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--- eeros_architecture:sequencer:start [2015/10/30 10:53] – graf
+++ eeros_architecture:sequencer:start [2017/09/24 10:48] – graf
@@ Line 1: / Line 1: @@
 ====== Sequencer ======
-Since robots have to execute a series of user-defined tasks, an additional component is needed. It can also be non-real-time, but it has to ensure the sequential execution of the tasks and has to be able to handle any possible exceptions.
+A sequencer ensures that a robots can execute a series of user-defined tasks. Such a sequencer runs in non-realtime. The robot's motions are defined as a sequence of steps. The sequencer, which is an integral part of the EEROS framework, has to be assigned such a sequence. Each sequence may include many single steps which must run to completion (unless interrupted by the safety system). Additionally, several subsequences may be defined and added to the same sequencer. \\
+As soon as a sequence should run concurrently to another sequence a second sequencer has to be defined. In such a case the two sequencers each run in a separate thread of execution. \\
+What happens if a certain step in a sequence cannot run due to some condition. In that case an exception might be thrown and a special exception handler has to take necessary steps. This could include repeating some steps or doing something completely different.
-The robot's motions are defined as sequence of steps. The sequencer, which is an integral part of the EEROS Framework, has to be assigned one main sequence. Additionally, several subsequences may be defined and added to the sequencer. Each sequence may include many single steps which must run to completion (unless interrupted by the safety system).
+[{{ sequenceroverview.png?500 | //The sequencer running various sequences// }}]
-{{ sequencerexample2.png?300 |A Sequence of Steps with a Subsequence}}
 Learn more about how to use the sequencer and how it handles exceptions:
-  * [[.:sequencer|Sequencer]
+  * [[.:sequencer]]
-  * [[.:sequence|Sequence]]
+  * [[.:sequence]]
-  * [[.:subsequence|Subsequence]]
+  * [[.:define_sequence]]
-  * [[.:exception_handling|Exception Handling]]
+  * [[.:monitors]]
+  * [[.:exceptions]]