CN109341951B - A static measurement method and device for the position of the center of mass of a vehicle - Google Patents

Abstract

A static measurement method and device for the position of the center of mass of a vehicle belong to the technical field of measurement of the center of mass of the vehicle. In order to solve the problem that the prior art cannot accurately measure the action point of the vehicle force Connected to the base, the upper part of the symmetrical parallelogram mechanism and the measuring platform are connected with the measuring platform hinge; the four wheel force measuring plates are arranged in the four empty slots of the measuring platform; Four force sensors are evenly distributed among them; the inclination sensor is installed on the bottom surface of the measuring platform; the upper end of the electric cylinder is connected to the measuring platform, and the base supports the lower end of the electric cylinder; the measuring platform and the base are connected by the base hinge; The position of the wheel force point on the wheel measuring plate is calculated, and the space coordinate of the wheel force point is obtained, which avoids the measurement error caused by the imprecise wheel force position and improves the measurement accuracy.

Description

A static measurement method and device for the position of the center of mass of a vehicle

technical field

The invention belongs to the technical field of vehicle mass center measurement, and provides a device designed for vehicle mass center position measurement and a static measurement method for vehicle mass center position.

Background technique

The position of the center of mass of the vehicle is divided into a horizontal position and a vertical position, and the vertical position is called the height of the center of mass. The measurement methods of the centroid are divided into static measurement methods and dynamic measurement methods. The static measurement method is based on the principle of static moment balance, and the dynamic measurement method is based on the dynamic theory. Dynamic measurement methods include compound pendulum method, moment of inertia method, dynamic balance method, etc. Static measurement methods, such as suspension method, zero position method, platform support reaction force method and mass response method, wherein the mass response method includes the hoisting method, the lifting method and the tiltable platform method. For heavy-duty multi-axle vehicles, the beam deformation of the suspension method is large, and the measurement accuracy of the hoisting method and the lifting method is low. For the measurement of general vehicles, static measurement methods are also commonly used.

The Chinese patent publication number is "CN102297746A", and the patent name is "Centre of Mass Measuring Device and Measuring Method for Multi-axle Vehicles". When measuring the position of the center of mass of the vehicle in the horizontal direction, the measuring platform is adjusted to be in the horizontal position by the hydraulic cylinder or the electric cylinder. reliability is not high. In addition, the action point of the support reaction force of the wheel load weighing plate on the measuring platform to the wheel is approximately processed at the center of the wheel, and the actual action point of the support reaction force cannot be accurately obtained, resulting in measurement errors. The large and heavy measurement platforms used in this method also bring measurement errors when measuring light vehicles.

SUMMARY OF THE INVENTION

In order to solve the problem of measurement error caused by the inability to accurately measure the action point of the vehicle force in the prior art, the present invention proposes a static measurement method and device for the position of the center of mass of the vehicle, which improves the measurement accuracy of the center of mass of the vehicle and has a wide range of applications.

The technical scheme adopted by the present invention to solve the above-mentioned technical problems is:

A static measuring device for the position of the center of mass of a vehicle, characterized in that the device includes: an electric cylinder, a base, four symmetrical parallelogram mechanisms, a wheel force measuring plate, a measuring platform, an inclination sensor, a force sensor, a measuring platform hinge and a base hinge; symmetrical The lower part of the parallelogram mechanism is connected to the base, and the upper part of the symmetrical parallelogram mechanism and the measuring platform are connected by a measuring platform hinge; the four wheel force measuring plates are placed in the four hollow slots of the measuring platform; the wheel force measuring plates are placed in the symmetrical parallelogram mechanism The upper part of the electric cylinder is evenly distributed between the four force sensors; the inclination sensor is installed on the bottom surface of the measuring platform; the upper end of the electric cylinder is connected with the measuring platform, and the base supports the lower end of the electric cylinder; the measuring platform and the base are connected by the base hinge.

The position of the center of mass of the vehicle is divided into a horizontal position and a vertical position, and the vertical position is called the height of the center of mass. The static measurement method of the position of the center of mass of the vehicle is as follows: the vehicle travels to the wheel force plate placed in the hollow slot of the measuring platform, and the wheel and the wheel force plate are in contact. The electric cylinder is used to adjust the measuring platform to be in a horizontal position. According to the force on the wheel measured by the force sensor, the horizontal position of the center of mass of the vehicle can be calculated. After the electric cylinder is extended to rotate the measuring platform to a certain angle, the inclination angle θ of the vehicle and the calculated horizontal position of the center of mass of the vehicle are measured according to the inclination sensor, and the height of the center of mass can be calculated.

