External kinematics (auxiliary API)

This collection of functions allows to perform the same kinematic calculations as you are able to do from within V-REP. Exception to this is the obstacle avoidance functionality which is only supported from within V-REP.

The idea is to normally build your kinematic tasks inside V-REP, then to export the kinematic content of a scene, which can then directly be used with the embeddable functions below. The required source code, in scrambled form, is located in the programming/externalIk folder. Make sure to include all files into your project, and include extIk.h in the files where you need access to the functions. Make also sure you know how to use the kinematics functionality from within V-REP first!! If you have access to the regular API, then you won't need this auxiliary API, since all following functions have their regular API equivalent.

The scrambled source code located in the programming/externalIk folder, meant for evaluation purpose, is fully functional, however with the following restriction: only about the first 40000 explicit calls to simEmbHandleIkGroup will have an effect. If you call the function in a non-explicit way (i.e. simEmbHandleIkGroup(sim_handle_all)), then each ik group will represent a distinct call. The scrambled source code without this restriction requires a separate licensing, please contact us for details.

Follow the method below to perform kinematic calculations from within your own external application:

  • Build your kinematic tasks within V-REP. Test them.
  • Export the kinematic content of the scene with [Menu bar --> File --> Export IK content...]
  • Include the external kinematics code in your own application (the code is located in the programming/externalIk folder)
  • Call simEmbLaunch at application start-up, and simEmbShutDown at application end.
  • Call simEmbStart to import the previously exported file. simEmbStart may be called as often as desired to reset the kinematic scene. A kinematic scene is similar to a scene in V-REP, except that it is stripped of everything non-kinematic.
  • Call various functions to shift / rotate the target dummies (e.g. with simEmbSetObjectTransformation), or to move non-active joints, i.e. joints that are not in IK mode (e.g. with simEmbSetJointPosition).
  • Call simEmbHandleIkGroup to perform one calculation pass (i.e. effectively bringing dummy tips onto their targets).
  • Repeat above last 2 steps as often as required. Make sure to check for return values to detect errors.
  • Refer also to the example application programming/externalIkDemo. That demo application uses the external kinematics routines described here, combined with the remote API functionality to control the IRB 360 "delta" robot in inverse kinematics mode. The demo scene "externalIkDemo.ttt" launches the externalIkDemo automatically.

    simEmbEulerAnglesToQuaternion
    simEmbGetIkGroupHandle
    simEmbGetJointPosition
    simEmbGetJointTransformation
    simEmbGetObjectHandle
    simEmbGetObjectParent
    simEmbGetObjectTransformation
    simEmbGetRotationAxis
    simEmbHandleIkGroup
    simEmbInterpolateTransformations
    simEmbInvertTransformation
    simEmbLaunch
    simEmbMultiplyTransformations
    simEmbMultTransformationWithVector
    simEmbQuaternionToEulerAngles
    simEmbRotateAroundAxis
    simEmbSetIkElementProperties
    simEmbSetIkGroupExplicitHandling
    simEmbSetIkGroupProperties
    simEmbSetJointMode
    simEmbSetJointPosition
    simEmbSetObjectParent
    simEmbSetObjectTransformation
    simEmbSetSphericalJointQuaternion
    simEmbShutDown
    simEmbStart
    



    simEmbEulerAnglesToQuaternion (regular API equivalent: simGetEulerAnglesFromMatrix)

    Description Retrieves a quaternion based on Euler angles. See also simEmbQuaternionToEulerAngles
    C++ synopsis int simEmbEulerAnglesToQuaternion(const float* euler,float* quaternion)
    parameters
    euler (input): the 3 Euler angles (alpha, beta, gamma)
    quaternion (output): the 4 values of a quaternion (x, y, z, w)
    return value
    -1 if operation failed

    simEmbGetIkGroupHandle (regular API equivalent: simGetIkGroupHandle)

    Description Retrieves the handle of an IK group based on its name. Specify the full IK group name, including suffixes.
    C++ synopsis int simEmbGetIkGroupHandle(const char* ikGroupName)
    parameters
    ikGroupName (input): the name of the IK group
    return value
    -1 if operation failed, otherwise the handle of the IK group.

    simEmbGetJointPosition (regular API equivalent: simGetJointPosition)

