check_force_condition (Auto Mode)

This section explains how to use check_force_condition during Auto (Run) operations to verify whether the measured force or torque on a selected axis remains within a defined threshold.

It is commonly used for contact detection, assembly checks, and other safety-related conditions during automated motion.

Typical usage

  • Monitor contact forces during assembly or insertion processes.

  • Detect surface contact or completion of tightening/pressing tasks.

  • Implement safety thresholds to stop or adjust operations when excessive force is detected.

  • Combine with check_position_condition for hybrid force–position validation.

  • Integrate into control loops for dynamic adjustment of robot behavior in real-time.

Note

  • Can be called cyclically (e.g., every 50–100 ms) within process loops for smooth feedback control.

Example: Force-Based Contact Detection in Auto Mode

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

int main() {
    CDRFLEx drfl;

    // Preconditions:
    // - Connection established
    // - Servo ON
    // - Auto (Run) mode active
    // - F/T sensor calibrated or internal force estimation enabled

    // 1) Define downward motion path
    float fPosStart[6] = {400.f, 300.f, 500.f, 180.f, 0.f, 0.f};
    float fPosApproach[6] = {400.f, 300.f, 450.f, 180.f, 0.f, 0.f};

    // 2) Move near the target surface
    drfl.movel(fPosStart, (float[2]){100.f, 50.f}, (float[2]){300.f, 100.f});
    drfl.mwait();

    // 3) Gradually approach the surface
    drfl.movel(fPosApproach, (float[2]){40.f, 15.f}, (float[2]){200.f, 100.f});
    drfl.mwait();

    // 4) Monitor contact condition: Z-axis force between 5 N and 20 N
    bool contactDetected = false;
    while (!contactDetected) {
        contactDetected = drfl.check_force_condition(FORCE_AXIS_Z, 5.f, 20.f, COORDINATE_SYSTEM_TOOL);
        std::this_thread::sleep_for(std::chrono::milliseconds(50));
    }

    printf("Surface contact detected (Z force within 5–20 N).\n");

    // 5) Stop motion or trigger next step
    drfl.stop(STOP_TYPE_QUICK);

    return 0;
}

In this example, the robot performs a downward motion during Auto mode and continuously checks the measured Z-axis force. When the detected force enters the defined range (5–20 N), the robot recognizes contact and stops motion automatically. This ensures reliable and safe contact-based task execution.

Tips

  • Use COORDINATE_SYSTEM_TOOL for tool-aligned force checks during insertion or pressing.

  • Set appropriate force thresholds to prevent damage to tools or workpieces.

  • Combine with stop() or move_pause() for automatic reaction upon detection.

  • Use short polling intervals (50–100 ms) for responsive control.