SYSTEM AND METHOD FOR CONTROLLING AUTOMATIC LEVELING OF HEAVY EQUIPMENT

• US 20090085311A1
• Filed: 09/26/2008
• Published: 04/02/2009
• Est. Priority Date: 10/02/2007
• Status: Active Grant

• Current Assignee: Volvo Construction Equipment Holding Sweden AB
• Original Assignee: Volvo Construction Equipment Holding Sweden AB
• Inventors: KIM, Jin Seop, Lee, Chang Soo, Kim, In Woo
• Granted Patent: US 8,145,392 B2
• Time in Patent Office: Days
• US Class Current: 280/6.154
• CPC Class Codes: B62D 33/0617 for tractors or off-the-road vehicles protective devices for drivers in case of overturning of tractors B60R21/131
• CPC Class Codes: B62D 33/063 movable from one position into at least one other position, e.g. tiltable, pivotable about a vertical axis, displaceable from one side of the vehicle to the other
• CPC Class Codes: B62D 33/07 characterised by the device for locking the cab in the tilted or in the driving position
• CPC Class Codes: B62D 55/116 Attitude or position control of chassis by action on suspension, e.g. to compensate for a slope
• CPC Class Codes: Y10S 280/01 Load responsive, leveling of vehicle
• CPC Class Codes: Y10S 37/907 Automatic leveling excavators

Abstract

A system and method for controlling an automatic leveling of heavy equipment is provided. The system for controlling an automatic leveling for heavy equipment, in which a lower frame having a traveling means and an upper frame are combined together by a tilting means, includes a sensor unit, provided in the equipment, for sensing twist angles of the lower frame and the upper frame against a reference horizontal surface and a traveling speed of the equipment; a control unit for receiving the twist angles and the traveling speed, setting a limit of an operation time for the automatic leveling in a standstill state of the equipment while calculating a corrected angle to which a twist angle of the upper frame is to be corrected, without setting the limit of the operation time for the automatic leveling, in a traveling state of the equipment, and generating a control signal for instructing an operation of a tilting means in accordance with the corrected angle; and a driving unit for performing a tilting control through the tilting means in accordance with the received control signal.

Claims

1. A system for controlling automatic leveling of heavy equipment with a lower frame, an upper frame and a tilting means, the lower frame having traveling means, the upper frame tiltably and swingably connected to the lower frame, and the tilting means for tiltably connecting the upper frame to the lower frame, the system comprising:

a sensor unit, provided in the equipment, for sensing twist angles of the lower frame and the upper frame against a reference horizontal surface and a traveling speed of the equipment;

a control unit for receiving the twist angles and the traveling speed, setting a limit of an operation time for an automatic leveling in a standstill state of the equipment while calculating a corrected angle to which a twist angle of the upper frame is to be corrected, without setting the limit of the operation time for the automatic leveling, in a traveling state of the equipment, and generating a control signal for instructing an operation of the tilting means in accordance with the corrected angle; and

a driving unit for performing a tilting control through the tilting means in accordance with the received control signal.

2. The system of claim 1, wherein the control unit comprises:

a receiving module for receiving a signal from the sensor unit sensing the twist angles of the lower frame and the upper frame against a reference horizontal surface, and the traveling speed of the lower frame;

a corrected angle calculation module for setting the twist angle of the upper frame in comparison to a first twist angle, and calculating the corrected angle from the first twist angle;

a control signal generation module for judging whether to perform a leveling control by calculating the twist angle of the upper frame on the basis of an expanded surface of the lower frame as a second twist angle, and generating the control signal in accordance with a period in which the actuator is to be operated, based on the corrected angle; and

an output module for transmitting the control signal to the driving unit.

3. The system of claim 2, wherein the control unit further comprises a display signal generation module for generating a display signal for displaying the twist angles of the lower frame and the upper frame through a display unit provided with an image display device.

4. The system of claim 2, wherein the control unit further comprises a time limit module for counting the operation time in a state that the traveling means is stopped, comparing the counted operation time with a predetermined reference operation time during leveling control, and if the counted operation time exceeds the predetermined reference operation time, terminating the performing of the corresponding leveling control.

5. The system of claim 2, wherein the control unit further comprises an emergency stop module for immediately terminating the leveling control if an emergency stop condition is satisfied during the performing of the leveling control.

6. The system of claim 2, wherein the corrected angle is determined by calculating “

twist angle of lower frame−

maximum allowable lower limit of the twist angle range−

first twist angle”

in the case where the reference angle is “

reference angle<

twist angle of lower frame−

maximum allowable lower limit of the twist angle range”

;

by calculating “

reference angle−

first twist angle”

in the case where the reference angle is “

twist angle of lower frame−

maximum allowable lower limit of the twist angle range≦

reference angle≦

twist angle of lower frame+maximum allowable upper limit of the twist angle range”

; and

by calculating “

twist angle of lower frame+maximum allowable upper limit of the twist angle range−

first twist angle”

in the case where the reference angle is “

twist angle of lower frame+maximum allowable upper limit of the twist angle range−

first twist angle”

.

