Method for determining a weight of a payload for a utility vehicle

Abstract

A method is provided for determining a weight of a payload carried by a support structure of an agricultural utility vehicle via a hitch. The hitch includes at least one upper link and at least one lower link. The method includes determining the weight based on at least one of (1) an angle between the upper link and a vehicle horizontal, and (2) a holding force that arises at a connection between the upper link and the payload and is effective along the upper link.

Claims

1. A method for determining a weight of a payload carried by a support structure of an agricultural utility vehicle via a hitch, comprising: providing the hitch with at least one upper link and at least one lower link and a lift cylinder connected to the at least one lower link, and determining the weight based on (1) an angle between the upper link and a vehicle horizontal, (2) a holding force at a connection between the upper link and the payload effective along the upper link, (3) a force in the lift cylinder, and (4) a lift height of the hitch.

2. The method of claim 1, wherein the lift height of the hitch is determined by measuring the angle between a lift arm connecting the lift cylinder to the lower link and the vehicle horizontal.

3. The method of claim 1, further comprising: determining the weight based on a tensile force at a connection between the lower link and the support structure instead of being based on the holding force at the connection between the upper link and the payload.

4. A control system of an agricultural utility vehicle for determining a weight of an implement, comprising: the vehicle including a cabin, a front axle, an engine for driving a rear axle, and a support structure; a hitch mounted to the vehicle at a front or rear region thereof, the hitch including an upper link hingedly mounted to the support structure and a lower link hingedly mounted to the support structure via a support bearing; the implement coupled to and supported by the hitch; a control device; and a plurality of sensors coupled to the vehicle and disposed in communication with the control device, the plurality of sensors including at least a first acceleration sensor, a second sensor for detecting hydraulic pressure of a lift cylinder, a third sensor for measuring an angle between the upper link and a vehicle horizontal, a fourth sensor for measuring a tensile force at the lower link, a fifth sensor for measuring a lift height of the hitch, and a sixth sensor for measuring a holding force of the upper link; wherein the control device is configured to receive a measurement value from at least one of the plurality of sensors, and based on the measurement value, determine the weight based on (1) the angle between the upper link and the vehicle horizontal, (2) the holding force at a connection between the upper link and the implement, (3) the lift height of the hitch, and (4) the hydraulic pressure of the lift cylinder.

5. The control system of claim 4, further comprising: wherein the control device is configured to determine the weight based on the tensile force at the lower link instead of the holding force at the connection between the upper link and the implement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 shows an agricultural utility vehicle with a three-point hitch in a side view,

(3) FIG. 2 shows a force diagram of the implement,

(4) FIG. 3 shows a force diagram of the lower link on the hitch,

(5) FIG. 4 shows a force diagram of the lift spindle on the hitch,

(6) FIG. 5 shows a force diagram of the lift arm on the hitch, and

(7) FIG. 6 shows a schematic representation of forces for determination of the weight according to one embodiment.

DETAILED DESCRIPTION

(8) FIG. 1 shows an agricultural utility vehicle 10, represented only schematically in part, in the form of a tractor with a cabin 12, a front axle 14, and a combustion engine 16 to drive at least one rear axle 18. A three-point hitch 20, which is shown in principle and not to scale, is mounted at the rear region of the utility vehicle 10. Additionally or alternatively, a three-point hitch can also be mounted at the front region of the utility vehicle 10. A plane kinematic diagram is defined by the three-point hitch 20 in a plane that is designated as an x-y plane in the further drawings. Here, the x direction corresponds to a lengthwise direction of the vehicle or the vehicle horizontal 22, while the y direction corresponds to a vehicle height direction or the vehicle vertical 24. The three-point hitch 20 serves to lift or carry an implement 26, which can be called a payload.

(9) The three-point hitch 26 includes an upper link 28, which is hinge mounted via a linkage 30 in the rear of a support structure 32 of the utility vehicle 10. Additionally, the three-point hitch 26 includes a lower link 34, which is likewise hinge mounted at the rear of the support structure 32 via a support bearing 36. The lower link 34 is connected to the one end of a lift arm 42 via a lift spindle 40 engaging in a lower link hinge 38, the lift arm being hinge connected to the support structure 32 of the utility vehicle 10 at its other end via a link 44. The lift arm 42 can be pivoted with respect to the supporting structure 32 via a hydraulic cylinder 48 supported by the supporting structure 32 and engaging in a lift arm link 46. The pivoting of the lift arm 42 by means of the hydraulic cylinder 48 is transferred to the lower link 34 via the lift spindle 40. The length of the lift spindle 40 is adjustable, so that the angles of the lift arm 42 and the lower link 34 can be adjusted with respect to each other. The upper link 28 and lower link 34 are connected to the implement 26 via an upper link articulation point 50 or a lower link articulation point 52 on the side turned away from the utility vehicle 10 in the lengthwise vehicle direction (x direction). The linkage 30 and the upper link articulation point 50 can be adjusted in the direction of vehicle height (y direction), so that the upper link 28 can take various vertical positions (not shown here) to establish a mast height.

(10) In FIG. 1, a plurality of sensors is shown schematically and not to scale on utility vehicle 10. The sensors serve to measure or register various physical parameters at individual components of the hitch 20 in order to determine a weight or mass of the implement 26 from them.

(11) First sensors 54 are designed as an acceleration sensor (alternatively, tilt or rotary speed sensor) affixed to the vehicle. The hydraulic pressure at lift cylinder 48 is measured by means of second sensors 56 on lift cylinder 48. In this case, before the measurement of the pressure in lift cylinder 48 to produce a defined status, a friction compensation can take place through defined, minimal travel of the cylinder piston. Third sensors 58 (e.g., inertia or tilt sensors) measure an angle between the upper link 28 and the vehicle horizontal 22. Fourth sensors 60 (for example, force sensing bolts, bending rod) measure a tensile force at lower link 34. Fifth sensors 62 (i.e., a sensor that is already present for measuring the angle between the lift arm 42 and the vehicle horizontal 22) measure the lift height of the hitch 20. Sixth sensors 64 measure a holding force F.sub.O of the upper link 28. For example, they can measure the pressure in the case of a hydraulic upper link 28. In each case, according to the present embodiment for determining the weight of the cargo load or the implement 26, individual ones of said sensors can be omitted so that various arrangements with a different combination of sensors for conducting the method for determining the weight or a mass derived therefrom can result. The measurement values provided by the sensors are sent to a control device for further processing. Said control device undertakes at the same time an averaging of the measurement data to compensate otherwise unaccounted rotary inertial forces that are induced by dynamic oscillations.

(12) FIG. 2 schematically shows the implement 26 attached to the three-point hitch 20, with the forces arising there. The x component F.sub.a,x and y component F.sub.a,y of the weight or inertial force, which is designated by F.sub.a, and which arise at the center of gravity of the implement 26, are represented, where the inertial force results from the addition of the weight and vertical accelerations that may arise due to vehicle movement. In addition, a holding force F.sub.O of the upper link 28 arises at the upper link articulation point 50 at an angle to the vehicle horizontal 22. A supporting force F.sub.UM, with its two force components F.sub.UM,x and F.sub.UM,y, arises at the lower link articulation point 52. A mast height is indicated by l.sub.M.

(13) By means of the equilibria of forces in the x and y direction in FIG. 2, the following equations can be derived for a determination of the weight F.sub.a or the mass m.sub.A of the implement 26:
0=F.sub.UM,xF.sub.a,xF.sub.O.Math.cos (1)
0=F.sub.UM,yF.sub.a,yF.sub.O.Math.sin (2)

(14) Here, the following equations are valid for the x and y components of the weight F.sub.a:
F.sub.a,x=m.sub.A.Math.a.sub.x(3)
F.sub.a,y=m.sub.A.Math.a.sub.y(3)

(15) Because of various slope gradients of the utility vehicle and additionally arising acceleration components during vehicle travel, variable acceleration components a.sub.x and a.sub.y which are the same for all considered objects, may result. They already contain the acceleration due to gravity and are registered by the sensors 54 affixed to the support structure 32.

