get_tool_force

This function retrieves the force and moment applied at the robot tool center point (TCP). The force is expressed relative to the specified coordinate system (default: BASE). Internally, it is estimated using joint torque sensors and the robot’s dynamic model.

Definition
DRFLEx.h within class CDRFLEx, public section

LPROBOT_FORCE get_tool_force(COORDINATE_SYSTEM eTargetRef = COORDINATE_SYSTEM_BASE) {
    return _get_tool_force(_rbtCtrl, eTargetRef);
};

Parameter

Parameter Name

Data Type

Default Value

Description

eTargetRef

COORDINATE_SYSTEM

COORDINATE_SYSTEM_BASE

Reference coordinate system in which the TCP force is expressed. Supported values are COORDINATE_SYSTEM_BASE, COORDINATE_SYSTEM_TOOL and COORDINATE_SYSTEM_WORLD; TOOL and WORLD require setup_monitoring_version(1).

Return

Value

Description

LPROBOT_FORCE

Pointer to a structure containing the estimated TCP force (Fx, Fy, Fz) and moment (Mx, My, Mz).
Force unit: N, Moment unit: N·m

Caution

The function does not refuse unsupported eTargetRef values; it returns the BASE values instead. With monitoring version 0, COORDINATE_SYSTEM_TOOL and COORDINATE_SYSTEM_WORLD also return the BASE values. Call setup_monitoring_version(1) before requesting TOOL or WORLD.

Example

// Assume robot connection and operation mode initialized

LPROBOT_FORCE lpForce = drfl.get_tool_force(COORDINATE_SYSTEM_BASE);
if (lpForce) {
    printf("Tool Force and Moment (Base Coordinate)\n");
    printf("Force  [N]:  Fx=%.2f  Fy=%.2f  Fz=%.2f\n",
           lpForce->_fForce[0],
           lpForce->_fForce[1],
           lpForce->_fForce[2]);
    printf("Moment [N·m]: Mx=%.3f  My=%.3f  Mz=%.3f\n",
           lpForce->_fForce[3],
           lpForce->_fForce[4],
           lpForce->_fForce[5]);
} else {
    fprintf(stderr, "Failed to retrieve tool force.\n");
}

This example prints the current force and torque applied at the TCP, expressed in the base coordinate system.
It can be used for:

  • Detecting contact with objects (e.g., surface alignment)

  • Measuring external forces during force-control applications

  • Validating compliance and impedance control responses