WO2019007259A1 - Device and method for measuring six-degree-of-freedom displacement of vehicle wheel during suspension characteristic test - Google Patents

Abstract

Disclosed in the present invention are a device and method for measuring the six-degree-of-freedom displacement of a vehicle wheel during a suspension characteristic test. The device mainly comprises a first binocular vision measuring instrument (41), a second binocular vision measuring instrument (42), optical targets, a data exchange unit (5), an upper computer (6), a vehicle wheel positioning fixture (3), and a reference fixture (2). A measured vehicle (8) is fixed on a test bench (7); the vehicle wheel positioning fixture and the reference fixture are mounted on a vehicle wheel and a vehicle frame respectively; the optical targets are distributed on the measuring planes of the fixtures and a vehicle body; the upper computer is connected to the binocular vision measuring instruments by means of the data exchange device, controls the binocular vision measuring instruments to measure the spatial coordinate changes of the optical targets, and calculates the six-degree-of-freedom displacement of the vehicle wheel in a vehicle coordinate system. According to the present invention, the six-degree-of-freedom displacement of the vehicle wheel in the vehicle coordinate system is calculated according to the spatial coordinate changes of the optical targets, and accurate non-contact measurement can be implemented. The present invention implements convenient and flexible measurement, achieves a wide test range and high precision, and has a good application prospect.

Description

Suspension characteristic test wheel six-degree-of-freedom displacement measuring device and method Technical field

The invention belongs to the technical field of automobile suspension performance testing, and particularly relates to a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel.

Background technique

Because most of the suspension parts are connected to the body through rubber bushings, and relative to the body movement, the characteristics of the suspension are usually described in the car coordinate system, and the influence of the body motion and the tire force on the wheel positioning parameters is studied. The traditional vehicle suspension characteristic test bench adopts a quasi-static loading method to simulate the force and displacement movement of the vehicle while driving on the road surface. Usually, the vehicle is fixed on the test bench to load the wheel through the wheel. The six-degree-of-freedom displacement measuring device and method measure changes of wheel alignment parameters in a vehicle coordinate system when the wheel is moving or loaded.

The wheel positioning parameters mainly include: wheel center space coordinates, wheel camber angle λ, wheel rotation angle θ, and wheel steering angle δ. The characteristics of the suspension are usually described in the car coordinate system, and the test result is the displacement of the wheel relative to the body. As shown in Fig. 1, the car coordinate system (X _V , Y _V , Z _V ) is a right-handed rectangular coordinate system with the sprung mass center (O _V ) as the origin. The coordinate system moves and rotates together with the sprung mass, at rest. In the state, the X _V axis points forward in the horizontal plane, the Y _V axis points to the left in the horizontal plane, and the Z _V axis points upward; the body coordinate system (X, Y, Z) is based on the wheel center (O) of the wheel. Right-handed rectangular coordinate system, the X-axis and the Z-axis are in the middle plane of the wheel, the X-axis is horizontally forward, and the Y-axis is the center line of the wheel rotation axis, and the Z-axis is upward. As shown in Fig. 2, the wheel coordinate system (X _W , Y _W , Z _W ) is a right-handed rectangular coordinate system with the wheel center (O _W ) as the origin, and the X _W axis and the Z _W axis are in the middle plane of the wheel. The X _W axis is horizontally forward, and the Y _W axis is the center line of the wheel rotation axis, and the Z _W axis is upward. The wheel steering angle δ is the angle between the vehicle coordinate system X _V axis and the wheel coordinate system X _W axis, and the wheel camber angle λ is the angle between the vehicle coordinate system Z _V axis and the wheel coordinate system Z _W axis, and the wheel rotation angle θ The angle at which the X _W axis and the Z _W axis are rotated about the wheel rotation axis Y _W axis. The six-degree-of-freedom displacement measuring device and method for measuring the variation of the main wheel positioning parameters with the test loading in the vehicle coordinate system.

In the prior art, the six-degree-of-freedom displacement measuring device for the suspension characteristic test bench has two main forms. One uses a measuring arm to measure the six-degree-of-freedom displacement of the wheel through six rotating shafts and corresponding angle sensors. The folding state of the measuring arm is the mechanical zero position, which is the zero position of each joint angle sensor. The state in which the joints of the measuring arm are perpendicular to each other is the measuring zero position. Usually, the six-degree-of-freedom displacement solving formula of the wheel is derived from this position.

The method needs to identify the relative position of the end axis of the measuring arm and the axis of rotation of the wheel, correct the parameters of the measuring arm solution model to ensure the accuracy of the six-degree-of-freedom displacement of the wheel, and the measuring arm mechanism is connected in series, there is a cumulative error; the measuring arm coordinates are required during the test. The coordinate axes of the system are parallel to the coordinate axes of the car coordinate system, and the installation accuracy of the measuring arm is high. One end of the measuring device is fixed with the clamp, and the impact, flexibility and gravity of the mechanism will affect the dynamic feedback of the corner of the joint; One end is fixed to the test stand and is inconvenient to move.

The other type uses a wire-type displacement sensor to measure the displacement of the six-degree-of-freedom of the wheel, mainly including five measuring cables for pulling the rope and fixing the rope. The wheel can be rotated relative to the measuring Y-axis, and the photoelectric encoder mounted on the measuring disk measures the wheel. The rotation angle is obtained by the rotation angle of the wheel. The longitudinal and vertical displacements of the wheel center are measured along the X and Z axes, and the lateral displacement, toe angle and camber angle of the wheel center are measured along the three lines of the Y axis. The displacement sensor better solves the problem of insufficient resolution of the early angle sensor, but the measurement accuracy will decrease when the body motion is faster.

Summary of the invention

In order to solve the above problems existing in the prior art, the present invention provides a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel, which makes the measurement of wheel positioning parameters more convenient, flexible and accurate during testing.

The invention is achieved by the following technical solutions:

Suspension characteristic test wheel six-degree-of-freedom displacement measuring device, the measuring device comprises a binocular vision measuring instrument, an optical target, a data exchange device, a host computer, a wheel positioning fixture and a reference fixture; the binocular vision measuring instrument Including a first binocular vision measuring instrument and a second binocular vision measuring instrument, the vehicle to be tested is fixed on a test rig for mounting on the left and right wheels of the vehicle under test, the reference The fixture is mounted on the vehicle to be tested and fixed to the vehicle to be tested, and the optical target is a plurality of, wherein a part of the optical target is distributed on the measurement plane of the wheel alignment fixture and the reference fixture, and another part of the optical target For distributing on the vehicle body of the vehicle to be tested; the first and second binocular vision measuring instruments are respectively configured to measure spatial coordinate changes of the optical target on the left and right sides of the vehicle body of the vehicle to be tested; The first and second binocular vision measuring instruments are simultaneously connected by the data exchange device, and are used for controlling the first and second binocular vision measuring instruments to measure and obtain measurement data, and Six degrees of freedom of the wheel displacement data calculated in the coordinate system of automobiles, according to the measurement.

Specifically, the wheel positioning fixture includes a disc, a nut, and a hexagon socket bolt; the disc has a circumferentially distributed straight slot extending in a radial direction, and a gap exists between the straight slot and the hexagon socket bolt. One end of the hexagon socket bolt is used for bolt connection with the wheel of the vehicle to be tested, and the other end passes through a straight slot distributed on the disc. The nut is disposed on both sides of the disc by a hexagon socket bolt, and the nut on both sides of the disc The direction of rotation is the same.

More specifically, the reference fixture includes a connecting bolt, a T-shaped plate, an L-shaped plate, and a flat plate. The T-shaped plates are asymmetric at both ends, and have a long end and a short end. The vehicle to be tested includes a frame, and the vehicle to be tested The frame has a longitudinal beam, the longitudinal beam has an upper plane and a side plane, and the two planes whose short ends of the T-shaped plate are perpendicular to each other are respectively used for attaching to the upper plane and the side plane of the frame rail and passing through the bolt and the frame Connected, the long end of the T-shaped plate protrudes out of the vehicle body, and the two ends perpendicular to each other of the L-shaped plate are respectively connected with the long end of the T-shaped plate and the flat plate by bolts.

More specifically, three optical targets are evenly distributed circumferentially on the measuring plane of the wheel positioning fixture mounted on the left wheel for evenly distributed on the measuring plane of the wheel positioning fixture mounted on the right wheel. Three optical targets having an interval of 120° between each of the optical targets distributed on a measurement plane of the wheel alignment fixture and distributed over each of the optical targets on a measurement plane of the wheel alignment fixture The shape is a circle.

More specifically, three optical targets are distributed on the measurement plane of the reference fixture, and the three optical targets are respectively an upper target, an intermediate target, and a right target, which are sequentially distributed in an “L” shape. The line connecting the intermediate target and the superscript target is perpendicular to the horizontal plane, and the line connecting the intermediate target and the right target is parallel to the advancing direction of the automobile, and the superscript target, the intermediate target and the right target are circular in shape.

More specifically, the first binocular vision measuring instrument is placed on the left side of the vehicle body facing the left side wheel, distributed on the measuring plane of the optical target and the reference fixture on the measuring plane of the wheel positioning fixture of the left side wheel The optical target is placed in the field of view of the first binocular vision measuring instrument; the second binocular vision measuring instrument is placed on the right side of the vehicle body facing the right side wheel, distributed on the measuring plane of the wheel positioning fixture of the right wheel The optical target is placed in the field of view of the second binocular vision measuring instrument; a circular optical target with a constant spacing is continuously distributed from the right side of the left wheel to the body directly above the right wheel, and the body of the left side of the wheel is on the body. A portion of the target is distributed within the field of view of the first binocular vision meter, and a portion of the target distributed on the body at one end of the right wheel is within the field of view of the second binocular vision meter.

The invention also includes a six-degree-of-freedom displacement measuring method for a suspension characteristic test wheel, which comprises a binocular vision measuring instrument, an optical target, a data exchange device, a host computer, a wheel positioning fixture and a reference fixture; the binocular vision measurement The apparatus includes a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning fixture comprising a disk, the reference fixture comprising a flat plate, the measuring method comprising the steps of:

E1: Fix the vehicle to be tested on the test rig, install the wheel alignment clamp on the wheel of the vehicle to be tested, make the disc parallel to the intermediate plane of the wheel and coaxial with the wheel, and install the reference fixture on the vehicle to be tested. On the frame, the flat plate is parallel to the longitudinal symmetry plane of the vehicle body of the vehicle under test;

E2: distributing optical targets from the left side to the right side of the vehicle body of the vehicle to be measured, and measuring the relative positional relationship between the optical targets on the vehicle body;

E3: The optical target is distributed on the wheel alignment fixture and the reference fixture so that the first binocular vision measuring instrument is facing the left wheel, the second binocular vision measuring instrument is facing the right wheel, and the binocular vision measuring instrument and the wheel are adjusted. The distance between the optical targets on the left side of the vehicle body is in the field of view of the first binocular vision measuring instrument, and the optical target on the right side of the vehicle body is located in the field of view of the second binocular vision measuring instrument;

E4: Connect one end of the data exchange device to the upper computer, the other end to the first and second binocular vision measuring instruments, start the upper computer, and establish the first and second pairs through the relative positional relationship between the optical targets on the vehicle body. The coordinate conversion relationship between the visual vision measuring instruments;

E5: Select the optical target on the wheel alignment fixture to load the vehicle to be tested, and control the first and second binocular vision measuring instruments to simultaneously measure the spatial coordinate changes of the selected target target, and pass the three optics on the wheel positioning fixture. The spatial coordinate change of the target and the distance between the disc measurement plane and the intermediate plane of the wheel are used to solve the spatial angle change of the midplane of the wheel in the vehicle coordinate system and the spatial coordinate change of the wheel center, and the left and right wheels in the vehicle coordinate system are obtained. Six degrees of freedom displacement.

Specifically, the relative positional relationship between the optical targets on the vehicle body in the above step E2 is established by the following method:

The optical target is continuously distributed from the left side to the right side of the vehicle body at regular intervals, and the first binocular vision measuring instrument is continuously moved to measure the relative positional relationship between the targets on the vehicle body, wherein the first binocular vision measurement after each step of movement The instrument's field of view has a portion of the old optical target remaining in the upper step and a new optical target that has just entered the field of view to ensure a continuous transition of the relative positional relationship.

More specifically, the coordinate conversion relationship between the first and second binocular vision measuring instruments is established in the above step E4, including:

Measuring the spatial coordinates of the optical target distributed on the right side of the vehicle body in the field of view of the second binocular vision measuring instrument in the coordinate system of the second binocular vision measuring instrument, and measuring the distribution within the field of view of the first binocular vision measuring instrument The spatial coordinates of the optical target on the left side of the body in the coordinate system of the first binocular vision measuring instrument,

Obtaining the spatial coordinates of the target on the right side body in the field of view of the first binocular vision measuring instrument in the coordinate system of the first binocular vision measuring instrument by the relative positional relationship between the targets on the vehicle body,

The number of targets on the right side of the vehicle body is greater than or equal to the unknown number of the conversion matrix T, thereby obtaining a conversion matrix T of the second binocular vision measuring instrument coordinate system relative to the first binocular vision measuring instrument coordinate system.

The invention also includes a six-degree-of-freedom displacement measuring method for a suspension characteristic test wheel, which comprises a binocular vision measuring instrument, an optical target, a plane fixture; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a A binocular vision measuring instrument, the measuring method comprising the following steps:

F1: The plane clamp is installed in front of the front of the vehicle to be tested, continuing from directly above the left wheel to directly above the right wheel, and distributing the optical target on the plane of the fixture fixed to the test bench, the first and the first Two binocular vision measuring instruments are respectively placed on the left and right sides of the vehicle body of the vehicle to be tested, and the coordinate conversion relationship between the first and second binocular vision measuring instruments is established according to the relative positional relationship between the optical targets on the vehicle body. The spatial coordinates of the optical target measured in the field of view of the binocular vision measuring instrument are converted to the coordinate system of the first binocular vision measuring instrument;

F2: establishing a six-degree-of-freedom displacement measurement reference coordinate system parallel to the vehicle coordinate system by spatial coordinates of three optical targets on the reference fixture;

F3: According to the principle of “determining a plane at three points”, the space of the middle plane of the wheel in the car coordinate system is solved by the spatial coordinate change of the three optical targets on the wheel alignment fixture and the distance between the disk measurement plane and the intermediate plane of the wheel. The angle change and the spatial coordinate change of the wheel center obtain the six-degree-of-freedom displacement of the left and right wheels in the vehicle coordinate system.

The invention also includes the following calculation method for the six-degree-of-freedom displacement of the wheel:

T31: The spatial coordinates of the coordinate points A4, A5, A6 of the optical target on the left wheel alignment fixture disc in the first binocular vision measuring instrument coordinate system are directly measured by the first binocular vision measuring instrument.

Indirect measurement of the spatial coordinates of the coordinate points A7, A8, A9 of the optical target on the disc of the right wheel alignment fixture in the coordinate system of the first binocular vision measuring instrument

T32: According to the vector operation, the rotation axis vector and the wheel center coordinate of the left and right wheels can be expressed in the first binocular vision measuring instrument coordinate system as:

Where, l _WL is the distance between the measurement plane of the left disc and the intermediate plane of the left wheel, and l _WR is the distance between the measurement plane of the right disc and the intermediate plane of the right wheel.

T33: According to the cosine theorem, the rotation axis vector and the wheel center coordinate of the left and right wheels can be transferred from the first binocular vision measuring instrument coordinate system to the vehicle coordinate system, which is expressed as:

T34: According to the spatial coordinate changes of the left and right wheel hubs in the car coordinate system, the three-degree-of-freedom line displacement of the left and right wheels in the vehicle coordinate system is measured, according to the left and right wheel rotation axes and the wheel positioning fixture. The change of the angle between the vector of the superscript target in the vehicle coordinate system and the coordinate axis of the car coordinate system measures the three-degree-of-freedom angular displacement of the left and right wheels in the vehicle coordinate system, and the left and right wheel angular displacements. The solution method is the same, which is the change of the toe angle, the camber angle and the rotation angle of the left and right wheels. Taking the left wheel as an example, the wheel toe angle δ is calculated by the wheel axis vector in the vehicle coordinate system. Wheel camber angle λ:

Using the car coordinate system

Vector solves the wheel rotation angle θ:

Optionally, the present invention is a suspension characteristic test wheel multi-degree of freedom displacement measuring device, wherein the measuring device comprises a binocular vision measuring instrument, an optical target, a data exchange device, a host computer, and a wheel positioning fixture. And a reference fixture; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the vehicle to be tested being fixed on the test bench, the wheel positioning fixture being used for mounting on the vehicle to be tested On the left and right wheels, the reference fixture is mounted on a frame of the vehicle under test, and the optical targets are plural, and a part of the optical targets are distributed in the measurement of the wheel alignment fixture and the reference fixture. In the plane, another part of the optical target is distributed on the vehicle body of the vehicle to be tested; the first and second binocular vision measuring instruments are respectively used to measure the optical target on the left and right sides of the vehicle body of the vehicle to be tested. Space coordinate change; the upper computer simultaneously connects the first and second binocular vision measuring instruments through the data exchange device, and is used for controlling the first and second binocular vision measuring instruments to be measured and obtained Measurement data, and multiple degrees of freedom of the wheel displacement data calculated in the coordinate systems of the measuring car.

The invention further comprises a suspension characteristic test wheel multi-degree of freedom displacement measuring method, which comprises a binocular vision measuring instrument, an optical target, a data exchange device, a host computer, a wheel positioning fixture and a reference fixture; The eye vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning fixture comprising a disk, the reference fixture comprising a flat plate, the measuring method comprising the steps of:

E1: Fix the vehicle to be tested on the test rig, install the wheel alignment clamp on the wheel of the vehicle to be tested, make the disc parallel to the intermediate plane of the wheel and coaxial with the wheel, and install the reference fixture on the vehicle to be tested. On the frame, the flat plate is parallel to the longitudinal symmetry plane of the vehicle body of the vehicle under test;

E2: distributing optical targets from the left side to the right side of the vehicle body of the vehicle to be measured, and measuring the relative positional relationship between the optical targets on the vehicle body;

E3: The optical target is distributed on the wheel alignment fixture and the reference fixture so that the first binocular vision measuring instrument is facing the left wheel, the second binocular vision measuring instrument is facing the right wheel, and the binocular vision measuring instrument and the wheel are adjusted. The distance between the optical targets on the left side of the vehicle body is in the field of view of the first binocular vision measuring instrument, and the optical target on the right side of the vehicle body is located in the field of view of the second binocular vision measuring instrument;

E4: Connect one end of the data exchange device to the upper computer, the other end to the first and second binocular vision measuring instruments, start the upper computer, and establish the first and second pairs through the relative positional relationship between the optical targets on the vehicle body. The coordinate conversion relationship between the visual vision measuring instruments;

E5: Select the optical target on the wheel alignment fixture to load the vehicle to be tested, and control the first and second binocular vision measuring instruments to simultaneously measure the spatial coordinate changes of the selected target target, and pass the three optics on the wheel positioning fixture. The spatial coordinate change of the target and the distance between the disc measurement plane and the intermediate plane of the wheel are used to solve the spatial angle change of the midplane of the wheel in the vehicle coordinate system and/or the spatial coordinate change of the wheel center, and the wheel is free in the car coordinate system. Degree displacement.

The beneficial effects of the invention are:

(1) The binocular vision measuring instrument is used to measure the multi-degree of freedom displacement of the wheel in the suspension characteristic test, which makes the arrangement, installation, adjustment and measurement of the measuring device more convenient and quicker;

(2) Established the coordinate transformation relationship between the two binocular vision measuring instruments, so that the six-degree-of-freedom displacement of the left and right wheels is unified in a coordinate system, and the motion relationship between the left and right wheels is analyzed. More convenient and accurate;

(3) The vehicle coordinate system fixed on the vehicle body is established by the target coordinates on the reference fixture, and the six-degree-of-freedom displacement of the measured left and right wheels is converted to the vehicle coordinate system to make the measurement reference and the measured displacement. More accurate in definition;

(4) Solving the six-degree-of-freedom displacement of the wheel by the change of the target coordinates on the positioning fixture, the mathematical model is simple and accurate, and the installation error when the measuring mechanism is connected with the positioning fixture during the contact measurement is eliminated;

(5) Control the two binocular vision measuring instruments to perform synchronous tracking measurement through the host computer program, which facilitates the integration of the test bed system and makes the six-degree-of-freedom displacement of the left and right wheels and the excitation of the test bench at each moment. Accurate correspondence.

DRAWINGS

Figure 1 is a schematic view of a car coordinate system;

Figure 2 is a schematic view of a wheel coordinate system;

Figure 3 is an overall schematic view of the present invention;

Figure 4 is a schematic view showing the measurement of the left wheel of the present invention;

Figure 5 is a schematic view showing the measurement of the right wheel of the present invention;

Figure 6 is a wheel positioning fixture structure of the present invention;

Figure 7 is a reference jig structure of the present invention;

Figure 8 is a schematic diagram of the measurement of the present invention;

Figure 9 is a schematic view of the wheel space angle;

Figure 10 is a schematic illustration of another embodiment of the present invention.

In the picture:

11, 12, 13. Reference fixture optical target, 14, 15, 16 left wheel positioning fixture optical target, 17, 18, 19. right wheel positioning fixture optical target; 2. reference fixture, 21. connection Bolt, 22.T-shaped plate, 23. L-shaped plate, 24. Flat plate; 3. Wheel positioning fixture, 31. Left wheel positioning fixture disc, 32. Nut, 33. Hexagon bolt, 34. Right wheel positioning Fixture disc; 41. First binocular vision measuring instrument, 42. Second binocular vision measuring instrument; 5. Data exchange device; 6. Host computer; 7. Test bench; 8. Vehicle under test, 81. Left Side wheel, 82. Right wheel, 83. Frame.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

