Mission monitor sequencer

Revision as of 18:58, 16 August 2008

Introduction

This plug-in implements a a language that is a mixture of a rule-based and a sequential based language. The idea is that a number of situations need permanent - or semi permanent - monitoring to get a good situation awareness for the root, and at the same time a large number of the robot tasks are better described by a sequential language.

This implementation attempts to cover this gab.

Language

An example function could look like this:

<?xml version="1.0" ?>
<plan name="CrossRoad">
   <init>
       odoPose.tripB = 0
       nearRoad = false // define local variable
       <plan name="maxOdoDist" if="odoPose.tripB > 250"> 
           print("Driven too far on odo " odoPose.tripB "m") // print message
           break CrossRoad // failed to cross road - could trigger a relocalization
       </plan>
       <plan name="closeToRoad" if="hypot(utmPose.poseY - 6174307, utmPose.poseX - 707873) < 15" >
           print("Cose to road slowing down) // print message
           smr.speed=0.5  // set the desired maximum speed in mrc interface module
           nearRoad = true  // set flag
           disable  // disable this rule (plan)
       </plan>
       <plan name="turn">
           <parameter angle="pi" dist=1.0/>
           <commands to="smr.send">
             # construct commands to MRC using the smr.send command
             'drive @v ' smr.speed ' : ($drivendist > ' dist ')'
             'turn ' angle
             'drive : ($drivendist > ' dist ')'
           </commands>
       </plan>
   </init>
   print("started")
   enable("maxOdoDist")   // should have found road by now
   enable("closeToRoad")  // active until disabled.
   roaddrive.right(0.75) : nearRoad // follow road 75cm from edge until near road
   // more stuff missing here to detect traffic etc.
   ...
   turn() // turn back - using a call to a plan
   success=true
   <post>
       print("finsihed crossRoad - success=" success)
   </post>
</plan>

A number of these plans can be started (enabled) simultaniously, an can in principle be total independant. I.e.one can control the robot arm whele another controls the navigation.

Language definition

The language definition is:

planBlock ::= planOpenTag planBody planCloseTag

planOpenTag ::= '<plan' 'name=' planName [runAttribute] [ruleCondition] '>' [remark] '\n'

planName :== '"' symbol '"'

runAttribute :== 'run="default"' (there may come more values later)

ruleCondition :== 'if="' expression '"'

planCloseTag ::= '</plan>' [remark] \n'

planBody ::= [parameters] [description] [planInitBlock] planMainBlock [planPostBlock]

parameters ::= '<parameters ' [symbol '="' [paramDefaultValue] '"']* '/>' [remark] \n'

paramDefaultValue :== constantValue

description ::= '<description>\n' xmlText '</description>\n'

xmlText ::= any 7-bit character except '\0', '&' and '<', these must be coded as & and <

planInitBlock :: '<init>\n' [declarationStatement]* '</init>\n'

declarationStatement ::= planBlock | executableStatement

planMainBlock ::= [statement]*

planPostBlock :: '<post>\n' [statement]* '</post>\n'

statement ::= executableStatement | controlStatement

executableStatement ::= assignment | procedureCall | blockStatement | breakStatement | enableStatement | ifStatement | emptyStatement

controlStatement ::= proceureCall ':' expression [remark] '\n'

assignment :== [symbol.]* symbol '=' expression [remark] '\n'

procedureCall :== [symbol.]* symbol '(' [expression [',' expression]* ')' [remark] '\n'

blockStatement ::= '<block>\n' [statement]* '</block>\n'

breakStatement ::= 'break' [symbol] | 'continue'

ifAtt ::= 'if="' booleanExpression '"'