Harvesters – Motorized harvester – With condition-responsive operation
Reexamination Certificate
1999-10-05
2001-06-12
Pezzuto, Robert E. (Department: 3671)
Harvesters
Motorized harvester
With condition-responsive operation
C172S004500
Reexamination Certificate
active
06244024
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to moveable machines such as agricultural machines; and more particularly to a position-finding device for locating the position of a working edge for the machine, especially the edge of a crop, wherein a position-finding signal therefrom is supplied in the form of a steering adjustment value to a steering device on the machine.
A position-finding device for controlling a steering mechanism is known from DE 195 08 941 A1. In this device, a third sub position-finding device whose transmitter and receiver are directed at the worked field serves for producing a further reference value and normalization value. This arrangement however, leads to high levels of signal distortion and hence an unwanted, non-stable steering characteristic when the reflective properties of the worked field constantly vary e.g. due to differing amounts of straw lying on the stubble or if the field boundary lies in the reflection zone. The focus and alignment of the various sub position-finding devices is such that their reflection zones are to a large extent mutually independent and there is no interaction.
Furthermore, various position-finding devices for controlling a steering mechanism are known from DE 195 08 942 A1. One of these devices uses two tightly focussed, diverging light beams. At the position of maximum divergence, one of these beams falls on the worked field and the other on the unworked field and their reflections are used, when deviations occur, to provide an on-off type of control process in correspondence with their transit times. However, this results in a steering action that wavers undesirably along the intended path. Moreover, this document also discloses an ultrasonic position-finding device for controlling a steering mechanism using a single ultrasonic transmitter and receiver combination whose reflection zone overlaps each side of the working edge. This device utilizes the differing transit times of the echoes coming from the upstanding grain and the lower lying stubble. Should the crop alternately lie flat and then upright, or, if it is low and the alignment of the stalks or crops varies, then it is not possible to discriminate between the echoes from the crops and the echoes from the stubble so that the steering action becomes uncontrollable due to the lack of a suitable reference value.
SUMMARY OF THE INVENTION
An object of the present invention is provide a device which overcomes one or more of the above described deficiencies.
Another object is to improve the device mentioned above in such a manner as to produce a more uniform pattern of steering control even when the unworked field has differing degrees of reflectivity.
In accordance with the invention there is provided a position-finding device including a first sub position-finding device including a first transmitter and a first receiver with a first reflection zone that extends mainly over a field, the field having a working edge with at least two sides, and a second sub position-finding device including a second transmitter and a second receiver with a second reflection zone, said second reflection zone being aligned such as to overlap at least two sides of the working edge.
The two transmitters are preferably triggered simultaneously by a transmitting pulse whereby the two receivers accordingly receive superimposed partial reception signals which respectively originate from the two transmitters and which have been reflected by the unworked field.
In a combine harvester, it has proved propitious for the two sub position-finding devices to be disposed such that one of them is aimed at the top surface of the grain field containing the crop and the second one is aimed so as to overlap the edge of the grain, whereby the signal from the first sub position-finding device determines the normalization value and provides the reference value. The normalized lower signal component of the second sub position-finding device that originates from the narrower, more closely located region of the upstanding crop is further processed to provide the steering positioning signal.
Advantageously, those areas of the stubble field and the grain field that are involved in the position-finding process are located sufficiently far in front of the harvesting machine that, by virtue of the compensatory effect, the normalized position-finding signal produced from the individual signal components exhibits only a slight dependence on the passage of the machine over uneven ground, especially bumpy ground, and on the inclination and tipping movements of the agricultural machine or of the cutter bars attached to the front thereof.
The position-finding device scanning the edge of the grain is advantageously aligned such that it captures an area located several meters in front of the cutter bars on the harvesting machine. The reason for this is that because the machine is steered by its rearwardly located wheels, a large distance will be covered before any departure from the intended path can be compensated.
It has proved useful in this arrangement for the signal representing the actual angle of the wheels to be introduced as a further input value into the control device so that the likely subsequent path of the harvesting machine can be conveniently taken into account, in advance, from this signal. The normalized position-finding signal and the wheel angle signal are the input signals to the control device that will form the appropriate steering adjustment value.
It has been demonstrated that approximately 60% of the operator's attention is devoted to the steering of the machine in the case of conventional combine harvesters. Steering is a particularly arduous activity due to the fact that a relatively long period of time elapses before there is a change in the lateral position of the combine harvester relative to the edge of the crop when the machine is being steered by its rear wheels, whereafter the machine has to be steered by an appropriate amount in the opposite direction in order to continue travelling in a straight line. By relieving the operator virtually completely from the steering task, this automatic steering process generally allows the machine to travel faster and also permits almost the full width of the cutter bars to be used, apart only from a margin of approximately 10 cm.
The sub position-finding devices are in the form of ultrasonic transmitter-receiver assemblies. The position-finding sensors incorporate focusing means producing a solid angle having a half-width intensity of approximately 7° and a 90% capture angle of approximately 14°. It has been found advantageous to dispose the sensors in the sub position-finding devices near the side edge of the cutter bar at a height of approximately 1.5 to 2.5 meters above the grain stock. The sensor in the first sub position-finding device is aligned at an angle to the grain and its sensing field extends approximately up to the edge of the crop. The solid angle has a capture area of approximately 0.5 meters in diameter at the point of incidence and reflection. The two reflection zones covered by the sub position-finding devices are relatively aligned such that they approximately semi-overlap. This result is achieved, in the case where the lateral divergence of the axes of the closely spaced transmitter and receiver is approximately 5°, when the sub position-finding devices are disposed directly adjacent to one another.
It has been found advantageous to pulse the ultrasonic transmitters simultaneously so that the overlapping echo signals of these two transmitters, from the overlapping areas of the reflection zones directly adjoining the edge of the grain, are incident quasi simultaneously on the receivers, thereby increasing the power of the received signal even when the power of the transmitted pulse is only moderate.
One component of the reflection signals is derived from an area of the worked field, in particular, the stubble in the field. However, such signal components are usually incident on the receiver at a lat
Diekhans Norbert
Huster Jochen
Claas Selbstfahrende Erntemaschinen GmbH
Husch & Eppenberger LLC
Kercher Kevin M.
Muir Robert E.
Pezzuto Robert E.
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