set_desired_force (Auto Mode)

This section explains how to use set_desired_force during Auto (Run) operations to apply a target force or torque along specific axes. It linearly transitions from the current force value to the desired one over the specified time, enabling controlled force application in automated tasks.

This function is commonly used in automated assembly, press-fitting, force-based insertion, and force feedback tasks to ensure precision and safety during automated processes.

Typical usage

  • Apply a defined force or torque in one or more axes during automated operations.

  • Perform press-fit, insertion, or force validation tasks during automatic operation.

  • Combine with task_compliance_ctrl to ensure stable force control during motion.

  • Use direction masking to control only selected axes (e.g., apply force only along Z-axis during assembly).

Note

  • Force direction and reference frame depend on eForceReference (TOOL or BASE).

Example: Apply 20 N Downward Force Along Z-Axis in Auto Mode

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

int main() {
    CDRFLEx drfl;

    // Preconditions:
    // - Connection established
    // - Auto mode active
    // - Servo ON and force control calibrated

    // 1) Move to initial pose
    float q0[6] = {0.0f, 0.0f, 90.0f, 0.0f, 90.0f, 0.0f};
    drfl.movej(q0, 60, 30);
    drfl.mwait();

    // 2) Apply downward force (+Z) of 20 N in TOOL frame
    float fTarget[6] = {0.f, 0.f, 20.f, 0.f, 0.f, 0.f};  // 20 N push along +Z
    unsigned char dir[6] = {0, 0, 1, 0, 0, 0};           // control Z-axis only

    // 3) Apply force smoothly over 0.3 seconds
    drfl.set_desired_force(fTarget, dir, COORDINATE_SYSTEM_TOOL, 0.3f, FORCE_MODE_ABSOLUTE);

    // ... perform automated insertion or calibration under force control ...

    // 4) Release force and return to position control
    drfl.release_force(0.2f);
    drfl.release_compliance_ctrl();

    return 0;
}

In this example, the robot applies a +20 N downward force along the TOOL Z-axis over 0.3 seconds. It then releases both force and compliance control for a smooth transition to position control. This ensures precision during automated insertion or force-based assembly tasks.

Tips

  • Start with moderate stiffness values (1000–3000 N/m) to ensure stable force application.

  • Use direction masks to control force along the relevant axes only (e.g., Z-axis for insertion).

  • Prefer COORDINATE_SYSTEM_TOOL for tool-aligned forces, and COORDINATE_SYSTEM_BASE for global forces.

  • Always call release_force before ending force control with release_compliance_ctrl.

  • Gradual force activation (0.2–0.5 s) prevents abrupt or unsafe force application in automated workflows.