release_force

This function gradually reduces the target force and torque values to zero over the specified transition time and returns the robot’s control mode to adaptive position control.

Definition
DRFLEx.h within class CDRFLEx, public section (line 953)

bool release_force(float fTargetTime = 0.f) {
    return _release_force(_rbtCtrl, fTargetTime);
};

Parameter

Parameter Name

Data Type

Default Value

Description

fTargetTime

float

0

Duration [sec] for reducing the target force to zero.
Range: 0–1.0 (linear interpolation over time).

Return

Value

Description

0

Failed

1

Success

Example A — Manual Mode (Force Release After Hand-Guiding)

#include "DRFLEx.h"
using namespace DRAFramework;

int main() {
    CDRFLEx drfl;

    // Preconditions:
    // - Connection established and servo ON
    // - Manual (Teach) mode active

    // 1) Set reference coordinate
    drfl.set_ref_coord(COORDINATE_SYSTEM_TOOL);

    // 2) Move to start pose
    float q0[6] = {0.0f, 0.0f, 90.0f, 0.0f, 90.0f, 0.0f};
    drfl.movej(q0, 60, 30);
    drfl.mwait();

    // 3) Enable compliance mode
    float stiff[6] = {1500.f, 1500.f, 1000.f, 150.f, 150.f, 150.f};
    drfl.task_compliance_ctrl(stiff);

    // 4) Apply downward force (+Z)
    float fTarget[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(fTarget, dir, COORDINATE_SYSTEM_TOOL, 0.3f);

    // 5) Gradually release the applied force
    drfl.release_force(0.4f);

    // 6) End compliance control
    drfl.release_compliance_ctrl();

    printf("Force released and compliance ended.\n");
    return 0;
}

Example B — Auto Mode (Force-Controlled Task Completion)

// Preconditions:
// - Auto mode active
// - Force control previously enabled during a process

// 1) Apply a downward insertion force
float fTarget[6] = {0.f, 0.f, 30.f, 0.f, 0.f, 0.f};
unsigned char dir[6] = {0, 0, 1, 0, 0, 0};
drfl.set_desired_force(fTarget, dir, COORDINATE_SYSTEM_TOOL, 0.3f);

// 2) Execute insertion motion
float p_insert[NUM_TASK] = {550.f, 200.f, 90.f, 180.f, 0.f, 0.f};
drfl.movel(p_insert, (float[2]){50.f, 20.f}, (float[2]){200.f, 80.f});
drfl.mwait();

// 3) Smoothly release the applied force after completion
drfl.release_force(0.4f);

// 4) Restore normal control and continue next motion
drfl.release_compliance_ctrl();

printf("Force smoothly released and returned to position mode.\n");

Notes & Best Practices

  • Always call release_force() before release_compliance_ctrl() to ensure a stable transition.

  • Use short transition times (0.3–0.5 s) for smooth and safe force decay.

  • Avoid releasing force suddenly when under external load — ensure stable contact conditions first.

  • Combine with set_desired_force and task_compliance_ctrl for full compliance-force control workflows.

  • In Auto mode, it’s recommended to wait for motion completion (e.g., using mwait()) before releasing the force.