RTRAlternateLocation OLP command

Owned by Alex Soler
Last updated: Nov 22, 2023
2 min read

What is a deadlock?

Deadlocks between two or more robots might occur if a number of robots block each other in such a way that none of them is able to continue along its trajectory without causing a collision.

Deadlock Avoidance

Realtime has a built-in deadlock resolution mechanism by default. This mechanism tries to move the robots away from each others paths in an attempt to continue operation. The automatic deadlock resolution might fail with Error 4023 (shown in the RapidPlan Control panel). At this stage, there are 2 options:

  • The user can add locations or wait statements to the Siemens PS path to avoid the deadlock

  • The user can define a position that will be used as a waiting position when robots are in a deadlock. We call this Alternate Location

In case the user wants to use the alternate location mechanism, a retreat location for one or more of the robots must be set. Set this location using the RTRAlternateLocation <LocationName> OLP command. We recommend adding a location with a unique name (for example, wait_pos) at the very end of the path when exporting to RTR, or using the home/start position.

When is Deadlock Avoidance triggered?

When a motion is sent but there is not an available path, RapidPlan will wait a certain time before issuing a timeout. The timeout can be set in the Realtime Robotics Settings menu, by showing the advanced options.

How to use it

  1. Chose the hubs in the toolkit that you would use for the retreat. You can use an existing one, or create new ones. Each position can have a different retreat position.

  2. Add the following command to the OLP as Free Text: RTRAlternateLocation <LocationName>

Example here: