WO1998012516A1 - Dynamic load weighing system - Google Patents
Dynamic load weighing system Download PDFInfo
- Publication number
- WO1998012516A1 WO1998012516A1 PCT/CA1997/000684 CA9700684W WO9812516A1 WO 1998012516 A1 WO1998012516 A1 WO 1998012516A1 CA 9700684 W CA9700684 W CA 9700684W WO 9812516 A1 WO9812516 A1 WO 9812516A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- measurements
- load
- container
- weight
- strain gauge
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G23/00—Auxiliary devices for weighing apparatus
- G01G23/18—Indicating devices, e.g. for remote indication; Recording devices; Scales, e.g. graduated
- G01G23/36—Indicating the weight by electrical means, e.g. using photoelectric cells
- G01G23/37—Indicating the weight by electrical means, e.g. using photoelectric cells involving digital counting
- G01G23/3728—Indicating the weight by electrical means, e.g. using photoelectric cells involving digital counting with wireless means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
- G01G19/08—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles
- G01G19/12—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for incorporation in vehicles having electrical weight-sensitive devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65F—GATHERING OR REMOVAL OF DOMESTIC OR LIKE REFUSE
- B65F3/00—Vehicles particularly adapted for collecting refuse
- B65F3/02—Vehicles particularly adapted for collecting refuse with means for discharging refuse receptacles thereinto
- B65F2003/022—Vehicles particularly adapted for collecting refuse with means for discharging refuse receptacles thereinto the discharging means comprising a device for determining the weight of the content of refuse receptacles
Definitions
- This invention relates generally to the field of load weighing systems, and in particular, to the use of strain gauges to weigh a load, for example, when a load is being emptied as in a refuse or waste dumping situation.
- Load weighing systems are generally known in the art. They have been used, in one application, in the weighing of loads carried by waste trucks. The need for accurate weighing systems in this industry are known and include the fact that waste carriers are charged an amount based on the weight dumped in landfill sites. The waste carriers in turn would also like to charge their customers on a per weight basis as this would be more fair and cost-effective.
- the load weighing systems of the prior art typically use load cells or they measure indirect forces in these applications.
- ⁇ load is placed, for example, on a fork lift assembly of a waste truck and measurements are taken.
- the load cells in the prior art systems generally isolate and measure forces acting in one axis only, being typically the vertical axis, and attempt to compensate, in their measurements, for forces acting in other axes.
- Prior art systems have also been used to measure indirect forces such as forces acting within the hydraulic cylinders used to lift the fork and forces on the arm of waste trucks.
- Waste trucks typically have arms or forks which engage, lift, empty and return containers or bins to the ground in a cycle.
- the preferred time to measure the weight of the load is usually during this cycle.
- these waste trucks contain powerful machinery and hydraulic cylinders in order to be able to lift large loads.
- Weighing systems which require the stopping or slowing down of the arms or forks in order to measure the load of the weight during the cycle suffer from several problems. There is firstly an unacceptable time loss with these systems; this type of static weighing reduces the productivity of the waste truck. There are secondly large vibrations generated by this type of system which cause wear and tear and premature breakdown of the parts associated with these systems. These drawbacks add costs to the systems which have been found to be unacceptable.
- United States Patent No. 4,645,018 to Garbade is an example of such a system.
- a method for determining a weight of a load using a lift assembly comprising at least one loadcell sensor, wherein each loadcell sensor comprises at least one weigh post and a plurality of strain gauges positioned on each weigh post to take measurements of forces wherein the measurements from these strain gauges will be related to the weight being lifted, the method comprising: a) lifting the load; b) taking strain gauge measurements of the forces acting on the weigh posts in at least two different axes while the load is being lifted; and taking multi-axis force measurements at at least one position while the load is being lifted and calculating the weight of the load with the use of a calibration table.