FIG. 3 is a schematic overall view of a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel according to the present invention, which mainly includes a first binocular vision measuring instrument 41 and a second binocular vision measuring instrument. 42. Data exchange device 5, host computer 6, wheel positioning jig 3, and reference jig 2. As shown in FIGS. 3-7, the vehicle 8 to be tested is fixed on the test rig 7, and the wheel alignment jig 3 is mounted on the left and right wheels 81, 82 of the vehicle 8 to be tested, and the reference jig 2 is mounted on the vehicle to be tested. And fixed to the vehicle to be tested, preferably fixed on the frame 83 of the vehicle under test; a part of the optical target is distributed on the measuring plane of the wheel positioning fixture 3 and the reference fixture 2, and another part of the optical target is distributed on the vehicle body. The first binocular vision measuring instrument 41 continuously measures the relative positional relationship between the targets on the vehicle body to solve the conversion matrix T between the coordinate systems of the two binocular vision measuring instruments; the two binocular vision measuring instruments 41 and 42 respectively Placed on both sides of the vehicle body of the vehicle under test 8, the spatial coordinate changes of the optical target on the plane of the measuring fixture are unified and unified in the coordinate system of the first binocular vision measuring instrument, and the upper computer 6 is connected to the binocular vision measuring instrument through the data exchange device 5. , controlling its measurement and obtaining measurement data, and calculating the six-degree-of-freedom displacement of the wheel in the vehicle coordinate system based on the measured data.

6 is a structural diagram of a left wheel alignment fixture of a six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel of the present invention, which includes a disk 31, six nuts 32, and three hexagon socket bolts 33. One end of the hexagon socket head bolt 33 is connected with the wheel bolt, and the other end passes through the straight slot 35 which is radially distributed on the disc 31. The diameter of the hexagon socket bolt is smaller than the slot width of the straight slot 35, and there is a gap between the hexagon socket bolt and the straight slot. The adjustment gap is fixed, so that the disc 31 can be moved along the axial direction of the hexagon socket bolt 33 and the radial direction of the disc 31 through the straight slot, and each side of the disc plane has a screw 32 having the same direction and screwed into the hexagon socket bolt. 33, the posture of the disc 31 is adjusted so as to be parallel and coaxial with the intermediate plane of the left wheel 81, and the posture of the disc 31 is determined by the two sides of the nuts 32 to be fixed and fixed, and the left and right wheels 81 The structure and installation requirements of the wheel positioning jig 3 on the 82 are the same. The stability of the clamp is ensured by screwing the same nut on each side of the plane to the hexagonal bolt. The arrangement of the straight slot makes the wheel alignment clamp easy to install and easy to adjust. It is suitable for all types of wheels. Applicability Strong.

FIG. 7 is a structural diagram of a reference fixture of a six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to the present invention. The reference jig can be mounted on either side of the vehicle body, and includes a connecting bolt 21, a T-shaped plate 22, and a L. The shape plate 23, the flat plate 24, and the T-shaped plate 22 are asymmetrical at both ends, and the planes perpendicular to the short ends of the T-shaped plate 22 are respectively attached to the upper plane and the side plane of the longitudinal beam of the frame 83, and are connected to the frame 83 through the bolts 21, The long ends of the T-shaped plates 22 extend out of the vehicle body, and the two ends perpendicular to each other of the L-shaped plates 23 are respectively connected to the long ends of the T-shaped plates 22 and the flat plate 24 by bolts 21, so that the flat plate plane is parallel to the longitudinal symmetry plane of the automobile, and passes through In the above structure, the reference jig is directly mounted on the frame, so that the reference jig has a simple structure, is convenient and stable to install, and has strong applicability.

FIG. 4 is a left side view showing a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel according to the present invention. The reference jig is mounted on the left side of the vehicle body as an example, as shown in FIG. 3-4. It mainly includes a first binocular vision measuring instrument 41, a left side wheel 81, a wheel positioning jig 3, a reference jig 2, an optical target; wherein the measuring plane upper edge of the positioning jig disk 31 fixed to the left side wheel 81 Three optical targets 14, 15, 16 are evenly distributed on the circumference, and the target interval is 120°; the optical planes of the reference fixture plate 24 fixed to the frame 83 are "L-shaped" on the measurement plane, and three optical targets 11 and 12 are distributed. 13, the target 11 is above the target 12, the target 13 is on the right side of the target 12, the connection between the target 12 and the target 11 is perpendicular to the horizontal plane, and the connection between the target 12 and the target 13 is connected to the vehicle. The forward direction is parallel; the first binocular vision measuring device 41 faces the wheel positioning jig 3 and the reference jig 2, about 2 meters from the measuring plane of the disc 31, and measures the targets 11, 12, 13 on the measuring plane of the fixture in the field of view. , 14, 15, 16 spatial coordinate changes in the coordinate system of the first binocular vision measuring instrument, 5 the amount of data transmitted through the data exchange device 6 to the host computer.

FIG. 5 is a schematic diagram of the right side of the six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel according to the present invention, including a second binocular vision measuring instrument 42, a right side wheel 82, and a wheel positioning fixture. 3. An optical target; wherein, on the measuring plane of the positioning fixture disc 34 fixed to the right wheel 82, three optical targets 17, 18, 19 are evenly distributed along the circumference, and the target is spaced by 120°; the second binocular The vision measuring device 42 faces the wheel positioning fixture disc 34 about 2 meters from its measuring plane, and measures the space of the targets 17, 18, 19 on the measuring plane of the fixture in the field of view of the first binocular vision measuring instrument. The coordinate changes and the measurement data are transmitted to the host computer 6 via the data exchange device 5.

