| A positioning apparatus, comprising first and second members relatively moveable in a substantially vertical degree of freedom. At least one energy conduit is mounted to at least one of the first and second members, which imparts a load on at least one of the members it is mounted to that varies dependent on the relative position of the first and second members. A compensatory member is configured to apply a load that varies, dependent on the relative position of the first and second members, inversely to the variation in load applied by the at least one energy conduit, so as to at least partially counteract the variation in load applied by the at least one energy conduit on said at least one of the members. |
