Excessive vibration on J5/J6 axes of LA013-002 at high speed with heavy payload

Description

We have a NexBot Drives LA013-002 robot arm installed on our primary press tending line. The robot is tasked with moving 110kg steel blanks. When we run the production program at speeds above 80%, the end-of-arm tooling exhibits significant oscillation, particularly in the wrist axes (J5 and J6). This vibration is causing inconsistent placement of the blanks into the stamping press, leading to misaligned parts and occasional machine stoppages. We are receiving an intermittent 'E-7112 Path Deviation Warning' which halts production until we reset the fault. We have double-checked that the tool and payload mass are correctly defined in the controller settings, but the problem persists. We are currently forced to run the robot at 70% speed override to avoid the issue, which is putting us behind our production quota. We need to resolve this performance issue to get back to our required cycle time.

Symptoms

• Visible oscillation in wrist axes (J5, J6) at high speed
• Inconsistent part placement accuracy
• Intermittent E-7112 Path Deviation Warning
• Reduced cycle time due to running at lower speed override

Resolution

The investigation determined that while the payload mass was correctly entered, the payload's center of gravity and moments of inertia were not accurately defined for the complex end-of-arm tooling. The default inertia values caused the motion planner to command accelerations that induced high-frequency resonance in the wrist axes under heavy load. The resolution involved accurately defining the tool's inertial properties and running the system's payload identification routine. This allowed the controller to optimize the servo gains for the specific dynamic load. Additionally, minor program path adjustments were made to smooth motion near the placement point, eliminating the root cause of the vibration at full production speed.

Resolution Steps

1. Connected to the robot controller and verified the active payload schedule matched the one used by the production program.
2. Navigated to Menu > Setup > Payload and selected the correct schedule.
3. Assisted the customer in calculating the accurate Center of Gravity (X, Y, Z) and Moments of Inertia (Ixx, Iyy, Izz) for their 110kg tooling assembly.
4. Input the corrected inertial values into the payload schedule.
5. Guided the on-site technician to run the 'Payload Identification' automated tuning routine, which allows the robot to self-adjust its dynamic model for the attached load.
6. Reviewed the robot program and changed the termination type of the motion instruction just before the 'place' position from 'FINE' to 'CNT10' to create a smoother deceleration.
7. Ran the production cycle multiple times at 100% speed override and confirmed that the vibration was eliminated and part placement was consistently accurate.
8. Cleared all logged warnings and advised the customer to monitor performance for the next 24 hours.