Wheel loader payload measurement system linkage acceleration compensation

• US 9,938,692 B2
• Filed: 01/04/2016
• Issued: 04/10/2018
• Est. Priority Date: 01/04/2016
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Shatters, Aaron R., Cler, Eric W.
• Primary Examiner(s): HULS, NATALIE F
• Application Number:
  US14/986,843
• Publication Number:
  US 20170191245A1
• Time in Patent Office: 827 Days
• CPC Class Codes: E02F 3/283 with a single arm pivoted directly on the chassis linkage mechanism for it E02F3/3405
• CPC Class Codes: E02F 3/422 Drive systems for bucket-arms, front-end loaders, dumpers or the like
• CPC Class Codes: E02F 9/2203 Arrangements for controlling the attitude of actuators, e.g. speed, floating function
• CPC Class Codes: E02F 9/26 Indicating devices E02F5/145 takes precedence
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/083 lift truck scale

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.

Claims

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,

the controller is configured to transmit payload weight signals to the display device to display the payload weight to an operator of the machine, and

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.

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 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.

4. The machine of claim 3, 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.

5. 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:

6. The machine of claim 5, wherein the acceleration compensation gain K is equal to approximately 0.7.

7. 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;

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,

wherein determining the lift arm angular acceleration comprises determining, at the controller, a valve command based angular acceleration based on a commanded fluid flow transmitted from the controller to a lift cylinder actuator in response to a control lever position sensor signal causing the implement to be raised through the weigh range.

8. The method for determining a payload weight of claim 7, wherein determining the lift arm angular acceleration comprises:

receiving, at the controller, an accelerometer signal from an accelerometer operatively connected to the lift arm; and

converting, at the controller, the accelerometer signal to the lift arm angular acceleration.

9. The method for determining a payload weight of claim 7, wherein determining the lift arm angular acceleration comprises determining, at the controller, a linkage angle based angular acceleration based on changes in a lift arm angle of the lift arm over time as the lift arm moves through the weigh range.

10. The method for determining a payload weight of claim 9, wherein determining the lift arm angular acceleration comprises calculating, at the controller, 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.

11. The method for determining a payload weight of claim 7, wherein determining the angular acceleration compensation factor comprises calculating, at the controller, the angular acceleration compensation factor according to an angular acceleration compensation factor formula:

12. The method for determining a payload weight of claim 11, wherein the acceleration compensation gain K is equal to approximately 0.7.

13. A payload weight calculation system for determining a payload weight of a load of material carried by an implement of a machine, comprising:

a lift arm angle sensor configured to sense a lift arm angle of a lift arm of the machine and output a lift arm angle sensor signal that corresponds to the lift arm angle;

a head end pressure sensor configured to sense a head end pressure of a lift cylinder connected to the lift arm and output a head end pressure sensor signal that corresponds to the head end pressure; and

a controller configured to;

determine a lift cylinder pressure differential based on the head end pressure from the head end pressure sensor signal in response to the lift arm rotating upwardly and determining that the lift arm angle in the lift arm angle sensor signal is within a weigh range of the lift arm,

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,

determine an angular acceleration compensation factor based on the lift arm angular acceleration,

determine a compensated pressure differential by multiplying the lift cylinder pressure differential by the angular acceleration compensation factor, and

determine the payload weight of the load of material in the implement based on the compensated pressure differential and a head end cross-sectional area of the lift cylinder,

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 a lift cylinder actuator in a lift cylinder control signal to extend the lift cylinder and rotate the lift cylinder upwardly.

14. The payload weight calculation system of claim 13, 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.

15. The payload weight calculation system of claim 14, 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.

16. The payload weight calculation system of claim 13, 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:

17. The payload weight calculation system of claim 16, wherein the acceleration compensation gain K is equal to approximately 0.7.