Measuring equipment for determining the result of earthmoving work. The invention relates to measuring equipment, which when combined with operational components of earth moving equipment comprising a bucket or corresponding earth holding implements enables the determination of the volume of earth removed from a pre-determined area. Earth moving equipment is used in transforming natural soil in a geographical location with a pre-existing local topology into a new local topology that is better suited to the purpose for which this geographical location will be used. Such equipment comprises buckets or similar digging containers, which are joined to arms or levers, or linkages, which are again joined to other levers or linkages, which are made operational by hydraulic cylinders for rotating them about their respective joints or varying their lengths, including hydraulic cylinders for moving those levers (frequently termed 'booms') that are directly joined to the chassis of the earth moving equipment. A bucket is moved by corresponding hydraulic means. In the present text 'earth' is intended to mean the natural ground upon which the earth moving equipment works, and it comprises clay, gravel, stones, and rocks in their dry or wet state, but not solid rock. It is also intended to cover any filling material that the equipment may be used to distribute according to a given schedule. In the present text the expression 'the outermost lever' is intended to mean the lever that carries the bucket or a similar digging container in an articulated hydraulically operated chain of levers connected to the chassis of the earth moving equipment. The outermost lever is indicated in the drawing. In the present text the expression 'the vertical ground distance' is intended to mean the calculated vertical distance to ground of a distance measuring device placed at a predetermined point of the outermost lever, calculated by means of an apparent distance measured at an angle, said angle being known by means of an inclination sensor. The vertical ground distance is indicated in the drawing. Expert operators may work with such earth moving equipment in order to transform the local topology according to set plans, and they are aided by measuring equipment systems that provide information about the implements that are directly engaging the ground. In operations removing earth there is a particular emphasis on knowing the depth of the implement with respect to a reference, either to the surrounding surface or to a computerised model of the topography. In the latter case it may be either a model of the topography as is or the topography to be obtained. The depth is an important parameter when it is desired to determine the volume of material removed either to monitor progress or to supply logistic information to the support in the form of transportation vehicles.

With the lengths of the levers and the angles between them known at any one instant, it is possible to refer any end point of a lever to the chassis of the earth moving equipment. If the earth moving equipment is fitted with an absolute position reference via any of the conventional systems (GNSS or local total station or the similar) it is possible to refer any end point of a lever to an absolute reference. In order to determine the depth of an implement (a bucket or similar digging container) fitted to the endpoint of the utmost lever with respect to any of the references mentioned, it is also necessary to know the implement's lowermost point at any one instant and the distance of that point from the endpoint of the utmost lever.

Similar problems are encountered in the field of robotics, where the end of an implement has to be controlled very precisely as it moves in space in order to perform the desired operation. However, the known solutions are very different from those that can be universally applied in the field of earth moving technology. First of all, the precision is at least one order of magnitude higher in the field of robotics, and secondly the environment for a robotic system working indoors is much less demanding than the environment in which earth moving equipment is used.

For this reason, robotic equipment is for instance frequently fitted with precision angle encoders at each joint, and trigonometric relations are used to calculate with high precision the position of a particular part with reference to a coordinate system that includes the robotic equipment and the real world it is operating in. Angle encoders are obviously also useful in earth moving equipment, but due to their environmental sensitivity they are frequently enclosed in the joints between levers, and this is done at the time of construction of the earth moving equipment.

Retrofitting angle encoders to pre-existing earth moving equipment is requires constructions that are water and dust proof. This would mean that in order to obtain the functionality of e.g. depth and volume determination with older, but technically sound mechanical constructions, some parts of these constructions would have to be replaced. According to the invention component parts of relevant measuring equipment may be retrofitted as well as installed on factory-new earth moving equipment.

According to the invention, a practical solution to the above problem is obtained in measuring equipment that is fitted to the outermost lever and the digging bucket of earth moving equipment, the instant end position of said outermost lever being calculated from pre-installed inclination and length determining instrumentation, said measuring equipment comprising a ground distance sensor fitted to the outermost lever and an inclination sensor fitted to the digging bucket, the volume determination being based on:

- the bucket dimensions and orientation,

- a vertical ground distance calculated from the position of a predetermined point of the outermost lever and the ground distance measured, and

- the horizontal distance travelled by the bucket as determined by signals from the pre-installed inclination and length determining instrumentation.

In an advantageous embodiment of the invention the predetermined point of the outermost lever is the end point of said lever. This is the point to which the bucket is fitted and around which it is pivoted to move.

An advantageous embodiment of the invention is particular in that a separate inclination sensor is fitted to the outermost lever in a known angular relationship to the orientation of the ground distance sensor, and in that the instant angle measured is used to obtain the vertical ground distance. A measure of this distance is hence obtained independent of the information provided by other sensors in the chain of levers constituting the digging equipment.