- a method for determining a weight of a material and container while the container is engaged by a lift assembly that travels through a lift-return cycle
- the lift assembly comprises at least one loadcell sensor, wherein each loadcell sensor comprises at least one weigh post and a plurality of strain gauges positioned on each weigh post to take measurements of forces wherein the measurements from these strain gauges will be related to the weight being lifted
- the method comprising: a) causing the lift assembly to travel through the lift-return cycle thereby lifting the container containing material, emptying the material, and returning the container; b) taking strain gauge measurements of the forces acting on the weigh posts in at least two different axes throughout the lift-return cycle; c) taking first multi-axis force measurements at a first position while the container is lifted, taking second multi-axis force measurements at a second position while the container is returned where the first position correlates with the second position; and calculating the weight of the material with the use of a calibration table.
- an apparatus for weighing a load when the load is being lifted by a lifting assembly comprising: a) at least one loadcell sensor positioned on the lifting assembly proximate of the load wherein each loadcell sensor comprises at least one weigh post; b) a plurality of strain gauges attached to each weigh post to take measurements of forces acting on the weigh post in at least two different axes; whereby strain gauge measurements of the forces acting on the weigh posts in at least two different axes are taken while a load is lifted in order to calculate the weight of the load.
- Figure 1 is a side perspective view of a front end loading waste truck having one embodiment of the dynamic load weighing system according to the present invention
- Figure 2 is a side perspective view illustrating the front end of the waste truck and the fork assembly of the embodiment of Figure 1 ;
- Figure 3 is a side perspective view of the fork assembly of Figure 2;
- Figure 4 is a perspective view of the loadcell sensor of Figure 3, illustrating the weigh posts, strain gauges and analog-digital converters;
- Figure 5 is a front perspective view of the loadcell plate of Figure 4;
- Figure 6 is a top view of the loadcell of Figure 4;
- Figure 7 is a schematic of the signal transmission in the embodiment of Figure l ;
- Figure 8 is a side view of the embodiment of Figure 1 illustrating the body portion of the waste truck in a pivoted position
- Figure 9 is a schematic of the circuitry in the embodiment of Figure 1 ;
- Figures 10-1 1 arc flow charts of some of the steps of one method of the present invention;
- Figure 12 is a side perspective view of a rear end loading truck of a second embodiment of the present invention.
- Figure 13 is a top perspective view of the second embodiment of the present invention.
- FIGS 14 and 15 are top and front perspective views, respectively, of the load cell assembly of the second embodiment of the present invention.
- Figure 16 is a side perspective view of a roll-off waste truck having a third embodiment of the present invention.
- FIG. 1 one embodiment of the present invention is illustrated, and in particular a waste truck 20 and an arm and fork means 22 is shown.
- a waste truck 20 and an arm and fork means 22 is shown.
- the particular embodiments described here are for use with refuse or waste trucks, it will be understood that the use of the present invention is not limited to such applications, but rather can include any case where the weight of a load must be determined.
- the numeral 24 generally refers to a lift or fork assembly. There are two fork assemblies 24 pivotally attached to two lift arms 26. As the two fork assemblies 24 and two lift arms 26 are identical, only one of the fork assemblies 24 and lift arms 26 will be described below.
- the fork assembly 24 is pivotally connected to lift arms 26.
- the fork assembly 24 generally engages a sleeve 27 of a container 28 in a horizontal fashion as illustrated in Figure 6.
- the operator of the waste truck 20 causes the fork assembly 24 to slide into the sleeves 27 of the container 28, lifts the container 28 with the lift arms 26, brings the container 28 over the cab of the truck 20 and empties the container 28 into the body portion 29 of the waste truck 20 and returns the container 28 to its original position. This is generally referred to as the lift-return cycle.
- Hydraulic lift cylinders 50 and 52 as illustrated in Figure 1 are pivotally mounted to the waste truck 20 and to the lift arms 26. Through extension and retraction of the cylinders 50 and 52, the lift arms 26 are able to lift and lower the fork assembly 24 and consequently the container 28 when so engaged.
- the fork assembly 24 as illustrated in Figure 2, comprises generally a fork 30 which is the load bearing portion of the fork assembly 24, a loadcell sensor 32 and a sensor plate assembly 34.
