom1=None, geom2=None)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjCamera(ncam, time, cam_xpos, cam_xmat, cam_mode, cam_bodyid, cam_targetbodyid, cam_pos, cam_quat, cam_poscom0, cam_pos0, cam_mat0, cam_fovy, cam_ipd)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjGLCamera(nglcam, time, fixedcamid, type, trackbodyid, lookat, distance, azimuth, elevation, pos, forward, up, frustum_center, frustum_bottom, frustum_top, frustum_near, frustum_far)

Bases: object

serialize()

static deserialize(data)

class robotblockset.mujoco.mujoco_api.mjInterface(host='localhost', port=50000)

Bases: object

Creation of MuJoCo interface

onebody = <robotblockset.mujoco.mujoco_api.mjOneBody object>

mjSetError(err)

mjSend(cmd, data=None)

mjRecv()

mjGetAck()

mj_get_state() → mjState

Read model state

Returns:

• ——-

• structure mjState –

  nqint

  number of data in qpos

  nvint

  number of data in qvel

  naint

  number of data in act

  timefloat)

  simulation time

  qposarray [nq]

  generalized positions

  qvelarray [nv]

  generalized velocities

  actarray [na]

  actuator activations

mj_get_control() → mjControl

Read control signals

Returns:

• ——–

• structure mjControl – nu (int) : number of data in ctrl time (float) : simulation time ctrl[nu] (float): control array

mj_get_applied() → mjApplied

Read applied forces

Returns:

• ——–

• structure mjApplied – nv (int) : number of data in forces nbody (int) : id of body time (float) : simulation time qfrc[nv] (float): applied generalized forces xfrc[nv] (float): Cartesian F/T applied to body

mj_get_onebody(bodyid: int) → mjOneBody

Read information about one body

Parameters:

• -----------

• (int) (bodyid)

Returns:

• ——–

• structure mjOneBody – bodyid; (int) : body id, provided by user get only: isfloating (int) : 1 if body is floating, 0 otherwise time (float) : simulation time linacc[3] (float): linear acceleration angacc[3] (float): angular acceleration contactforce[3] (float) : net force from all contacts on this body

• get for all bodies; set for floating bodies only – pos[3] (float) : position quat[4] (float) : orientation quaternion linvel[3] (float): linear velocity angvel[3] (float): angular velocity

• get and set for all bodies – force[3] (float) : Cartesian force applied to body CoM torque[3] (float): Cartesian torque applied to body

mj_get_mocap() → mjMocap

Read mocaps

Returns:

• ——–

• structure mjMocap – nmocap (int) : number of mocap bodies time (float) : simulation time pos[nmocap][3] (float) : positions quat[nmocap][4] (float): quaternion orientations

mj_get_dynamics() → mjDynamics

Read forward dynamics

Returns:

• ——–

• structure mjDynamics – nv (int) : number of generalized velocities na (int) : number of actuator activations time (float) : simulation time qacc[nv] (float) : generalized accelerations actdot[na] (float): time-derivatives of actuator activations

mj_get_sensor() → mjSensor

Read sensor data from the simulator.

Use the sensor descriptors available in mjInfo to decode the returned values.

Returns:

Sensor data structure with:

• nsensordata: number of sensor values

• time: simulation time

• sensordata: sensor data array

Return type:

mjSensor

mj_get_body() → mjBody

Read body positions

Returns:

• ——–

• structure mjBody – nbody (int) : number of bodies time (float) : simulation time pos[nbody][3] (float): positions mat[nbody][9] (float): frame orientations

mj_get_geom() → mjGeom

Read geom positions

Returns:

• ——–

• structure mjGeom – ngeom (int) : number of geoms time (float) : simulation time pos[ngeom][3] (float): positions mat[ngeom][9] (float): frame orientations

mj_get_site() → mjSite

Read site positions

Returns:

• ——–

• structure mjSite – nsite (int) : number of bodies time (float) : simulation time pos[nsite][3] (float): positions mat[nsite][9] (float): frame orientations

mj_get_tendon() → mjTendon

Read tendons data

Returns:

