Method for reducing test error of pitching moment of inertia of counterbalanced forklift around its center of mass

Abstract

The present invention discloses a method for reducing the test error of the pitch moment of inertia of a counterbalanced forklift around its centroid, including: 1) obtaining the centroid position of the forklift through testing, and establishing a coordinate system XOY with the obtained centroid position as the origin; 2) determining 4 rotation hinge points in the 4 quadrants of XOY and 2 spring suspension points on the positive and negative half-axes of the X-axis; 3) fixing the spring at the spring suspension point on the positive half-axis of the X-axis, and freely vibrating around the rotation hinge points in the 2nd and 3rd quadrants respectively to test and obtain two groups of the pitch moment of inertia of the forklift around its centroid; 4) fixing the spring at the spring suspension point on the negative half-axis of the X-axis, and freely vibrating around the rotation hinge points in the 1st and 4th quadrants respectively to test and obtain two groups of the pitch moment of inertia of the forklift around its centroid; 5) taking the average value of the moment of inertia obtained by testing around different rotation hinge points. The present invention can solve the problem of large errors in the pitch moment of inertia of the forklift around its centroid and improve the accuracy of the dynamic simulation of the forklift.

Description

Technical Field

[0001] The present invention relates to the field of engineering vehicles, and specifically to a method for reducing the test error of the pitch moment of inertia of a counterbalanced forklift around its center of mass. Background Art

[0002] During the R & D and design stage of a forklift, it is necessary to carry out the calculation analysis and evaluation of dynamic performance. For example, in the longitudinal stability analysis of a forklift, the pitch moment of inertia parameter of the forklift around its center of mass is crucial for the evaluation result of the longitudinal stability analysis of the forklift. Due to the high cost of a dedicated moment of inertia test bench, in engineering practice, the moment of inertia is usually tested by means of elastic suspension. The elastic suspension test fixes one end of the forklift on the rotating shaft and the other end on the spring suspension device, collects the free vibration period of the forklift in the elastic suspension state, and calculates the distance from the center of mass to the rotating shaft, the free vibration period, and other parameters of the forklift according to the center of mass position to calculate the pitch moment of inertia of the forklift around its center of mass. However, there are deviations between the longitudinally measured center of mass position and the center of mass height obtained by testing the counterbalanced forklift and the actual center of mass position. As Figure 1 shown, when there is a deviation in the longitudinal direction of the center of mass, if the test is only carried out by hinging at point O1, the moment of inertia J around point O1 obtained by the test a1 . At this time, the moment of inertia in the pitch direction of the center of mass is calculated by the parallel axis theorem: At this time, the distance l1 from the measured center of mass to the rotation center used in the calculation is greater than the actual distance l1' from the center of mass to the rotation center, resulting in the moment of inertia obtained by the test being less than the actual moment of inertia. If point O2 is used as the rotation center, since the distance l2 from the measured center of mass to the rotation center is less than the actual distance l'2 from the center of mass to the rotation center, the moment of inertia J2 obtained by the test is greater than the actual moment of inertia. Therefore, taking the average value of J1 and J2 can reduce the error of the pitch moment of inertia around the center of mass. Figure 2 When there is a deviation in the center of mass height, the same situation as in Figure 1 will also occur. The calculation error of the moment of inertia caused by the deviation of the center of mass position will have a non-negligible impact on the evaluation conclusion of the longitudinal stability of the forklift. Therefore, the present invention proposes a method for reducing the test error of the pitch moment of inertia of a counterbalanced forklift around its center of mass, which can reduce the moment of inertia error caused by the deviation of the center of mass position. Summary of the Invention

[0003] The present invention is to solve the above-mentioned deficiencies existing in the prior art, and proposes a method for reducing the test error of the pitch moment of inertia of a counterbalanced forklift around its center of mass, in order to reduce the moment of inertia error caused by the deviation of the center of mass position, thereby improving the accuracy of forklift dynamics simulation.

[0004] The present invention adopts the following technical solutions to solve the technical problems:

[0005] The method for reducing the test error of the pitching moment of inertia of a counterbalanced forklift around its center of mass according to the present invention is characterized in that it is carried out according to the following steps:

[0006] Step 1: Obtain the position of the center of mass of the forklift through testing, and establish a coordinate system XOY with the obtained center of mass position as the origin O, the direction parallel to the chassis as the X-axis direction, and the direction perpendicular to the chassis as the Y-axis direction;

[0007] Step 2: Use equations (1)-(4) to respectively determine the coordinates (X1, Y1) of the first rotary hinge point O1, the coordinates (X2, Y2) of the second rotary hinge point O2, the coordinates (X3, Y3) of the second rotary hinge point O3, and the coordinates (X4, Y4) of the second rotary hinge point O4 in the four quadrants of XOY:

[0008]

[0009]

[0010]

[0011]