FIG. 8 is a schematic diagram of a six-degree-of-freedom displacement measurement method for a suspension characteristic test wheel according to the present invention. The target coordinate of the second binocular vision measuring instrument in the coordinate system can be obtained by the conversion matrix T. Converting to the coordinate system of the first binocular vision measuring instrument, the optical target 11, 12, 13 on the reference fixture plate 24 and the left wheel alignment fixture disk 31 can be directly measured by the first binocular vision measuring instrument 41. The spatial coordinates of coordinates A1, A2, A3, A4, A5, A6 of 14, 15, 16 in the coordinate system of the first binocular vision measuring instrument

The spatial coordinates of the coordinate points A7, A8, A9 of the optical targets 17, 18, 19 on the right binocular positioning fixture disk 34 in the coordinate system of the first binocular vision measuring instrument can be indirectly measured.

The vector of the vehicle coordinate system X _V , Y _V , Z _V axis can be expressed as:

The vector between the optical targets on the left wheel alignment fixture disc 31 can be expressed as:

The vector between the optical targets on the right wheel alignment fixture disc 34 can be expressed as:

The left and right wheel rotation axis vectors can be expressed as:

Where, l _WL is the distance between the measurement plane of the left wheel alignment fixture disc and the intermediate plane of the left wheel, and l _WR is the distance between the measurement plane of the right wheel alignment fixture disc and the intermediate plane of the right wheel.

The vector between the origin O _{V of the} car coordinate system and the left and right wheel centers can be expressed as:

Left and right wheel rotation axis vectors and vectors

Expressed in the car coordinate system as:

The coordinates of the left and right wheel center points in the car coordinate system are:

According to the six-degree-of-freedom displacement diagram of the right wheel in FIG. 9, the six degrees of freedom of the wheel include three degrees of freedom of movement and three degrees of freedom of rotation of the wheel in the vehicle coordinate system, and the translational displacement of the wheel in the vehicle coordinate system is a wheel. The displacement of the heart W along the X _V , Y _V , and Z _V axes of the vehicle coordinate system, that is, the spatial coordinate of the wheel center W in the vehicle coordinate system; the rotational displacement of the wheel in the vehicle coordinate system is the wheel coordinate system X _W , Z _W The change of the angle between the axis and the vehicle coordinate system X _V and the Z _V axis and the change of the X _W and Z _W axes around the Y _W axis;

It can be seen that the wheel rotation axis vector

Coincident with the Y _W axis, the X _W axis is in the X _V -Y _V plane, and the angle between the X _W axis and the X _V axis is the wheel toe angle δ, and the tangent is equal to that in the car coordinate system.

The ratio of the components of the vector on the X _V and Y _V axes. The Z _V axis is in the Y _W -Z _W plane, and the angle between the Z _V axis and the Z _W axis is equal to the angle between the Y _W axis and its projection on the X _V -Y _V plane, which is the wheel camber λ, which is sinusoidal. The value is equal to the car coordinate system

The ratio of the component of the vector on the Z _V axis to its modulus. The wheel rotation angle θ is the angle at which the X _W axis and the Z _W axis are rotated about the wheel rotation axis Y _W axis. Since the wheel center measurement point P is also on the Y _W axis, the vector rotation between the wheel rotation angle and the wheel positioning fixture target is performed. The point P is rotated at the same angle, which is approximately equal to the change of the angle between the vector between the wheel positioning fixture target and the Z _V axis in the vehicle coordinate system. The sine value of the angle is equal to the position between the wheel positioning fixture targets in the vehicle coordinate system. The ratio of the component of the vector on the Z _V axis to its modulus.

The left and right wheel angular displacements are solved in the same way, and the left and right wheel toe angles, camber angles and rotation angles are changed. Taking the left wheel as an example, the wheel rotation axis solution in the vehicle coordinate system is used. Calculate the wheel toe angle δ and the wheel camber λ:

Using the vector between the wheel alignment fixture targets in the car coordinate system

Solve the wheel rotation angle θ:

One embodiment of the invention includes the following test steps:

S1: Fix the test vehicle 8 on the test bench 7, and install the reference clamp 2 and the wheel alignment clamp 3:

S11: Mounting the wheel alignment jig 3 on the wheel, connecting one end of the three hexagon socket bolts 33 to the wheel bolt, and the other end passing through the straight slot radially distributed on the disc 31, passing through the pair of nuts 32 on both sides of the disc The top determines the posture of the disc 31 and fixes it, rotates the wheel after the wheel is suspended, and uses a dial gauge to measure the amount of runout of the disc plane during rotation. If the jump of the disc edge is large, the circle is adjusted. The front and rear positions of the disc on the axis of the bolt adjust the spatial attitude of the plane of the disc until the disc axis is considered to be parallel to the axis of rotation of the wheel, and the wheel is also rotated, and the rotational offset of the cylindrical surface of the disc is measured using a dial gauge. Adjusting the position of the disc along the radial direction of the disc in the chute to adjust the spatial position of the disc axis so as to coincide with the axis of rotation of the wheel;

S12: The reference jig 2 is mounted on the frame 83, and the planes perpendicular to the short ends of the T-shaped plate 22 are respectively attached to the upper plane and the side plane of the longitudinal beam of the frame 83, and are connected to the frame 83 by bolts 21, and L The two ends of the plate 23 perpendicular to each other are respectively connected with the long end of the T-shaped plate 22 and the flat plate 24 by bolts 21, so that the flat plate is parallel to the longitudinal symmetry plane of the vehicle body;

