WO2002097381A1

WO2002097381A1 - Dynamic weighing system

Info

Publication number: WO2002097381A1
Application number: PCT/AU2002/000665
Authority: WO
Inventors: Mario Mariani
Original assignee: Trans Lock Industries Australasia Pty Limited
Priority date: 2001-05-25
Filing date: 2002-05-24
Publication date: 2002-12-05
Also published as: GB0329699D0; GB2392734A; AUPR523801A0; GB2392734B; WO2002097381A8

Abstract

A dynamic weighing system for weighing an article which is lifted, the weighing system including a support device (24) on which a load to be weighed is adapted to be supported and lifted. A first transducer (42) is adapted to measure apparent weight of the load and adapted to provide a first output data stream embodying information relating to that apparent weight. A second transducer means (42) is adapted to measure gravitational and motion forces on the support device relative to a datum and provide a second output data stream embodying information relating to those forces. A central processor (76) receives the first and second output data streams and processes those output data streams as the load is being lifted to determine a series of estimated true weights of the load. The processor is then able to determine a final true weight of the load by averaging at least some of the estimated true weights in the series.

Description

Dynamic weighing system

Field of the invention

This invention relates to a dynamic weighing system of the type which can be used to accurately determine the weight of a load being lifted and deposited. The invention can be used to determine the weight of a load being lifted and deposited in a refuse or waste disposal truck but it is to be understood that the invention can be used in other applications.

Background of the invention

Waste disposal organisations involved in the disposal of waste material at dumping sites are generally charged for the load deposited by an amount which is determined by the weight of that load. In other words, the heavier the load which is dumped the more the company will be charged. Operators of a waste site will generally have a weighing platform over which the dumping vehicle will drive when both full and empty. The difference in measured weight will give the waste site operator an accurate determination of the weight of the dumped load.

A typical waste disposal organisation will collect waste material from a number of different sites and it is important to be able to accurately determine the weight of the material collected from each site so that the operator can apportion the charge for the waste collection service in accordance with the respective weights of the waste material collected from each site. In other words, some waste loads will be high volume low weight whereas others will be high weight low volume and it is appropriate that those with high weight loads are charged a greater amount than those with low weight loads. Also, some waste collection bins might not be full at the time of collection.

Many waste disposal organisations employ the services of a specially designed vehicle having a hydraulically powered lifting apparatus adapted to lift up a waste bin and tip the contents of the waste bin into a large waste receptacle carried on the back of the truck. One type of vehicle has a pair of forward pointing tines mounted to a pivotable frame. The driver of the vehicle manoeuvres the vehicle so that these tines slide into engagement with a waste bin having a pair of channels or slots on opposite sides of the bin into which the tines are inserted. Once the tines are correctly located in the channels the frame is pivoted over the top of the cab of the vehicle to a point where the bin is inverted over the load carrying receptacle of the vehicle and the contents of the waste bin tipped into the receptacle of the vehicle. Estimation of the weight of the waste material in each waste bin can be determined in various different ways. For example, if a load cell is carried on the receptacle of the vehicle, it should be possible to determine the weight of the increased load in the receptacle after the waste of each particular bin has been deposited. However, such arrangements require special mounting arrangements for the receptacle, and because of the high loads often carried in the receptacle, such systems tend to be unacceptably inaccurate.

Another method of determining the weight in a particular waste bin is to include some form of strain gauge in the lifting frame. The strain gauge should be able to determine the weight of the loaded bin being lifted and the weight of the empty bin as it is moved back to the offload position and by subtracting the difference between the full and empty weights, the weight of the deposited load can be determined. However, strain gauge type weight determining arrangements are also inaccurate, and are susceptible to changes in temperature, and variations over time. Frequent recallibration and maintenance is thus required. It is desirable that a weighing system is accurate to within 5 per cent, otherwise errors become unacceptable both to the waste materials operator and the customers from whom waste material is being collected. It is also desirable that calculation of the weight in a bin can be established without delaying the collection operation in any way. It is undesirable for the operator to have to wait for any significant period of time during the lift . nd dump cycle for the system to settle. Not only is this time consuming, but the need to allow the system to settle can lead to unacceptably high errors, especially where there is a pressure on the operator to be time efficient. Summary of the Invention

According to a first aspect of the invention there is provided a dynamic weighing system for weighing an article which is lifted, the weighing system including: a support device on which a load to be weighed is adapted to be supported and lifted; a first transducer means adapted to measure apparent weight of the load .and adapted to provide a first output data stream embodying information relating to that apparent weight; a second transducer means adapted to measure agricultural and/or motion force experienced by the support device relative to a datum and provide a second output data stream embodying information relating to that force;and a central processor adapted to receive said first and second output data streams and process said output data streams as said load is being lifted to determine a series of estimated true weights of the load, and to determine a final true weight of the load by averaging at least some of the estimated true weights in the series.

Preferably the first and second transducers provide a substantially continuous output data streams, and said central processor samples said streams at regular intervals. It is desirable that the final true weight established by the system is within 5% of the actual weight of the load. The central processor may discard a selected proportion of estimated true weights which fall above and below a central estimated weight, or weight range.

In one form of the invention the support device is fitted to a vehicle which has a load carrying receptacle, and the support device is movable between a load lifting position and a load dumping position in which a load supported on the support device is dumped into the receptacle. The support device may take the form of a frame which is pivotally mounted to the vehicle and is movable about said pivotal mount between said positions. The frame may have a pair of tines mounted thereto adapted to engage within channels formed on either side of a load carrying bin. Preferably, said second transducer means is adapted to measure forces on the support device relative to horizontal in two orthogonal directions. The orthogonal directions are preferably perpendicular to and parallel to the direction of forward travel of the vehicle. The second transducer means may take the form of an accelerometer. An accelerometer which detects acceleration due to gravity can operate as a clinometer. The accelerometer is preferably a two-axis accelerometer.

Optionally the weighing system may include a third transducer means which is mounted to the frame and is adapted to provide an indication as to measure the angle or position of the frame -relative to a datum, said third transducer means adapted to provide a third output data stream embodying information relating that position. The third transducer means may be adapted to determine when the frame has moved from a load lifting position, into a load dumping position, and returned into the load lifting position, the central processor being adapted to estimate the weight of the load before and after the frame has moved into the load dumping position, and by determining the difference between the estimated weights, establish the weight of the load dumped when the frame is in the load dumping position.

The frame may include a pair of forward projecting tines adapted to engage on opposite sides of a load, and said first and second transducers may be included in said tines. Said tines may thus include means to measure weight and angle of tilt of a load being lifted, h the preferred form of the invention the tines are mounted to the frame and extend forwardly of the vehicle, the tines being cantilever mounted to the frame. Each tine may include a microprocessor adapted to receive and process data streams from said first and second transducers, and means for carrying processed data to said central processor. Each tine may include independent electrical power means. Preferably communication between said microprocessors and said central processor is via a wireless transmitter. Preferably each tine includes a pair of load cells spaced apart along the length of the tine for determining the load carried by each tine. The load cells may be shear beam load cells.

The third transducer means may be connected to a control unit mounted to said frame and adapted to communicate with said central processor when conditions are within defined parameters for establishing the weight of an article. The parameters will typically include defined angular limits determined by the second and/or third transducer means. The control unit will include a control processor, and communication means for connecting with the central processor. The central processor preferably includes visual output means which is located within the vehicle cabin which will provide a vehicle operator with a visual indication of one of more aspects of a lift and dump cycle. The central processor is adapted to establish the weight of a load and bin lifted prior to dumping, and the weight of the bin after dumping, and subtract the difference to establish the weight of the dumped load for each dumping cycle.

Preferably the central processor is adapted to communicate with data storage means located exterior of the vehicle. Communication with the data storage means may be by a wireless transmitter. This will allow data from the vehicle to be downloaded on a regular basis and thereafter allow individual charges to be allocated to customers whose waste materials have been collected by the waste disposal operator.

The invention extends to a method of determining the weight of a load whilst the load is being lifted. These and further features of the invention will be made apparent from the description of an embodiment thereof given below by way of example. In the description reference is made to the accompanying drawings, but these specific features shown in the drawings should not be construed as limiting on the invention.

Brief description of the drawings

Figure 1 shows a side view of a vehicle with a dynamic weighing system according to the invention fitted thereto.

Figure 2 shows a plan view of the vehicle and system shown in figure 1. Figure 3 shows in diagrammatic form, the lifting tines and processor associated therewith for the weighing system shown in system 1.

Figure 4 shows in diagrammatic form a control unit for mounting to the frame of a weighing system according to the invention. Figure 5 shows diagrammatically the central unit and display means adapted to be mounted in a cab of a vehicle to which the weighing system is mounted.

Figure 6 shows a flowchart depicting the manner in which the processor samples the data and establishes a final true weight from the continuous stream of data being supplied from the tines.

Figure 7 depicts diagrammatically the manner in which the processor of the system applies a correction factor to the weight registered by the load cells.

Figure 8 shows cross-sectional detail of the tine structure and load cell arrangement. Figures 9 and 10 show enlarged details of the front and rear of the tine, respectively.

Detailed description of the embodiments

A weighing system according to the invention is diagrammatically shown in figures 1 to 5 of the drawings. The system shown is specifically adapted for establishing the weight of loads lifted by a waste disposal truck and dumped into a receptacle located in the back of the truck as will be described in more detail below. However, it must be understood that the invention might be used in other applications, for example, applications for lifting and weighing any load, such as, weighing of animals, weighing of produce, and the like. A problem with weighing articles or loads dynamically, that is, weighing a load at the same time as the load is being moved, is that accurate establishment of the weight of the load is difficult to determine. This is particularly so where the load is being rotated about an axis as it is being lifted. If it were not important to establish an accurate weight quickly then a load could be lifted, the system be allowed to settle for any harmonics to damp down, and then a weight could be established. However, the time delays associated with allowing a system to settle will be unacceptably high and will significantly delay the operation of weighing. In many situations, profitability of an operation can be significantly adversely effected by forcing the operator to delay the time for lifting and dumping a load in order to accurately establish the weight of the load. Thus, the present invention seeks to provide a system which allows the load to be accurately determined even though the load is being moved and rotated by the lifting mechanism whilst the weight is being established.

Turning specifically to the drawings, a waste disposable truck 10 is shown having a receptacle 12 towards the rear of the truck and an operator cab 14 towards the front of the truck. A load lifting frame 16 is pivotally mounted to the truck about pivotal mount

18 and a hydraulic ram 20 is used for rotating the frame 16 in the direction of arrow 22 about pivotal mount 18.

The frame 16 includes a pair of forwardly projecting tines 24 which themselves are mounted pivotally so as to be rotatable about the reminder of the frame at pivotal connection 26. Pivoting of the tines 24 is achieved by a second hydraulic ram numbered 28. The tines 24 are spaced apart and are adapted to support a load carrying bin 30 therebetween. Each of the tines 24 includes apparatus to establish the weight of the load carried by that tine 24, as well as the angle which the tine is aligned relative to the horizontal. This apparatus is described in detail below, particularly with reference to figure 3.

In use, the vehicle 10 will be driven forward by an operator so that the tines 24 engage in slots (not shown) located on opposite sides of the bin 30. Once the bin is properly located on the tines 24 the frame 16 will be lifted above the cab 14 by the hydraulic ram 20 until such time as the bin 30 becomes inverted which will occur after the bin 30 is located over the receptacle 12, and the contents of the bin 30 will then be deposited in the receptacle 12. Thereafter the hydraulic ram 20 will move the frame back to the position shown in figure 1 with the now empty bin still located on the tines 24. By establishing the weight of the bin in both full and empty conditions the weight of the load dumped into the receptacle 12 can be established.

Turning now to figure 3 each tine is shown in more detail. The tine 24 includes a main body 32 which has a forward end 34 protected by a nose cap 36. The tine is adapted to be mounted at its rear end 38 to the frame 16, cantilever fashion, and the tine 24 may be easily replaced if it is damaged or requires maintenance. The tine 24 also includes a weighbridge or load strip 40 which is mounted on load cells 42 located at opposite ends of the tine 24 , the load cells 42 adapted to determine the load carried by the load strip 40. The load strip 40 stands somewhat proud of the main body 32 such that the full load of the bin 30 rests on the load strip 40 thereby ensuring that the two load cells 42 on each tine correctly measure the full weight carried by that tine 24. The load cells 42 may be shear beam load cells. The orientation of the load cells is preferably eliminated or mirrored so that the effect of side force is opposite at each load cell. This will result in the effect of the side forces being reversed when the load cell outputs are summed.

It will be appreciated that the pair of load cells 42 on each tine 24 will experience a relatively direct load, as a bin is lifted. Thus, twisting forces which might be applied to a tine as a load is engaged and lifted, due for example to uneven ground on which the truck is operating, will not significantly affect the weight applied to the load cells. Providing two load cells 42, spaced apart, also ensures the full load is measured by each tine, irrespective of where contact is made between the bin and the load strip 40.

The tine 24 also includes a processor 44 which incorporates a two axis accelerometer 46, a memory device 48, a battery powered management system 50, and an analog to digital converter 54. A wireless transmitter 56 is used to communicate information gathered by the accelerometer 46 and the load cells 42 to a receiver 58 mounted to the frame 16. It will also be possible to use other means for communication, including wire based communication devices. The accelerometers 46 are two-axis accelerometers, as discussed in more detail below with reference to figure 7. The accelerometers measure the gravitational and motion forces experienced by the tines and provide a data stream embodying this information.