    Description Retrieves the intrinsic position of a joint. This function cannot be used with spherical joints (use simEmbGetJointTransformation instead). See also simEmbSetJointPosition
    C++ synopsis int simEmbGetJointPosition(int jointHandle,float* position)
    parameters
    jointHandle (input): handle of the joint
    position (output): intrinsic position of the joint. This is a one-dimensional value: if the joint is revolute, the rotation angle is returned, if the joint is prismatic, the translation amount is returned, etc.
    return value
    -1 if operation failed

    simEmbGetJointTransformation (regular API equivalent: simGetJointMatrix)

    Description Retrieves the intrinsic transformation of a joint (the transformation caused by the joint movement). See also simEmbSetSphericalJointQuaternion.
    C++ synopsis int simEmbGetJointTransformation(int jointHandle,float* position,float* quaternion)
    parameters
    jointHandle (input): handle of the joint
    position (output): the position component of the transformation (x, y, z)
    quaternion (output): the orientation component of the transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbGetObjectHandle (regular API equivalent: simGetObjectHandle)

    Description Retrieves an object handle based on its name. Specify the full object name, including suffixes.
    C++ synopsis int simEmbGetObjectHandle(const char* objectName)
    parameters
    objectName (input): name of the object
    return value
    -1 if operation failed, otherwise the handle of the object

    simEmbGetObjectParent (regular API equivalent: simGetObjectParent)

    Description Retrieves the handle of an object's parent object. See also simEmbSetObjectParent.
    C++ synopsis int simEmbGetObjectParent(int objectHandle)
    parameters
    objectHandle (input): handle of the object
    return value
    -1 if operation failed, otherwise the handle of the parent object

    simEmbGetObjectTransformation (regular API equivalent: simGetObjectMatrix)

    Description Retrieves the transformation (position / orientation) of an object. See also simEmbSetObjectTransformation.
    C++ synopsis int simEmbGetObjectTransformation(int objectHandle,int relativeToObjectHandle,float* position,float* quaternion)
    parameters
    objectHandle (input): handle of the object
    relativeToObjectHandle (input): indicates relative to which reference frame we want the transformation. Specify -1 to retrieve the absolute transformation, sim_handle_parent to retrieve the transformation relative to the object's parent, or an object handle relative to whose reference frame we want the transformation.
    position (output): the position component of the transformation (x, y, z)
    quaternion (output): the orientation component of the transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbGetRotationAxis (regular API equivalent: simGetRotationAxis)

    Description Retrieves an axis and rotation angle that brings one transformation onto another one. The translation part of the transformations is ignored. This function, when used in combination with simEmbRotateAroundAxis, can be used to build interpolations between transformations.
    C++ synopsis int simEmbGetRotationAxis(const float* positionStart,const float* quaternionStart,const float* positionGoal,const float* quaternionGoal,float* axis,float* angle)
    parameters
    positionStart (input): the position component of the first transformation (x, y, z)
    quaternionStart (input): the orientation component of the first transformation (x, y, z, w)
    positionGoal (input): the position component of the second transformation (x, y, z)
    quaternionGoal (input): the orientation component of the second transformation (x, y, z, w)
    axis (output): the rotation axis (x, y, z vector)
    angle (output): the rotation angle
    return value
    -1 if operation failed

    simEmbHandleIkGroup (regular API equivalent: simHandleIkGroup)

    Description Handles (i.e. solves) an IK group (i.e. by trying to respect the given constraints).
    C++ synopsis int simEmbHandleIkGroup(int ikGroupHandle)
    parameters
    ikGroupHandle (input): handle of the IK group or sim_handle_all or sim_handle_all_except_explicit. (sim_handle_all will handle all IK groups, while sim_handle_all_except_explicit will only handle those that are not marked as "explicit handling")
    return value
    number of performed calculations (i.e. when IK group calculation results are different from sim_ikresult_not_performed) if no specific IK group was specified, or a value of type IK result if a specific IK group was specified, -1 in case of an error (a failed IK group calculation is not considered as an error)

    simEmbInterpolateTransformations (regular API equivalent: simInterpolateMatrices)

