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check_position_condition

This function checks whether the position of a specified axis lies within a defined range with respect to a given target position, supporting both absolute and relative comparison modes.

When eMode is MOVE_MODE_RELATIVE, it behaves as check_position_condition_rel. When eMode is MOVE_MODE_ABSOLUTE, it behaves as check_position_condition_abs.

Definition
DRFLEx.h within class CDRFLEx, public section (line 958)

bool check_position_condition(FORCE_AXIS eForceAxis,
                              float fTargetMin,
                              float fTargetMax,
                              float fTargetPos[NUM_TASK],
                              MOVE_MODE eMode = MOVE_MODE_ABSOLUTE,
                              COORDINATE_SYSTEM eForceReference = COORDINATE_SYSTEM_TOOL) {
    return _check_position_condition(_rbtCtrl, eForceAxis, fTargetMin, fTargetMax, fTargetPos, eMode, eForceReference);
};

Parameter

Parameter Name	Data Type	Default Value	Description
eForceAxis	FORCE_AXIS		Axis to check position condition (X, Y, Z or rotation axes Rx, Ry, Rz).
fTargetMin	float		Minimum threshold value for position comparison.
fTargetMax	float		Maximum threshold value for position comparison.
fTargetPos	float[6]		Reference target task position for comparison (X, Y, Z, Rx, Ry, Rz).
eMode	MOVE_MODE	`MOVE_MODE_ABSOLUTE`	Specifies comparison mode MOVE_MODE_ABSOLUTE: compares current position to global coordinates. MOVE_MODE_RELATIVE: compares deviation relative to target position.
eForceReference	COORDINATE_SYSTEM	`COORDINATE_SYSTEM_TOOL`	Reference coordinate system for comparison (BASE, TOOL, WORLD, etc.).

Return

Value	Description
1	Condition True — position is within defined range.
0	Condition False — position is outside defined range.

Example A — Manual Mode (Teaching Position Validation)

#include "DRFLEx.h"
#include <cstdio>
using namespace DRAFramework;

int main() {
    CDRFLEx drfl;
    // Preconditions: Connected, servo ON, Teach mode active

    // Define reference target pose
    float targetPose[6] = {400.f, 500.f, 600.f, 0.f, 180.f, 0.f};

    // 1) Check relative Z-axis offset from target (±5 mm)
    bool relCond = drfl.check_position_condition(FORCE_AXIS_Z, -5.f, 5.f, targetPose, MOVE_MODE_RELATIVE);

    // 2) Check absolute X-axis position range in BASE frame
    bool absCond = drfl.check_position_condition(FORCE_AXIS_X, 100.f, 200.f, targetPose, MOVE_MODE_ABSOLUTE, COORDINATE_SYSTEM_BASE);

    printf("Relative condition (Z): %s\n", relCond ? "TRUE" : "FALSE");
    printf("Absolute condition (X): %s\n", absCond ? "TRUE" : "FALSE");

    return 0;
}

Example B — Auto Mode (Process Approach Detection)

// Preconditions:
// - Auto mode active
// - Robot executing approach motion

// Define target pose for insertion
float targetPose[NUM_TASK] = {550.f, 200.f, 80.f, 180.f, 0.f, 0.f};

// Move near target
drfl.movel(targetPose, (float[2]){80.f, 25.f}, (float[2]){300.f, 100.f});
drfl.mwait();

// Check if Z position is within ±3 mm of target (relative check)
bool inRange = drfl.check_position_condition(FORCE_AXIS_Z, -3.f, 3.f, targetPose, MOVE_MODE_RELATIVE, COORDINATE_SYSTEM_TOOL);

if (inRange)
    printf("Robot has reached insertion tolerance zone.\n");
else
    printf("Robot not yet in target range.\n");

// Proceed to next force-controlled insertion step if within range
if (inRange) {
    float fForce[6] = {0.f, 0.f, 20.f, 0.f, 0.f, 0.f};
    unsigned char dir[6] = {0, 0, 1, 0, 0, 0};
    drfl.set_desired_force(fForce, dir, COORDINATE_SYSTEM_TOOL, 0.3f);
}

Notes & Best Practices

Use MOVE_MODE_ABSOLUTE for global safety validation, zone checks, or workspace boundary logic.
Use MOVE_MODE_RELATIVE for approach precision, fine motion alignment, or contact tolerance verification.
When eForceReference is COORDINATE_SYSTEM_TOOL, define fTargetPos in BASE coordinates.
The function only evaluates conditions; it does not perform motion commands.
Combine with check_force_condition for hybrid force-position control.
For continuous monitoring, call periodically (every 50–200 ms) inside motion or feedback loops.