Clearly the loads or weight measured by the load cells 42 will change as the forces on the mass supported by the load cells vary. Because the system is a dynamic system those forces vary constantly, that is, the angle of inclination of the tines vary, and the motion forces caused by the lifting and lowering of the times also cause a variation in those forces. The accelerometers are provided to obtain an accurate estimation of those forces on a continuing basis, to enable an accurate determination of weight to be made. The outputs from each accelerometer is fed through an analog to digital converter, and then transmitted to a central processor to allow for computation of estimated tine weight of the load on the load cells. Thus, the net effect is the accelerometers provide the information necessary to determine an accurate correction of the load as determined by the load cells. The load cells 42 will also play an important part in determining specific steps of the dump cycle. As a load is tipped into the receptacle the load will come. If the load cells, that is the load on the load cells drops below a predetermined value.

The processor 44 is thus adapted to gather data streams from two sources and provide a signal which a central processor uses in order to establish the weight of the load carried on each tine 24. Those two data streams relate to firstly the load detected by the load cells 42 and secondly to the forces acting on the tines determined by the accelerometers 46. The manner in which the processor operates is described in detail below.

Clearly, as the load is lifted and rotated about pivot point 18 the angle of the tines 24 will change continuously. Thus, it is envisaged that the accelerometer 46 and the load cells 42 will provide continuously changing streams of data to the processor 44. Typically the processor 44 will estimate on a continuous basis the apparent true weight of the article. Using a filtering and averaging process, an accurate true weight can be established. These aspects will be described in more detail below. A control unit 60 is mounted to the frame 16 of the vehicle and the transmitter 56 is in communication with the receiver 58 located in that control unit 60. The control unit 60 is shown in more detail, although diagrammatically, in figure 4 of the drawings. The control unit 60 includes a processor 62, an accelerometer 64, a memory device 66, a battery power management system 68, a clock 70, and radio transmitter receiver 72. The unit 60 is in radio communication via transmitter receiver 72 with a central processor 76 located within the cab 14 of the vehicle. The control unit 60 will collect data from the tines 24 and tilt sensor 64 to determine when conditions are valid to calculate the weight carried by the tines and also to control the automatic lift and dump sequence. The results determined in each lift and dump cycle will be conveyed to the central control unit 76 via the transmitter 72. The control unit will also establish when the load has been dumped, that is, when the bin has been inverted over the receptacle 12. In this manner the system estimates the weight when the full load has been lifted, and when the empty bin is being set down, and by subtracting the empty weight from the full weight, the weight of the dumped load can be accurately established.

In broad terms, the system will only be able to determine the weight of the load carried by the tines when the frame 16 is reasonably close to its rest position. When the tines are tilted at an angle greater than about 15° inaccuracy becomes unacceptable. Thus, control unit 60 will only communicate the true weight of the load during such time the frame 16 is in a valid weight determining position.

The accelerometer 64 has a vertical axis, that is, it measures forces in the Y, or vertical, direction. The accelerometer 64 will thus be able to provide a signal which accurately establishes when the frame 16 is in a position which allows for accurate determination of weight carried by the tines 24. Because the axis of the accelerometer is vertical, it will also be able to provide a signal reflective of the motion forces applied to the bin and hence the load cells, on account of the bin being lifted. If desirable this information can be used to filter out increased load readings caused by acceleration or deceleration of the frame.

The unit 60 will also establish when the frame 16 has moved to a dump position so that false readings are not transmitted to the central unit 76.

The accelerometer 64, because it has a vertical axis, will in effect provide a signal which will accurately determine exactly what position the frame is in at any point in a lift and dump cycle. Clearly, when the frame is about to engage a bin, the axis of accelerometer 64 will be vertical and will provide a reading of 1. As the frame rotates up and over the truck the reading on the accelerometer 64 will reduce from 1 to 0 (ie when the axis of the accelerometer 64 is horizontal.) This will in effect establish when the bin has dumped its load in the receptacle.

In a typical cycle, therefore, the control unit 60 will enable the weight to be computed after the bin has been lifted but before the bin has been moved to a non-valid reading position (approximately 15°). The unit 60 will determine once the load has been deposited in the receptacle 12, and will thereafter allow the empty bin weight to be computed after the bin has again moved into a valid weight determining position. Without the unit 60 located on the frame, it would be difficult for the system to establish the point at which the weights determined by the processor 44 are no longer valid. The system would also not be able to automatically establish when a load might have been lifted close to, but short of the dumping position. The unit 60 thus serves to avoid false readings.

