WO2021048745A1 - Improvements in and relating to excavator arm mounted ground modifying accessories - Google Patents

Abstract

A ground modifying assembly is intended for attachment to the movable support arm of a vehicle such as an excavator. The assembly includes a mount arm portion for attachment to the vehicle's support arm, and a main body portion for supporting various components of the assembly. A pivotable connection about a transverse axis links the main body portion and the mount arm portion. The assembly includes or allows for attachment of ground working accessories such as blades, rakes, and mouldboards, which may be mounted on a separate accessory body portion pivotably attached to the main body portion to allow cross-fall inclination of the accessory. Guidance devices allow for the assembly to work with positioning systems common on worksites.

Description

IMPROVEMENTS IN AND RELATING TO EXCAVATOR ARM MOUNTED GROUND MODIFYING ACCESSORIES

FIELD OF INVENTION

The present invention comprises ground modifying assemblies suitable for use on support arms. Typical support arms include excavator arms including a boom and dipper arm. Ground modifying operations may include levelling and thus preferred embodiments employ a blade or mouldboard. Ground modifying assemblies may include guidance control devices for use with 2D and 3D surveying and control systems often used on worksites. Considered are alternatives to using the support vehicle as a an intermediate guidance reference platform for guidance control calculations, and where slew operations of excavators create significant issues along with the slow response time of slope sensors used in such systems.

BACKGROUND DESCRIPTION

The present invention was developed with the consideration of ground working, profiling and earth levelling operations in mind. As a background, many construction and development sites rely on equipment with controllable ground working elements such as blades or mouldboards (hereinafter we shall refer to these and similar devices as "blades" unless otherwise specifically stated). Traditionally ground working equipment was mounted or fixed on a vehicle which an operator guided around a work site to perform the necessary ground working operations. Similarly, raising and lowering the ground working element, and angling it if this was an option, was performed manually by the operator.

Systems evolved to employ devices such as laser guidance, Total Stations, and GPS controllers so that, as the vehicle was guided around the work site, the elevation and any angling of the ground working device could be automatically controlled. In less sophisticated 2D (two dimensional) type systems the positional characteristics of the vehicle mounted accessory (or ground working element within same) would be altered to match a single (often projected) pre-determined reference plane for the work site. In a more sophisticated 3D system, such as provided by Total Stations, a contoured profile can be loaded for a site and the vehicle mounted accessory (and included ground working element) adjusted - based on position - to match this profile.

Laser based systems can be used to guide a vehicle with a blade. Common practice uses a master station which sends out a rotary laser signal (which may employ a rotating prism) at a known height to prescribe a plane. This becomes the reference point for the worksite. This is an example of one of the most commonly used methods in current use. Such systems are not relatively cheap, can be set up on tripods, are generally effective as long as there are no line of sight obstructions on the work site - multiple laser stations may be positioned around the work site. This does increase capital cost for the guidance equipment.

Vehicles with appropriate sensors can detect their height, or the height of the blade/ground working accessory (when a sensor array is mounted to the blade or associated mounting assembly) relative to this reference point. Hence the blade/ground working edge can be maintained at a specific height relative to the reference beam plane.

The present applicant has developed ground levelling and modifying assemblies which can be attached to vehicles such as skid steer loaders, as well as excavators. Vehicles such a tractors and skid-steer loaders are relatively straight forward in operation as the main control for an operator is the elevation of the ground modifying assembly - up and down. This also makes it easy to control with sensor control equipment as well, as usually only the elevation control needs to be controlled and adjusted, for which there are many commercially available control units available for controlling hydraulic actuators and such like. In some embodiments of ground modifying assemblies the relative inclination of the blade or accessory within a lateral vertical plane (i.e. roll, as opposed to pitch or yaw) has been provided, and is typically an additional feature of the attached assembly rather than the mounting assembly on the vehicle. Additional or separate controls may be provided to the vehicle operator for such adjustments, though their control may be part of the guidance control system - such as to compensate for any roll of the vehicle (about a longitudinal x-axis), or when a the ground working edge of the vehicle mounted accessory must follow a slope or contoured site profile. For such guided systems the vehicle is often the ubiquitous skid-steer loader or tractor - there is no real limitation, as long as the ground working accessory can be mounted and at least its height and/or other operational characteristics controlled. Occasionally excavators have been used, though the design and manner of operation of excavators have limited their use for precision work over a work site. With excavators another level of complexity comes into play. Instead of keeping the ground modifying assembly relatively fixed to the vehicle, with up and down movement permitted in typical arrangements and travelling movement of the mounted accessory achieved by driving the vehicle forward, excavators operate an accessory while they are stationary. The accessory, mounted on the dipper arm at the end of the boom (arm), is drawn towards the vehicle for operation. The operator must extend the accessory forwardly (by operation of the dipper and boom arms), lower it, adjust the angle of the accessory (i.e. pitch of the accessory about a transverse horizontal axis) by an adjustable and controllable mounting linkage at the end of the dipper arm, and draw it back in. Because of the geometry of a typical excavator arm, the operator is continually adjusting elevation of the boom, adjusting extension of the dipper arm actuator (between the dipper arm and boom) to adjust the angle of the dipper arm, and also adjusting the accessory mount actuator to keep the pitch of the accessory constant.

In such a case it would appear that it would be relatively easy for guidance associated sensors and/or transmitters on the mounted ground working accessory to maintain the accessory at a constant (relative to the reference plane/contour) elevation as it is drawn towards the excavator cab. Unfortunately the dual arm (boom and dipper) arrangement of an excavator tends to want to make any mounted accessory travel through an arcuate rather than linear path. Following a scooping type arcuate path does not provided a flat planar result which is what is normally required. In practice the operator has to balance individual control of the boom and dipper arms to create as close to a linear path as possible. However, even the best operators may have an accuracy of ±25mm, whereas site managers are increasingly wanting tolerances within ±2mm - if a contoured site is to have concrete poured those larger tolerances can require significantly more material to be poured if minimum required thicknesses are to be maintained. Similarly, if the worked area is to be a sealed area such as a carpark with rain fall-off, depressions which can collect water in pools are not acceptable.