7. The system of claim 2, wherein the control signal of the control signal generation module is generated in a manner that, if the first twist angle is within a marginal convergence range or within a reference convergence range, a second control signal for operating the actuator at low speed is generated;

and

if the first twist angle is out of the marginal convergence range and the reference convergence range, a first signal that does not limit the operation speed of the actuator is generated;

wherein the marginal convergence range is calculated through “

twist angle of lower frame−

maximum allowable lower limit of the twist angle range≦

marginal convergence range≦

twist angle of lower frame−

maximum allowable lower limit twist angle range+constant angle”

or “

twist angle of lower frame+maximum allowable upper limit of the twist angle range−

constant angle≦

marginal convergence range≦

twist angle of lower frame+maximum allowable upper limit of the twist angle range”

; and

the reference convergence range is calculated through “

reference angle−

constant angle≦

reference convergence angle≦

reference angle+constant angle”

.

13. The method of claim 1, wherein the step (b3) of generating the control signal comprises the steps of:

(b31) comparing the first twist angle with the marginal convergence range, and if the first twist angle is out of the marginal convergence range, comparing the first twist angle with the reference convergence range;

(b32) if the first twist angle is out of the reference convergence range in step (b31), generating the first control signal that does not limit the operation speed of the actuator; and

(b33) if the first twist angle is within the marginal convergence range in step (b31) or within the reference convergence range in step (b33), generating the second control signal for operating the actuators at low speed;

wherein the marginal convergence range is calculated through “

twist angle of lower frame−

maximum allowable lower limit of the twist angle range≦

marginal convergence range≦

twist angle of lower frame−

maximum allowable lower limit of the twist angle range+constant angle”

or “

twist angle of lower frame+maximum allowable upper limit of the twist angle range−

constant angle≦

marginal convergence range≦

twist angle of lower frame+maximum allowable upper limit of the twist angle range”

; and

the reference convergence range is calculated through “

reference angle−

constant angle≦

reference convergence angle≦

reference angle+constant angle”

.

8. A method for controlling automatic leveling of heavy equipment with a lower frame, an upper frame and a tilting means including a sensor unit, a control unit, and a driving unit, the lower frame having traveling means, the upper frame tiltably and swingably connected to the lower frame, and the tilting means for tiltably connecting the upper frame to the lower frame, the method comprising the steps of:

(A) the sensor unit sensing twist angles (i.e. pitching angles and rolling angles) of the lower frame and the upper frame against a reference horizontal surface as an inclination sensor mounted on the lower frame and the upper frame, and measuring a traveling speed of the heavy equipment as a traveling sensor;

(B) the control unit limiting an operation time to a predetermined reference operation time in a standstill state of the heavy equipment or the traveling means of the heavy equipment while calculating a corrected angle to which the upper frame is to be tilted based on the twist angle, without limiting the operation time, in a traveling state thereof, generating a control signal for controlling actuators for performing a leveling control of the upper frame in accordance with the corrected angle, and transmitting the control signal to the driving unit 50; and

(C) the driving unit performing a leveling control by operating the actuators on the basis of the control signal.

9. The method of claim 8, wherein the step (B) comprises the steps of:

(b1) setting the sensed tilting angle of the upper frame as a first twist angle, and calculating a corrected angle for tilting the upper frame from the first twist angle;

(b2) if the corrected angle is “

0”

, returning to the step (b1), while if the corrected angle is not “

0”

, calculating a second twist angle, and if the second twist angle is less than or exceeds the maximum allowable twist angle range, terminating the tilting control;

(b3) if the second twist angle is within the maximum allowable twist angle range, gene rating a control signal for controlling the actuators for tilting in accordance with the corrected angle and the second twist angle;

(b4) if the equipment is in a traveling state, returning to the step (b1);

(b5) if the equipment is not in a traveling state in step (b4), starting counting of the operation time;

(b6) performing the steps (b1) to (b3) after the step (b5), if the corrected angle is “

0°

”

in step (b2), terminating the tilting control, judging whether the equipment is in a traveling state after step (b3), and if the equipment is in a traveling state, returning to the step (b1); and

(b7) if the equipment is not in a traveling state in step (b6) and the operation time exceeds the predetermined reference operation time, terminating the tilting control, while if the operation time is less than the reference operational time, returning to the step (b6).

10. The method of claim 9, further comprising the step of judging conditions precedent to the leveling control before the step (b1), and if the conditions precedent to the leveling control is not satisfied, terminating the leveling control.

11. The method of claim 10, wherein the conditions precedent to the leveling control are satisfied in the case where the control lock lever is in an inactive state and a posture controller is positioned in the center.

12. The method of claim 9, wherein the step (b1) of calculating the corrected angle comprises the steps of:

(b11) judging whether the condition “

reference angle<

twist angle of lower frame−

maximum allowable lower limit of the twist angle range”

is satisfied, and if the condition is satisfied, calculating the corrected angle as “

twist angle of lower frame−

maximum allowable lower limit of the twist angle range−

first twist angle;

(b12) judging whether the condition “

reference angle≦

twist angle of lower frame+maximum allowable upper limit of the twist angle range”

is satisfied if the reference angle condition in step (b11) is not satisfied, and if the condition is satisfied, calculating the corrected angle as “

reference angle−

first twist angle”

; and

(b13) calculating the corrected angle as “

twist angle of lower frame+maximum allowable upper limit of the twist angle range−

first twist angle”

if the reference angle condition in step (b12) is not satisfied.

14. The method of claim 8, wherein the step of performing the tiling control is terminated in the case where the emergency stop condition is satisfied.

15. The method of claim 14, wherein the emergency stop condition is judged by an activation/inactivation of a control lock lever, variation of a posture controller, an on/off state of an auto leveling switch, an operation state of the working device, or a traveling state of the traveling means.