The central processing unit 76 is within the cab 14 and is depicted diagrammatically in figure 5 of the drawings. Unit 76 includes a transceiver 80, a processor 82 which incorporates a memory device 84 and a clock 86, a power management system 88 and a display panel 90. The unit 76 provides the driver with a visual indication of the status of the weighing system and also the weights of the waste bins as they are lifted and emptied and returned to the ground. By summing the different loads in the receptacle 12 the driver will be able to establish the total load in the receptacle 12. Optionally, control buttons 92 may be provided to allow the driver to interrogate the system for other control purposes. It is envisaged that the communication between the central unit 76 and the control unit 60 will be a local radio frequency digital communication which is bi-directional. It is envisaged that the power for the unit 76 will be provided via the electrical system of the vehicle. The clock 86 will be used to ensure the data from the control unit 60 can be synchronised with the data in the central unit. Typically the clock 70 will be synchronised with the clock 86 in the central unit 76. The memory 84 will typically be adapted to store all data relating to lift and dump cycles for a pre-determined period, typically 7 days. In a typical lift and dump cycle the processor of 44 will sample data continuously from the load cells 42 and the accelerometers 46. This processor 44 will estimate the true weight of the bin using the algorithms set forth below. However, in practice it is found that the weight established in any one sample is not an accurate true weight unless the system has been allowed to settle for a significant period of time. Estimated weights will vary due to harmonics in the system, bouncing of the vehicle and its suspension, and like factors. It is thus found that it is necessary to read a series of weights and then implementing a form of averaging of that series in order to determine a "final true weight". The term "final true weight" is used to indicate the weight which the system determines is the actual weight of the load being lifted. Of course, the final true weight may differ from the actual weight by the error margin of the system, but it is anticipated that the error margin will be less than 5%, and hopefully less than about 2%.Typically the accuracy of the system can be enhanced, it has been found, if the highest weights and lowest weights on opposite sides of the mean weight are discarded from the computation so that only the middle range of weights are used to establish the final true weight. Any suitable filtering technique can be used to discard weights falling outside a central band and typically the highest 20% and lowest 20% of the weights estimated by the system are discarded.

Turning now to Figure 6 of the drawings, a flowchart is shown which depicts the manner in which the central processor establishes a final true weight from the data supplied to it by the units on the tines, and the unit 60 on the frame. Typically the system will be in a power save mode, as indicated by box 94, but when the tines and frame are positioned by the operator in a bin engaging position the system will be powered-up, the load cells 42 will be turned on, the weight on the load cells will be set at zero, and the system will wait for significant weight to be registered by the load cells. This process is indicated by decision box 96. Digital processing, position monitoring, and weight calculations are carried out using digitized values of apparent weight, and acceleration in two axes by each tine and the acceleration in two axes sensed by the lifting frame. The accelerometers are "DC" coupled providing acceleration values in a known direction due to gravity and motion of the sensors. The powering up of the system is indicated by box 98 in the flowchart.

It will be noted that as indicated in item 3 in box 98 the system is initiated once the load cells 42 experience significant weight.

The system stays in a waiting mode until the tines begin to register significant weight, but as indicated by decision box 100, when weight on the tines exceeds a minimum, weights will be computed by the system, as indicated by box 101. As described previously, the processors in the system will calculate sample weights, that is, it will estimate a series of "true weights". Likewise, as indicated by box 101, weights in the series which fall outside of a central band will be discarded, and it is envisaged that the top and bottom 20% of weights so determined will be discarded. The processors will also, of course, adjust the weights registered by the load cells 42 to counter the effect of tilt angle effects. The system will then be able to compute the weight of the bin plus load, as indicated by box 103.

Once the tines move to a position at or near where the load in the bin will fall out, as indicated by decision box 104, the processors will stop computing the weights, and monitoring of the position of the tines and frame will again take place, as indicated by box 106.

Once the tines and frame move down to a position where the weight can again be reasonably accurately determined, as indicated by decision box 108, the system will again begin computing the weight of the empty bin, as indicated by box 110. Thus, the weight of the empty bin will be determined. The system will also monitor whether or not the bin has been returned to the ground, as indicated by box 112, and until such time as the bin has been returned to the ground a series of weights will be determined. Once the bin has been returned to the ground, as indicated by decision box 114, the system will compute the weight of the empty bin, and by subtracting the weight of the full bin as determined in box 103 the weight of the dumped load can be calculated, as indicated by box 116. The system will know when the bin has been returned to the ground since the load cells 42 will then register zero weight. Thus, the load cells provide significant assistance in automating the process.