Consequently automated control systems have been attempted though have been problematic. These have relied on determining the precise location of the excavator cab assembly (the rotating portion on the typically tracked base) by the guidance system and using this as a reference point. Slope sensors on the boom, dipper arm help determine the relative position of the mounted accessory compared to the reference cab portion. Unfortunately, slope sensors by their mechanical design are slow to respond. Consequently any movement of the excavator geometry can only be done slowly - slower than a typical operator. If operated to fast you can also get correction loops where one slope sensor updates, then the control system updates the position of another arm portion only to have its slope sensor providing slightly out of date information about its position - in effect the slope sensors lag actual position and where multiple inputs provide information for cross correction of component position they can start to cause jittery movements due to attempted corrections based on out of date positional information.

If this was not problematic enough, the cabs on excavators can also slew (rotate) about a vertical z-axis. This makes it difficult to not only predict the path that a mounted ground working accessory may take as it is drawn towards the cab portion - unless you know the angle of slew/rotation of the reference cab portion. In theory a solution can be simple. In practice, the cost becomes insurmountable or runs into limitations of technology.

If a total station system is being used, being able to detect the slew of the reference cab portion requires multiple total stations. In reality the very high cost of each total station means that only one is ever used per site, and a contractor could not be financially competitive if an investment in multiple stations was required.

Dual GPS, especially mm GPS, based systems could also detect slew. However GPS technology has limitations - on a 2-dimensional ground map position precision may be within several mm. However it struggles with accurately determining height and we are again facing the issues associated with low accuracies of ±25mm or so. Further, GPS accuracy can vary over time, with different satellites changing for each other, as well as magnetic and electric fields from power lines, buildings, and large metal structures affecting accuracy. For instance drone operators in the South Island of NZ know that variations of the earth's magnetic field in some locations can also be problematic, as they have watched their GPS controlled drones fly off into the distance instead of returning to home.

Consequently, there is a real and frustrating problem associated with being able to use a ground working accessory on an excavator to the required degree of speed and accuracy that is achieved with stand skid-steer vehicles and tractors etc. It is also a frustrating problem as it precludes available excavators from being used, especially in contouring areas which a skid steer or tractor can't readily be used - e.g. precision work in tight confines, levelling materials (such as concrete) without driving on it, and certain specialist operations. Solutions for employing available guidance systems are either unviable or prohibitively expensive. Further slow sensor response, and difficulty in calculating for slew in the reference platform (cab portion) make it difficult to calculate the position, let alone control, the ground working accessory with any degree of precision or without constant recalibration (some of which require a complete rotation of the cab portion); all these dog the cab reference platform excavator mounted accessory platform.

It would therefore be extremely desirable, and address a valuable and long-felt and outstanding want, if there was an option which addressed such issues. It would be useful if an option was provided which went towards addressing simplifying the control of the attitude and position of an accessory on an arm like an excavator arm, to make it easier for operators and/or control systems.

It is an object of the present invention to consider the problems of the art, such as aforementioned, and provide alternatives to the art which go towards addressing at least some of the issues thereof.

It is an object of the present invention to provide at least an alternative ground modifying assembly, including or to which may be mounted a ground working accessory, capable of attachment to a movable support arm, including arms such as excavator-style arms. At the very least it is an object of the present invention to provide the public with a useful alternative choice.

Aspects of the present invention will be described by way of example only and with reference to the ensuing description.

GENERAL DESCRIPTION OF THE INVENTION For clarity, it is beneficial to define several of the terms used within this specification:

The terms roll, pitch, and yaw are used in the same manner as aeronautics. Here the vehicle is equivalent to the aircraft and pitch is movement about a transverse y-axis or otherwise an arcuate motion within a sagittal vertical plane within which lie the longitudinal x-axis and vertical z-axis of the accessory or vehicle portion to which it is mounted.

Roll is rotational movement, or changes of inclination, about a longitudinal x-axis or otherwise arcuate movement within a coronal vertical plane in which the transverse y- axis and vertical z-axis of the vehicle lies. Sometimes, in relation to setting up a ground working edge, this can be referred to as cross-fall. Yaw is rotational movement within a transverse horizontal plane normal to the vertical z-axis. This is often also referred to as slew when referencing the position of an excavator cab portion relative to its base.

Horizontal will typically mean true horizontal, though more precisely it shall be the reference plane for the site where appropriate (in case for some reason this has been set other than to the true ground horizontal) in some applications of the present invention.

According to one aspect of the present invention there is provided a ground modifying assembly for attachment to a movable support arm, said assembly comprising: - a mount arm portion; a main body portion; a ground working accessory or means of attachment thereof; mount arm pivot means between said mount arm portion and main body portion, and - arm connection means allowing for connection of said mount arm portion to a movable support arm on a vehicle.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, said assembly also including: an accessory body portion able to pivot relative to said main body portion, - said pivoting being about an axis parallel or coaxial to the main longitudinal axis of said ground modifying accessory.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which the pivot axis between said main body and accessory body portions is positioned towards an outer end of a said ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is provided actuator means for controlling the degree of pivoting of the accessory body portion relative to the main body portion.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said mount arm pivot means is close to the ground.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which the pivot axis of said mount arm pivot means, when viewed from the side, is below the top edge of a said ground working accessory. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein there is provided ground travelling means positioned forwardly of said mount arm pivot point.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said ground travelling means is attached to said accessory body portion such that its inclination from pivoting of the accessory body portion matches said ground working accessory.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, including biasing means acting between said mount arm portion and ground travelling means. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which the bias acts to provide a downward force on said ground travelling means.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said biasing means comprises any one or more of: a pressurised strut, a spring According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, including at least one guidance related device suitable for interacting with a guidance positioning system.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said guidance related device is positioned to be laterally near to the outer edges of a said ground working accessory when viewed from above.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, attached to a movable support arm of a vehicle, and connected to guidance control means capable of interacting with said guidance positioning system to provide correctional information regarding either or both of the elevation or cross-slope attitude of said ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said movable support arm is an excavator type arm.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said ground working accessory is a blade and/or mouldboard. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is present a skid portion on the back non-operational face of said blade and/or mouldboard, near the bottom edge of same