- the sensor plate assembly 34 is comprised of an upper torque tube support 35, a lower torque tube support 36 and a sensor plate 37.
- the sensor plate assembly 34 is attached to the truck torque tube 38, which in turn is attached between the lift arms 26 of the truck 20.
- a pinch bolt 40 is used to secure the sensor plate assembly 34 into a level position and then welded into place.
- the sensor plate assembly 34, the loadcell sensor 32 and the fork 30 are sequentially attached to each other. Referring to Figures 5 and 6, a loadcell plate 46 defines a series of apertures 45 through which the loadcell plate 46 is attached to the sensor plate assembly 34 and to the fork 30.
- the loadcell sensor 32 comprises a block of metal out of which material is removed from the central portion wherein two loadcell plates 46 and four weigh posts 48 are formed. It will be appreciated by those skilled in the art that this metal can be of various types and in this embodiment of the present invention, the load cell sensor 32 is made of stainless steel.
- the loadcell sensor 32 further comprises four sensor arrays 54, each comprising a weigh post 48 to which strain gauges 42 and 43 are attached. Within each sensor array 54, the strain gauges 42. 43 take first measurements with respect to a first axis and second measurements with respect to a second axis located 90° from the first axis. It will be appreciated that measurements for a third axis can be determined mathematically or a third pair of strain gauges can be used in order to measure the third axis.
- the loadcell sensor 32 further comprises two analog-digital converters 44. Strain gauges 42 and 43 contained in the four sensor arrays 54 take measurements with respect to the first and second axes and send their respective signals to each of the analog-digital converters 44.
- the force of the load is transferred to the loadcell sensor 32.
- the load that is placed on the fork plate 30 generates a strain that is detected by the strain gauges 42 and 43 in the loadcell sensors 32.
- Analog signals corresponding to this strain are then sent from the strain gauges 42 and 43 to the analog-digital converters 44.
- the location of the loadcell sensor 32. being directly adjacent to the fork 30, minimizes the path that the strain travels prior to being sensed by the strain gauges 42 and 43 and therefore results in greater accuracy .
- the strain gauges 42 used in this embodiment typically have a rated +/- error of 0.1%.
- the prior art devices have typically used larger weldable gauges which have a rated +/- error in the range of 1 %.
- Strain gauges used in this embodiment can be obtained from Measurements Group Inc.. Raleigh, North Carolina, U.S.A.
- the location of the analog-digital converters 44 within the loadcell sensor also minimizes the distance over which the analog signals produced by the strain gauges 42 and 43 are sent.
- the analog signals are converted to digital signals by the analog digital converter 44 which are then transmitted via a sensor cable 56 to a cable junction box 58 and then relayed via a retractable sensor cable 60 to a computer 53 which can be located remote from the loadcell sensor 32 as illustrated in Figure 8.
- the conversion of the signal from an analog format to a digital format within the loadcell sensor 32 allows the transmission of digital signals which increases the accuracy of the system as the integrity of digital signals, unlike analog signals, is less affected by such factors as vibration, bends in the cable or engine noise.
- the digital data is received by a computer 53 which can be located in the waste truck 20, for example, in the cab of the truck 20. This data is processed and the weight of the load can be calculated and this information along with other information such as customer identification, odometer readings and engine hour readings can be transmitted to further destinations by wireless modem if desired.
- the circuitry and signal transmission are schematically outlined in Figures 7 and Figure 9.
- the signals can be transmitted via wireless technology such as a wireless modem, instead of by the cable 60, to the computer 53 located in the cab of the truck or to a location remote from the truck itself, for instance directly to an office.
- wireless technology such as a wireless modem
- the data sensed by the strain gauges can be processed and the weight of the load calculated within the loadcell sensor itself and the information then transmitted to a desirable location.
- the transmission of digital signals allows the retractable sensor cable 60 to be used as digital signals are less affected than analog signals by severe bends in the cable 60.
- the retractable sensor cable 60 extends and when the truck body 29 is returned to its initial position, the cable 60 retracts. This reduces the length of cable needed, the amount of potential breaks in the cable resulting from wear and tear and the amount of money and time spent on repairs.