The valid sensor data is stored during each of the weighing periods, allowing that weight to be post processed in a number of ways. The current embodiment filters the sensor values to reduce the effects of resonance and motion. As mentioned above, a simple yet effective filter is to discard the top and bottom 20% of the weights in each lifting and lowering cycles. The processors correct for tilt angle and average the samples deemed least effected by tine motion and tilt. Clearly other filtering techniques can be employed, for example, filtering out a greater number of apparent true weights as the angle of the tines increase, or when adjacent weight determinations differ too markedly from each other.

The manner in which the angle of inclination of the tines is used to correct the apparent weight determined by the load cells 42 to establish a series of "true weights" is more clearly understood with regard to the Figure 7. Figure 7 depicts a series of vectors aligned in a Cartesian coordinate system.

The system, as applied to a vehicles, has a Z+ve axis in the normal forward direction of the vehicle, X+ve is the direction from the right hand side to left hand side of the vehicle, and Y +ve is vertical increasing in height. Clearly, the tines are not kept horizontal in either the X plane or the Y plane as the load is lifted. The angle of the tines, continuously change during the lifting and lowering cycle, and thus the processor needs to make allowances for change of angle frequently, say between 10 and 60 times per second, depending on the accuracy required by the system.

The information provided via a two axis accelerometer will be able to determine the tilt of the tines relative to the X axis and the Z axis, and thus determine the correction factor necessary to apply to the estimated weights registered by the load cells.

If reference is made to Figure 7, vector AH represents the full vertical weight of the load which has been tilted through an angle ø about the Z axis and an angle θ about the X axis. The two axis accelerometer is able to determine both the angles ø and θ and thus the angle ψ thereby enabling an accurate correction factor to be established. Of course, the factor changes as the tines rotate which is why multiple sampling of both weight and angle is essential if accurate determination of the weight is required. Weight and angle determinations thus need to be extremely closely correlated.

It is important to note that rather than having the accelerometer 46 measure acceleration in both the X and Z directions, it will be possible to measure these accelerations with a single axis devices which measure acceleration in only the Y or vertical direction. Thus, when the tines are horizontal the accelerometers 46 will have a value of 1 and the load cells will measure true weight. Any variation measured by the accelerometers 46 will then be used to apply a correction factor to the apparent weight measured by the load cells. Thus, when the tines are at an angle, the accelerometer will measure a value of less than 1 and an appropriate correction can be applied. When the frame is lifted the motion forces on the accelerometer will cause an increase in the value registered by the accelerometer, and one again, an appropriate correction factor may be applied to the weight measured by the load cells. The accelerometers 46 can thus be use to correct the weight reading which continuously change as both the angle and acceleration of the tines move through the lift and dump cycle, and as system harmonics and dynamics alter the weight measured by the load cells.

Obviously other estimation techniques can be used but in practical test runs in which known weights are dumped, a filtering system which discards the highest weights and the lowest weights has been found to be able to determine with a high degree of accuracy the true weight of the load dumped in the receptacle. Indeed, it is found that the system establishes the weight which is dumped in the receptacle to an accuracy of significantly better then the 5% accuracy which the applicant believes is important. The tines 24 are shown in more detail in Figures 8 to 10 of the drawings. As shown, the tines 24 are formed of a pre-cast mould 204 that are mounted to interface sockets 122 and held into position by the bolts 205 for attaching to the frame 16. Variations in attachment to the frame 16 and interface socket 122 will apply to differing truck designs. Nose cap 36 protects the forward end of the tine and stops the load strip 40 from being removed. Rear key cap 206 is mounted to the surface of the tine and is fixed into place by key section 208 and pin 209. Rear key cap 206 also stops the load strip 40 from being removed. Electronics module 210 is mounted to rear key cap 206 and has microprocessors and accelerometers for data logging. The load strip 40 extends the length of the tine as shown, the load strip 40 being mounted on the front load cell 24 and fixed into position by the load cell pins 201 attached to the load cells 202 within the tube section of the tine 24 at either end of the load strip 40. The load cells 202 are held in position to the bottom internal surface of the tube within the tine 24 by the bolts 203. Any load applied to the load strip 40 will transfer through the load cell pins 201 to the load cells 24. The load cells 24 include strain gauges which provide a signal reflective of the load applied to the load cells. Bolts 203 hold the load cells 24 stationary to the bottom internal surface of the tube within the tine 24. Thus, in effect, all load supported on the load strip 40 will be registered by the front and back load cells. Variation in the point of contact on the load strip 40 will not alter the accuracy of the total weight measured since the load cells are located at opposite ends of the load strip. Clearly there may be many variations to the above described embodiment without departing from the scope of the invention.