S2: The optical target 1 is continuously distributed from the left side to the right side of the vehicle body at a distance of about 0.5 m (as shown in FIG. 3), and the relative positional relationship between the targets on the vehicle body is measured by continuously moving the first binocular vision measuring instrument. It is required that the old target with partial upper step residual and the new target just entering the field of view in the field of view after each step of movement ensure a continuous transition of the relative positional relationship, for example, measured in the i-th step of the movement of the first binocular vision measuring instrument. The spatial coordinates of the optical targets a and b in the field of view obtain the relative positional relationship between the targets a and b, and the optical target in the field of view is measured in the i+1th step of the movement of the first binocular vision measuring instrument. The spatial coordinates of b and c obtain the relative positional relationship between the targets b and c. The relative positional relationship between the targets a and c can be calculated by the target b. Similarly, all the distributions on the body can be obtained. Relative positional relationship of the target;

S3: The optical target is distributed on the wheel positioning fixture 3 and the reference fixture 2 as required, so that the targets on both sides of the vehicle body are respectively located in the field of view of the first and second binocular vision measuring instruments:

S31: three circular optical targets 14, 15, 16 are uniformly applied circumferentially on the measuring plane of the left wheel positioning fixture disc 31, and are evenly distributed on the measuring plane of the right wheel positioning fixture disc 34. Three circular optical targets 17, 18, 19 are attached, and the targets at both locations are spaced 120° apart;

S32: three circular optical targets 11, 12, 13 are attached in an "L shape" on the measurement plane of the reference fixture plate 24, the target 11 is above the target 12, and the target 13 is at the target 12. On the right side, the line connecting the target 12 and the target 11 is perpendicular to the horizontal plane, and the line connecting the target 12 and the target 13 is parallel to the horizontal plane;

S33: placing the first binocular vision measuring instrument 41 on the left side of the vehicle body of the vehicle 8 to be tested and facing the measuring plane of the wheel positioning jig disk 31 and the reference jig plate 24 (taking the reference jig on the left side of the vehicle body as an example), Adjusting the distance between them so that the optical targets 11, 12, 13, 14, 15, 16 are distributed within the field of view of the first binocular vision measuring instrument;

S34: placing the second binocular vision measuring instrument 42 on the right side of the vehicle body of the vehicle 8 to be tested and facing the measuring plane of the wheel positioning fixture disk 34, adjusting the distance between them to make the optical targets 17, 18, 19 Distributed within the field of view of the second binocular vision measuring instrument;

S4: connecting one end of the data exchange device 5 with the upper computer 6, and the other end is connected with two binocular vision measuring instruments, starting the upper computer 6, running the measuring instrument control program, and introducing the relative positional relationship between the targets on the vehicle body to establish two sets. The coordinate conversion relationship between the binocular vision measuring instruments, selecting the optical target on the fixture, and controlling the two binocular vision measuring instruments to start synchronous tracking and measuring the spatial coordinate changes of the selected target target while the test bed starts loading, the test ends When the measurement is stopped, the meter control program stops running.

The invention includes the following calculation steps:

T1: According to the relative positional relationship between the targets on the vehicle body, the coordinate conversion relationship between the two binocular vision measuring instruments is established, and the spatial coordinate points of the optical targets measured in the field of view of the second binocular vision measuring instrument are converted to Under the first binocular vision measuring instrument coordinate system:

T11: The spatial coordinates and distribution of the target on the right side body of the second binocular vision measuring instrument in the field of view of the second binocular vision measuring instrument are known to be within the field of view of the first binocular vision measuring instrument. The space coordinates of the target on the left side of the body in the coordinate system of the first binocular vision measuring instrument, and the right position of the vehicle in the field of view of the first binocular vision measuring instrument can be obtained by the relative positional relationship between the targets on the vehicle body. The space coordinates of the target in the first binocular vision measuring instrument coordinate system, the number of targets on the right side of the vehicle body is greater than or equal to the unknown number of the conversion matrix T, thereby solving the second binocular vision measuring instrument The coordinate system is the transformation matrix T of the coordinate system of the first binocular vision measuring instrument;

T12: multiplying the optical targets 17, 18, 19 on the disc 34 by coordinate points B7, B8, B9 in the coordinate system of the second binocular vision measuring instrument to multiply the conversion matrix T to obtain optical targets 17, 18, 19 Spatial coordinates of coordinate points A7, A8, A9 in the coordinate system of the first binocular vision measuring instrument

T2: the spatial coordinates of the three optical targets 11, 12, 13 on the reference fixture 2 in the field of view measured by the first binocular vision measuring instrument 41 establish a six-degree-of-freedom displacement measurement reference coordinate parallel to the vehicle coordinate system system:

T21: The spatial coordinates of the coordinate points A1, A2, A3 of the optical targets 11, 12, 13 on the reference fixture plate 24 in the coordinate system of the first binocular vision measuring instrument can be measured by the first binocular vision measuring instrument 41.

vector

Z _V with the vehicle coordinate system parallel to the axis vector

X _V with the vehicle coordinate system parallel to the axis vector

versus

Parallel to the axis of the outer product vector car axis coordinate system X _V Y _V automobiles coordinate system may be expressed as

Automotive vector coordinate axis Z _V can be expressed as

The vector of the vehicle coordinate system Y _V axis can be expressed as

T3: According to the principle of "three points to determine a plane", the space coordinate of the three optical targets on the wheel alignment fixture and the distance between the disk measurement plane and the intermediate plane of the wheel are used to solve the space of the middle plane of the wheel in the vehicle coordinate system. The angle change and the spatial coordinate change of the wheel center obtain the six-degree-of-freedom displacement of the left and right wheels in the vehicle coordinate system:

T31: The coordinate points A4 and A5 of the optical targets 14, 15, 16 on the left binocular positioning fixture disk 31 in the coordinate system of the first binocular vision measuring instrument can be directly measured by the first binocular vision measuring instrument 41. , A6 space coordinates

The spatial coordinates of the coordinate points A7, A8, A9 of the optical targets 17, 18, 19 on the right binocular positioning fixture disk 34 in the coordinate system of the first binocular vision measuring instrument can be indirectly measured.