• ——–

• structure mjTendon – ntendon (int) : number of tendons time (float) : simulation time length[ntendon] (float) : tendon lengths velocity[ntendon] (float): tendon velocities

mj_get_actuator() → mjActuator

Read tendons data

Returns:

• ——–

• structure mjTendon – nu (int) : number of actuators time (float) : simulation time length[nu] (float) : actuator lengths velocity[nu] (float): actuator velocities force[nu] (float) : actuator forces

mj_get_force() → mjForce

Read tendons data

Returns:

• ——–

• structure mjTendon – nv (int) : number of generalized velocities/forces time (float) : simulation time nonconstraint[nv] (float): sum of all non-constraint forces constraint[nv] (float) : constraint forces (including contacts)

mj_get_contact() → mjContact

Read tendons data

Returns:

• ——–

• structure mjTendon – ncon (int) : number of detected contacts time (float) : simulation time dist[ncon : contact normal distance pos[ncon][3] (float) : contact position in world frame frame[ncon][9] (float): contact frame relative to world frame (0-2: normal) force[ncon][3] (float): contact force in contact frame geom1[ncon] (float) : id of 1st contacting geom geom2[ncon] (float) : id of 2nd contacting geom (force: 1st -> 2nd)

mj_get_camera() → mjCamera

Read camera data

Returns:

• ——–

• structure mjCamera

mj_get_glcamera() → mjGLCamera

Read GL camera data

Returns:

• ——–

• structure mjGLCamera

mj_set_state(state: mjState)

Set simulator state

Parameters:

• -----------

• state (mjState) – structure mjState

Returns:

• ——–

• int – API return code

mj_set_control(control: mjControl)

Set control signals

Parameters:

• -----------

• control (mjControl) – structure mjControl

Returns:

• ——–

• int – API return code

mj_set_applied(applied: mjApplied)

Set applied forces

Parameters:

• -----------

• applied (mjApplied) – structure mjApplied

Returns:

• ——–

• int – API return code

mj_set_onebody(onebody: mjOneBody)

Set one body data

Parameters:

• -----------

• onebody (mjOneBody) – structure mjOneBody

Returns:

• ——–

• int – API return code

mj_set_mocap(mocap: mjMocap)

Set mocap positions

Parameters:

• -----------

• mocap (mjMocap) – structure mjMocap

Returns:

• ——–

• int – API return code

mj_get_rgba(typ: str, id: int) → array

mj_set_rgba(typ: str, id: int, rgba: array) → int

mj_load(model_filename: str = None) → int

Show text message in simulator

Parameters:

• -----------

• message (string) – message, None: clear currently shown message

Returns:

• ——–

• int – API return code

mj_connect()

Connect to Haptix simulator

Parameters:

• -----------

• ip (string) – host IP

Returns:

• ——–

• int – API return code

connect()

Connect to MuJoCo simulator (alias)

mj_close()

Close connection to Haptix simulator

Returns:

• ——–

• int – API return code

close()

Close connection to MuJoCo simulator (alias)

mj_result()

Return the last API result code.

Returns:

Last result code reported by the MuJoCo interface.

Return type:

str

mj_connected()

Return the connection status.

Returns:

1 if connected to the simulator, otherwise 0.

Return type:

int

connected()

Returns connection status (alias)

mj_info()

Get static properties of current model

Returns:

