Dynamic control and simulation of actively-coordinated robotic terrain-adaptive wheeled vehicles

Terrain-adaptive vehicles, including legged and wheeled ones, with active coordination possess the ability to distribute the contact forces among the legs/wheels and vary their configuration to accommodate terrain obstacles. Therefore, they are very desirable to be used in many off-road applications that conventional vehicles cannot undertake, such as those in the exploration of planetary surfaces, mining, agriculture, forestry, and military locomotion. This dissertation is directed towards the development of efficient algorithms for the coordination, control, and dynamic simulation of actively-coordinated wheeled vehicle systems.; Force distribution is one of the most important issues to coordinate and control actively-coordinated vehicles. It is associated with the problem of allocation of the desired contact forces among the wheels or legs to balance the resultant inertial force/moment of the vehicle under a commanded motion. An efficient formulation of the force distribution equations for general tree-structured robotic mechanisms is developed. The applicable platforms include not only systems with star topologies, such as walking machines that have multiple legs with a single body, but also general tree-structured mechanisms, such as variably-configured wheeled vehicles having multiple modules.; Several objective functions have also been developed to investigate and control actively-articulated wheeled vehicles. The adopted optimization criteria for the system performance include Minimum Force, Load Balance, and Maximum Safety-Margin. Also, an objective function for the vehicle to cross an obstacle, such as a ditch, is created.; Dynamic simulation is very useful to verify and evaluate the coordination schemes that are developed. It is an important alternative to vehicle trials and demonstrations especially during the early stages of the control development of a system. A dynamic simulator that is able to simulate multiple-module variably-configured wheeled vehicles operating on uneven, faceted terrain is created. An efficient wheel-terrain contact model is developed to compute the contact positions and forces for wheeled vehicles traversing planar surfaces and crossing edges or vertices of the faceted terrain.