Wheel Loader Payload Measurement System Linkage Acceleration Compensation

Patent metadata

Field	Value
Publication number	US-2017191245-A1
Application number	US-201614986843-A
Country	US
Kind code	A1
Filing date	Jan 4, 2016
Priority date	Jan 4, 2016
Publication date	Jul 6, 2017
Grant date	—

Abstract

A payload weight of a load of material carried by an implement of a machine may be estimated taking into account angular acceleration of the payload. A lift cylinder pressure differential and a lift arm angular acceleration may be determined as the implement is raised through a weigh range. An angular acceleration compensation factor may be determined from the lift arm angular acceleration, and a compensated differential pressure may be calculated by multiplying the lift cylinder pressure differential by the angular acceleration compensation factor. The estimated payload weight may then be determined based on the compensated pressure differential and a head end cross-sectional area of the lift cylinder.

First claim

What is claimed is:

1 . A machine comprising:
an end frame; a lift arm pivotally connected to the end frame and having a lift arm angle that is equal to an angle between a horizontal line and a lift arm longitudinal axis; an implement pivotally connected to the lift arm; a lift cylinder having a lift cylinder head end pivotally connected to the end frame and a lift cylinder rod end pivotally connected to the lift arm; a lift cylinder actuator operatively coupled to the lift cylinder to provide pressurized fluid flow to the lift cylinder to cause the lift cylinder to extend and retract to correspondingly cause the lift arm to rotate to raise and lower the implement; a control lever position sensor operatively connected to a control lever to sense a displacement of the control lever and output a control lever position sensor signal that corresponds to the displacement of the control lever; a lift arm angle sensor operatively connected to the lift arm to sense the lift arm angle of the lift arm and output a lift arm angle sensor signal that corresponds to the lift arm angle; a head end pressure sensor operatively connected to the lift cylinder to sense a head end pressure of the lift cylinder and output a head end pressure sensor signal that corresponds to the head end pressure; a display device; and a controller operatively connected to the lift cylinder actuator, the control lever position sensor, the lift arm angle sensor, the head end pressure sensor, and the display device, wherein:
the controller is configured to detect the control lever position sensor signal and to transmit a lift cylinder control signal to cause the lift cylinder actuator to create fluid flow to cause the lift cylinder to extend in response to receiving the control lever position sensor signal,
the controller is configured to determine a lift cylinder pressure differential based on the head end pressure from the head end pressure sensor signal in response to determining that the lift arm angle in the lift arm angle sensor signal is within a weigh range of the lift arm,
the controller is configured to determine a lift arm angular acceleration in response to determining that the lift arm angle in the lift arm angle sensor signal is within the weigh range of the lift arm,
the controller is configured to determine an angular acceleration compensation factor based on the lift arm angular acceleration,
the controller is configured to determine a compensated pressure differential by multiplying the lift cylinder pressure differential by the angular acceleration compensation factor,
the controller is configured to determine a payload weight of a load of material in the implement based on the compensated pressure differential and a head end cross-sectional area of the lift cylinder, and
the controller is configured to transmit payload weight signals to the display device to display the payload weight to an operator of the machine.

2 . The machine of claim 1 , comprising an accelerometer operatively connected to the lift arm to sense the lift arm angular acceleration and output an accelerometer signal that corresponds to the lift arm angular acceleration, wherein the controller is configured to determine the lift arm angular acceleration based on the accelerometer signal received from the accelerometer.

3 . The machine of claim 1 , wherein the controller being configured to determine the lift arm angular acceleration comprises the controller being configured to determine a valve command based angular acceleration based on a commanded fluid flow transmitted from the controller to the lift cylinder actuator in the lift cylinder control signal.

4 . The machine of claim 3 , wherein the controller being configured to determine the lift arm angular acceleration comprises the controller being configured to determine a linkage angle based angular acceleration based on changes in the lift arm angle in the lift arm angle sensor signal over time as the lift arm angle sensor signal indicates that the lift arm angle is within the weigh range of the lift arm.

5 . The machine of claim 4 , wherein the controller being configured to determine the lift arm angular acceleration comprises the controller being configured to calculate the lift arm angular acceleration according to an angular acceleration formula:
α= M*α L +(1− M )*α C

where α is the lift arm angular acceleration, M is an acceleration gain factor having a dimensionless value from 0 to 1, α L is the linkage angle based angular acceleration and α C is the valve command based angular acceleration.

6 . The machine of claim 1 , wherein the controller being configured to determine the angular acceleration compensation factor comprises the controller being configured to calculate the angular acceleration compensation factor according to an angular acceleration compensation factor formula:

W
=

1

1
+

K



α




r
P

g



cos



θ

where W is the angular acceleration compensation factor that is dimensionless, K is an acceleration compensation gain that is dimensionless, α is the lift arm angular acceleration, r P is a payload distance from a pivot pin pivotally connecting the lift arm to the end frame to a center of mass of the load of material and the implement, g is acceleration due to gravity, and θ is the lift arm angle of the lift arm.

7 . The machine of claim 6 , wherein the acceleration compensation gain K is equal to approximately 0.7.

8 . A method for determining a payload weight of a load of material carried by an implement of a machine, comprising:
raising the implement through a weigh range between a lower lift limit and an upper lift limit of the implement; determining, at a controller of the machine, a lift cylinder pressure differential in a lift cylinder of the machine based on a head end pressure of the lift cylinder; determining, at the controller, a lift arm angular acceleration of a lift arm of the machine raising the implement through the weigh range; determining, at the controller, an angular acceleration compensation factor based on the lift arm angular acceleration; determining, at the controller, a compensated pressure differential by multiplying the lift cylinder pressure differential by the angular acceleration compensation factor; and determining, at the controller, the payload weight of the load of material based on the compensated pressure differential and a head end cross-sectional area of the lift cylinder.

9 . The method for determining a payload weight of claim 8 , wherein determining the lift arm angular acceleration comprises:
receiving, at the controller, an acceleromete

Assignees

• Caterpillar Inc

Inventors

• Shatters Aaron R
• Cler Eric W

Classifications

• E02F3/283

  with a single arm pivoted directly on the chassis (linkage mechanism for it E02F3/3405) · CPC title

• E02F3/422

  Drive systems for bucket-arms, front-end loaders, dumpers or the like · CPC title

• E02F9/26 Primary

  Indicating devices {(E02F5/145 takes precedence)} · CPC title

• G01G19/083 Primary

  lift truck scale · CPC title

• E02F9/2203

  Arrangements for controlling the attitude of actuators, e.g. speed, floating function · CPC title