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fkin (forward kinematics)

This function computes the TCP pose (Task Space Position and Orientation) from the given joint angles in the robot’s kinematic chain. It is the inverse operation of ikin, converting joint values to Cartesian coordinates.

Definition
DRFLEx.h within class CDRFLEx, public section (line 670)

LPROBOT_POSE fkin(
    float fSourcePos[NUM_JOINT],
    COORDINATE_SYSTEM eTargetRef = COORDINATE_SYSTEM_BASE
) {
    return _fkin(_rbtCtrl, fSourcePos, eTargetRef);
};

Parameter

Parameter Name	Data Type	Default Value	Description
fSourcePos	float[6]		Joint positions for each axis (in degrees or radians, depending on system setting). Represents the current robot configuration in joint space.
eTargetRef	COORDINATE_SYSTEM	COORDINATE_SYSTEM_BASE	Reference coordinate system for TCP output.

Return

Value	Description
LPROBOT_POSE	Structure containing the resulting TCP position and orientation (x, y, z, Rx, Ry, Rz).

Example

float q1[6] = { 0.f, 90.f, 0.f, 90.f, 90.f, 0.f };
drfl.movej(q1, 60, 30);  // Move robot to initial joint pose

float q2[6] = { 30.f, 0.f, 0.f, 0.f, 90.f, 0.f };
LPROBOT_POSE res = drfl.fkin(q2, COORDINATE_SYSTEM_WORLD);

float vel[2] = { 100, 100 };
float acc[2] = { 200, 200 };

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

drfl.movel(tcp, vel[0], acc[0]);

This example calculates the forward kinematics for joint angles q2 in the WORLD coordinate system, producing a TCP pose tcp. The resulting pose is then used as a motion target for movel(), demonstrating how FK results can be directly reused for Cartesian control.