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which a said blade and/or mouldboard is present such that its preferred direction of operation faces horizontally towards the arm connection means when viewed from the side. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said mount arm pivot means allows arcuate movement between said mount arm portion and main body portion, said arc lying substantially within a vertical plane relative to the ground when said assembly is such that a said ground working accessory on the ground modifying assembly is positioned such that the bottom edge of said ground working accessory is in contact with the ground.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in the preceding paragraph, in which said mount arm pivot means is positioned close to the ground when said bottom edge of said ground working accessory is in contact with the ground.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which close to the ground means 500mm or less. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which, when viewed from the side, the relative vertical position of said mount arm pivot means is relatively close to the bottom edge of a ground working accessory present on said ground modifying assembly. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which relatively close means 500mm or less.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which relatively close is preferably 350mm or less.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is present a riser portion, horizontally forward of the position of a ground working accessory present on the ground modifying assembly, with forward being opposite to said arm connection means relative to said ground working accessory.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is a pressure linkage portion between said riser portion and mount arm portion.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said pressure linkage portion is pivotable connected to each of said riser portion and mount arm portion. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said pressure linkage portion comprises an actuator arrangement which is extendable in length.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said actuator arrangement of said pressure linkage portion comprises means for maintaining a force between said riser portion and the mount arm portion, the bias of said force being to extend the actuator arrangement.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which the actuator arrangement is hydraulic and/or pneumatic in operation.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which the pressure linkage portion comprises a mechanical spring or equivalent arrangement to create a bias to increase the distance between the connection points with the mount arm portion and the riser portion.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein unopposed action of the pressure linkage portion is to cause relative arcuate pivoting of the main body portion and mount arm portion about said mount arm pivot means.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is provided at least one ground travelling portion on or connected to said main body portion, and forward of the position of a ground working accessory on the ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said ground travelling portion comprises at least one of: a skid, a wheel, a carriage with wheels.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said ground working accessory is connected to said main body portion by a lateral inclination portion allowing the inclination of said ground modifying assembling to be varied relative to the ground, substantially within a vertical plane (relative to the ground) which is substantially perpendicular to the longitudinal axis of the mount arm portion when viewed from above.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein said lateral inclination portion comprises a pivot arrangement.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein said pivot arrangement is displaced from the middle and towards one end of the ground modifying assembly when viewed from above. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which an actuator arrangement controls, effects, and maintains the inclination of the ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which said actuator arrangement is hydraulic in operation.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which there is included at least one positioning aid comprising any of: levelling sensor, levelling transmitter, levelling transceiver, GPS transceiver and GPS receiver; a said levelling aid being for use with levelling and/or positioning systems.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein a said levelling and/or positioning system is a level and/or position type system commonly used on construction sites and surveying. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein a positioning aid comprises a level sensor capable of interacting with the signal from an external transmitting in an area where the ground modifying assembly is intended to be used.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, wherein said a said positioning aid sends signal data to a support arm control system, said support arm control system affecting control of movement of said movable support arm.

According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which a positioning aid is positioned at a fixed and predetermined height above the bottom of a said ground modifying assembly. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described above, in which, from the side and projected onto the ground, a said positioning aid is within 250mm horizontally of the bottom ground contacting portion of a said ground modifying assembly. According to another aspect of the present invention there is provided a ground modifying assembly, substantially as described in any one of the preceding claims, mounted on a movable support arm.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which said movable support arm is an excavator arm comprising at least a boom portion attached or attachable to a vehicle, and a dipper arm portion pivotable connected to the boom portion distal to a said vehicle.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which said ground modifying assembly is attached to the dipper arm portion distal to its connection to the boom portion.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which said ground modifying assembly is non-pivotable attached to the end of said dipper arm portion.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which said movable support arm includes a dipper arm actuator capable of adjusting the angle of pivot of said dipper arm portion relative to the boom portion. According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which the movable support arm includes a boom arm actuator capable of adjusting the angle of the boom arm relative to the vehicle.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which operation of the boom arm actuator is assignable to the operator.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which the ground modifying assembly includes at least one positioning aid, and wherein control of the dipper arm actuator can be assigned to a said support arm control system which adjusts said dipper arm actuator to maintain the elevation of said ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which the elevation of said ground modifying assembly is relative to an external reference signal or coordinates.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which the vehicle is an excavator.

According to another aspect of the present invention there is provided a ground modifying assembly mounted on a movable support arm, substantially as described above, in which the ground working accessory is a blade or mould board.

According to a further aspect of the present invention there is provided a method of operation of a ground modifying assembly (substantially as described above) comprising its attachment to a movable support arm comprising a boom portion, dipper arm portion, and actuators controlling the pivoting of same about their points of attachment, and wherein the ground modifying assembly is non-pivotably attached to the end of said dipper arm portion; the boom arm actuator is controllable to alter the reach of said ground modifying assembly relative to a vehicle on which the movable support arm is mounted or to be mounted, and the dipper arm actuator is controllable to maintain the ground modifying assembly on the ground and/or at a predetermined elevation, and the mount arm pivot assists in allowing the ground modifying assembly maintain the same attitude horizontally as the geometry of the boom and dipper arm portions vary.

