A Visual Velocity Impedance Controller

Successful object insertion systems allow the object to translate and rotate to accommodate contact forces. Compliant controllers are used in robotics to provide this accommodation. The impedance compliant controller is one of the more researched and well known compliant controllers used for assembly. The velocity filtered visual impedance controller is introduced as a compliant controller to improve upon the impedance controller. The velocity filtered impedance controller introduces a filter of the velocity impedance and a gain from the stiffness. The velocity impedance controller was found to be more stable over larger ranges of stiffness values than the position based impedance controller. This led to the velocity impedance controller being more accurate and stable with respect to external forces. The velocity impedance controller was also found to have a better compliant response when tested on various insertion geometries in various configurations, including a key insertion acting against gravity. Finally, a novel kinetic friction cone compliance model is introduced for the velocity impedance controller. It was determined that the new compliance model provided a more reliable insertion than the standard insertion model by increasing the error tolerance for failure

A Configuration Space Friction Cone

Provides a geometric representation of friction for a rigid planar part with two translational and one rotational degrees of freedom. The construction of a generalized friction cone is accomplished by imbedding into the part's configuration space the constraints that define the classical friction cone in real space. The resulting representation provides a simple computational method for determining the possible motions of a part subjected to an applied force and torque. The representation has been used both for simulating part motions and for planning assembly operations. Generalizations to the six-dimensional configuration space of a three-dimensional part are possible