• ——–

• myInfo (structure) – nq (int) : number of generalized positions nv (int) : number of generalized velocities na (int) : number of actuator activations njnt (int) : number of joints nbody (int) : number of bodies ngeom (int) : number of geoms nsite (int) : number of sites ntendon (int) : number of tendons nu (int) : number of actuators/controls neq (int) : number of equality constraints nkey (int) : number of keyframes nmocap (int) : number of mocap bodies nsensor (int) : number of sensors nsensordata (int) : number of elements in sensor data array nmat (int) : number of materials timestep (float) : simulation timestep apirate (float) : API update rate sensor_type[nsensor] (int) : sensor type sensor_datatype[nsensor] (int) : type of sensorized object sensor_objtype[nsensor] (int) : type of sensorized object sensor_objid[nsensor] (int) : id of sensorized object sensor_dim[nsensor] (int) : number of sensor outputs sensor_adr[nsensor] (int) : address in sensor data array sensor_noise[nsensor] (float) : noise standard deviation jnt_type[njnt] (int) : joint type (mjtJoint) jnt_bodyid[njnt] (int) : id of body to which joint belongs jnt_qposadr[njnt] (int) : address of joint position data in qpos jnt_dofadr[njnt] (int) : address of joint velocity data in qvel jnt_range[njnt][2] (float) : joint range (0,0): no limits geom_type[ngeom] (int) : geom type (mjtGeom) geom_bodyid[ngeom] (int) : id of body to which geom is attached eq_type[neq] (int) : equality constraint type (mjtEq) eq_obj1id[neq] (int) : id of constrained object eq_obj2id[neq] (int) : id of 2nd constrained object -1 if not applicable actuator_trntype[nu] (int) : transmission type (mjtTrn) actuator_trnid[nu][2] (int) : transmission target id actuator_ctrlrange[nu][2](float): actuator control range (0,0): no limits

mj_step() → int

Advance simulation if paused, no effect if running

Returns:

• ——–

• int – API return code

mj_pause() → int

Pause simulation

Returns:

• ——–

• int – API return code

mj_run() → int

Run simulation

Returns:

• ——–

• int – API return code

mj_update(control: mjControl) → int

Advance the simulation and refresh sensor data.

The method sends the control command, advances the simulation, and returns the refreshed sensor data structure received from the simulator.

Parameters:

control (mjControl) – Control command structure to send to MuJoCo.

Returns:

Updated sensor data returned by the simulator.

Return type:

mjSensor

mj_reset(keyframe: int = None) → int

Reset simulation to specified key frame

Parameters:

• -----------

• keyframe (int, optional) – key frame; -1: reset to model reference configuration

Returns:

• ——–

• int – API return code

mj_equality(eqid: int, state: int) → int

Modify state of specified equality constraint

Parameters:

• -----------

• eqid (int) – equality id

• state (int) – equality constraint, 1: enable, 0: disable

Returns:

• ——–

• int – API return code

mj_message(message: str = None) → int

Show text message in simulator

Parameters:

• -----------

• message (str, optional) – message, None: clear currently shown message

Returns:

• ——–

• int – API return code

mj_name2id(typ: str, name: str) → int

Return the id of an object with the specified type and name.

Valid object types are body, geom, site, joint, tendon, sensor, actuator, and equality.

Parameters:

• typ (str) – Object type.

• name (str) – Object name.

Returns:

Object id. Returns -1 if not found and -2 on error.

Return type:

int

mj_id2name(typ: str, id: int) → str

Returns name of object with specified type and id

valid object types: body, geom, site, joint, tendon, sensor, actuator, equality

Parameters:

• -----------

• typ (str) – object type

• id (int) – object id

Returns:

• ——–

• string – object name

robotblockset.mujoco.mujoco_api.isMuJoCo(scn)

Functions

isMuJoCo(scn)

Classes

mjActuator(nu, time[, length, velocity, force])
mjApplied([nv, nbody, time, qfrc_applied, ...])
mjBody(nbody, time[, pos, mat])
mjCamera(ncam, time, cam_xpos, cam_xmat, ...)
mjContact(ncon, time[, dist, pos, frame, ...])
mjControl([nu, time, ctrl])
mjDynamics(nv, na, time[, qacc, actdot])
mjForce(nv, time[, nonconstraint, constraint])
mjGLCamera(nglcam, time, fixedcamid, type, ...)
mjGeom(ngeom, time[, pos, mat])
mjInfo(nq, nv, na, njnt, nbody, ngeom, ...)
mjInterface([host, port])	Creation of MuJoCo interface
mjMocap(nmocap, time[, pos, quat])
mjOneBody([bodyid, isfloating, time, ...])
mjSensor(nsensordata, time[, sensordata])
mjSite(nsite, time[, pos, mat])
mjState(nq, nv, na, time[, qpos, qvel, act])
mjTendon(ntendon, time[, length, velocity])