Modular approach to compact low-speed kinematic modelling of multi-articulated urban buses for motion algorithmization purposes

Motion planning & control systems (i.e., motion algorithmization systems) used in intelligent/autonomous vehicles usually require mathematical models to predict a vehicle behaviour. The models should be flexible in use, reliable, and sufficiently compact to be tractable in the analysis and by the on-board (embedded) computational devices. A modular approach to modelling presented in this paper allows building compact nonholonomic kinematic models of multi-articulated buses comprising a car-like tractor and the arbitrary number of segments (wagons) interconnected with passive rotary joints, and with fixed or steerable wheels of the wagons. The modelling methodology is flexible in use by admitting various locations of a traction drive in a kinematic chain, and letting for various selections of a guiding point for a vehicle. The models are valid under assumption of pure rolling of all the vehicle wheels (no skid/slip motion) which is reasonable for low-speed maneuvering conditions. Derivations of kinematic models for two popular structures of urban buses (i.e., articulated and bi-articulated pushers) are provided.