The EEROS Education Robotics Platform

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====== Sequencer and Sequences ======

For more informations how sequences and the sequencer work, have a look at[[http://wiki.eeros.org/eeros_architecture/sequencer/start|]] in the [[http://wiki.eeros.org|eeros wiki]].

An overview of all sequences is show below.
{{ :delta:software:sequencer.png?900 |Sequences of the Delta roboter}}

===== Main Sequence =====
The main sequence starts shortly after the executor started running. It is responsible to initialize the robot by stepping through the safety levels up to ''slSystemReady''. From there the user can choose whether she wants to start normal operation or switch off the system again. The main sequence has an associated ''EmergencyMonitor''. This monitor helps to detect an emergency condition (if the red button was pressed) and will interrupt the main sequence. Upon returning from the emergency state the monitor will cause a restart of the main sequence. 

===== Homing =====

The homing of the Delta robot is done in the ''Homing Sequence''. The three axis are raised by driving the three motors upwards with constant speed until the end stop. At this point the encoders are set to their initial position. The angle of this initial position can be determined from the mechanical constraints, see [[motors_init|]]. From there the tool center point is moved to position //ready//. As soon as ''Homing Sequence'' finishes a safety event is triggered, which causes the safety system to change to ''slHomed'' level.
===== Circle Sequence=====
As soon as the safety system reaches the level ''slAutoMoving'' it will start the ''CircleSequence''. First the TCP is moved to a start position on the circle. Then the circle planner in the Control System is activated and the robot will perform a circular movement. The ''CircleSequence'' repetitively runs step ''Wait''. \\
The ''CircleSequence'' is equipped with two monitors. 
  * Mouse Monitor: This monitor checks if the mouse is moved. As soon as this condition is met, the current sequence is aborted and the ''MoveMouseExceptionSequence'' gets started. This sequence triggers the safety event "doMouseControl". This causes the safety system to change to ''slMouseControl'' level.
  * BlueButton Monitor: Another monitor permanently checks if the blue button is pressed. Its associated exception sequence stops the current sequence, moves the TCP to its initial position and triggers a ''stopMoving'' event. The safety system will return to ''slSystemReady''.

===== Mouse Sequence =====
The ''MainSequence'' starts the ''MouseSequence'' as soon as the safety system jumps into level ''slMouseControl''. As long as the mouse gets moved, the ''MouseSequence'' will be active and the TCP will duly follow the position given by the mouse. This sequence is equipped with two monitors.
  * Timeout Monitor: If the mouse doesn't send any event for 2 seconds, this monitor starts the ''MouseTimeoutExpectionSequence''. This exception sequence aborts the ''MouseSequence'' and causes the safety system to fall back to level ''slAutoMoving'', which in turns restarts ''CircleSequence''.
  * BlueButton Monitor: Another monitor permanently checks if the blue button is pressed. Its associated exception sequence stops the current sequence, moves the TCP to its initial position and triggers a ''stopMoving'' event. The safety system will return to ''slSystemReady''.

===== Parking Sequence =====
The ''MainSequence'' starts the ''ParkingSequence'' as soon as the safety system jumps into level ''slParking''. The TCP moves to a park position before the driving signals to the motors are set to zero. Finally a ''parkingDone'' event is triggered. 

===== Abort Monitor and Condition =====
For a system under development it is advantageous to be able to stop the running application by pressing ''CTRL-C''. For this purpose every sequence and step is equipped with an abort monitor together with an abort condition, see [[https://wiki.eeros.org/eeros_architecture/sequencer/monitors]]