Testing apparatus utilizing position-force cross coupling control

Claim 2

A position-force cross coupling control system for a test specimen mounted for movement in at least one axis and mounted to receive a load application in a different axis, including means to move said specimen along said one axis and means to apply a load to the specimen along said different axis, the control system comprising means providing a first signal representative of the displacement of the specimen along said different axis with respect to its displacement along said one axis, means providing a second signal representative of the displacement of said specimen with respect to time along said one axis, means for multiplying said first and second signals together to provide a product signal, and means connected to said multiplying means for modifying the load applied to said specimen in accordance with said product signal to compensate for changes in the load being applied due to the position of the specimen along said one axis.

Claim 3

Testing apparatus comprising first actuating means for moving a test specimen along a first axis, second actuating means for applying a load along a second axis at an angle to said first axis, means providing a first signal representative of the displacement of the specimen along said second axis with respect to its displacement along said first axis, means providing a second signal representative of the velocity of said specimen along said first axis, a multiplier for multiplying said first and second signals together to provide a product signal, and means connected between said multiplier and said second actuating means for controlling said second actuating means in accordance with the value of said product signal to adjust the magnitude of the load being applied to compensate for movement of said specimen along said first axis.

Claim 4

Testing apparatus comprising first actuating means for moving a test specimen along a first axis, second actuating means for applying a load along a second axis at an angle to said first axis, means providing a first signal representative of the displacement of the specimen along said second axis with respect to its displacement along said first axis, means providing a second signal representative of the velocity of said specimen along said first axis, a multiplier for multiplying said first and second signals together to provide a product signal, and means connected between said multiplier and said second actuating means for controlling said second actuating means in accordance with the value of said product signal to adjust the magnitude of the load being applied to compensate for movement of said specimen along said first axis.

Claim 5

Test apparatus for providing a position control along a first axis and a load control along a second axis with respect to specimen having a common reaction point comprising means to move said specimen along said first axis and means to load the specimen along the second axis, first means providing a signal representative of the amount of movement along the first axis, second means providing a signal representative of the amount of load applied along the second axis, a shaping network connected to said first means for providing a first signal representative of the rate of change of the displacement of said second means with respect to said first means, a differentiator connected to said first means for providing a second output signal representing the amount of displacement along said first axis with respect to time, multiplying means for multiplying said first and second signals together to provide a product signal representing the rate of change of the displacement along said second axis with respect to time, and means for providing a control signal for said means to load said specimen which contains therein command information Provided by said product signal and the signal from said second means.

Claim 6

Test apparatus for providing a position control along a first axis and a load control along a second axis with respect to specimen having a common reaction point comprising means to move said specimen along said first axis and means to load the specimen along the second axis, first means providing a signal representative of the amount of movement along the first axis, second means providing a signal representative of the amount of load applied along the second axis, a shaping network connected to said first means for providing a first signal representative of the rate of change of the displacement of said second means with respect to said first means, a differentiator connected to said first means for providing a second output signal representing the amount of displacement along said first axis with respect to time, multiplying means for multiplying said first and second signals together to provide a product signal representing the rate of change of the displacement along said second axis with respect to time, and means for providing a control signal for said means to load said specimen which contains therein command information Provided by said product signal and the signal from said second means.

Claim 7

Test apparatus as defined in claim 3 in which a wheel spindle provides said common reaction point, said apparatus including a first pivotally mounted actuator for moving the spindle along the first axis, said means providing a signal representative of the amount of movement along the first axis including a transducer connected to said shaping network and to said differentiator, a first program device for producing a signal indicative of said spindle along said first axis, means for comparing the signal from said first program device with the signal from said transducer, said means providing a signal representative of the amount of load applied along the second axis including a load cell, a second program device for producing a signal indicative of a desired load to be applied to said specimen along said second axis, said means for providing a control signal for said means to load said specimen including a summing junction having first and second inputs and an output, said first input being connected to said load cell and said second input to said multiplying means whereby the signal from said second program device is modified by said product signal to change the control signal for said means to load said specimen to compensate for the change of position of said spindle along said first axis.

Claim 8

Test apparatus as defined in claim 4 including a cross coupling compensation adjusting means connected between said multiplying means and said summing junction.

Claim 9

A position-force cross coupling control system for a test specimen mounted for movement under load along a first axis including means for moving said specimen under load along said first axis, means comprising pivotally mounted extendable and retractable load actuator coupled to the specimen on a coupling pivot for applying load to the specimen along a second axis at an angle to said first axis and which actuator normally moves in an arc as the specimen moves along the first axis, the control system comprising means providing a first signal representative of the displacement of said coupling pivot along said second axis with respect to its displacement along said first axis, means providing a second signal representative of the displacement of said specimen with respect to time along said first axis, means for multiplying said first and second signals together to provide a product signal, and means connected to the multiplying means to modify the length of the actuator to compensate for displacement of the specimen along said first axis without substantially changing the load applied to the specimen by said actuator along said second axis.

Claim 10

A position-force cross coupling control system for a test specimen mounted for movement under load along a first axis including means for moving said specimen under load along said first axis, means comprising pivotally mounted extendable and retractable load actuator coupled to the specimen on a coupling pivot for applying load to the specimen along a second axis at an angle to said first axis and which actuator normally moves in an arc as the specimen moves along the first axis, the control system comprising means providing a first signal representative of the displacement of said coupling pivot along said second axis with respect to its displacement along said first axis, means providing a second signal representative of the displacement of said specimen with respect to time along said first axis, means for multiplying said first and second signals together to provide a product signal, and means connected to the multiplying means to modify the length of the actuator to compensate for displacement of the specimen along said first axis without substantially changing the load applied to the specimen by said actuator along said second axis.

Claim 11

The combination as specified in claim 6 wherein said actuator comprises a hydraulic actuator, and wherein said means connected to the multiplying means to modify the length of the actuator includes control means for controlling the load applied by said actuator, signal means for determining the load applied by said actuator along said second axis, said means connected to the multiplying means also being connected to said signal means.