[0012] In equations (1)-(4), δ is the deviation coefficient, L f is the horizontal distance from the center of mass of the forklift to the front end of the mast, L r is the horizontal distance from the center of mass of the forklift to the rearmost end of the forklift body, H S is the vertical distance from the center of mass of the forklift to the axis of the front wheel, and r is the rolling radius of the front wheel;

[0013] Step 3: Use equations (5) and (6) to determine the coordinates (X5, Y5) of the first spring suspension point S1 and the coordinates (X6, Y6) of the second spring suspension point S2:

[0014]

[0015]

[0016] Step 4: Using S1 as the spring suspension point, freely vibrate around O2 and O3 respectively, and correspondingly obtain the free vibration period T2 around the second rotary hinge point and the free vibration period T3 around the third rotary hinge point. Calculate the second pitching moment of inertia J2 around the center of mass using equation (7) and calculate the third pitching moment of inertia J3 around the center of mass using equation (8):

[0017]

[0018]

[0019] In equations (7) and (8), k is the spring stiffness, and m is the curb mass of the forklift;

[0020] Step 5: Take S2 as the spring suspension point and vibrate freely around O1 and O4 respectively. The period T1 of free vibration around the first rotating hinge point and the period T4 of free vibration around the fourth rotating hinge point are obtained accordingly. The first moment of inertia J1 around the center of mass in the pitch direction is calculated using formula (9), and the fourth moment of inertia J4 around the center of mass in the pitch direction is calculated using formula (10):

[0021]

[0022]

[0023] Step 6: Calculate the average value of J1, J2, J3, and J4 to obtain the pitch moment of inertia around the center of mass after the error is reduced.

[0024] An electronic device of the present invention includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the method, and the processor is configured to execute the program stored in the memory.

[0025] The present invention provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and the computer program executes the steps of the method when executed by a processor.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention proposes a method for reducing the test error of the pitch moment of inertia around the center of mass of a counterbalanced forklift. Different pitch moments of inertia around the center of mass are obtained by rotating four hinge points in four quadrants of the center of mass coordinate system. These four moments of inertia will produce two larger moments of inertia and two smaller moments of inertia due to the deviation of the center of mass position. The larger and smaller errors are offset by taking the average value.

[0028] 2. In the test of the moment of inertia in the pitch direction around the center of mass based on the elastic suspension method involved in the present invention, the error caused by the deviation of the center of mass position on the moment of inertia can be reduced, the progress of the calculation analysis and evaluation of the forklift's dynamic performance is improved, and the situation where the stability calculation results in the forklift design stage are too different from the stability test results of the prototype vehicle is avoided, thereby improving the research and development efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the reduction of the moment of inertia test error caused by the longitudinal deviation of the center of mass;

[0030] Figure 2Schematic diagram for reducing the measurement error of the moment of inertia caused by the deviation of the centroid height;

[0031] Figure 3 It is a schematic diagram of the free vibration of the rotating platform around point O1;

[0032] Figure 4 It is a schematic diagram of the free vibration of the rotating platform around point O2;

[0033] Figure 5 It is a schematic diagram of the free vibration of the rotating platform around point O3;

[0034] Figure 6 It is a schematic diagram of the free vibration of the rotating platform around point O4. Specific implementation method

[0035] The following is a detailed description of the embodiments of the present invention. The embodiments are implemented on the premise of the technical solution of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0036] In this embodiment, a method for reducing the measurement error of the pitch moment of inertia of a counterbalanced forklift around its centroid includes the following steps:

[0037] Step 1: Obtain the longitudinal position of the centroid by weighing the front and rear axles of the forklift, and record the change in the weight of the front axle when the rear axle is raised to obtain the vertical position of the centroid;

[0038] Step 2: Establish a coordinate system XOY with the centroid position obtained by measurement as the origin, the direction parallel to the chassis as the X-axis direction, and the direction perpendicular to the chassis as the Y-axis direction;

[0039] Step 3: Use equations (1)-(4) to respectively determine the coordinates (X1, Y1) of the first rotation hinge point O1, the coordinates (X2, Y2) of the second rotation hinge point O2, the coordinates (X3, Y3) of the second rotation hinge point O3, and the coordinates (X4, Y4) of the second rotation hinge point O4 in the four quadrants of XOY:

[0040]

[0041]

[0042]

[0043]

[0044] In equations (1)-(4), δ is the deviation coefficient, generally taking 0.05 - 0.1, L f is the horizontal distance from the centroid of the forklift to the front end of the mast, L r is the horizontal distance from the centroid of the forklift to the rear end of the forklift body, H Sis the perpendicular distance from the centroid of the forklift to the axis of the front wheel, and r is the rolling radius of the front wheel.