According to another aspect of the present invention there is provided a method of operation of a ground modifying assembly, substantially as described above, in which there is a positioning aid provided on the ground modifying assembly, which provides information to a support arm control system which adjusts the dipper arm actuator in accordance to information from said positioning aid.

According to another aspect of the present invention there is provided a ground modifying system comprising a ground modifying assembly, substantially as described above, and connected to guidance control means capable of interacting with said guidance positioning system to provide correctional information regarding either or both of the elevation or cross-slope attitude of said ground modifying assembly.

According to another aspect of the present invention there is provided a ground modifying system comprising a ground modifying assembly, substantially as described above, in which said correctional information is provided to a control system to adjust the attitude of a said movable support arm assembly to which said ground modifying assembly is attached to effect correctional changes.

According to another aspect of the present invention there is provided a ground modifying system comprising a ground modifying assembly, substantially as described above, in which the vehicle is an excavator and corrections are made to the boom elevation of the movable support arm assembly thereof.

One aspect of the present invention comprises a ground modifying assembly, which in turn includes or allows for the attachment of a ground working accessory. The ground working accessory may vary according to use and embodiment, though typical examples include (but are not restricted to), blades and mouldboards, ground breaking rakes, dethatching accessories, powered drums (which may include teeth, blades, tines etc.), Harley rakes and so on. For simplicity of description we shall refer to accessories comprising rakes in the description herein, and it is envisaged that the skilled reader will be able to understand the principles of the invention when other accessories are used. When we use the term "ground edge" herein, we shall generally be referring to the ground contacting portion of the ground working accessory where work is theoretically taking place.

The ground modifying assembly includes means for attachment to a movable support arm. While there are different types of support arms envisaged within the scope of the present invention, we shall for simplicity of description refer to common excavator type arms (unless specifically mentioned otherwise) in the description herein. The ground modifying assembly could in theory be attached to any suitable vehicle mounting system, though as the specification attempts to describe the invention in relation to the issues associated with excavators the description here in (for simplicity) shall refer primarily to a typical excavator coupling such as is commonly present on the dipper arm. Again, it is envisaged that the typical skilled reader will be able to apply the principles and teachings herein to other types of arms.

For simplicity the typical type of excavator arm we shall use for discussing embodiments of the present invention generally comprise a boom connectable to a vehicle, be it excavator or not, in a manner that it can be raised and lowered by a boom arm actuator. The boom, from the side, typically has a bend giving it a boomerang shape such as in the figures herein. Pivotably connected to the boom, distal to the vehicle, is a dipper arm. There is typically a dipper arm actuator controlling pivoting relative to the boom and within the general plane of the arm.

At the distal end of the dipper arm is a bucket attachment linkage for mounting buckets or other accessories. There are bucket linkages and actuators allowing the angle of the bucket/accessory relative to the dipper arm to be altered.

In embodiments of the present invention the bucket linkages and actuators are not generally used - i.e. they are locked or fixed so as to be non-operational in terms of geometry adjustment of any attached accessory - such as the ground modifying assembly. While this can vary in differing embodiments, this is the case in currently preferred embodiments. In practical terms, this means trying to control the geometry of this part of the movable support arm (excavator arm) is no longer a consideration. This significantly simplifies operation for an operator and/or control system, meaning that in preferred embodiments only operation of the boom and dipper arm actuators needs to be considered. Having described a rather standard excavator arrangement for the purposes of simplicity of description, we shall talk more of the ground modifying assembly.

In preferred embodiments the mount arm portion of the ground modifying assembly extends forwardly of the dipper arm (forward being facing away from the vehicle the movable support arm is attached to). The mount arm may be adapted to couple to the mount provided on the dipper arm end, or may rely on an intermediate adaptor. Preferred embodiments are adapted for the common quick coupling attachments common in the field.

The mount arm in preferred embodiments bends or extends downwardly to allow a pivotable connection (mount arm pivot means) to the main body portion of the ground modifying assembly. Ideally this pivot point should be close (vertically) to the ground plane, or the lowest point on a provided or attached ground working accessory. It is considered that this low mounting point can simplify the geometry in preferred embodiments towards allowing the preferred situation of the bucket attachment linkage geometry remaining fixed in position during operation of the apparatus (see above). Simplifying the geometry, as earlier mentioned, can simplify control of the elevation and path of the mounted accessory during operation.

In practice (we will use the embodiment where a blade is present) keeping the pivot point at a constant height relative to the ground, or reference horizontal, plane means that the bottom edge of the blade will also remain at a constant height. Keeping the mount arm pivot point low, and in proximity to the ground edge/contacting part of the blade (or accessory) helps keep the height of the ground contact part of the blade relatively constant - even if the pitch of the ground modifying assembly alters due to pivoting and ground contours (see also later). Hence we can now set up any control apparatus to use the pivot point as a reference point for adjustments are made. Due to the proximity of the ground contact edge to the pivot, any changes in attitude involving pivoting (e.g. pitch) of the assembly which could occur during operation are unlikely to result in any significant unwanted variation in elevation or lateral height of the ground edge.

The result in these embodiments is that the operator (and/or control system) only needs to operate the boom and dipper arm actuators. In a typical system the dipper arm actuator (which varies the angle of the dipper arm relative to the boom) is used to draw an extended ground modifying assembly (i.e. the ground modifying assembly is as far from the excavator cab as possible) towards the cab.

