Terramechanics with the application of mobility analysis for planetary exploration rovers
The study of the performance of an off-road vehicle in relation to its operating environment (the terrain) has now become known as 'Terramechanics' with its basic fields of application of military off-road vehicles (wheeled and tracked), transportation aircraft and planetary rovers. Main issue of investigation is the tyre-soil contact because manoeuvrability in soft terrain depends on tyre sinkage, rolling resistance and tractive performance. Current approaches handle these problems by means of multibody system simulation and finite element software tools. The rheological soil model is used as analytical approach for the multibody system and for finite element simulations the Drucker-Prager soil model is used.
The rolling resistance of a tyre on soft soil consists mainly of the following components:
Therefore the assumption of a rigid wheel on soft soil is quite a good approximation for the tyre-soil interaction. Bekker's measurements with plate sinkage experiments led to the equation of pressure-sinkage relationship which describes the quasi-static behaviour of soil. This equation is still valid for simple tyre-soil investigations and led to further investigations especially conducted by Wong.