A further advantageous embodiment of the invention is particular in that the inclination of the outermost lever is determined trigonometrically by means of extension sensors for the piston rods of operational hydraulic cylinders manipulating the earth moving equipment. In certain earth moving equipment, the determination of the angular position of a given lever may be obtained by trigonometric calculation based on the geometrical position of the points of attack of the hydraulic cylinders used to move the levers with respect to each other, the geometrical position of the joints of the levers, and on the instant extension of each piston rod as determined by built-in extension determining sensors. A stick is merely a lever that may be longer or shorter according to the extension of a piston rod, and its angular position is not changed thereby.

The distance measuring instrument may advantageously be a retroreflective laser sensor because it is better adapted to provide precise data without compensation for eg. humidity and temperature that would be required for an ultrasound sensor. The invention comprises use of the above equipment in order for calculating the amount of material removed by the bucket, either individually for one bucket or accumulated over a period of work. The measurements may be made continuously as the work progresses, and in practice this means that many data samples per second are created to base the calculations on.

The invention will be explained in more detail with reference to the drawing, in which

Fig. 1 shows a simplified section of the chain of levers that carries a bucket, and

Fig. 2 shows a block diagram of data and calculating units.

The individual items shown and referred to in the claims are merely examples of items that function in the given environment, and the skilled person will be able to • devise combinations that function in the same way in order to obtain the inventive result.

In Fig. 1 is shown a stick 1 of an earth moving machine, which is hydraulically operated as to its extension and its angular relationship to a boom. The various hydraulic cylinders and joints that are well-known in the trade are not shown in this drawing. The stick carries a bucket 2 that is capable of digging and holding earth, which is pivotable around a pivot P by means of hydraulics. The bucket is provided with an inclination sensor 3, and the stick 1 is provided with a laser distance measuring instrument 4 that measures the distance to a point R on the ground. The inclination sensor 3 is shown symbolically by a shape reminiscent of a spirit level but may be of any type delivering an electric output at a useful rate. The stick is furthermore provided with an inclination sensor 5. These sensors are firmly fitted to the stick, and this may be done at any time of the lifetime of the earth moving machine, i.e. they may be retrofitted in order to give a machine the advantage of the invention. The laser distance measuring instrument 4 measures the distance DL by retro-reflection from a point R hit by the laser beam, and this is converted in a calculator into the vertical distance D to the ground G from the laser window, based upon the indication of the inclination sensor 5. The inclination sensor 5 is also shown symbolically by a shape reminiscent of a spirit level but may be of any type delivering an electric output at a useful rate.

The bucket is used both as a receptacle and as a measuring implement. In order to calculate the volume of the earth that is held at any one instant it is necessary to know the width of the bucket, the depth it is digging into the ground at any one instant and the length the bucket has travelled since it started digging. The depth is the difference between the level of the ground G before working and the level Gw after working. The distance after working may be calculated by means of the distance Bh between the bottom of the bucket 2 and the pivot P, and the knowledge of the position of the pivot P. This, in its turn, may be calculated by means of the fixed measurements of the position of the laser distance measuring instrument 4 with respect to the pivot P and the inclination data provided by the inclination sensor 5 The depth may hence be calculated as the sum of the distance Bh and the distance DL, from which is subtracted the distance D.

It is by now well-known how to calculate the position of any pivot in a chain of levers that are connected to the chassis of an earth moving machine. Some lengths are defined by the constructional elements and points of attack by the hydraulic cylinders on these constructional elements and the extension at any given instant of the respective piston rods, and some angles may be obtained from angle encoders built-in at the time of construction of the machine. The lengths are sufficient to enable a calculation by trigonometric and geometric calculating units the position of any pivot, such as the outer joint of the outermost lever with respect to global coordinates obtained from a GNSS. If angle measurements are available, either in the form of the output of angle encoders or in the form of outputs from inclination sensors the same trigonometric and geometric approaches apply.

Fig. 2 shows a schematic representation of data sources and a calculating unit containing trigonometric calculating functions known per se for determining the depth of digging by the bucket 2 shown in Fig. 1. As described in connection with Fig. 1 this depth may be determined via data related to the specific geometry of the earth moving equipment, and this is one set of data input to the calculating unit. Another set of data comprises data related to the joints between the levers, which may be obtained by angle encoders, either built into the equipment at the time of its manufacture or retrofitted. A third set of data is obtained from inclinometers on the various levers included in the linkage of the earth moving equipment, which may be retrofitted to the equipment. This data as well as information on the bucket dimensions and its horizontal travel as it is filled with earth that is removed is combined in the calculating unit, having as its output the accumulated volume of earth removed. This means that it is possible to let the earth moving equipment work until a given limit is reached, such as reliable filling of a lorry or truck for transportation of the earth.