To maintain the ground modifying assembly at a constant and/or correct elevation, the boom elevation is adjusted using the boom actuator. This could be done by the operator and a guidance system (from a sensor of the ground working assembly - see later) used to indicate whether the boom needs to go up or down to maintain the correct elevation of the ground contact edge. In a more sophisticated arrangement the guidance information is sent to a control system which operates the boom actuator to adjust the boom elevation as the dipper arm swings towards the cab. Since the pivot point of the mount arm is close to the ground edge, the everchanging angle of the dipper arm (and fixed mount arm) as the dipper arm swings inwardly does not result in any major fluctuations in elevation of the ground edge (as would be the case if, for instance, the pivot point was instead where the mount arm coupled to the end of the dipper arm. Hence, in practice, really only the boom arm elevation needs to be adjusted to correspond to changes in dipper arm position (and hence distance of the ground modifying assembly from the excavator main body) so as to keep the ground edge at the correct elevation. The mount arm pivot allows the attitude (particularly pitch) of the ground working assembly to adjust and remain in the correct position (relative to the ground plane or determined work contour plane) regardless of the position of the dipper arm - and the proximity of the ground edge to the mount arm pivot means that angular changes between the ground working assembly and dipper arm during operation do not introduce any significant elevation changes to the contact edge (as would be the case if it was distanced from the pivot point axis).

Various position and guidance aid(s) or controls may be employed, including ultrasonic, laser, radar, and GPS etc. In preferred embodiments a reasonably ubiquitous laser sensor or rotating prism is used. The guidance system can determine if the guidance reference point rises above or dips below a reference work plane - or more specifically if the contact edge of the ground working accessory falls above below a reference plane in its region of presence.

Generally the low level of the ground contact edge of the ground working accessory is too low for a guidance related device to be positioned. Ideally a riser for a guidance related device is elevated on a riser above the main body of the ground modifying assembly. This helps avoid obstacles present on a site being worked. Ideally, when viewed from the side, the riser is close (horizontally) to the ground contacting portion of any ground working accessory and ideally in the same general vertical plane of the ground contact edge of the ground working accessory.

Also, if so aligned, any change in pitch of the ground modifying assembly will rotate the arm elevating the guidance related device. This may occur if the ground working assembly encounters an obstruction (or digs into the ground) as it is drawn towards the cab. This will result in a change in detected elevation which can signal/control the operator/control system to alter the elevation of the boom. This will help return the device to zero pitch assuming the ground is relatively level, though is typically more important in final precision levelling operations rather than bulk contouring/grading operations.

Multiple sensors, typically near either end of a ground working accessory, can also provide inclination information. Some embodiments provide a connection for the ground working accessory to the main body portion which allows the inclination of the accessory to be altered (i.e. roll, as opposed to pitch or yaw). This typically includes a pivotable connection and actuator means for controlling the inclination. These embodiments can allow for the roll inclination of the accessory to be adjusted when the vehicle is off-level. Also, it can allow for inclination to be adjusted when a reference plane is off-horizontal (such as when fall needs to be contoured into the ground) and when SD contour type systems are employed.

In preferred embodiments allowing the angle of the ground contact edge to be varied about a longitudinal x-axis (such as to create cross fall, or counter when the excavator body is not on true level), the pivot point for roll (rotation about a longitudinal x-axis) is ideally positioned at the left hand or right hand end rather than in the middle (as is traditional). Ideally it is also directly under the elevated guidance related device or close thereto. A purpose for this is that regardless of the degree of roll on the ground contact edge, the elevation of the ground contact edge at the point of pivoting remains the same. The elevation of the ground contact edge changes progressively as one moves along the ground contact edge away from the roll pivot point. If the guidance related device and roll pivot point are substantially vertically aligned, we always precisely know the elevation of the ground contact edge under the guidance related device. Hence the ground contact edge at this point is virtually a reference point and stable relative to the guidance related device. As a consequence adjustments to calculate changing relative elevation between the two - which would be the case if the standard middle mounted pivot was used - are not required. If the roll pivot point and guidance related device are laterally separated, adjustments to alter the boom elevation to compensate for changes in vertical distance between the ground contact edge under the guidance related device (GRD), and said GRD would need to be continually recalculated as roll angle changed about the roll pivot point. This not only introduces continuous minor adjustments to the boom elevation, it also introduces complexity and possible reductions in precision during grading and ground working operations. Hence, in preferred roll-enabled embodiments, the roll pivot point and GRD are not laterally separated by any significant amount if possible.

To relieve download load on the excavator arm assembly, but also to help keep the ground modifying assembly level, a ground travelling portion is provided in preferred embodiments. Typically this comprises an assembly which rests upon and can travel across the ground. It may be a skid plate or caster in its simplest form, though a wheel or carriage assembly is preferred - this can reduce resistance to travel of the ground modifying assembly during use.

In preferred embodiments the wheels are present and mounted in a position such that if the ground modifying assembly is resting on the wheels and ground contact edge (of the ground modifying assembly), the assembly is substantially level - which typically means any sensor or guidance means is mounted so that this is attitude is regarded as level. Ideally also any mounted sensor/guidance device will be close to being above the ground contact edge of the ground working accessory, or at in the vicinity thereof. In practice preferred embodiments have the sensor/guidance related device positioned, when the apparatus is viewed from the side, between vertical coronal planes extending from the ground contact edge and mount arm pivot point - the situation in figure 1 herein. Any sensor/guidance device may be positioned outside these preferred parameters in preferred embodiments providing the decreasing level of operational accuracy is acceptable to the user/operator. To avoid a ground working accessory digging into the ground, especially blades, a skid plate or like may be mounted or present near to the ground contacting portion of the a ground working accessory. This is optional and may not be necessary for many worksites. However, where the ground being worked on is quite rough or has foreign objects, the presence of a submarining-reduction portion such as a skid plate can improve operation and reduce additional activity for the control system to counter pitch changes resulting from the ground working edge submarining into the ground from encountering excessive resistance. Ideally, for preferred embodiments, the consideration is that the less the sensor guidance control system (or operator) has to correct then the smoother the operation and potentially the faster operations can be completed. Even if corrections are made quickly by the system, an uneven surface (with fine transverse ridges or valleys) can still result should submarining occur - this being related to the horizontal velocity of the ground modifying assembly and how far it travels while elevation corrections are applied by the system to counter submarining. Hence the presence of a submarining reduction portion has the potential to provide improved final results during operation.

