Postural stability evaluation of spatial wheeled mobile robots with flexible suspension over rough terrains

The mobility requirements on a rough terrain make a suspended wheeled mobile robot (SWMR) with multiple dexterous manipulators an appropriate choice. In this study, dynamics and stability appraisal of such systems will be discussed. First, based on Newton-Eulerpsilas formulation for a chain of rigid bodies, the closed-form dynamics model of such complicated systems in three dimensional maneuvers is developed. To this end, a sixteen degree-of-freedom SWMR is considered as a benchmark system. The studied platform contains both sprung and unsprung elements. The presented approach can take into account and add any kind of tire friction model. Next, using the obtained dynamics, the tip-over stability of such systems will be investigated. To this end, the new dynamic tip-over moment-height stability (MHS) measure will be extended for suspended wheeled mobile robotic systems. Proposing the concept of virtual structure, the obtained spatial model of SWMR has been employed to evaluate the behavior of the system on rough terrain in terms of its stability. Therefore the presented model and the MHS measure can be employed for stable planning and model-based control of autonomous SWMR during object manipulation tasks. In addition, the obtained simulation model provides an inexpensive tool for designers of such systems to examine the behaviors of them and optimize their various characteristics.