Troubleshooting Error E-1404: Joint 4 Position Following Error on FLR022-005 Cobot

Related Products

Tools Required

• Teach Pendant
• Lockout/Tagout (LOTO) kit
• Hex key set
• Multimeter

Article

Overview

This article provides a diagnostic and resolution guide for the error code E-1404: Joint 4 Position Following Error on the NexBot Robotics FLR022-005 Collaborative Robot (SKU: NXB-ROB-FLR022-005). A position following error occurs when the controller detects a significant discrepancy between the commanded position for a joint and the actual position reported by the joint's absolute encoder. This safety feature halts robot motion to prevent damage to the equipment or workpiece.

Symptom

When error E-1404 occurs, the operator will typically observe the following:

• The robot immediately stops its current program.
• The message "E-1404: Joint 4 Position Following Error" is displayed on the teach pendant or HMI.
• The robot's brakes engage, making the arm rigid and difficult to move manually.
• In some cases, a brief, audible clunk or hesitation from the Joint 4 area may precede the fault.

Cause

The root cause of a position following error can be mechanical or electrical. The most common causes are listed below in order of likelihood:

1. Physical Obstruction: The robot arm has collided with an object in its workspace (e.g., a fixture, workpiece, or other equipment), preventing Joint 4 from reaching its target position.
2. Excessive Payload or Inertia: The combined weight of the end-of-arm tooling (EOAT) and the workpiece exceeds the specified 10 kg payload, or the center of gravity is too far from the tool flange, creating excessive torque on the joint.
3. Loose or Damaged Cabling: The power or data cable for the Joint 4 servo motor and encoder is loose, disconnected, or damaged. This can cause intermittent signal loss.
4. Incorrect Acceleration/Deceleration Parameters: The programmed motion profile demands acceleration or deceleration rates that exceed the physical capabilities of the joint given the current payload.
5. Servo Drive Fault: The servo drive module controlling Joint 4 (related part: NXB-SRV-SD131-004) has malfunctioned.
6. Encoder Malfunction: The absolute encoder (related part: NXB-SNS-ABS141-008) for Joint 4 is failing, providing incorrect position feedback to the controller.
7. Mechanical Binding: There is an internal mechanical issue within the Joint 4 gearbox or bearings, causing high resistance to movement.
8. Brake Malfunction: The electromechanical brake for Joint 4 is not fully disengaging, causing drag on the motor.

Resolution Steps

WARNING: Always follow proper safety procedures, including engaging the emergency stop and performing Lockout/Tagout (LOTO) before physically inspecting the robot or entering its workspace.

1. Power Down and Secure the Robot: Press the Emergency Stop button. If physical inspection is required, perform a full LOTO procedure on the robot controller's main power source.

1. Inspect the Workspace: Carefully examine the entire range of motion for Joint 4. Look for any physical obstructions, foreign objects, or points of collision that may have impeded the robot's movement.

1. Verify Payload: Confirm that the total weight of your EOAT and workpiece does not exceed the 10 kg payload limit of the NXB-ROB-FLR022-005. Check the tooling's center of gravity and ensure it complies with the specifications in the robot's technical manual.

1. Inspect Joint 4 Cabling: Visually inspect the cables leading to and from Joint 4. Check that connectors are securely seated at both the joint and within the control cabinet. Look for signs of abrasion, pinching, or sharp bends. A damaged cable (e.g., NXB-CBL-512-001) must be replaced.

1. Review Program Parameters: Analyze the robot program steps that were running when the fault occurred. Reduce the programmed acceleration and deceleration values for the move that triggered the error and test the program at a reduced speed.

1. Check Servo Drive Status: Power on the controller (after clearing the workspace and removing LOTO). Navigate to the diagnostics screen on the teach pendant and check the status of the servo drive associated with Joint 4. Note any additional alarm codes displayed by the drive itself, as this can help pinpoint the issue (e.g., overcurrent, overvoltage).

1. Attempt to Re-Home: After clearing the fault, try to re-home the robot. If the E-1404 error reoccurs on the same joint during the homing sequence, it is more likely to be a hardware issue (encoder, drive, or mechanical binding).

1. Contact Technical Support: If the steps above do not resolve the issue, the problem may be due to a failed component like the servo drive or encoder. Contact NexBot Robotics technical support and provide them with the error code, a description of the symptoms, and any logs from the robot controller.

Prevention

• Path Validation: Always run new or modified programs at a low speed to verify the path is completely clear of obstacles.
• Payload Compliance: Maintain a log of all EOAT weights and ensure all applications operate within the robot's 10 kg payload and inertia limits.
• Scheduled Maintenance: Follow the maintenance schedule for the NXB-ROB-FLR022-005. Periodically inspect cable harnesses for wear and ensure all connectors are secure.
• Proper Programming: Use smooth, controlled motion profiles. Avoid unnecessarily high acceleration/deceleration values, especially with heavy or off-center payloads.

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