In preferred embodiments it is desirable to apply downward pressure to the ground contacting portion(s) of the ground travelling portion. This is not (in preferred embodiments) a case of adding weight, but applying a downward pressure by inducing a forward (nosedive) pitch into the main body portion (to which the ground travelling portion is attached) and about the mount arm pivot point. In this the pitch change associated with "nose-dive" is the opposite in rotation to that of "submarining" described above. Also it should be noted that during operation the ground modifying assembly travels rearwardly towards the excavator cab (e.g. the configuration of figure 2 follows that of figure 1 in typical operation) and the wheels are at the nose/front of the ground modifying assembly as it appears when mounted on an excavator or vehicle.

Providing a nose-dive pitch bias to the ground travelling portion can also help reduce downward weight/load at the ground working assembly - which can further assist in reducing any submarining during operation. It can also make the system more responsive - the less the vertical load in the vicinity of the mount arm pivot then the more responsive any elevation corrections can be (based on control system or operator responses). In practice, this potentially means that lighter capacity excavators (i.e. less requirements on the excavator) can be used which can be a significant real advantage There are a number of ways of achieving this nose-dive type bias, but a simple method used in preferred embodiments creates a bias (force) between a point on the mount arm portion and body portion. An upward riser on the mount arm portion can provide one connection point while a suitable connection point can be provided low on the main body portion and ideally near the ground travelling portion. The outward bias (resistant to contraction) can be provided by various spring, mechanical, hydraulic, and pneumatic solutions etc. Being able to adjust this bias is also an option in the most preferred embodiments

While this nose-dive type bias will attempt pivot the ground travelling portion downwardly, operation of the dipper arm actuator will attempt to maintain the mount arm pivot connection close the ground at the correct height. The bias of the pressure linkage accordingly results in a downward force on the ground travelling portion.

Alternatively the arrangement in some embodiments is that the pressure linkage extends between a riser near the ground travelling portion and a point of the mount arm (see drawings below). Various mechanically equivalent arrangements may be employed in various embodiments to create/maintain a nose-dive bias. Where bias adjustment is provided, the operator has the option to optimise bias for the particular worksite and equipment combination so as to achieve optimum results should they desire. In practice embodiments of the present invention can be used with a variety of guidance systems. Of particular not is that the apparatus of preferred embodiments of the present invention allow any guidance relative device (sensor, transceiver, marker, emitter, etc) to be mounted on the ground modifying assembly. This is in contrast to the present systems which determine the position of the excavator cab as a reference platform and then try to calculate the position of the ground working assembly (or more precisely the ground contact edge of any ground working accessory) relative to the reference cab portion platform. Most systems struggle with determining the precise orientation of the excavator cab portion due to its ability to slew, and to slew quickly. Hence problems immediately arise in determining the necessary spatial coordinates of the cab portion (and most can't tell if the excavator is off-level either). This remains a significant problem.

As previously mentioned the difficulty of determining the relative position of the ground modifying assembly at any time, relative to the cab portion, is also difficult. 5 Slope sensors struggle in providing information fast enough (they are sensitive to movement of the equipment) for accurate determinations of the relative position of the ground modifying assembly to be made. Further, such systems cannot make accurate determinations of the attitude of the ground modifying assembly (e.g. pitch and roll) relative to the reference cab portion. As a consequence excavators have been under let utilised for levelling operations, and virtually excluded from precision levelling operations.

By way of explanation only, and without intending to be limiting, the present invention seeks to remove the excavator from the guidance equation, instead providing guidance related means on the ground modifying assembly itself. This is potentially a significant 15 advantage, as this is what the guidance system is trying to determine anyway - it is the ground contact edge of any ground working assembly that it is trying to guide or control. It also makes such solutions amenable to existing guidance systems without any significant modification.

In reality it is not merely a case of moving a guidance related device from the excavator 20 cab portion to the ground modifying assembly. For precision work the ground modifying device is adapted for use with an excavator. Considerations include that excavators are not designed as cranes and are designed for drawing loads towards them rather than lifting operations. Hence ground modifying assemblies which reduce the vertical load requirements on the excavator allow a larger assembly to be used on a smaller capacity 25 excavator (and with more responsive operations).

Excavators move accessories through an arcuate movement due to their operational geometry. This needs to be consider and the design of any ground modifying assembly for attachment needs to address for precision work - scalloped finished surfaces are not acceptable. In preferred embodiments of the present invention, the geometry of the ground modifying assembly in relation to the dipper arm is considered, and the low mount arm pivot point (as discussed previously) is one such solution addressing the aforesaid considerations. Maintaining, knowing and/or controlling the pitch of the attached ground modifying assembly is also a consideration in precision work. The design of preferred embodiments where the mount pivot is near the ground contact edge of the ground working accessory helps reduce the influence of pitch changes. However there are also submarining considerations, and changes in pitch can alter the position and elevation of an elevated mounted guidance related device. It has been noted that the position of the guidance related device in preferred embodiments can also be used to provide pitch correctional information to the operator and/or control system.

If a relatively stable platform can be produced for the attached ground modifying assembly, then it is also possible to more accurately control the angling/slope of the ground working assembly relative to the main body/platform of the ground modifying assembly. This is desirable for precision work and allows work-sites with contours or cross-fall slopes to be more easily created between the guidance system and operator/control system. Further, it can also be used to compensate if the main body of the excavator is not level - the ground contacting edge can be adjusted to the attitude it needs to be regardless of whether the excavator is level or not. Further, an off-level excavator body will impose a different attitude to the ground modifying assembly at different slew angles (rotation of the cab portion relative to the base). The cross-slope angle of any attached accessory will be greatest when the excavator arms are perpendicular to the direction of the slope and almost zero when parallel to the direction of the slope - varying between the two. Correcting such issues have proved extremely difficult or unreliable in existing systems using the main cab portion as the guidance system reference and thus having been a further limiting factor, in practice, for the use of excavators in precision levelling or ground working. It should be appreciated also that a range of guidance systems may be used in conjunction with the present invention, including but not limited to: optical and laser systems, GPS systems, ToF (Time of Flight) and visual systems, ultrasonic systems, TOP stations etc. The present invention can be used for 2D, 3D, and intermediate (e.g. 2.5D) systems. Multiple guidance related devices can be positioned on the ground modifying assembly; this may be to provide more detailed attitudinal information, or to counter obstruction (with worksite devices) of one of the guidance related devices by the excavator or boom/dipper etc. during normal operation.

