| 摘要 |
<p>The positioning device (2) allows an object (3) of spherical shape to be positioned or orientated. This spherical object is placed and held under gravity on three support points (P, P', P'') of the positioning device (2). The positioning device comprises means particularly for rotating the object, of which the centre of gravity in any position or orientation lies inside the triangle formed by the three support points. The drive means comprise a drive member (20, 21, 22) of which contact with the exterior surface of the object or spherical element constitutes one of the support points (P) of the positioning device. The drive member comprises a drive wheel 10 which comes into contact with the exterior surface of the spherical object in order to rotate it. The axis of rotation of the wheel is mounted at the end of a support (22) capable of rotating about another axis passing through the point (P) of contact of the wheel with the exterior surface of the spherical object and the centre of the object. This drive member thus allows the object to be rotated via the wheel in all directions. The other two support points (P' P'') are formed using two ball swivels (30, 40) the balls of which are held on a cushion of air in a housing belonging to the swivel.</p> |
