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Händelsebaserade system, Discrete Event Systems
Signals and Systems Supervisory Control for Robot Coordination Signals and Systems Outline Something about what we do at Chalmers Automation Martin Fabian • • • • Sweden, Göteborg, Chalmers ― Where, What, When? Chalmers Automation ― Depend on us Robot Coordination ― Police and Chiefs Supremica ― The Supremal Tool? Visit at Politecnico di Milano, May 2007 1 Martin Fabian Chalmers Automation 2 Martin Fabian Chalmers Automation Signals and Systems Sweden – Where is it? What is it? • • • Ultimate north 449 964 square km (Italy 301 277 ) 9 million people (Italy 57 million) IKEA, H&M ABB Volvo (Ford) Saab (GM) Ericsson (Sony) 3 Martin Fabian Glenn Strömberg • Gunnar Gren – Il Professore – – – – – Figurehead king Right wing government Chalmers Automation Inter ”Nacka” Skoglund • – Government – – Yes! Football! Zlatan Ibrahimovic – – Swedish companies – – – – – • Sweden + Italy = true? Sweden – Ultima Thule – – – • Signals and Systems Atalanta From Göteborg AC Milan Gunnar Nordahl Nils Liedholm Gre-No-Li 4 Martin Fabian Chalmers Automation 1 Signals and Systems Göteborg – Where is it? Chalmers University of Technology • • • – • Dutch built canal Scotsmen, English, German immigrants • Many Scotsmen involved – 5 Martin Fabian Chalmers Automation 2355 employees 10300 students 1062 PhD students (28% female) 337 examined graduates • 179 PhD • 158 Licentiate 1994 – “Private” – – Among them William Chalmers 2150 MSEK (~220 M€) • 1435 MSEK research • 723 MSEK education People (2005) – – – – Swedish goods traded in Cadiz Silver taken to East-India Tea, china, herbs, silk etc One of four main technical universities Financially (2005) 500 000 people (Milano 1.3M) Swedish East-Indian Trading Company – – – • • Founded in 1621 – – Chalmers University – Port town • 14th largest in Europe • 64th largest in the world Second biggest city in Sweden – • • Göteborg – Gothenburg – Göteborg Signals and Systems Non-governmental university Foundation owned Martin Fabian Chalmers Automation Signals and Systems Chalmers Automation – Who are we? • • • Since 1998 Three senior researchers 10 in-house PhD students 6 ”out-house” • • Volvo ABB SSF, ProViking Vinnova, VR Martin Fabian 7 Chalmers Automation Flow simulation Geometry simulation Off-line programming Formal methods – – – – – Wingqvist Laboratory Structure and design Functionality and interactions Information reuse Simulation – – – Dept Signals and Systems • and others… Reference architectures – – – Collaborators - Funding – – – – • Chalmers Automation – Research Overview Belong to – • Signals and Systems Spin-off from Control Engineering – – – – 6 Modeling Finite automata Supervisor synthesis and verification Optimization Code generation and execution Virtual Factory 8 Martin Fabian Chalmers Automation 2 Signals and Systems Chalmers Automation – Robot Cells • • – – Servo control Axes movements, trajectories Degrees of freedom Coordinate systems calculations • Versatile production resources Product-specific use of resources, operations Large product flora – – Pick and place Material handling We do not consider – – – – Multi Purpose Batch Plants Highly flexible production system – – Welding robots Material handling Packaging industry – – • • • Concurrently working Confined workspace Automotive industry – – • Chalmers Automation – Chemical Batch Processes Multiple robots – – • Signals and Systems Frequently changing Each product distinct processing sequence Sequences of operations Described by recipes Safety critical 9 Martin Fabian Chalmers Automation 10 Martin Fabian Signals and Systems Chalmers Automation – Embedded Systems • • • • • • • Requirements, constraints What (not) to do when Functionality – – – – Signals and Systems Outline Complex logic – – Implemented in software Integrating many components