Further aspects of the present invention will become apparent from the description in relation to the following drawings.

DESCRIPTION OF DRAWINGS

Figure 1 is a schematic side view of one embodiment of the present invention attached to a movable support arm on an excavator, in an extended reach position, Figure 2 is a schematic side view of one embodiment of the present invention attached to a movable support arm on an excavator, in a partially retracted reach position

Figures 3a and 3b are end views of an alternative embodiment of a ground modifying assembly providing for cross-slope inclination of the ground working accessory, illustrating the relative position of the mount arm portion when in maximum reach and minimum reach configurations respectively during operation,

Figures 4a and 4b are perspective elevated rear views of the embodiments of figures 3 in the same respective configurations, Figs 5a, 5b, and 5c are front views of the embodiment of figures 3 and 4 when the ground working accessory has been given different degrees of cross-fall inclination, and Figure 6 is a front elevated view of the embodiment of figures 3 through 5 illustrating additional components.

DESCRIPTION OF PREFERRED EMBODIMENT

With reference to the drawings there is provided a ground modifying assembly (generally indicated by 1) for attachment to a movable support arm (generally indicated by 2) , said assembly (1) comprising: a mount arm portion (3); a main body portion (4); a ground working accessory or means of attachment thereof (5); - mount arm pivot (6) means between said mount arm portion (3) and main body portion (4), and arm connection means (7) allowing for connection of said mount arm portion to a movable support arm on a vehicle.

In figure 1 can also be seen a skid bar (8) to help stop the blade (5) digging/submarining into the ground.

A riser (9) on the main body portion (4) near the wheeled ground travelling means (10) allows a biased pressure linkage (11) to extend between the riser (9) and the mount arm portion (3). This bias may be adjustable. This also maintains pressure of the wheels (which are travelling over levelled ground as the assembly (1) travels from left to right during operation in figures 1 and 2. This can also reduce the downward load on the mount portion (3) and dipper arm (15) - this can reduce any tendency to submarine, and can make it easier for actuators (18) to adjust elevation as required.

The arm connection means (7) connects to the bucket linkage (14) on the dipper arm (15), which are shown greatly simplified in these schematic views. This is typically a ubiquitous bucket quick-hitch compatible mount, though can be changed in various embodiments, or used with an adaptor, according to specific excavator requirements.

In practice, in preferred embodiments of an assembly (1) and preferred methods of operation, the mount arm (3) remains fixed in position relative to the dipper arm (15). This reduces the complexity of compensating for another movable linkage when controlling the assembly (1) during normal operation. The actuator typically provided at the end of dipper arm, for bucket rotation relative to the dipper arm, has been omitted for simplicity. Once set up and attached, that actuator is normally locked or just not used during normal operation. The support arm (2) (comprising dipper arm and boom) in figure 1 is shown in the extended position, with dipper arm actuator (16) being largely contracted to extend the dipper arm (15). The boom actuator (18) has the boom (17) lowered for maximum reach from the excavator vehicle mount(20).

In figure 2 the boom (17) is shown raised as the dipper arm (15) is drawn closer to the excavator (20). In currently preferred practice the operator operates the dipper arm actuator (16) to decrease the dipper arm's (15) reach and draw the ground modifying assembly toward the excavator (19). The boom arm actuator (18) is operated to raise the boom (as we travel towards the configuration of figure 2) to maintain the correct elevation of the guidance related device (12). In this type of operation the distance of the assembly (1) from the cab portion (19) in manually controlled (typically) by the operator through the dipper arm actuator (16). Maintenance of the ground edge (58) of the ground working accessory (5) at the correct elevation is accomplished by the guidance system either providing guidance information to the operator (e.g. raise or lower boom) or directly to a control system to adjust the boom elevation. Hence, in practice for preferred embodiments, only the position of the boom needs to be adjusted in response to travelling movement of the assembly (1) - in contrast to existing solutions which try to simultaneously adjust the boom, dipper arm, and bucket connection actuators - which often fails or results in feedback loops when adjustment of one then effects corrections in the other actuators, which then promulgate further corrections as every adjustment affects the geometry of the arms and attachments (1).

This is the preferred method of operation, though in practice other methods of control and operation may be employed. Some applications of the invention may require differing methods of operation and/or control.

Figures Sa and Sb illustrate a more detailed view of a preferred embodiment of a ground modifying assembly (SI) from the right hand side (i.e. right of the saggital plane when looking forward from the excavator cab). For clarity the excavator and boom and dipper arms are not shown. In figure 3a the mount arm portion (33) is shown in its typical position for the excavator arms at full reach (e.g. figure 1). Figure 3b shows the mount arm portion in its attitude at minimum reach - when the assembly (31) is closest to the excavator cab portion (for reference, Figure 2 shows the assembly (1) at an intermediate position between full and minimum reach).

The dipper arm coupling (37) is shown and comprises in this embodiment a typical bucket quick connect connection. The biased pressure linkage (41) extends from the mount arm portion (33) near coupling (37), and at its alternate end to a bracket 52 which is fixed relative to the main body's sidearm portions (34a, b) and to which the roller (40) is attached. Hence a nose-dive type bias can be maintained between the mount arm portion (33) and the wheel/roller (40) regardless of the relative pivoting positions between the mount arm portion (33) and main body portion (34).

