Towards a global traffic control (dispatcher) algorithm - interface prototype design

Abstract

This paper presents an overview of the design and development of a prototype Global Dispatcher Interface (GDI) for the control of a group of lifts. The role of the dispatcher is to assign passenger calls to the optimal lift in a group, as decided by a dispatcher algorithm. The GDI is independent of the underlying algorithm, which may be distributed remotely, and provides a standard means through which all interactions may occur. To warrant the “Global” appellation the GDI must support any of the currently available, as well as anticipated, call station modes, types and configurations of cars, topology of control equipment and buildings. The design process is a continuation of a recognised Software Development Lifecycle, centred on Use Cases in a UML model, the initiation of which is covered in a previous paper. Significant diagrams from the model are presented and discussed to illustrate the evolution of the prototype design. One of the requirements, resulting from analysis of the Use Cases, identifies that the GDI design must be compatible with a publish-and-subscribe architecture and a RESTful interface is selected for this purpose. Where possible, the prototype design uses open standards with an emphasis on demonstrating aspects that are specific to lift system dispatcher operation, while attempting to demonstrate independence from implementation details such as programming language, network protocols, etc. The Standard Elevator Information Schema is particularly relevant and fulfils these objectives. The operation of the working prototype, in conjunction with simulated lifts and passengers, is presented as a validation of the design.