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Alarm 4315: Collision detect

Type: minor alarm (can be reset once the cause is removed) · Sub-code: the axis that detected the collision

How it works​

While the robot is moving, the collision detection function calculates the motor torque on each axis and compares it with a preset allowed value. If the calculated torque goes above the allowed value, the controller decides that the arm has hit a fixture, workpiece or nearby equipment, and stops the robot in both teach and play mode. When this happens during playback, alarm 4315 is displayed.

At shipment the function is enabled, with settings that leave a large margin.

Collision detection does not guarantee the safety of people or peripheral equipment. Always provide separate safety measures such as safety fences.

Suspect the settings first​

The alarm often occurs because of a setting error, even though nothing was actually hit.

  • Tool mass, centre of gravity and inertia settings. If they are wrong, the torque calculation is off.
  • The tool number used in the job.
  • The collision detection level (sensitivity) setting.
  • The job's speed and any ACC/DEC (acceleration/deceleration) settings.
  • The length and thickness of equipment cables (such as power feed cables) that may pull on the arm.

Adjusting the detection level​

Once you have confirmed that there is no real interference, you can raise the detection level (lower the sensitivity). The upper limit is 500%.

The Smart Pendant can hold nine settings in total: default settings for play and for teach, plus play conditions 1 to 7. The general procedure is:

  1. Run the actual application for up to about one hour and record the maximum measured torque for each axis (the values settle over time).
  2. Use "copy measured value to allowed value with margin" to set the allowed value to the measured value plus a margin.

If there really was interference​

Remove the interference with the fixture or workpiece. Review the taught positions and the layout of peripheral equipment.

When acceleration is the cause​

The alarm can occur when the following conditions coincide: acceleration and deceleration are calculated automatically from the start and end postures; the job was stopped by a category 1 stop or a hold; and the motor is heavily loaded in that posture. In this case, use ACC/DEC on the step concerned to reduce acceleration and deceleration. In cold surroundings of around 10 °C, warm the robot up thoroughly before production.

Order for checking hardware​

If the settings are fine, check in this order:

  1. Connectors on the servo board and amplifier, the motor power lines (U/V/W phases) and the brake wiring.
  2. The servo control board, amplifier and motor.
  3. The reducer: measure the iron powder concentration in the grease; if wear is advanced, replace the grease or the reducer.

Source: Based on YASKAWA manuals HW1485508 and RE-CER-A600.