US 6,473,679 B1Granted

Angular velocity control and associated method for a boom of a machine

AssigneeCaterpillar Inc.

InventorsStephen T. Tady, Brian D. Rockwood, Everett G. Brandt

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Abstract

An angular velocity control for a boom of a machine is disclosed and a method for controlling the angular velocity of a boom of a machine. The angular velocity control includes a calculator that detects input signals from an operator control lever, a boom angle sensor, a cylinder length sensor, a chassis cant sensor, and a chassis tilt sensor. Movement of the operator control lever allows an operator to pre-select a desired angular velocity. Based on the geometry of the boom to the machine the calculator calculates a boom gain associated with the current boom angle. The calculator then calculates a necessary cylinder velocity to achieve the desired angular velocity. The calculator sends a control signal to an electrohydraulic control module which in turn sends a signal to an electrohydraulic valve associated with a boom lift cylinder. The electrohydraulic valve alters the flow rate of hydraulic fluid into or out of the boom lift cylinder to produce a cylinder velocity that in turn produces the desired angular velocity of the boom.

Claims19

Dependent claims

A method for maintaining a constant angular velocity for a boom of a machine comprising the steps of:

pre-selecting a desired angular velocity for a boom of a machine;
forming a triangle, the first leg comprising a fixed distance A between a pivot point of the boom to the machine and an attachment point of a boom lift cylinder to the boom, the second leg comprising a fixed distance B between the pivot point of the boom to the machine and an attachment point of the boom lift cylinder to the machine, and the third leg comprising a variable distance C between the attachment point of the boom lift cylinder to the boom and the attachment point of the boom lift cylinder to the machine, distance C varying as the boom lift cylinder extends and retracts to lift and lower the boom;
determining the length of distances A, B and C at a first point in time;
determining at the first point in time the value of the sine of an angle θ formed by the intersection of the first leg and the second leg;
calculating at the first point in time a boom gain value by dividing the product of A, B, and the sine of θ by C;
calculating a desired boom lift cylinder velocity at the first point in time by taking the product of the boom gain at the first point in time and the pre-selected desired angular velocity;
adjusting an actual boom lift cylinder velocity to equal the desired boom lift cylinder velocity, thereby producing an actual angular velocity of the boom that equals the pre-selected desired angular velocity;
and
repeating the step of determining the length of distances A, B and C at a first point in time through the step of adjusting an actual boom lift cylinder velocity to equal the desired boom lift cylinder velocity, thereby producing an actual angular velocity of the boom that equals the pre-selected desired angular velocity at a second point in time wherein the length of C and therefore the value of the sine of angle θ are different at the second point in time from the first point in time.

6 more elements

An angular velocity control for a boom of a machine comprising:

a boom pivotally attached to a pivot point on a machine;
an operator control lever, movement of the control lever from a reference position to a first position different from the reference position generating a first angular velocity signal, the first angular velocity signal associated with a desired angular velocity of the boom;
a hydraulic boom lift cylinder having a first end attached to the boom at a cylinder attachment point spaced a distance A from the pivot point, a second end attached to the machine at a point spaced a distance B from the pivot point, and a distance C between the first and the second ends, with extension and retraction of the cylinder pivoting the boom about the pivot point;
a triangle having as apexes the pivot point, the first end and the second end, and an angle θ within the triangle having the pivot point as an apex;
a sensor, the sensor detecting one of the distance C or the angle θ;
a calculator, the calculator calculating the other of the distance C or the angle θ based on the distance A, the distance B and the sensed one of the distance C or the angle θ, the calculator calculating a boom gain by dividing the product of the distance A, the distance B and a sine of the angle θ by the distance C, the calculator detecting the first angular velocity signal and calculating a desired cylinder velocity equal to the product of the desired angular velocity and the boom gain, and the calculator generating a control signal associated with the desired cylinder velocity;
and
an electrohydraulic control module, the control module detecting the control signal and actuating an electrohydraulic valve associated with the cylinder, actuation of the valve flowing a hydraulic fluid into or out of the cylinder at a flow rate based on the control signal, the flow rate producing an actual cylinder velocity of the cylinder equal to the desired cylinder velocity.

5 more elements

Dependencies are inferred from the claim text.