Servo Circular

SUMMARY

Servo Circular commands a circular arc motion by providing a via-point (or target) TCP pose. The robot traces a circular arc defined by the current pose, the via-point, and the target pose.

UNITS

Waypoint poses in meters and Euler XYZ degrees. speed in m/s, acceleration in m/s².

The Skill

robot.servo_circular(
    pose=via_point_pose,
    speed=0.25,
    acceleration=1.2,
    blend=0.0,
)

The Code

Safety first!

A real robot will faithfully do whatever you ask of it - so please take a moment to clear the workspace, keep an E-Stop within reach, and be ready to disconnect.

Operating real hardware is at your own risk.

Example: Execute a Circular Arc Move

Move the robot along a circular arc by providing a via-point offset from the current pose.

"""
Commands a circular-arc move from the current TCP pose to an offset target pose using servo_circular.

Supports Universal Robots (UR).

Usage:
    python servo_circular.py [--ip <ROBOT_IP>]
"""

import argparse
import time

from loguru import logger

from telekinesis.synapse.robots.manipulators import universal_robots


def main(ip: str) -> None:
    """Drive a circular arc from the current TCP pose to an offset target."""

    #===================== Create Robot ==========================================
    robot = universal_robots.UniversalRobotsUR10E(name='UR10e')

    # ==================== Visualization (Optional) =============================
    # Live: subscribes to the robot's state topic and redraws as it moves.
    robot.visualize_rerun(live=True)

    try:
        #===================== Connect Robot ==========================================
        if ip:
            robot.connect(ip=ip)

        #===================== Prepare Target ==========================================
        # Target pose: 2 cm out in Y and 2 cm down in Z from the current pose.
        current = robot.get_cartesian_pose()
        target = list(current)
        target[1] += 0.02
        target[2] -= 0.02

        # ==================== Run Skill ============================================
        logger.warning(
            f"About to move real robot along a circular arc from {current} to {target}. "
            "Make sure it's safe to move there."
        )
        logger.info(f"servo_circular target: {target}")

        # Command the circular servo move, then stop streaming to end the motion.
        robot.servo_circular(
            pose=target,
            speed=0.1,
            acceleration=0.1,
            blend=0.0,
        )

        # In a real application, you would typically stream continuously until some
        # condition is met (e.g. a certain time has elapsed, or a sensor triggers).
        time.sleep(2.0)
        robot.servo_stop()
        logger.success("servo_circular complete.")
    except (ConnectionError, OSError) as e:
        logger.error(f"Error occurred: {e}")
    finally:
        robot.disconnect()
        robot.shutdown()


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="UR10e servo_circular example")
    parser.add_argument("--ip", type=str, default=None,
                         help="UR robot IP address for real hardware, e.g. 192.168.1.100")
    args = parser.parse_args()

    main(ip=args.ip)

Running the Example

Real

python servo_circular.py --ip 192.168.1.100

For all options:

python servo_circular.py --help

Parameter Configuration

Parameter	Type	Default	Description
pose	list[float]	-	Via-point TCP pose [x, y, z, rx, ry, rz].
speed	float	0.25	TCP speed in m/s.
acceleration	float	1.2	TCP acceleration in m/s².
blend	float	0.0	Blend radius in meters.

Returns

Value	Description
None	This skill returns nothing.

Raises

Exception	Condition
RuntimeError	The robot is not connected.

How to Tune the Parameters

blend controls how sharply the arc's endpoint transitions into the next queued motion segment: 0.0 brings the robot to a full stop at the end of the arc, while a non-zero radius (in meters) lets the controller round the corner and carry velocity into the next segment - useful for chaining multiple arcs or an arc into a line without stopping, at the cost of the path deviating from the exact via-point near the blend region.

Where to Use the Skill

• Arc weld paths.
• Circular polishing trajectories.
• Any application requiring a curved TCP path.

When Not to Use the Skill

Use a different skill instead in these cases:

• Use Set Cartesian Pose for straight-line moves.