Also visible is the right hand (one of a pair) guidance related device (42a) adjustably mounted on pole extension (43a). The actual device (42a, b) will depend on the guidance system being used on the work site. Hence, it is possible that these may be interchanged as the equipment travels from site to site with different guidance systems.

In figures 4a and 4b we can see the respective mount arm positions of figures 3a and 3b, though from an elevated right hand perspective, looking towards the ground working accessory - a blade (35). A transverse skid plate (53) extends between side arms (54a, b) directly behind the blade (35) to counter submarining (vide supra).

What can be more clearly seen is the pivoting accessory body portion (54) to which the blade/accessory (35) is mounted, and wheel/roller (40) supporting side arm structures (54a, b). This assembly (54, 54a, 54b) and its attached components can rotate relative to the main body portion 34 to which the mount arm (33) is fixedly attached. In figure 4b the pivot connection (56) between the two (34, 54...) allows pivoting about a longitudinal axis so as to allow a cross-fall or roll type pivoting. This pivot axis (56) is near the side arm (54b) by preference, though could be near the other side arm. It is more important that it is substantially vertically aligned with a provided guidance device (42a, b).

The degree of pivoting is controlled by a separate actuator (57) either by the operator, though more preferably by the control system in response to guidance system correction information. Figures 5a, 5b, and 5c show the assembly (1) in left tilted, level, and right tilted configurations respectively when looking from the excavator. The pivot point (56) between the main body portion (34) and the accessory body portion (54) is visible. As it is close to the outer edge of the blade (35) the ground contact edge (58) in the vicinity of the outer edge of the blade (35) does not vary in elevation much - as opposed to the alternate end of the blade. A slope sensor (not shown) or other sensor to determine the degree of relative pivoting (between 34 and 54) is additional control information is required. However the guidance system will typically adjust the elevation of the boom arm, and the degree of pivoting of body portions (34, 54) to ensure guidance related devices indicate the outer edges (left and right) of the blade (35) are each at the correct elevation (which will conform to any planar sensor guidance or contour information being mapped by the guidance system). As an option, the angle from vertical of the guidance related devices can be determined to make minor corrections for the guidance devices (42) not being truly vertical above the outer edges of the blade (35) though this is more likely to be an issue when ground working accuracy needs to be in the low mm range.

Figure 6 provides an elevated perspective view from the nose end of the assembly (31). Here the main arm (33) pivot point (36) can be seen. The main body portion (34) and the pivoting accessory body portion (54) can be more clearly seen one behind the other, along with their pivoting connection (56). Transversely distal to the pivot (56) is the actuator (57) controlling the pivot angle between the two (34, 54).

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the spirit or scope of the present invention as described herein.

It should also be understood that the term "comprise" where used herein is not to be considered to be used in a limiting sense. Accordingly, 'comprise' does not represent nor define an exclusive set of items, but includes the possibility of other components and items being added to the list. This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being authoritative disclosure on the true state of the prior art but rather as referencing considerations brought to the mind and attention of the inventor when developing this invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE:

1. A ground modifying assembly for attachment to a movable support arm, said assembly comprising: a mount arm portion; a main body portion; a ground working accessory or means of attachment thereof; mount arm pivot means between said mount arm portion and main body portion, and arm connection means allowing for connection of said mount arm portion to a movable support arm on a vehicle.

2. A ground modifying assembly for attachment to a movable support arm, as claimed in claim 1, said assembly also including: an accessory body portion able to pivot relative to said main body portion, said pivoting being about an axis parallel or coaxial to the main longitudinal axis of said ground modifying accessory.

3. A ground modifying assembly for attachment to a movable support arm, as claimed in claim 2, in which the pivot axis between said main body and accessory body portions is positioned towards an outer end of a said ground modifying assembly.

4. A ground modifying assembly as claimed in either claim 2 or claim 3 in which there is provided actuator means for controlling the degree of pivoting of the accessory body portion relative to the main body portion.

5. A ground modifying assembly as claimed in any one of the preceding claims in which said mount arm pivot means is close to the ground.

6. A ground modifying assembly as claimed in claim 5 in which the pivot axis of said mount arm pivot means, when viewed from the side, is below the top edge of a said ground working accessory.

7. A ground modifying assembly as claimed in any one of the preceding claims wherein there is provided ground travelling means positioned forwardly of said mount arm pivot point.

8. A ground modifying assembly as claimed in the previous claim, when dependent upon any one of claims 2 through 4, in which said ground travelling means is attached to said accessory body portion such that its inclination from pivoting of the accessory body portion matches said ground working accessory.

9. A ground modifying assembly as claimed in claim 7 or claim 8 including biasing means acting between said mount arm portion and ground travelling means.

10. A ground modifying assembly as claimed in claim 9 in which the bias acts to provide a downward force on said ground travelling means.

11. A ground modifying assembly as claimed in claim 10 in which said biasing means comprises any one or more of: a pressurised strut, a spring

12. A ground modifying assembly as claimed in any one of the previous claims including at least one guidance related device suitable for interacting with a guidance positioning system.

13. A ground modifying assembly as claimed in claim 12 in which said guidance related device is positioned to be laterally near to the outer edges of a said ground working accessory when viewed from above.

14. A ground modifying system comprising a ground modifying assembly as claimed in claim 12 or claim 13 attached to a movable support arm of a vehicle, and connected to guidance control means capable of interacting with said guidance positioning system to provide correctional information regarding either or both of the elevation or cross-slope attitude of said ground modifying assembly.

15. A ground modifying system as claimed in claim 14 in which said correctional information is provided to a control system to adjust the attitude of a said movable support arm assembly to which said ground modifying assembly is attached to effect correctional changes.

16. A ground modifying system as claimed in claim 15 in which the vehicle is an excavator and corrections are made to the boom elevation of the movable support arm assembly thereof.