Research On Petri Nets-based Aircraft Routing And Conflict Control For A-SMGCS

Establishing integrated air traffic control system to achieve seamless air traffic control is thestrategic goal for next generation air transportation system. Advanced Surface Movement Guidanceand Control Systems (A-SMGCS) will support seamless operation in airport surface throughmonitoring and control on movement objects (aircrafts and cars). It will play an essential role in thefuture air traffic control system. In the modularize implementation scheme for A-SMGCS, routingfunction model and conflict control function model are key models. The former is in charge ofproviding conflict-free taxi trajectories for movement objects; the latter takes charge in preventingobjects running into conflict situation or colliding with each other. However, past research onA-SMGCS routing and conflict control was mostly for some concrete airport, lacking of research oncorresponding universal theory. In this thesis, human-in-the-loop multilevel hierarchical controlstructure for A-SMGCS was established, and A-SMGCS routing and control were integrated into ahierarchical control structure. The Petri Net theory and analysis method was introduced into theresearch on A-SMGCS routing and control. Corresponding research fruit will provide universal theoryguidance for A-SMGCS implementation. Main research work in this thesis was as following:Universal A-SMGCS routing mechanism of three stages was proposed, which includes initialtaxi routes planning, dynamic taxi route assignment, and taxi route updating in real-time. For theresearch of each stage, corresponding surface operation modeling methods and routing algorithmswere investigated to form the A-SMGCS routing theory.On the initial taxi routes planning, based on the surface typical operation zone division, one kindof Extended Timed Place Petri Net (ETPPN) was proposed and used to establish correspondingsurface ETPPN model. The initial taxi routes planning method was provided based on this model.Places in surface ETPPN model was defined using control regulations for its related operation zone,which overcome the disadvantage on control regulations representation in surface node-link model.The reconfiguration principle for structure dynamic adjustment in ETPPN model was proposed,which reflected the change on surface operation condition and supported consistent initial taxi routesplanning based on this model. The Genetic Algorithm (GA) was adopted and transition firingsequences of the ETPPN model were used as chromosomes. In order to ensure the practicability ofinitial taxi routes, algorithm for chromosome validation and amendment was provided. Finally, theinitial taxi routes set of defined number for aircraft taxi on surface was provided. On the dynamic taxi route assignment, one kind of Time Window Constrained Petri Net(TWCPN) was defined and used to establish the surface TWCPN. One taxi routes assignment methodbased on the TWCPN model was proposed to assign taxi routes for new flight. Meanwhile, routing forcurrently taxiing aircrafts were adjusted. Places in surface TWCPN model was defined using timewindow for its related operation zone, which reflected the dynamic occupation and release foraircrafts in divided operation zone. The state transition algorithm for surface TWCPN model wasprovided, fulfilling conflict avoidance and feasible taxi routes search. And then, Partheno-Geneticalgorithm (PGA) for minimizing the taxi cost was proposed and one new mixed switch and mutationoperator was designed, fulfilling reasonable taxi route search and the dynamic taxi route assignment.The proposed taxi routes assignment method overcome disadvantage of operations model, which settoo many parameters leading complication on computation and can’t meet requirement of real timesurface operation.On the taxi route updating in real-time, the uncertainties in surface operation was analyzed andone kind of taxi route updating method which integrated surface operation tendency monitoring wasprovide. And also, one concrete taxi routes updating algorithm was proposed for aircraft taxitrajectory postponed occupying one zone comparing to the assigned taxi routes. In the taxi routeupdating method, optimization and feedback mechanism were integrated, and the surface operationtendency was used to drive the update process. And then, this process was fulfilled using concretealgorithms for different scenarios. In concrete taxi routes updating algorithm designing, the regularand non-regular taxi route updating algorithms were provided, which overcome the disadvantage ofpast method updating taxi routs every few minutes and can not tackle surface uncertainties.Virtual zone division, decentralized and coordinated-based control mechanism was proposed.And also, the corresponding surface conflict feedback control structure was provided, in which, theconflict prediction and avoidance, conflict detection and resolution were investigated fromimplementation scheme, surface operation modeling and controller design, finally forming theA-SMGCS conflict control theory.On conflict prediction and avoidance, one implementation scheme based on the discrete eventsupervisor theory was proposed, the surface operation process modeling method from discreteperspective was provided, and the controller design method for head-on conflict prediction andavoidance was provide. In surface discrete operation process modeling, the controlled Petri Net modelfor surface movement area was constructed. In this model, the controlled Places could represented thecontrol role from outside, and then the token was colored using the residual taxi route forcorresponding aircraft, which represented the aircraft taxi tendency and finally formed the Controlled Color Petri Net (CCPN) for surface operation. In the surface CCPN model, the least controlled taxisegment for aircrafts was proposed. In its related sub-model, the controller design algorithm forhead-on conflict prediction and avoidance was proposed, according to conflict category oriented andproduction rules-based conflict prediction and avoidance controller design method. The proposedmethod overcomes the disadvantage of routing-based taxi conflict avoidance method which can nottackle surface event directly.On conflict detection and resolution, one implementation scheme based on hybrid model wasproposed, the surface operation process modeling method from hybrid perspective was provided, andthe controller design method for intersection conflict detection and resolution was provided. One kindof Extended Hybrid Petri Net (EHPN) was defined and used to model surface operation. Thecontrolled Places in surface EHPN could represent control role from outside. Meanwhile, thesynchronizing event defined on ordinary Places and the force enable conditions for transitions couldtrack the surface hybrid state. Based on the intersection EHPN model, the corresponding controller forconflict detection and resolution was designed. The discrete and continuous conflict cautionconditions were proposed to reduce the probability on false alarm and missed alarm. In order todirectly provide visual guidance for pilot, the intersection stop bars were used to execute the conflictresolution command.