MOTN-018: Commanded position not reachable

What it means

The robot cannot reach the commanded Cartesian position. This can happen because the point is outside the reachable workspace, or because the Cartesian path or jog passes near a J1 singularity (where the wrist center lines up on the J1 axis). Offsets can also push an otherwise valid position into an unreachable one.

Common causes

Ranked by what technicians most often find, most likely first.

1. The taught position simply lies outside the robot's reach.
2. The Cartesian motion path passes near a J1 singularity, with the wrist center sitting on the J1 axis.
3. A Cartesian jog was attempted near the J1 singularity.
4. The base position combined with a position, tool, or vision offset lands out of reach or near J1 singularity.
5. An offset (position, tool, or vision) rotated the wrist axis 180 degrees.

How to fix it

1. Reteach the position so it falls within reach.
2. For a singularity-related fault, reteach to avoid the J1 singularity, add intermediate points to route around it, or switch the segment to Joint motion.
3. If jogging triggered it, use Joint jog to move the robot away from the J1 singularity.
4. When offsets are the cause, apply the reachability or singularity fix to the pre-offset position, and repeat for each stacked offset if they overlap.
5. If an offset rotates the wrist axis 180 degrees, adjust the offset amount so that rotation no longer occurs.

Related codes

• MOTN-019: Robot Near Singularity
• MOTN-023: Robot in singularity
• MOTN-000: Unknown Internal Motion Error
• MOTN-063: Position Configuration Mismatch
• MOTN-095: Not Enough Distance for Corner Blending
• MOTN-098: Circle angle too large
• MOTN-110: Previous Motion Must Finish With FINE Termination
• MOTN-136: Circular Points Too Close