Central locking, alarm, … Embedded control system Sweden, Göteborg, Chalmers ― Where, What, When? Chalmers Automation ― Depend on us Robot Cell Coordination ― Police and Chiefs Supremica ― The Supremal Tool? Reactive systems – – – Interact with their environment Safety critical Must work correctly 11 Martin Fabian Chalmers Automation Chalmers Automation 12 Martin Fabian Chalmers Automation 3 Signals and Systems Robot Cell – Automotive Industry • • Specific work cycle Each robot has its own schedule – – • Working on a single product Welding Material handling Confined workspace – • Cells Car body Multiple robots – – – • Robot Cell – Program Line consisting of – – A sequence of operations to carry out Each operation performed once Constraints – Signals and Systems Interlocks, safety constraints 13 Martin Fabian Chalmers Automation ;Program reversed 29/07/29 by pc54464 ctime (TRUE ) O_HOMEPOS=FALSE P26lSegment1 ( ) WAIT FOR I_BODY_OK==TRUE O_OUT_BDY_LF=FALSE WAIT FOR I_INTLOCK_3 ; 3737_3 O_INTLOCK_3=FALSE ; to 3737_3 WAIT FOR I_INTLOCK_3 ; 3737_3 P26lSegment2 ( ) WAIT FOR I_INTLOCK_1 ; 3735 O_INTLOCK_1=FALSE ; to 3735 WAIT FOR I_INTLOCK_1 ; 3735 P26lSegment3 ( ) O_INTLOCK_3=TRUE ; to 3737_3 P26lSegment4 ( ) O_INTLOCK_1=TRUE ; to 3535 WAIT FOR I_INTLOCK_5 ; 3737_5 O_INTLOCK_5=FALSE WAIT FOR I_INTLOCK_5 ; 3737_5 P26lSegment5 ( ) O_INTLOCK_5=TRUE ; to 3537_5 O_OUT_BDY_LF=TRUE O_HOMEPOS=TRUE ctime (FALSE ) END • Operations • Interlocks – – – – • Waiting for interlocks Reserving interlocks Releasing interlocks With multiple robots – – • In sequence Running concurrently Need to coordinate interlocks Must guarantee – – Mutual exclusion • Never two reserving same interlock Non-blocking • Two or more never wait for each other forever 14 Martin Fabian Chalmers Automation Signals and Systems Home pos Robot Cell - Model en te E v e r c Dis DES Body OK? ys t e m Body OK • Interlock 3 tS Segment 2 Interlock 1 • Interlock 1? Release IL 3? Expresses regular languages • Interaction – – – Interlock 5? States Events Transitions associated with events • Release IL 1? Interlock 5 Process algebra Petri nets Formal languages Finite state machines - Automata – – – Segment 3 Segment 4 DES modeling – – – Interlock 3? Sequences of events Synchronous composition A||B Segment 5 Release IL 5? Martin Fabian Discrete Event System – Modeling Leave home position Segment 1 ;Program reversed 29/07/29 by pc54464 ctime (TRUE ) O_HOMEPOS=FALSE P26lSegment1 ( ) WAIT FOR I_BODY_OK==TRUE O_OUT_BDY_LF=FALSE WAIT FOR I_INTLOCK_3 ; 3737_3 O_INTLOCK_3=FALSE ; to 3737_3 WAIT FOR I_INTLOCK_3 ; 3737_3 P26lSegment2 ( ) WAIT FOR I_INTLOCK_1 ; 3735 O_INTLOCK_1=FALSE ; to 3735 WAIT FOR I_INTLOCK_1 ; 3735 P26lSegment3 ( ) O_INTLOCK_3=TRUE ; to 3737_3 P26lSegment4 ( ) O_INTLOCK_1=TRUE ; to 3535 WAIT FOR I_INTLOCK_5 ; 3737_5 O_INTLOCK_5=FALSE WAIT FOR I_INTLOCK_5 ; 3737_5 P26lSegment5 ( ) O_INTLOCK_5=TRUE ; to 3537_5 O_OUT_BDY_LF=TRUE O_HOMEPOS=TRUE ctime (FALSE ) END Signals and Systems 15 Chalmers Automation 16 Martin Fabian Chalmers Automation 4 Signals and Systems Robot Cell – Coordination Problem • Coordinates resource usage Restricts access • Non-blocking • Controllable • Optimality – – – • Combinatorial explosion – – – – Useful work always possible Uncontrollable choices considered Exhaustive testing • Blocking may occur – A supervisor – Safety critical systems – 7 robots that can do n things each 2 7 = 128 combinations 3 7 = 2187 combinations In practice less, but many • – Restrict as little as possible We call such a cop – • And why would this be hard? Need a traffic cop – – • Signals and Systems Practically impossible What is allowed now, can cause problems later ”Later” can be far later Must work correctly 17 Martin Fabian Chalmers Automation 18 Martin Fabian Chalmers Automation Signals and Systems Signals and Systems Automatic Robot Cell Coordination – Example And why would this be hard? • • Example – Valve battery – – – – – • • • • • Process simulation 2 persons 3 shift 8 full weeks – Robots must not collide • Robots must not block – Not at the same target simultaneously Not wait for each other forever How many undetected? 