(16) In a first embodiment, the upper link holding force F.sub.O and the angle of the upper link 28 are determined by means of the sensor means 64 and 58. A determination of the support force F.sub.UM or its x and y components at articulation point 52 is not necessary. Thus, the corresponding sensors 60 on support bearing 36 can be omitted. Instead, the two force components F.sub.UM,x and F.sub.UM,y are correlated with other physical relationships. The instantaneous equilibrium about the support bearing 36 on lower link 34 is suitable for this. The following equations, which contain the force components F.sub.UM,x and F.sub.UM,y as unknowns, result from FIG. 3:
0=M(F.sub.US)+M(F.sub.UI)+M(F.sub.UM)(5)
with
M(F.sub.US)=F.sub.US.Math.l.sub.1.Math.(cos .sub.S.Math.cos .sub.Usin .sub.S.Math.sin .sub.U)(6)
M(F.sub.UI)=r.sub.UI.Math.(F.sub.UI,x.Math.sin .sub.U+F.sub.UI,y.Math.cos .sub.U)(7)
M(F.sub.UM)=l.sub.U.Math.(F.sub.UM,x.Math.sin .sub.U+F.sub.UM,y.Math.cos .sub.U)(8)

(17) Equations (6) through (8) can be substituted into equation (5). Then, by means of the equations (1) to (4), the mass m.sub.A or the corresponding weight F.sub.a can be determined.

(18) In this case, the force components F.sub.UI,x and F.sub.UI,y, the angles .sub.S and .sub.U, and the force F.sub.US may still be determined. The force components F.sub.UI,x and F.sub.UI,y can be measured by means of an acceleration sensor disposed on the lower link 34 (FIG. 3). The angles .sub.S and .sub.U can be calculated from the geometry of the hitch and the lift height (extension) of the lift cylinder. The lift height can be measured in particular by capacitive means and is already normally available via a data bus (for example CAN bus) of the utility vehicle 10.

(19) For the force F.sub.US to be calculated, the following equations can be determined by means of FIG. 4:
F.sub.US,x=F.sub.SH,x+F.sub.SI,x(9)
F.sub.US,y=F.sub.SH,yF.sub.SI,y(10)
and
F.sub.SH,x=F.sub.SH.Math.sin .sub.S(11)
F.sub.SH,y=F.sub.SH.Math.cos .sub.S(12)

(20) The force components F.sub.SI,x and F.sub.SI,y are provided by an acceleration sensor on the hub spindle 40 (FIG. 4). The force F.sub.SH can be calculated by means of the forces arising on lift arm 42 in FIG. 5, as follows:
F.sub.SH=(M.sub.Z+M.sub.HI)/(l.sub.H.Math.cos .sub.H.Math.cos .sub.Hl.sub.H.Math.sin .sub.H.Math.sin .sub.H)(13)
with
M.sub.Z=F.sub.,x.Math.(sin .sub.H.Math.r.sub.HZ,x+r.sub.HZ,y.Math.cos .sub.H)F.sub.,y.Math.(cos .sub.H.Math.r.sub.HZ,xr.sub.HZ,y.Math.sin .sub.H)(14)
M.sub.HI=F.sub.HI,x.Math.(r.sub.SH,x.Math.sin .sub.Hr.sub.SH,y.Math.cos .sub.H)F.sub.HI,y.Math.(r.sub.SH,x.Math.cos .sub.H+r.sub.SH,y.Math.sin .sub.H)(15)
and
F.sub.Z,x=F.sub.Z.Math.sin (16)
F.sub.Z,y=F.sub.Z.Math.cos (17)

(21) The angle .sub.H forms the angle between the lift arm 42 and the vehicle horizontal 22. Said angle .sub.H can be calculated from the geometry of the hitch 20 and the lift height (extension) of the lift cylinder. The force components F.sub.HI,x and F.sub.HI,y are provided by an acceleration sensor on the lift arm 42 (FIG. 5).

(22) Lastly, the force F.sub.US is calculated in dependence on the force F.sub.z in lift cylinder 48 and the angle between the lift cylinder 48 and the vehicle vertical 24. The force F.sub.z in lift cylinder 48 is preferably determined by measuring the hydraulic pressure in lift cylinder 48 via the sensors 56 disposed on lift cylinder 48. The angle can be determined via the geometry of the hitch 20 and the angle .sub.H in a way that is not shown here in more detail.

