the movement is blocked to be more readily resolved a complete blockage of the translational and rotational movement can be detected for example by monitoring the motor current or by suitable motion sensors the use of the terms u201c a u201d and u201c an u201d and u201c the u201d and u201c at least one u201d and similar referents in the context of describing the invention especially in the context of the following claims are to be construed to cover both the singular and the plural unless otherwise indicated herein or clearly contradicted by context the use of the term u201c at least one u201d followed by a list of one or more items for example u201c at least one of a and b u201d is to be construed to mean one item selected from the listed items a or b or any combination of two or more of the listed items a and b unless otherwise indicated herein or clearly contradicted by context the terms u201c comprising u201d u201c having u201d u201c including u201d and u201c containing u201d are to be construed as open ended terms i e meaning u201c including but not limited to u201d unless otherwise noted all methods described herein can be performed in any suitable.