US Patent 8632064 Positioning apparatus with lockable joints and method of use

A positioning system having a base, a manually movable end effector and a first joint interposed between the base and the end effector is disclosed. The first joint may comprise a proximal portion and a distal portion coupled together by magnetic attraction and configured to be intermittently separated by a pressurized gas cushion. The first joint may be configured to be changeable between a movable state and a fixed state. In the movable state, the proximal and distal portions are separated by the pressurized gas cushion and are movable relative to each other. In the fixed state, the proximal and distal portions contact each other and relative movement is thereby impeded.