While significant recent progress has been made in development of mobile robots for planetary surface exploration, there remain major challenges. These include increased autonomy of operation, traverse of challenging terrain, and fault-tolerance under long, unattended periods of use. We have begun work which addresses some of these issues, with an initial focus on problems of "high risk access," that is, autonomous roving over highly variable, rough terrain. This is a dual problem of sensing those conditions which require rover adaptation, and controlling the rover actions so as to implement this adaptation in a well understood way (relative to metrics of rover stability, traction, power utilization, etc.). Our work progresses along several related technical lines: 1) development a fused state estimator which robustly integrates internal rover state and externally sensed environmental information to provide accurate "configuration" information; 2) kinematic and dynamical stability analysis of such configurations so as to determine "predicts" for a needed change of control regime (e.g., traction control, active c.g. positioning, rover shoulder stance/pose); 3) definition and implementation of a behavior-based control architecture and action-selection strategy which autonomously sequences multi-level rover controls and reconfiguration. We report on these developments, both software simulations and hardware experimentation. Experiments include reconfigurable control of JPL's Sample Return Rover geometry and motion during its autonomous traverse over simulated Mars terrain.
In'process control of metal forming proeesses is Dften dificult owing to the lack of access to shape during the process and the lack of control inputs to the process, Consequently, such processes are usually left to statistical process contrel methods, which only identify problems without specifying solutions. The use of feedback control on a cycle to cycle basis (i.e. measurement and control between proeess qycles) has the prospect of impreving oveT statistical menitoring witheut incurring the limitations of high' balldwidth in'process feedback. Simple single input'single output systems of this type have been analyzed and implernented at MIT on both simple metal bending and plastie molding processes with encouraging re" sults. These include rejection ofmean value errers and bounded changes in precess variance. In this paper we address the extension of cycle to cycle contro] to the multivariable case, with an eye te a three' dimensional sheet forming shape eontrol problem. This problem arises from the eflbrt at MIT to contrel a ])rocess with a reconfigurable tool surface.With thousands of degrees of freedom, the choiee of a suitable control algorithm is vital.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.