.. _ikin:

ikin
------------------------------------------
This function receives a task-space pose (`fSourcePos`, [X, Y, Z, Rx, Ry, Rz]) in the coordinate system given by `eTargetRef` and returns the joint angles that reach it in the solution space selected by `iSolutionSpace`.

**Definition** |br|
``DRFLEx.h`` within class `CDRFLEx`, public section

.. code-block:: cpp

    LPROBOT_POSE ikin(
        float fSourcePos[NUM_TASK],
        unsigned char iSolutionSpace,
        COORDINATE_SYSTEM eTargetRef = COORDINATE_SYSTEM_BASE
    ) {
        return _ikin(_rbtCtrl, fSourcePos, iSolutionSpace, eTargetRef);
    };

**Parameter**

.. list-table::
   :widths: 18 18 18 46
   :header-rows: 1

   * - **Parameter Name**
     - **Data Type**
     - **Default Value**
     - **Description**
   * - fSourcePos
     - float[6]
     - -
     - Target task pose [X, Y, Z, Rx, Ry, Rz] to solve for, in the coordinate system given by `eTargetRef`.
   * - iSolutionSpace
     - unsigned char
     - -
     - Solution space index (0–7), or 255 to let the controller choose the reachable solution. |br|
       Indicates which inverse kinematics configuration to use (e.g., elbow up/down, wrist flip, etc.).
   * - eTargetRef
     - :ref:`COORDINATE_SYSTEM <enum_coordinate_system>`
     - COORDINATE_SYSTEM_BASE
     - Reference coordinate system of `fSourcePos`.

**Return**

.. list-table::
   :widths: 25 75
   :header-rows: 1

   * - **Value**
     - **Description**
   * - :ref:`ROBOT_POSE <struct_robot_pose>`
     - Joint angles [deg] (J1–J6) in `_fPosition` that reach `fSourcePos` in the solution space selected by `iSolutionSpace`.

.. note::

   This call waits for the controller to answer.

   The call overwrites the data returned earlier by ``get_current_posx``, ``get_desired_posx``, ``fkin``, the other ``ikin`` overloads, ``ikin_norm``, ``trans``, ``coord_transform``, ``calc_coord``, ``get_user_home``, ``get_user_cart_coord`` and ``flange_serial_read``. The pointer is never NULL; if the request cannot be sent, all joint angles are 0. Do not use a NULL check to detect failure.

.. Caution::

   The returned pointer refers to one ``ROBOT_POSE`` shared by all CDRFLEx objects in the process. The next call to this 3-argument ``ikin`` on any CDRFLEx object overwrites it. Copy the joint angles before calling it again, and do not call it on two CDRFLEx objects at the same time.

**Example**

.. code-block:: cpp

   float x1[6] = { 370.9, 719.7, 651.5, 90, -180, 0 };
   LPROBOT_POSE res = drfl.ikin(x1, 2);

   float q1[6] = { 0 };
   for (int i = 0; i < 6; i++) {
       q1[i] = res->_fPosition[i];
   }

   drfl.movej(q1, 60, 30);

In this example, the function computes the **inverse kinematics** of the task pose `x1` to get the joint angles for solution space 2, and the robot moves to them with `movej`. By selecting `iSolutionSpace`, the user controls which configuration (among multiple possible IK solutions) the robot uses.