Robotic Assembly Using a Singularity-Free Orientation Representation Based on Quaternions

New robotic applications often require physical interaction between the robot and its environment. To this purpose, external sensors might be needed, as well as a suitable way to specify the tasks. One complication that might cause problems in the task execution is orientation representation singularities. In this paper quaternions are used as a singularity-free orientation representation within the constraint-based task specification framework. The approach is experimentally verified in a force controlled assembly task. The task chosen contains a redundant degree of freedom that is exploited using the constraint-based task specification framework.