Allen J Clark

US Patent:

40742040, Feb 14, 1978

Filed:

Nov 22, 1976

Appl. No.:

5/743977

Inventors:

Gregory W. Broburg - White Bear Lake MN
Allen C. Clark - Minneapolis MN

Assignee:

Van Alstine Audio Systems, Inc. - Burnsville MN

International Classification:

H03F 136

US Classification:

330109

Abstract:

A fully passive frequency contouring amplifier using segregated passive networks to shape the different portions of the signal thus avoiding all phase distortion and permitting the stages to be coupled without coupling capacitors, thus avoiding distortion caused by the nonlinearities of capacitors. In addition, a special DC servo loop is used to drastically reduce DC amplification.

US Patent:

45370770, Aug 27, 1985

Filed:

Feb 8, 1984

Appl. No.:

6/578055

Inventors:

Allen J. Clark - Minnetonka MN
Dale N. Maue - Minnetonka MN

Assignee:

MTS Systems Corporation - Eden Prairie MN

International Classification:

G01N 2900
G01N 332
B06B 118
G01M 700

US Classification:

73665

Abstract:

A load dynamic compensation circuit for a servohydraulic control system for fixtures and specimens being tested operating in various degrees of freedom, for example in an environment to simulate earthquakes to test building specimens, or to provide road profile simulation for rail and automobile vehicles, or wind buffet loads for aircraft. A compensation circuitry compensates for specimen displacement disturbances in the control loop that are a function of the force exerted from the specimen and the acceleration of the test mass. This specimen disturbance factor may be provided by adding only a differential pressure transducer to measure the force on the actuator, and an accelerometer to measure the mass acceleration, to obtain the necessary electrical signals, which after being modified by factors including the oil column compliance spring factor, the piston area and the servovalve flow gain, is differentiated to compensate for the piston integration, and is then added in a summing junction into the servovalve command signal loop. The compensation signal is an anticipatory signal compensating for load dynamics on the specimen.