    Description Computes the interpolated transformation between 2 transformations.
    C++ synopsis int simEmbInterpolateTransformations(const float* position1,const float* quaternion1,const float* position2,const float* quaternion2,float interpolFactor,float* positionOut,float* quaternionOut)
    parameters
    position1 (input): the position component of the first transformation (x, y, z)
    quaternion1 (input): the orientation component of the first transformation (x, y, z, w)
    position2 (input): the position component of the second transformation (x, y, z)
    quaternion2 (input): the orientation component of the second transformation (x, y, z, w)
    interpolFactor (input): the interpolation factor, a value between 0.0 and 1.0 (0.0--> transformationOut=transformationIn1, 1.0--> transformationOut=transformationIn2)
    positionOut (output): the position component of the interpolated transformation (x, y, z)
    quaternionOut (output): the orientation component of the interpolated transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbInvertTransformation (regular API equivalent: simInvertMatrix)

    Description Inverts a transformation matrix
    C++ synopsis int simEmbInvertTransformation(float* position,float* quaternion);
    parameters
    position (input/output): the position component of the transformation (x, y, z)
    quaternion (input/output): the orientation component of the transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbLaunch

    Description Initializes the external kinematics routines. Should be the very first function called. See also simEmbShutDown.
    C++ synopsis bool simEmbLaunch()
    parameters
    none
    return value
    false if operation failed.

    simEmbMultiplyTransformations (regular API equivalent: simMultiplyMatrices)

    Description Multiplies two transformation
    C++ synopsis int simEmbMultiplyTransformations(const float* position1,const float* quaternion1,const float* position2,const float* quaternion2,float* positionOut,float* quaternionOut);
    parameters
    position1 (input): the position component of the first transformation (x, y, z)
    quaternion1 (input): the orientation component of the first transformation (x, y, z, w)
    position2 (input): the position component of the second transformation (x, y, z)
    quaternion2 (input): the orientation component of the second transformation (x, y, z, w)
    positionOut (output): the position component of the multiplication (x, y, z)
    quaternionOut (output): the orientation component of the multiplication (x, y, z, w)
    return value
    -1 if operation failed

    simEmbMultTransformationWithVector (regular API equivalent: simTransformVector)

    Description Multiplies a vector with a transformation (v=tr*v)
    C++ synopsis int simEmbMultTransformationWithVector(const float* position,const float* quaternion,float* vect);
    parameters
    position (input): the position component of the transformation (x, y, z)
    quaternion (input): the orientation component of the transformation (x, y, z, w)
    vect (input/output): the vector to transform (x, y, z)
    return value
    -1 if operation failed

    simEmbQuaternionToEulerAngles (regular API equivalent: simGetQuaternionFromMatrix)

    Description Retrieves Euler angles based on a quaternion. See also simEmbEulerAnglesToQuaternion
    C++ synopsis int simEmbQuaternionToEulerAngles(const float* quaternion,float* euler)
    parameters
    quaternion (input): the 4 values of a quaternion (x, y, z, w)
    euler (output): the 3 Euler angles (alpha, beta, gamma)
    return value
    -1 if operation failed

    simEmbRotateAroundAxis (regular API equivalent: simRotateAroundAxis)

    Description Rotates a transformation around a specific axis in space. This function, when used in combination with simEmbGetRotationAxis, can be used to build interpolations between transformations.
    C++ synopsis int simEmbRotateAroundAxis(const float* positionIn,const float* quaternionIn,const float* axisVector,const float* axisPosition,float angle,float* positionOut,float* quaternionOut)
    parameters
    positionIn (input): the position component of a transformation (x, y, z)
    quaternionIn (input): the orientation component of a transformation (x, y, z, w)
    axisVector (input): the axis vector (x, y, z)
    axisPosition (input): the axis position (x, y, z)
    angle (input): the desired rotation angle
    positionOut (output): the position component of the rotated transformation (x, y, z)
    quaternionOut (output): the orientation component of the rotated transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbSetIkElementProperties (regular API equivalent: simSetIkElementProperties)

    Description Sets properties of a specific IK element. See also simEmbSetIkGroupProperties and simEmbGetIkGroupHandle.
    C++ synopsis int simEmbSetIkElementProperties(int ikGroupHandle,int tipDummyHandle,int constraints,const float* precision,const float* weight)
    parameters
    ikGroupHandle (input): handle of the IK group
    tipDummyHandle (input): handle of the tip dummy object of the IK element
    constraints (input): the constraints of the ik element. sim_ik_avoidance_constraint is not allowed
    precision (input): an array of two values where the first represents the linear precision, and the second the angular precision. Can be NULL to keep current settings.
    weight (input): an array of two values that represent the linear and angular resolution weights. Can be NULL to keep current settings
    return value
    -1 if operation failed

    simEmbSetIkGroupExplicitHandling (regular API equivalent: simSetExplicitHandling)