[0045] Step 4: Determine the coordinates (X5, Y5) of the first spring suspension point S1 and the coordinates (X6, Y6) of the second spring suspension point S2 by using equations (5) and (6):

[0046]

[0047]

[0048] Step 5: As shown in Figure 4 Connect the spring tooling to point S1 of the rotating platform. Hinge O2 of the rotating platform with the support device, and fix the angular velocity sensor on the rotating platform;

[0049] Step 6: Use another forklift to lift the rotating platform to the horizontal position, use a crane to lift the spring tooling, and adjust the spring to its original length and vertical state;

[0050] Step 7: Quickly release the rotating platform to let it vibrate freely, collect the period T2 of free vibration around the second rotating hinge point, and calculate the second pitching moment of inertia J2 about the centroid according to equation (7);

[0051]

[0052] Step 8: As shown in Figure 5 Connect the spring tooling to point S1 of the rotating platform. Hinge O3 of the rotating platform with the support device, and fix the angular velocity sensor on the rotating platform;

[0053] Step 9: Use another forklift to lift the rotating platform to the horizontal position, use a crane to lift the spring tooling, and adjust the spring to its original length and vertical state;

[0054] Step 10: Quickly release the rotating platform to let it vibrate freely, collect the period T3 of free vibration around the third rotating hinge point, and calculate the third pitching moment of inertia J3 about the centroid according to equation (8);

[0055]

[0056] Step 11: As shown in Figure 3 Connect the spring tooling to point S2 of the rotating platform. Hinge O1 of the rotating platform with the support device, and fix the angular velocity sensor on the rotating platform;

[0057] Step 12: Use another forklift to lift the rotating platform to the horizontal position, use a crane to lift the spring tooling, and adjust the spring to its original length and vertical state;

[0058] Step 13: Quickly release the rotating platform to make it vibrate freely, collect the period T1 of the free vibration around the first rotating hinge point, and calculate the first pitching moment of inertia J1 around the center of mass according to Equation (9).

[0059]

[0060] Step 14: As Figure 6 shown, connect the spring tooling to point S2 of the rotating platform, hinge O4 of the rotating platform to the support device, and fix the angular velocity sensor on the rotating platform.

[0061] Step 15: Use another forklift to lift the rotating platform to the horizontal position, use a hoist to lift the spring tooling, and adjust the spring to its original length and vertical state.

[0062] Step 16: Quickly release the rotating platform to make it vibrate freely, collect the period T4 of the free vibration around the fourth rotating hinge point, and calculate the fourth pitching moment of inertia J4 around the center of mass according to Equation (10).

[0063]

[0064] Step 17: Take the average of the moments of inertia J1, J2, J3, and J4 to obtain the pitching moment of inertia around the center of mass with reduced error.

[0065] In this embodiment, an electronic device includes a memory and a processor. The memory is used to store a program that supports the processor to execute the above method, and the processor is configured to execute the program stored in the memory.

[0066] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is run by a processor, it executes the steps of the above method.

Claims

1. A method for reducing the test error of the pitching moment of inertia of a counterbalanced forklift around its center of mass, characterized in that it is Proceed as follows: Step 1: Obtain the centroid position of the forklift through testing. Establish a coordinate system XOY with the centroid position obtained from the test as the origin O, the direction parallel to the chassis as the X-axis direction, and the direction perpendicular to the chassis as the Y-axis direction. Step 2: Use Equations (1)-(4) to determine the coordinates (X1, Y1) of the first rotary hinge point O1, the coordinates (X2, Y2) of the second rotary hinge point O2, the coordinates (X3, Y3) of the second rotary hinge point O3, and the coordinates (X4, Y4) of the second rotary hinge point O4 in the four quadrants of XOY respectively: In formulas (1)-(4), δ is the deviation coefficient, and L f is the horizontal distance from the center of mass of the forklift to the front end of the mast, and L r is the horizontal distance from the center of mass of the forklift to the rear end of the forklift body, H S is the vertical distance from the center of mass of the forklift to the axis of the front wheels, and r is the rolling radius of the front wheels; Step 3: Use Equations (5) and (6) to determine the coordinates (X5, Y5) of the first spring suspension point S1 and the coordinates (X6, Y6) of the second spring suspension point S2: Step 4: With S1 as the spring suspension point, freely vibrate around O2 and O3 respectively, and correspondingly obtain the vibration period T2 of free vibration around the second rotary hinge point and the vibration period T3 of free vibration around the third rotary hinge point. Use Equation (7) to calculate the second pitching moment of inertia J2 around the centroid and use Equation (8) to calculate the third pitching moment of inertia J3 around the centroid: In Equations (7) and (8), k is the spring stiffness and m is the curb mass of the forklift. Step 5: With S2 as the spring suspension point, freely vibrate around O1 and O4 respectively, and correspondingly obtain the vibration period T1 of free vibration around the first rotary hinge point and the vibration period T4 of free vibration around the fourth rotary hinge point. Use Equation (9) to calculate the first pitching moment of inertia J1 around the centroid and use Equation (10) to calculate the fourth pitching moment of inertia J4 around the centroid: Step 6: Take the average of J1, J2, J3, and J4 to obtain the pitching moment of inertia around the centroid with reduced error.

2. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program for supporting the processor to execute the method described in Claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium, on which a computer program is stored, characterized in that, When the computer program is run by the processor, it executes the steps of the method described in Claim 1.

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