A static measurement method for the position of the center of mass of a vehicle, characterized in that the method comprises the following steps:

根据空间力系平衡原理计算出第i个车轮受力点坐标(x_i，y_i)为：Step 1. Calculate the position of the wheel force point: the wheel is on the wheel force plate, the force point of the wheel is the concentrated load action point of the wheel force plate on the wheel, and a local coordinate system is established at the center of the i-th wheel force plate xoy, F _ij represent the measured value of the j-th force sensor on the i-th wheel force plate, (x _ij , y _ij ) are the j-th force sensor coordinates on the i-th wheel force plate, G _i represents the i-th force sensor The magnitude of the force on each wheel,

According to the balance principle of the space force system, the coordinates (x _i , y _i ) of the i-th wheel force point are calculated as:

Step 2: Make the measuring platform in a horizontal state by adjusting the electric cylinder, and calculate the horizontal position of the center of mass of the vehicle; establish the horizontal coordinate system OX'Y'Z' of the measuring platform in the center of the measuring platform, and calculate the horizontal position of the center of mass of the vehicle according to the balance principle of the space force system ( X', Y') is:

为第i个车轮测力板中心在测量平台水平坐标系OX′Y′Z′坐标值，(X′_i，Y′_i)为第i个车轮受力点在测量平台水平坐标系OX′Y′Z′坐标值；where:

is the coordinate value of the i-th wheel force plate center in the horizontal coordinate system OX'Y'Z' of the measurement platform, (X' _i , Y' _i ) is the force point of the i-th wheel in the horizontal coordinate system OX'Y of the measurement platform 'Z' coordinate value;

Step 3: Elongate the electric cylinder to incline the measuring platform by a certain angle θ, and calculate the height of the center of mass of the vehicle; according to the balance principle of the space force system, calculate the height of the center of mass Z' of the vehicle as:

l₂为测量平台铰链到测量平台表面的垂直距离，G为车辆的重力，(X″_i，Y″_i，Z″_i)为车轮受力点在测量平台倾斜坐标系OX″Y″Z″下的坐标值，(X_i，Y_i，Z_i)＝(0，0，l₂)+(x_i，y_i，0)＝(x_i，y_i，l₂)。where:

l ₂ is the vertical distance from the hinge of the measuring platform to the surface of the measuring platform, G is the gravity of the vehicle, (X″ _i , Y″ _i , Z″ _i ) is the wheel force point in the measuring platform inclined coordinate system OX″Y″Z″ The coordinate values below, (X _i , Y _i , Z _i )=(0, 0, l ₂ )+( _xi , y _i , 0)=( _xi , y _i , l ₂ ).

Beneficial effects of the present invention:

(1) The present invention can calculate the position of the wheel force point on the wheel measuring plate according to the measurement value of the force sensor, obtain the spatial coordinates of the wheel force point, avoid the measurement error caused by the imprecise wheel force position, and improve the measurement accuracy .

(2) The present invention adopts a symmetrical parallelogram mechanism to ensure that the measuring platform is always in a horizontal state during the tilting motion. When it is in a static state, it is ensured that the wheels are only subjected to the vertical force of the measuring platform, so as to avoid frictional force affecting the measuring accuracy. At the same time, there is no need to research and design additional wheel load weighing plates and related force sensors, and the present invention only needs to measure the normal force. Therefore, the cost is saved and the structure is simple. According to the existing mature force sensor, the performance is more reliable than that of the additional design, and it is easier to ensure the measurement accuracy.

(3) The present invention can increase the number of symmetrical parallelogram mechanisms, arrange symmetrical parallelograms according to the wheelbase and wheelbase of the wheels, and measure the coordinates of the center of mass of the multi-axle vehicle. Adding brackets to the wheel force plate can measure the coordinates of the center of mass of the armored vehicle.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the static measuring device for the position of the center of mass of the vehicle according to the present invention.

FIG. 2 is a schematic diagram of the symmetrical parallelogram structure according to the present invention.

Figure 3 is the analysis diagram of the wheel force on the wheel force plate. The origin o of the wheel force coordinate system oxyz is the center of the wheel force plate.

Figure 4(a) is a three-dimensional schematic diagram of the horizontal coordinate system OX'Y'Z' of the measuring platform, and Figure 4(b) is the wheel on the X'OZ' plane of the horizontal coordinate system OX'Y'Z' of the measuring platform. Force analysis diagram, Figure 4(c) is the wheel force analysis diagram on the X'OY' plane of the horizontal coordinate system of the measurement platform.