- the processing steps used to calculate the weight of the load are outlined in Figures 10 - 1 1. Strain measurements are taken during the lift cycle and calculations made of forces and moments around the X and Y axes by strain gauges 42, 43.
- Prior art devices have used inclinometers to measure for example, the angles of lift arms, in order to determine the point during the lift cycle and during the return cycle to take measurements.
- the embodiment of the present invention eliminates the need for inclinometers. While it is preferred to calculate the weight of the load at certain points during the lift cycle and at certain points during the return cycle, it is understood that measurements can be taken at any point after the container has been lifted, prior to it being emptied or after the container has been emptied, prior to it being returned to its original starting position in order to determine the weight of the load. It will also be understood that taking measurements at a range of positions can improve the accuracy of the system.
- Quptotal The value corresponding to the weight of the material and container 28 being lifted, referred to in Figure 10 as Quptotal, can then be calculated using these measurements and a pre-calibrated table. Similarly values are taken from the return cycle to obtain a Qdowntotal value. A Qnet value is then obtained by subtracting
- Quptotal from Qdowntotal and Qnet is compared to a pre-calibrated table to obtain the net weight of the material emptied from the container.
- F(x) K0 + Kl(sigl) + K2(sig2)
- F(y) LO + LI (sigl) + L2(sig2)
- F(z) NO + N 1 (sig 1 ) + N2(sig2)
- M(x) PO + PI (sigl) + P2(sig2)
- M(y) RO + Rl(sigl) + R2(sig2)
- M(z) SO + S 1 (sig 1 ) + S2(sig2)
- the distance that the strain has to travel has been minimized and the physical properties of the lift arm, such as cracks or welds will have little effect on the strain measured by the loadcell sensor 32.
- the multi-axis loadcell sensor 32 as used in the present invention has the ability to measure all of the forces acting during the lift cycle and is capable of computing an accurate weight for the load. Since the multi-axis loadcell sensor 32 has the capability to directly measure forces in the X, Y and Z axes and consequently moments about the Mx, My and Mz axes, the measurements can be used to accurately and efficiently calculate the weight of a load.
- Single axis load cell devices which attempt to measure forces in one axis suffer from off-axis loading inaccuracies and errors contributed through the use of inclinometers, accelerometers, complicated mathematical algorithms and calibration curves. The removal of these devices or steps decreases the amount of possible error and inaccuracy in the system.
- Figures 12 -15 illustrate a second embodiment of the present invention. This embodiment can be used to determine the weight of refuse emptied from smaller containers 80, for instance in a residential or recycling situation, into a rear loading waste truck 82 as illustrated in Figure 12.
- the container 80 is lifted by a generic lifting arm assembly represented by the numeral 82, for instance one manufactured by Equipment Labrie Ltee, Quebec, Canada.
- the weight of the contents of the container 80 is determined during the lift-return cycle.
- a sensor mounting plate 86 is attached to the rear of the waste truck 78. Attached to the sensor mounting plate 86 is a loadcell sensor 84.
- the lifting arm assembly 82 is then attached to a lifting arm assembly plate 83 which is attached to the loadcell sensor 84.
- This type of lifting arm and load cell assembly can also be used in side and front loading residential and recycling waste trucks.
- strain gauge 80 on the lifting arm assembly 82 is transmitted to and sensed by strain gauges located in the loadcell sensor 84.
- the strain gauges are mounted on weighing posts 88 as in the first embodiment. Measurements can be taken when the container 80 is being lifted with respect to forces acting in a plurality of axes. The points of measurement can again be correlated through determining relationships, such as ratios, of the forces and moments acting in different axes. The weight of the load can be calculated from these measurements.
- the loadcell sensor 84 further comprises an analog-digital converter similar to the first embodiment so as to immediately convert the signal produced by the strain gauge into a digital signal. This signal can then be sent to a computer located in the cab of the truck or located remote to the truck.
- the device for and method of determining the weight in the second embodiment is similar to that described for the first embodiment.
