Robust Pivoting: Exploiting Frictional Stability Using Bilevel Optimization
This work addresses the challenge of generalizable robot manipulation in uncertain environments, though it is incremental as it builds on existing optimization methods for a specific task.
The paper tackles the problem of robust pivoting manipulation under uncertainty in object physical properties by deriving analytical expressions for frictional stability margins and using them in a bilevel optimization controller to maximize robustness, demonstrating it on a 6 DoF manipulator with various objects.
Generalizable manipulation requires that robots be able to interact with novel objects and environment. This requirement makes manipulation extremely challenging as a robot has to reason about complex frictional interaction with uncertainty in physical properties of the object. In this paper, we study robust optimization for control of pivoting manipulation in the presence of uncertainties. We present insights about how friction can be exploited to compensate for the inaccuracies in the estimates of the physical properties during manipulation. In particular, we derive analytical expressions for stability margin provided by friction during pivoting manipulation. This margin is then used in a bilevel trajectory optimization algorithm to design a controller that maximizes this stability margin to provide robustness against uncertainty in physical properties of the object. We demonstrate our proposed method using a 6 DoF manipulator for manipulating several different objects.