servol_rt

This function performs real-time task-space (TCP) position control from an external controller. It commands the robot’s tool center point (TCP) position and orientation at each real-time control cycle, based on the target pose, velocity, acceleration, and interpolation time.

Definition
DRFLEx.h within class CDRFLEx, public section (line 601)

bool servol_rt(float fTargetPos[NUM_TASK],
               float fTargetVel[NUM_TASK],
               float fTargetAcc[NUM_TASK],
               float fTargetTime) {
    return _servol_rt(_rbtCtrlUDP, fTargetPos, fTargetVel, fTargetAcc, fTargetTime);
};

Caution

• The current servol_rt command is preliminary, and jerky motion may occur depending on communication latency or network jitter.

• It is recommended to tune the target time (fTargetTime) and use a slow response speed, or alternatively use speedl_rt for smoother motion.

• When running at high frequency (1 kHz), ensure that fTargetTime is slightly greater than the control cycle time for stable interpolation.

Parameter

Parameter Name	Data Type	Default Value	Description
fTargetPos	float[6]		Target TCP position and orientation [x, y, z, Rx, Ry, Rz] (position in mm, rotation in deg, using Euler ZYX convention)
fTargetVel	float[6]		Target TCP velocity [mm/s, deg/s] If set to -10000, velocity is automatically calculated from fTargetPos
fTargetAcc	float[6]		Target TCP acceleration [mm/s², deg/s²] If set to -10000, acceleration is automatically computed
fTargetTime	float		Target interpolation duration [s]

Note

• Asynchronous command.

• The internal motion profile interpolates between current and target states
  (fTargetPos, fTargetVel, fTargetAcc) over fTargetTime.

• If fTargetTime ≤ controller’s cycle (~1 ms), interpolation is skipped.

• If the next command is not received before completion, the motion decelerates
  using the system’s global acceleration setting.

Caution

• The current implementation is not linked with Operation Speed [%].

• Jerky motion may occur if the command interval exceeds 1 ms.

• Recommended to set fTargetTime ≥ 20 × communication_period or use speedl_rt instead.

• Not compatible with force/compliance control or DR_VAR_VEL near singularities;
  the system automatically reverts to DR_AVOID mode in such cases.

Return

Value	Description
1	Success — command accepted and executed.
0	Error — invalid parameter or RT communication failure.

Example

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

int main() {
    CDRFLEx drfl;
    drfl.connect_rt_control("192.168.137.100", 12347);

    std::string version = "v1.0";
    float period = 0.001f; // 1 ms
    int lossCount = 4;

    // Configure real-time streaming
    drfl.set_rt_control_input(version, period, lossCount);
    drfl.set_rt_control_output(version, period, lossCount);
    drfl.start_rt_control();

    // Define target TCP pose
    float fTargetPos[6] = {150.f, 0.f, 100.f, 0.f, 0.f, 0.f};
    float fTargetVel[6] = {200.f, 100.f, 100.f, 20.f, 20.f, 20.f};
    float fTargetAcc[6] = {1000.f, 800.f, 800.f, 100.f, 100.f, 100.f};
    float fTargetTime = 0.06f; // 60 ms (recommended ≥ 20 ms)

    // Send real-time task-space motion command
    if (drfl.servol_rt(fTargetPos, fTargetVel, fTargetAcc, fTargetTime))
        std::cout << "Task-space motion command successful." << std::endl;
    else
        std::cout << "Task-space motion failed." << std::endl;

    drfl.stop_rt_control();
    drfl.disconnect_rt_control();
    return 0;
}

This example shows how to control TCP motion in real time by sending continuous task-space commands at 1 ms intervals.

Tips

• Use servol_rt for precise Cartesian interpolation control in external systems.

• Always ensure consistent timing between cycles for smooth motion.

• For joint-level streaming, refer to servoj_rt.