- FIG 14 illustrates a third embodiment of the present invention that can be adapted for use on a typical roll-off waste truck 90.
- Loadcell sensors are placed on both sides of the truck, however, as the placement of the loadcell sensors will be identical on both sides, only one side as illustrated in Figure 14 will be described.
- Rear loadcell sensors 92 are placed as shown and the front loadcell sensors 93 and 94 can be placed at either or both of the locations represented by the numerals 93 or 94.
- a trip switch 96 identifies when the roll-off container is completely off the ground so as to begin the method of determining the weight of the load.
- strain gauges located in the rear loadcell sensors 92 and the front loadcell sensors, 93 and 94.
- Strain gauges are mounted on weighing posts similar to the first embodiment. Measurements of multi axis forces acting on the strain gauges can be taken once the container 98 is lifted completely off the ground. The points of measurement can again be correlated through determining relationships, such as ratios, of the forces and moments acting in different axes. The weight of the load can be calculated from these measurements.
- the method of determining the weight in the third embodiment is similar to that described for the first embodiment.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Forklifts And Lifting Vehicles (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU42922/97A AU4292297A (en) | 1996-09-20 | 1997-09-19 | Dynamic load weighing system |
EP97918860A EP0927340A1 (en) | 1996-09-20 | 1997-09-19 | Dynamic load weighing system |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002186094A CA2186094A1 (en) | 1996-09-20 | 1996-09-20 | Dynamic load weighing system |
CA2,186,094 | 1996-09-20 | ||
US08/870,466 US5917159A (en) | 1996-09-20 | 1997-06-06 | Dynamic load weighing system |
US08/870,466 | 1997-06-06 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998012516A1 true WO1998012516A1 (en) | 1998-03-26 |
Family
ID=25678694
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/CA1997/000684 WO1998012516A1 (en) | 1996-09-20 | 1997-09-19 | Dynamic load weighing system |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0927340A1 (en) |
AU (1) | AU4292297A (en) |
WO (1) | WO1998012516A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2526687A (en) * | 2014-04-29 | 2015-12-02 | Gary O'riordan | Weighing system for a front-end-loading waste-hauling vehicle |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3020323A1 (en) * | 1980-05-29 | 1981-12-03 | Hans-Günther 4286 Südlohn Pfreundt | Measurement of excavator and bucket loader loads - using strain gauges on housing to measure hydraulic pipe pressure |
EP0154728A1 (en) * | 1984-03-13 | 1985-09-18 | Yotaro Hatamura | Load detector |
US5178226A (en) * | 1990-12-21 | 1993-01-12 | Allan Bowman | Load measuring system for refuse trucks |
US5230393A (en) * | 1991-06-27 | 1993-07-27 | Mezey Armand G | Refuse collection and weighing system |
-
1997
- 1997-09-19 AU AU42922/97A patent/AU4292297A/en not_active Abandoned
- 1997-09-19 EP EP97918860A patent/EP0927340A1/en not_active Withdrawn
- 1997-09-19 WO PCT/CA1997/000684 patent/WO1998012516A1/en not_active Application Discontinuation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3020323A1 (en) * | 1980-05-29 | 1981-12-03 | Hans-Günther 4286 Südlohn Pfreundt | Measurement of excavator and bucket loader loads - using strain gauges on housing to measure hydraulic pipe pressure |
EP0154728A1 (en) * | 1984-03-13 | 1985-09-18 | Yotaro Hatamura | Load detector |
US5178226A (en) * | 1990-12-21 | 1993-01-12 | Allan Bowman | Load measuring system for refuse trucks |
US5230393A (en) * | 1991-06-27 | 1993-07-27 | Mezey Armand G | Refuse collection and weighing system |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2526687A (en) * | 2014-04-29 | 2015-12-02 | Gary O'riordan | Weighing system for a front-end-loading waste-hauling vehicle |
Also Published As
Publication number | Publication date |
---|---|
EP0927340A1 (en) | 1999-07-07 |
AU4292297A (en) | 1998-04-14 |
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