Figure 5 is an analysis diagram of the wheel force on the X"OZ" plane under the inclined coordinate system OX"Y"Z" of the measuring platform obtained by rotating the horizontal coordinate system OX'Y'Z' of the measuring platform by an angle θ.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1-2, a static measuring device for the position of the center of mass of a vehicle includes: an electric cylinder 1, a base 2, a symmetrical parallelogram mechanism 3, a wheel force measuring plate 4, a measuring platform 5, an inclination sensor 7, a force sensor 8, Measure the platform hinge 9 and the base hinge 10. The lower part of the symmetrical parallelogram mechanism 3 is connected to the base 2, and the upper part of the symmetrical parallelogram mechanism 3 and the measuring platform 5 are connected with the measuring platform hinge 9; the four wheel force measuring plates 4 are arranged in the four empty slots of the measuring platform 5; The force plate 4 is placed on the upper part of the symmetrical parallelogram mechanism 3, and four force sensors 8 are evenly distributed between the two. The inclination sensor 7 is installed on the bottom surface of the measuring platform 5 for measuring the inclination of the platform. The upper end of the electric cylinder 1 is connected with the measuring platform 5 , the base 2 supports the lower end of the electric cylinder 1 ; the measuring platform 5 and the base 2 are connected by the base hinge 10 .

As shown in FIG. 2 , the symmetrical parallelogram mechanism 3 includes a lower support plate 3-1, an upper support plate 3-2, and two common-edge parallelogram mechanisms connecting the two.

Four symmetrical parallelogram mechanisms 3 are arranged between the base 2 and the measuring platform 5 according to the wheelbase and wheelbase of the vehicle. The lower support plate 3-1 of the symmetrical parallelogram mechanism 3 is connected to the base 2 with bolts, and the upper support plate 3-2 and the measuring platform 5 are connected with the measuring platform hinge 9 . The wheel force measuring plate 4 is placed on the upper support plate 3-2 in the hollow slot of the measuring platform 5. The force sensor 8 is installed between the upper support plate 3-2 and the wheel force measuring plate 4, distributed on the four corners of the upper support plate 3-2, and is used to measure the wheel force.

The measuring platform 5 is driven by the extension of the electric cylinder 1 to rotate around the base hinge 10 on a fixed axis. The rotational movement of the measuring platform 5 drives the upper support plate 3-2 of the symmetrical parallelogram mechanism 3 to do translational movement through the measuring platform hinge 9, wherein the upper support plate 3-2 under the front wheel of the vehicle translates upward, and the upper support plate under the rear wheel of the vehicle moves upward. Plate 3-2 translates down. Finally, the translational movement of the symmetrical parallelogram mechanism 3 tilts the vehicle.

The electric cylinder 1 can be replaced by a hydraulic cylinder.

Increasing the number of symmetrical parallelogram mechanisms 3 can measure the position of the center of mass of a multi-axle vehicle.

A bracket is installed on the wheel force plate 4, which can measure the position of the center of mass of the armored vehicle.

A static measurement method for the position of the center of mass of a vehicle includes the following steps:

利用空间力系平衡原理求出车轮受力点的位置坐标(x_i，y_i)为：(1) The horizontal coordinate system OX'Y'Z' of the measuring platform and its X'OY' plane established according to Figure 4(b) and (c), Figure 4(a) is the horizontal coordinate system OX'Y'Z of the measuring platform ′, the origin of the horizontal coordinate system of the measuring platform is established on the center of the measuring platform 5 . As shown in FIG. 3 , a local coordinate system oxyz is established on each wheel force plate 4 , and the origin o of the local coordinate system is established at the center of the wheel force plate 4 . In the local coordinate system oxyz, the wheel is forced

Using the balance principle of the space force system, the position coordinates (x _i , y _i ) of the wheel force point are obtained as:

On the horizontal coordinate system OX'Y'Z' of the measuring platform, according to the obtained wheel force point position coordinates (x _i , y _i ), the horizontal position coordinates of the vehicle mass center (X', Y) are obtained by using the balance principle of the space force system ')for:

为第i个车轮测力板的中心在测量平台水平坐标系OX′Y′Z′的坐标值，

l₁为车轮测力板中心在X′轴方向上的距离，l₂为测量平台铰链到测量平台表面的垂直距离，l₃为车轮测力板中心在Y′轴方向上的距离。where:

is the coordinate value of the center of the i-th wheel force plate in the horizontal coordinate system OX'Y'Z' of the measuring platform,

l ₁ is the distance from the center of the wheel force plate in the direction of the X' axis, l ₂ is the vertical distance from the hinge of the measuring platform to the surface of the measuring platform, and l ₃ is the distance from the center of the wheel force plate in the direction of the Y' axis.

(2) After the electric cylinder 1 rotates the measuring platform 5 by a certain angle θ, the height of the center of mass of the vehicle is measured at this time. The established measurement platform tilt coordinate system OX"Y"Z", as shown in Figure 5, the balance equation of the force system is:

Find: the height coordinate of the center of mass is

G为车辆的重力，(X″_i，Y″_i，Z″_i)为车轮受力点在测量平台倾斜坐标系OX″Y″Z″下的坐标值，(X_i，Y_i，Z_i)＝(0，0，l₂)+(x_i，y_i，0)＝（x_i，y_i，l₂)。where:

G is the gravity of the vehicle, (X″ _i , Y″ _i , Z″ _i ) is the coordinate value of the wheel force point under the inclined coordinate system OX″Y″Z″ of the measuring platform, (X _i , Y _i , Z _{i )} )=(0, 0, l ₂ )+( _xi , _yi , 0)=( _xi , _yi , l ₂ ).