It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

The foregoing describes embodiments of the present invention and modifications, obvious to those skilled in the art can be made thereto, without departing from the scope of the present invention.

Claims

Claims:

1. A dynamic weighing system for weighing an article which is lifted, the weighing system including: a support device on which a load to be weighed is adapted to be supported and lifted; a first transducer means adapted to measure apparent weight of the load and adapted to provide a first output data stream embodying information relating to that apparent weight; a second transducer means adapted to measure gravitational and/or motion force experienced by the support device relative to a datum and provide a second output data stream embodying information relating to that force ; and a central processor adapted to receive said first and second output data streams and process said output data streams as said load is being lifted to determine a series of estimated true weights of the load, and to determine a final true weight of the load by averaging at least some of the estimated true weights in the series.

2. A dynamic weighing system according to claim 1 wherein the first and second transducers provide a substantially continuous output data streams, and said central processor samples said streams at regular intervals.

3. A dynamic weighing system according to either claim 1 or 2 wherein the final true weight established by the system is within 5% of the actual weight of the load.

4. A dynamic weighing system according to any preceding claim wherein the central processor is adapted to discard a selected proportion of estimated true weights which fall above and below a central estimated weight, or weight range.

5. A dynamic weighing system according to claim 4 wherein the central processor is adapted to discard weights which fall in the top 20% and bottom 20% of estimated true weights determined by the system.

6. A dynamic weighing system according to any preceding claim wherein the support device is fitted to a vehicle which has a load carrying receptacle, and the support device is movable between a load lifting position and a load dumping position in which a load supported on the support device is dumped into the receptacle.

7. A dynamic weighing system according to claim 6 wherein the support device comprises a frame which is pivotally mounted to the vehicle and is movable about said pivotal mount between said positions.

8. A dynamic weighing system according to claim 7 wherein the frame has a pair of tines mounted thereto adapted to engage with locating formations on either side of a load carrying bin.

9. A dynamic weighing system according to claim 8 wherein said first transducer means comprises a pair of load cells mounted to each of said tines, said load cells on each respective tine being spaced apart long the length of the tine.

10. A dynamic weighing system according to claim 9 wherein on each tine said load cells are connected together by a load strip on which a bin is supported in use.

11. A dynamic weighing system according to claim 9 or 10 wherein said load cells are shear beam type load cells.

12. A dynamic weighing system according to any one of claims 6 to 11 wherein said second transducer means is adapted to provide a data stream indicative of gravitational forces on said support device in at least one direction.

13. A dynamic weighing system according to claim 12 wherein said direction is vertical.

14. A dynamic weighing system according to claim 13 wherein said data stream is also indicative of motion forces on said support device.

15. A dynamic weighing system according to claim 12 wherein said second transducer means is adapted to provide a data stream indicative of gravitational and motion forces on said support device.

16. A dynamic weighing system according to claim 15 wherein said direction is vertical.

17. A dynamic weighing system according to claim 15 wherein said data stream is indicative of gravitational forces in two orthogonal directions, at least one of which is horizontal.

18. A dynamic weighing system according to claim 17 wherein the orthogonal directions are perpendicular to and parallel to the direction of forward travel of the vehicle.

19. A dynamic weighing system according to any preceding claim wherein the second transducer means comprises an accelerometer.

20. A dynamic weighing system according to claim 19 wherein the accelerometer is a two axis accelerometer.

21. A dynamic weighing system according to claim 7 which includes a third transducer means which is mounted to the frame and is adapted to provide an indication as to position of the frame relative to a datum, said third transducer means adapted to provide a third output data stream embodying information relating that position .

22. A dynamic weighing system according to claim 21 wherein the third transducer means comprises an accelerometer.

23. A dynamic weighing system according to claim 22 wherein the accelerometer has an axis which is vertical.

24. A dynamic weighing system according to any one of claims 21 to 23 wherein the third transducer means is adapted to determine when the frame has moved from a load lifting position, into a load dumping position, and returned into the load lifting position, the central processor being adapted to estimate the weight of the load before and after the frame has moved into the load dumping position, and by determining the difference between the estimated weights, establish the weight of the load dumped when the frame is in the load dumping position.