    Description Sets the explicit handling flags for an IK group. An IK group flagged as "explicit handling" will only be handled or solved when called explicitely with simEmbHandleIkGroup(ikGroupHandle) or simEmbHandleIkGroup(sim_handle_all).
    C++ synopsis int simEmbSetIkGroupExplicitHandling(int ikGroupHandle,bool explicitHandling)
    parameters
    ikGroupHandle (input): handle of the IK group
    explicitHandling (input): the desired explicit handling state
    return value
    -1 if operation failed

    simEmbSetIkGroupProperties (regular API equivalent: simSetIkGroupProperties)

    Description Sets properties of an IK group. See also simEmbSetIkElementProperties
    C++ synopsis int simEmbSetIkGroupProperties(int ikGroupHandle,int resolutionMethod,int maxIterations,float damping)
    parameters
    ikGroupHandle (input): handle of the IK group
    resolutionMethod (input): the IK resolution method
    maxIterations (input): the maximum number of iterations for the calculations
    damping (input): the DLS damping factor
    return value
    -1 if operation failed

    simEmbSetJointMode (regular API equivalent: simSetJointMode)

    Description Sets the operation mode of a joint. Might have as side-effect the change of additional properties of the joint.
    C++ synopsis int simEmbSetJointMode(int jointHandle,int jointMode)
    parameters
    jointHandle (input): handle of the joint
    jointMode (input): a joint mode value
    return value
    -1 if operation failed

    simEmbSetJointPosition (regular API equivalent: simSetJointPosition)

    Description Sets the intrinsic position of a joint. This function cannot be used with spherical joints (use simEmbSetSphericalJointQuaternion instead). See also simEmbGetJointPosition
    C++ synopsis int simEmbSetJointPosition(int jointHandle,float position)
    parameters
    jointHandle (input): handle of the joint
    position (input): position of the joint (angular or linear value depending on the joint type)
    return value
    -1 if operation failed

    simEmbSetObjectParent (regular API equivalent: simSetObjectParent)

    Description Sets an object's parent object. See also simEmbGetObjectParent.
    C++ synopsis int simEmbSetObjectParent(int objectHandle,int parentObjectHandle,bool keepInPlace)
    parameters
    objectHandle (input): handle of the object that will become child of the parent object
    parentObjectHandle (input): handle of the object that will become parent, or -1 if the object should become parentless
    keepInPlace (input): indicates whether the object's absolute position and orientation should stay same
    return value
    -1 if operation failed

    simEmbSetObjectTransformation (regular API equivalent: simSetObjectMatrix)

    Description Sets the transformation (position / orientation) of an object. See also simEmbGetObjectTransformation.
    C++ synopsis int simEmbSetObjectTransformation(int objectHandle,int relativeToObjectHandle,const float* position,const float* quaternion)
    parameters
    objectHandle (input): handle of the object
    relativeToObjectHandle (input): indicates relative to which reference frame the transformation is specified. Specify -1 to set the absolute transformation, sim_handle_parent to set the transformation relative to the object's parent, or an object handle relative to whose reference frame the transformation is specified.
    position (input): the position component of the transformation (x, y, z)
    quaternion (input): the orientation component of the transformation (x, y, z, w)
    return value
    -1 if operation failed

    simEmbSetSphericalJointQuaternion (regular API equivalent: simSetSphericalJointMatrix )

    Description Sets the intrinsic quaternion of a spherical joint object. This function cannot be used with non-spherical joints (use simEmbSetJointPosition instead). See also simEmbGetJointTransformation.
    C++ synopsis int simEmbSetSphericalJointQuaternion(int jointHandle,const float* quaternion)
    parameters
    jointHandle (input): handle of the joint
    quaternion (input): the quaternion (x, y, z, w)
    return value
    -1 if operation failed

    simEmbShutDown

    Description Deinitializes the external kinematics routines. Should be the very last function called. See also simEmbLaunch.
    C++ synopsis bool simEmbShutDown()
    parameters
    none
    return value
    false if operation failed.

    simEmbStart

    Description Imports a previously exported kinematic scene content. Can be called at any time to reset the object/joint configurations.
    C++ synopsis int simEmbStart(unsigned char* data,int dataLength)
    parameters
    data (input): pointer to the data to import
    dataLength (input): the size of the data to import
    return value
    -1 if operation failed, otherwise the number of imported objects