Claims (5)

1. The static measuring device for the position of the center of mass of the vehicle, characterized in that the device comprises: an electric cylinder (1), a base (2), four symmetrical parallelogram mechanisms (3), a wheel force measuring plate (4), a measuring platform ( 5), inclination sensor (7), force sensor (8), measuring platform hinge (9) and base hinge (10); The lower part of the symmetrical parallelogram mechanism (3) is connected to the base (2), and the upper part of the symmetrical parallelogram mechanism (3) and the measuring platform (5) are connected with the measuring platform hinge (9); the four wheel force measuring plates (4) are arranged on the in the four empty slots of the measuring platform (5); the wheel force measuring plate (4) is placed on the upper part of the symmetrical parallelogram mechanism (3), and four force sensors (8) are evenly distributed between the two; The inclination sensor (7) is installed on the bottom surface of the measuring platform (5); the upper end of the electric cylinder (1) is connected with the measuring platform (5), and the base (2) supports the lower end of the electric cylinder (1); the measuring platform (5) and the base ( 2) Connected by the base hinge (10). 2. The static measuring device for the position of the center of mass of the vehicle according to claim 1, wherein, The symmetrical parallelogram mechanism (3) comprises a lower support plate (3-1), an upper support plate (3-2) and two parallelogram mechanisms connecting the two with a common edge; The lower support plate (3-1) of the symmetrical parallelogram mechanism (3) is connected to the base (2) with bolts, and the upper support plate (3-2) and the measuring platform (5) are connected by a measuring platform hinge (9); Four force sensors (8) are installed between the upper support plate (3-2) of the symmetrical parallelogram mechanism (3) and the wheel force measuring plate (4), and are distributed on the upper support plate (3-2) of the symmetrical parallelogram mechanism (3). 3-2) to measure the wheel force. 3 . The static measuring device for the position of the center of mass of a vehicle according to claim 1 , wherein the electric cylinder ( 1 ) is replaced by a hydraulic cylinder. 4 . 4 . The static measuring device for the position of the center of mass of a vehicle according to claim 1 , wherein the number of symmetrical parallelogram mechanisms ( 3 ) is increased to measure the position of the center of mass of the multi-axle vehicle. 5 . 5. A static measurement method for the position of the center of mass of a vehicle, characterized in that the method comprises the following steps: Step 1. Calculate the position of the wheel force point: the wheel (6) is on the wheel force plate (4), and the force point of the wheel (6) is the concentrated load action point of the wheel force plate (4) on the wheel (6). , a local coordinate system xoy is established at the center of the i-th wheel force plate, F _ij represents the measured value of the j-th force sensor on the i-th wheel force plate, and (x _ij , y _ij ) is the i-th wheel measurement value The coordinate of the jth force sensor on the force plate, G _i represents the force on the ith wheel,

According to the balance principle of the space force system, the coordinates (x _i , y _i ) of the i-th wheel force point are calculated as:

Step 2: The measuring platform (5) is in a horizontal state by adjusting the electric cylinder (1), and the horizontal position of the center of mass of the vehicle is calculated; the horizontal coordinate system OX'Y'Z' of the measuring platform is established in the center of the measuring platform (5), according to the space force system According to the balance principle, the horizontal position (X', Y') of the vehicle's center of mass is calculated as:

where:

is the coordinate value of the i-th wheel force plate center in the horizontal coordinate system OX'Y'Z' of the measurement platform, (X' _i , Y' _i ) is the force point of the i-th wheel in the horizontal coordinate system OX'Y of the measurement platform 'Z' coordinate value; Step 3: Elongate the electric cylinder (1) to incline the measuring platform (5) by a certain angle θ, and calculate the height of the center of mass of the vehicle; according to the balance principle of the space force system, calculate the height of the center of mass Z' of the vehicle as:

where:

_l2 is the vertical distance from the hinge (9) of the measuring platform to the surface of the measuring platform (5), G is the gravity of the vehicle, (X″ _i , Y″ _i , Z″ _i ) is the wheel force point in the inclined coordinate system of the measuring platform The coordinate value under OX"Y"Z", (X _i ,Y _i ,Z _i ) is the coordinate value of the wheel force point in the local coordinate system with the measuring platform hinge (9) as the origin, (X _i ,Y _i , Z _i )=(0,0,l ₂ )+( _xi ,y _i ,0)=( _xi ,y _i ,l ₂ ).

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