25. A dynamic weighing system according to claim 24 wherein the frame includes a pair of forward projecting tines adapted to engage on opposite sides of a load, and said first and second transducers are mounted to said tines

26. A dynamic weighing system according to claim 25 in which the tines are mounted to the frame and extend forwardly of the vehicle, the tines being cantilever mounted to the frame.

27. A dynamic weighing system according to claim 26 wherein each tine includes a micro-processor adapted to receive and process data streams from said first and second transducers, and means for communicating processed data to said cenfral processor.

28. A dynamic weighing system according to claim 27 wherein each tine includes independent electrical power means.

29. A dynamic weighing system according to claim 28 wherein communication between said micro-processors and said central processor is via a wireless transmitter.

30. A dynamic weighing system according to any one of claims 21 to 29 wherein each tine includes a pair of load cells spaced apart along the length of the tine for determining the load carried by each tine.

31. A dynamic weighing system according to claim 30 wherein the load cells comprise shear beam load cells.

32. A dynamic weighing system according to any one of claims 21 to 31 wherein the third transducer means is connected to a control unit mounted to said frame and adapted to communicate with said central processor when conditions are within defined parameters for establishing the weight of an article.

33. A dynamic weighing system according to claim 32 wherein the parameters include angular limits determined by the second and/or third transducer means.

34. A dynamic weighing system according to either claim 32 or 33 wherein the control unit includes a control processor, and communication means for connecting with the central processor.

35. A dynamic weighing system according to claim 24 wherein the central processor includes visual output means which is located within the vehicle cabin which will provide a vehicle operator with a visual indication of one of more aspects of a lift and dump cycle.

36. A dynamic weighing system according to claim 35 wherein the central processor is adapted to establish the weight of a load and bin lifted prior to dumping, and the weight of the bin after dumping, and subtract the difference to establish the weight of the dumped load for each dump cycle.

37. A dynamic weighing system according to claim 36 wherein the central processor is adapted to communicate with a data storage means located exterior of the vehicle.

38. A dynamic weighing system according to claim 37 wherein communication with the data storage means is via a wireless transmitter.

39. A method of determining the weight of a load as the load is being lifted using a processor, said method including the steps of: locating the load on a support device, the support device incorporating a first transducer means to determine the apparent weight of the load, and a second transducer means to determine gravitational and/or motion force applied to the support device relative to a datum, both first and second transducer means adapted to provide respective output data streams embodying information as to weight and force respectively; lifting the support device with the load located thereon; feeding said data streams to said processor, and causing said processor to determine a series of estimated true weights of said load, and causing said processor to determine a final true weight of said load by averaging at least some of said estimated true weights in the series.

40. A waste disposal vehicle including a body having a receptacle and a support device mounted thereto, the support device adapted to lift a load and deposit said load in said receptacle, said support device including a first transducer means adapted to measure apparent weight of the load and adapted to provide a first output data stream embodying information relating to that apparent weight, and a second transducer means adapted to measure gravitational and/or motion forces acting on the support device relative to a datum and provide a second output data stream embodying information relating to those forces , and a central processor adapted to receive said first and second output data streams as said load is being lifted to determine a series of estimated true weights of the load, and to determine a final true weight of the load by averaging at least some of the estimated true weights in the series.

41. A waste disposal vehicle according to claim 40 wherein the support device comprises a frame pivotally mounted to the body and movable between load engaging and load dumping positions, and a pair of tines mounted to the frame and adapted to engage with a load to be lifted, at least one of said tines including said first and second transducers.

42. A waste disposal vehicle having a receptacle into which waste material is dumped, said vehicle having a pair to tines adapted to engage with a load carrying bin, said tines being mounted to a frame which is pivotable between load engaging and load dumping positions, each of said tines including first transducer means for determining the load carried by that tine, and second transducer means for determining at least the gravitational forces acting on that tine relative to a datum, each transducer means being connected to a central processor adapted to calculate the weight of waste material by computing the weight of the load carrying bin before and after a dump cycle by using the weight determined by the pair of first transducer means both before and after the waste material is dumped in the receptacle, and correcting that weight by a factor related to the gravitational forces acting on said tines as determined by said second transducer means as the load carrying bin is lifted.

43. A dynamic weighing system substantially as hereinbefore described with reference to the accompanying drawings.

Dated this 24th day of May 2002.

TRANS LOCK INDUSTRIES AUSTRALASIA PTY LIMITED by its attorneys Freehills Carter Smith Beadle