Estimating first-order geometric parameters and monitoring contact transitions during force-controlled compliant motion

This paper uses (linearized) Kalman filters to estimate first-order geometr ic parameters (ie., orientation of contact normals and location of contact points) that occur in force-controlled compliant motions. The time variance of these parameters is also estimated. In addition, transitions between co ntact situations can be monitored. The contact between the manipulated obje ct and its environment is general, i.e., multiple contacts can occur at the same rime, and both the topology and rite geometry of each single contact are arbitrary. The two major theoretical contributions are 1) the integration of the gener al contact model, developed previously by the authors, into a state-space f orm suitable for recursive processing; and 2) the use of the reciprocity co nstraint between ideal contact forces and motion freedoms as the "measureme nt equation" of the Kalman filter. The theory is illustrated by full 3-D ex periments. The approach of this paper allows a breakthrough in the state of the art do minated by the classical, orthogonal contact models of Mason that can only cope with a limited (albeit important) subset of all possible contact situa tions.