19 Martin Fabian Each with three targets I1 → A → C → B → I1 I2 → B → C → A → I2 • – 48 8-hour weeks, a full person-year! 700 logical errors... Detected! 3D simulation environment ABB robots Same software as in robot controller Accurate simulation Two robots – – – Manual testing of controller program – – – – Robot Studio – – – – Collection of valves Flexible routing Operator commands From this to that... Automatic Chalmers Automation 20 Martin Fabian Chalmers Automation 5 Signals and Systems Automatic Robot Cell Coordination – Example Signals and Systems Automatic Robot Cell Coordination – Example Home • Sweep volumes – – – • I1A1 !I1A1_finish Wait1 Intersect the volumes – – Free I1A1_start Span of robot motions Generated by simulation tool Time consuming Generates zones Matches critical need • I1A1_start I2B2_start Booked • A1C1_start !A1C1_finish Wait2 C1B1_start C1B1 • !C1B1_finish Finite automata One for each zone Reserving, releasing (booking, unbooking) Model the robot paths – – – – – – A1C1 !B1I1_finish Model the zones – – – !B1I1_finish !A2I2_finish Finite automata One for each robot Sequence of zone use Waiting Reserving Releasing Automatic – “Collisions” with the zones Wait3 B1I1_start 21 Martin Fabian Chalmers Automation 22 B1I1 Martin Fabian Chalmers Automation Signals and Systems Automatic Robot Cell Coordination – Example • • I2B2_start !I1A1_finish I2B2_start A1C1_start I2B2_start I1A1_start !I2B2_finish !I1A1_finish !I2B2_finish 8 !B1I1_finish !A1C1_finish C1B1_start I2B2_start I2B2_start 8 8 !C1B1_finish B1I1_start 8 • Blocking (deadlock) States that only lead to blocking !I2B2_finish I1A1_start !I2B2_finish !I2B2_finish !I1A1_finish 8 A1C1_start B2C2_start 8 !I1A1_finish 8 !A1C1_finish A1C1_start 8 !B1I1_finish – C2A2_start !B2C2_finish I1A1_start !C2A2_finish !I1A1_finish C1B1_start C2A2_start • • A2I2_start A2I2_start Chalmers Automation Guarantees always possible to finish all work No collisions Given accurate time estimates – – – !C1B1_finish !C2A2_finish Only prohibits bad things Only allows good things Allows all allowable things Maximally permissive Running according to the cop – !A1C1_finish !B2C2_finish 8 !B2C2_finish !B2C2_finish All sequences of allowed zone reservations Supervisor - Traffic cop – – – – • !A2I2_finish I1A1_start 23 Martin Fabian !I1A1_finish B2C2_start B2C2_start Result – I1A1_start Analyze system – – 8 !I2B2_finish I2B2_start 8 A1C1_start !A1C1_finish • Synchronous composition B2C2_start 8 !A2I2_finish Automatic Robot Cell Coordination – Example Generate model of total system – I1A1_start Signals and Systems Could calculate time schedule Best way to run A* algorithm Software exists B1I1_start 24 Martin Fabian Chalmers Automation 6 Signals and Systems Supremica – A Useful Tool Outline • • • • Signals and Systems • Sweden, Göteborg, Chalmers ― Where, What, When? Chalmers Automation ― Depend on us Robot Coordination ― Police and Chiefs Supremica ― The Supremal Tool? A platform for the formalism – – – – – – – • Master Thesis work – – – – Chalmers Automation Martin Fabian Signals and Systems BoxSweeper – Plugin to RobotStudio 26 Chalmers Automation Signals and Systems We’re done! 27 Martin Fabian Luisa Losito Emanuela Calò Domenico Spensieri Anton & Andreas www.supremica.org 25 Martin Fabian Modeling Verification Synthesis Simulation Optimization Automatic implementation Execution, Soft PLC Chalmers Automation 28 Martin Fabian Chalmers Automation 7 Signals and Systems Supervisory Control for Robot Coordination Something about what we do at Chalmers Automation Grazie per la vostra attenzione Martin Fabian 29 Chalmers Automation 8
