Joseph L Barnett

US Patent:

47144009, Dec 22, 1987

Filed:

Apr 14, 1986

Appl. No.:

6/851509

Inventors:

Joseph A. Barnett - Endicott NY
Joseph M. Gomez - Vestal NY
William F. Green - Vestal NY
Vincent M. Lisica - Vestal NY
Arnold B. Rosenthal - Vestal NY

Assignee:

IBM Corporation - Armonk NY

International Classification:

B25J 902

US Classification:

414751

Abstract:

A robotic system includes two joints moving a common load-bearing member along a path for positioning a load. Each joint includes a linear electric motor and a feedback loop, the latter driving the motor accurately in response to a commanded position signal, and a true position signal provided by sensor apparatus disposed alongside a track of each linear motor. Cross-coupling circuitry connects with the sensor apparatus of each joint to produce signals representing differences in positional error and in speed of the joints. The signals are injected into the feedback loops of the joints to effect a shift of power between the joints to synchronize their travel. Window comparator circuitry is employed for introduction of variable gains to the feedback loops for values of positional error and velocity which are greater than reference values in a window. Simultaneous injection of phase lead angle to the electric motors is employed for transition to a high speed mode while retaining synchronized operation of the motors.