Manipulator-head drive assembly

Claim 1

A head assembly for a manipulator, the assembly comprising: a rear segment rotatable about a rear axis fixed relative to the manipulator and extending through the rear segment; an intermediate segment; intermediate pivot means for supporting the intermediate segment on the rear segment for rotation relative to the rear segment about an intermediate axis fixed relative to the rear segment and intersecting the rear axis at an acute intermediate angle; a front segment having a holder adapted to carry a tool; front pivot means for supporting the front segment on the intermediate segment for rotation about a front axis fixed relative to the intermediate segment, extending through the front segment, and intersecting the rear axis at an acute front angle; and drive means for rotating the intermediate and front segments on the rear segment about the intermediate axis and for simultaneously rotating the front segment about the front axis, the drive means including: an intermediate shaft extending along the intermediate axis, a front shaft extending along the front axis, angle gearing interconnecting the intermediate and front shafts for joint synchronous rotation, an intermediate stepdown transmission with a high stepdown ratio of N:1 connected between the intermediate shaft and the intermediate segment for relatively slowly rotating the intermediate segment relative to the rear segment, and a front stepdown transmission with a high stepdown ratio of (N+/-1):1 connected between the front shaft and the front segment for relatively slowly rotating the front segment relative to the intermediate segment, N being a whole number, whereby the drive means counter rotates the front segment relative to the intermediate segment by an amount which cancels discrepancies introduced into the movement of the front segment by the movement of the intermediate segment relative to the rear segment.