Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Construction or agricultural-type vehicle
Reexamination Certificate
1999-02-04
2001-01-30
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Construction or agricultural-type vehicle
C172S004500, C172S009000, C414S699000
Reexamination Certificate
active
06181999
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a dozing system well suited for use in a bulldozer and more particularly to a leveling control technique for adequately controlling the position of the cutting edge of the blade in relation to the ground during the dozing operation of a bulldozer.
BACKGROUND ART
Normally, the dozing operation of a bulldozer of the above type is carried out under manual control by the operator. Concretely, the blade is manually controlled so that digging or soil carrying is performed with the blade being lifted and lowered, or leveling is performed with the cutting edge of the blade kept in a certain position in relation to the ground.
In such manual operation to lift or lower the blade, or keep the position of the cutting edge, the operator is required to frequently manipulate the blade so that he gets tremendous fatigue, no matter how skillful he is. In addition, such manipulation is too complicated for an inexperienced operator.
As an attempt to solve this problem, the applicant of the present invention has proposed a leveling control system for a bulldozer in Japanese Patent Publication (KOKAI) No. 7-48855 (1995), which enables leveling work in dozing operation by simple manipulation without causing extreme fatigue. In this leveling control system, a lift operation amount is obtained from a load control characteristic map to make the actual tractive force of the bulldozer equal to a target tractive force, while a lift operation amount is obtained from a leveling control (smoothing control) characteristic map to make the actual position of the cutting edge relative to the ground coincident with a target cutting edge position. These lift operation amounts are respectively weighted with a value obtained from a load-leveling control weight characteristic map, based on the difference between the actual and target tractive forces and then summed, in order that a final lift operation amount is obtained.
The leveling control system of this publication, however, presents the following problem. In this system, even when the load exerted on the blade is greatly changed, a target value for the load control is corrected by a target value for the smoothing control. Therefore, upon completion of carrying operation for example, the load control is so performed as to lift the blade, whereas the smoothing control is so performed as to lower the blade to restrict the fluctuation of the target cutting edge position. Consequently, the resultant ground surface after dozing operation will be undulated.
In addition, according to the publication, the load-leveling control weighting characteristic map is always set based on a constant weight function notwithstanding changes in the working states of dozing operation, and therefore the weight function of such a map is inevitably a combination of a weight function for digging work and a weight function for carrying work. This poses an obstacle to improvements in control performance.
The above publication has a further disadvantage in that when performing digging work and carrying work a plurality of times in the same lane, a target value is reset for every cycle of dozing operation so that improvement cannot be expected from the repetitive cycles and consequently there remain difficulties in adjusting the dozing operation to soil property and working conditions which vary every excavation site.
The invention is directed to overcoming the above problems and a prime object of the invention is therefore to provide a dozing system for a bulldozer, which provides improved operational efficiency for dozing operation while achieving a smooth excavation face. A second object of the invention is to provide a dozing system for a bulldozer, which is capable of adequately setting a weight function according to whether a digging mode or carrying mode is presently selected, thereby achieving better control performance. A third object of the invention is to provide a dozing system for a bulldozer, which exhibits good conformability to variations in the conditions of every excavation site to thereby achieve improved operational efficiency.
DISCLOSURE OF THE INVENTION
The first object can be achieved by a dozing system for use in a bulldozer according to a first aspect of the invention, the dozing system comprising:
(a) cutting edge position detecting means for detecting the position of the cutting edge of a blade in relation to the ground;
(b) target cutting edge position setting means for setting a target position of the cutting edge of the blade in relation to the ground;
(c) load condition detecting means for determining whether the load exerted on the blade is in a stable state;
(d) target cutting edge position correcting means for correcting the target cutting edge position set by the target cutting edge position setting means to the actual position of the cutting edge at that time, if the load condition detecting means determines that the load exerted on the blade is in a stable state when dozing operation is performed in an automatic digging mode; and
(e) blade controlling means for controlling the blade to be lifted or lowered such that the position of the cutting edge of the blade detected by the cutting edge position detecting means is made coincident with the target cutting edge position corrected by the target cutting edge position correcting means.
According to the first aspect of the invention, if it is determined when dozing operation is carried out in an automatic digging mode that the load exerted on the blade is in a stable state, in other words, if automatic digging is stably carried out, a target position of the cutting edge of the blade is corrected to the actual position of the cutting edge at that time. According to this corrected target cutting edge position, the control (smoothing control) is carried out for adjusting the position of the cutting edge of the blade in relation to the ground. With this arrangement, the blade control can be accurately carried out and improved efficiency can be achieved. In addition, automatic digging can be so performed as to flatten the face of the excavation, and it becomes possible to cope with variations in the inclination of the land and with the ground surface having irregular hardness.
In the invention, the actual position of the cutting edge used for correcting a target cutting edge position by the target cutting edge position correcting means is preferably obtained from a moving average. This enables high accuracy control.
The second object of the invention can be achieved by a dozing system for use in a bulldozer, according to the second aspect of the invention, the dozing system comprising:
(a) actual tractive force detecting means for detecting the actual tractive force of a vehicle body;
(b) cutting edge position detecting means for detecting the position of the cutting edge of a blade in relation to the ground;
(c) loading ratio detecting means for detecting a loading ratio that is the ratio of the amount of excavated soil loaded on the front surface of the blade to the loading capacity of the blade front surface;
(d) first operation amount calculating means for calculating an operating amount for controlling the blade to be lifted or lowered such that the actual tractive force detected by the actual tractive force detecting means is made equal to a preset target tractive force if there is a difference between the actual tractive force and the preset target tractive force;
(e) second operation amount calculating means for calculating an operating amount for controlling the blade to be lifted or lowered such that the actual position of the cutting edge detected by the actual cutting edge position detecting means is made coincident with a preset target cutting edge position if there is a difference between the actual cutting edge position and the preset target cutting edge position;
(f) weight characteristic setting means for setting a weight characteristic for automatic digging, which gives importance to weighting of the operation amount calculated by the first operati
Nagase Hidekazu
Yamamoto Shigeru
Armstrong, Westerman Hattori, McLeland & Naughton
Arthur Gertrude
Cuchlinski Jr. William A.
Komastsu Ltd.
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