System interface elevator controller Unit 驴 Control State Transitions down open floor req floor Request Resolver buttors floor bl inside b2 elevator bN floor pl up/down up2 buttors on floor dn2 each up3 floor dn3 floor dnN Hoistway
elevator controller • State Transitions floor floor floor floor floor Hoistway
三种描述方法：自然语言、形式化（算法、状图 "If the elevator is stationary and the loop floor requested is equal to the if(req_floor curr_floor)then current floor,then the elevator direction :idle; remains idle. If the elevator is stationary and the elseif(req_floor curr_floor)then floor requested is less than the direction down; current floor,then lower the elseif(req_floor curr_floor)then elevator to the requested floor. direction :up; If the elevator is stationary and the end if; floor requested is greater than end loop; the current floor,then raise the elevator to the requested floor" req_floor=curr_floor req_floor>curr_floor req_floor<curr_floor req_floor<curr_floor req_floor>curr_floor down) reg floor=curr floor idle req_floor=curr_floor reg floor>curr floor reg floorscurr floor llxx@ustc.edu.cn 17/112
三种描述方法：自然语言、形式化（算法、状态图） llxx@ustc.edu.cn 17/112
建模与实现：Models&Languages Pure Pure Modelling Implementation Systems Languages compiled into set of methods for functional composing objects objects machine code configuration files A model provides an abstract view of: simulation for testing .its functionality and verification .its characteristics .how the system works llxx@ustc.edu.cn 18/112
建模与实现：Models & Languages llxx@ustc.edu.cn 18/112
Characteristics of Models ·Comprehensible designers can understand it ·Formal -contains no ambiguity ·Flexible -easy to modify its functionality ·Complete describes the entire system ·Natural -aids rather than impedes the design llxx@ustc.edu.cn 19/112
Characteristics of Models • Comprehensible – designers can understand it • Formal – contains no ambiguity • Flexible llxx@ustc.edu.cn 19/112 – easy to modify its functionality • Complete – describes the entire system • Natural – aids rather than impedes the design
Model Taxonomy:ABC? structure-oriented heterogeneous data-oriented block diagram; control/ program entity schematic dataflow state relationship graphs machine state-oriented activity-oriented finite hierarchical Petri state concurrent finite nets machines state machines dataflow flow graphs charts transition state (Mealy) (Moore) llxx@ustc.edu.cn 20/112
Model Taxonomy：ABC？ llxx@ustc.edu.cn 20/112