Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Content or effect of a constituent of a liquid mixture
Patent
1976-08-23
1978-06-27
Ruehl, Charles A.
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Content or effect of a constituent of a liquid mixture
73 93, G01N 308
Patent
active
040967417
ABSTRACT:
The invention provides a d.c. motor and motor control circuit to conduct characterization tests on materials by applying constant loads to or affecting constant displacements of physical samples of various materials for transient tests purposes. The actuator, a voice coil motor, and a wave shaping input circuit in associated motor control circuitry provide stable, precise control of load during creep tests without backlash and stick slip and stable precise control of displacement during a relaxation test without dither thus providing rapid response whereby results may be obtained in milliseconds and further permitting the same equipment to be employed for dynamic tests. The motor is controlled by an underdamped servo loop which in turn receives a command signal from a filter circuit having a rise time optimized with respect to the mechanical constants of the system. In this manner the leading edge of an input step signal is delayed before being applied to the underdamped servo so as to avoid overshoot and yet reach maximum value in the shortest time possible for the overall system. A further feature of the present invention is an interlock arrangement which prevents calibration signals for a measured parameter from being applied to the system during a test in which that parameter is controlling closed loop servo loop operation.
REFERENCES:
patent: 3374665 (1968-03-01), Preston
patent: 3712125 (1973-01-01), Meyer
patent: 3777557 (1973-12-01), Dunlap et al.
patent: 3826902 (1974-07-01), Claxton
Kronick et al.-"Transducer for Studies of Active Muscle"-23rd ACEMB-Wash. D.C.-Nov. 15-19, 1970-p. 63.
"New Range of Materials Testers"-Elec. & Electron, M.F.R. (G.B.)-vol. 14, No. 12, Dec. 1970 -- pp. 12 to 14.
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