(23) Thus, in the first embodiment, the angle of the upper link 28 is measured by means of the sensors 58, the holding force F.sub.O of the upper link 28 is measured by means of the sensors 64, and the pressure (F.sub.Z) in lift cylinder 48 is measured by means of the sensors 56 in order to determine the weight F.sub.a of the implement 26 or its mass m.sub.A as a function of these parameters.

(24) In a second embodiment for determining the weight or mass of the implement 26, the sensors 64 for measuring the upper link holding force F.sub.O are omitted. Instead, the measurement values of the sensors 60 (e.g., tensile force sensors) of the force F.sub.U at support bearing 36 of the lower link 34 are taken into account. The force F.sub.US is again, analogous to the first embodiment, determined via the measurement of the pressure (F.sub.Z) in lift cylinder 48. The force components F.sub.UM,x and F.sub.UM,y can then be explicitly calculated. This takes place with consideration of the force diagram of the lower link 34 according to FIG. 3, using the equations (5) to (8) and the following force equilibrium in the x direction:
F.sub.UM,x=F.sub.U,xF.sub.UI,xF.sub.US.Math.sin .sub.B(18)

(25) The x component F.sub.U,x of the tensile force F.sub.U is measured by means of sensors 60. Then, taking into account the measured angle of the upper link 28 and the equations (1), (2), the mass m.sub.A or the weight F.sub.a can be determined.

(26) In this embodiment therefore the angle of the upper link 28 is measured by means of the sensors 58, the tensile force F.sub.U, in particular its x component F.sub.U,x, on support bearing 36 of the lower link 34 is measured by means of the sensors 60, and the pressure (F.sub.Z) in the lift cylinder 48 is measured by means of the sensors 56, in order to determine the weight F.sub.a of the implement 26 or its mas m.sub.A in dependence on these parameters.

(27) In a third embodiment for determining the weight or mass of the implement 26, the sensors 58 for measurement of the upper link angle are omitted. First, the force components F.sub.UM,x and F.sub.UM,y are calculated analogously to the second embodiment and, in addition, the upper link holding force F.sub.O is determined via the sensors 64. After employing the corresponding equations, two possible solutions arise for the weight F.sub.a in this embodiment.

(28) The two possible solutions are graphically represented in FIG. 6. The resultant from the force components F.sub.UM,x and F.sub.UM,y is designated as F.sub.UM and represented as a vector. The direction of the weight F.sub.a is known via the acceleration components a.sub.x and a.sub.y and is established by the angle .sub.a. The contribution of the upper link holding force F.sub.O is known. However, its direction is unknown because of the missing measurement of the angle . The possible directions are described as a circle with the radius |F.sub.O| and the center of the force vector F.sub.UM. This circle intersects the direction of the weight F.sub.a at two points, so that two possible solutions (F.sub.a, 1 and F.sub.a, 2) arise for the weight F.sub.a.

(29) The calculation of the two possible weights arises through transposition of the law of cosines:
|F.sub.a,1|=|F.sub.UM.Math.cos +{square root over ((F.sub.UM.Math.cos ).sup.2(F.sup.2.sub.UMF.sup.2.sub.O))}|(19)
|F.sub.a,2|=|F.sub.UM.Math.cos {square root over ((F.sub.UM.Math.cos ).sup.2(F.sup.2.sub.UMF.sup.2.sub.O))}|(20)

(30) The decision of which weight or mass of the implement 26 is the correct one can be made via a plausibility assessment. For example, a second measurement can be conducted with the sensors that are used at a different lift height of the hitch 20 or a limiting of the possible angle of the upper link 28 can be done.

(31) When the measurement is made at a different lift height of the hitch 20, two new possible values result for the weight, of which one corresponds within measurement precision with one of the values from the first measurement. In this way, the weight or mass can be unambiguously determined.

(32) In the case of the limiting of the upper link angle , each of the two possible solutions in FIG. 6 can be assigned an upper link angle 1 and 2. Of these two angles, one is normally not compatible with the kinematics and geometry of the hitch 20. For a limiting of the upper link angle that is as accurate as possible, one takes into account in particular the mast height l.sub.M, the current length of the upper link 28, and the mounting position of the upper link 28 on the support structure 32.

(33) While embodiments incorporating the principles of the present disclosure have been described hereinabove, the present disclosure is not limited to the described embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.