  This paper presents a novel concept to support physically impaired humans in
daily object manipulation tasks with a robot. Given a user's manipulation
sequence, we propose a predictive model that uniquely casts the user's
sequential behavior as well as a robot support intervention into a hierarchical
multi-objective optimization problem. A major contribution is the prediction
formulation, which allows to consider several different future paths
concurrently. The second contribution is the encoding of a general notion of
constancy constraints, which allows to consider dependencies between
consecutive or far apart keyframes (in time or space) of a sequential task. We
perform numerical studies, simulations and robot experiments to analyse and
evaluate the proposed method in several table top tasks where a robot supports
impaired users by predicting their posture and proactively re-arranging
objects.