T32: According to the vector operation, the rotation axis vector and the wheel center coordinate of the left and right wheels can be expressed in the first binocular vision measuring instrument coordinate system as:

Where, l _WL is the distance between the measurement plane of the left disc and the intermediate plane of the left wheel, and l _WR is the distance between the measurement plane of the right disc and the intermediate plane of the right wheel.

T33: According to the cosine theorem, the rotation axis vector and the wheel center coordinate of the left and right wheels can be transferred from the first binocular vision measuring instrument coordinate system to the vehicle coordinate system, which is expressed as:

T34: According to the spatial coordinate changes of the left and right wheel hubs in the car coordinate system, the three-degree-of-freedom line displacement of the left and right wheels in the vehicle coordinate system is measured, according to the left and right wheel rotation axes and the wheel positioning fixture. The change of the angle between the vector of the superscript target in the vehicle coordinate system and the coordinate axis of the car coordinate system measures the three-degree-of-freedom angular displacement of the left and right wheels in the vehicle coordinate system, and the left and right wheel angular displacements. The solution method is the same, which is the change of the toe angle, the camber angle and the rotation angle of the left and right wheels. Taking the left wheel as an example, the wheel toe angle δ is calculated by the wheel axis vector in the vehicle coordinate system. Wheel camber angle λ:

Using the car coordinate system

Vector solves the wheel rotation angle θ:

Optionally, although the present invention is a suspension six-degree-of-freedom displacement measuring device and method for suspension characteristics, the present invention can be used to measure a certain degree of freedom displacement of a wheel or a certain degree of freedom displacement according to actual measurement requirements. That is, the present invention is also a suspension multi-degree of freedom displacement measuring device and method for suspension characteristics test, and is not limited to measuring only six degrees of freedom.

As shown in FIG. 10, another embodiment of the present invention resides in that an optical target 111 for establishing a coordinate conversion relationship between two binocular vision measuring instruments is distributed on a jig plane of a plane jig 9 fixed to a test gantry. The plane jig 9 is installed in front of the front end of the vehicle, and extends from directly above the left side wheel to directly above the right side wheel. The measurement requirements of the optical target 111 and the relative positional relationship are measured in the same manner as in the above embodiment, and the optical target room is The relative positional relationship can be used in subsequent tests after being measured for the first time.

The above embodiments are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and changes can be made without departing from the spirit and scope of the invention. Equivalent technical solutions fall within the scope of protection of the present invention.

Claims (10)

1. Suspension characteristic test wheel six-degree-of-freedom displacement measuring device, characterized in that the measuring device comprises a binocular vision measuring instrument, an optical target, a data exchange device (5), a host computer (6), a wheel positioning fixture ( 3) and a reference fixture (2); the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, and the vehicle to be tested (8) is fixed on the test bench (7), The wheel positioning fixture is mounted on the left and right wheels of the vehicle to be tested, and the reference fixture is mounted on the vehicle to be tested and fixed to the vehicle to be tested, and the optical target is a plurality of parts, some of which are The optical target is distributed on the measurement plane of the wheel alignment fixture and the reference fixture, and the other part of the optical target is distributed on the vehicle body of the vehicle under test; the first and second binocular vision measuring instruments are respectively placed on the Measuring spatial coordinate changes of the optical target on the left and right sides of the vehicle body of the vehicle to be tested; the upper computer simultaneously connecting the first and second binocular vision measuring instruments through the data exchange device for controlling the first and second Binocular vision measuring instrument And obtaining measurement data, and measured data can be calculated based on the six degrees of freedom of displacement of the wheel under the vehicle coordinate system.
2. The six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to claim 1, wherein the wheel positioning clamp comprises a disc (31), a nut (32), and a hexagon socket bolt (33); The disc has a circumferentially distributed straight slot extending radially, a gap exists between the straight slot and the hexagon socket bolt, and one end of the hexagon socket bolt is used for bolt connection with the wheel of the vehicle under test, and the other end Through the straight slot distributed on the disc, the nut is placed on both sides of the disc by a hexagon socket bolt, and the nuts on both sides of the disc are rotated in the same direction.
3. A six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to claim 1, wherein said reference clamp comprises a connecting bolt (21), a T-shaped plate (22), an L-shaped plate (23), a flat plate (24), the T-shaped plate is asymmetric at both ends, and has a long end and a short end, the vehicle to be tested comprises a frame, and the frame of the tested vehicle has a longitudinal beam, the longitudinal beam has an upper plane and a side plane The two ends of the short end of the T-shaped plate are respectively used for attaching to the upper plane and the side plane of the longitudinal beam of the frame and are connected with the frame by bolts. The long end of the T-shaped plate protrudes out of the vehicle body, and the L-shaped plate The two ends perpendicular to each other are respectively connected to the long end of the T-shaped plate and the flat plate by bolts.
4. A six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to any one of claims 1 to 3, characterized in that it is mounted on the measuring plane of the wheel positioning jig of the left side wheel (81) along the circumference Three optical targets (14, 15, 16) are evenly distributed for circumferentially distributing three optical targets (17, 18, 19) on the measuring plane of the wheel positioning fixture mounted on the right wheel (81). The spacing between each of the optical targets distributed on the measurement plane of the wheel alignment fixture is 120°, and the shape of each of the optical targets distributed on the measurement plane of the wheel alignment fixture is circular .
5. A six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to any one of claims 1 to 3, characterized in that three optical targets (11, 12, 13) The three optical targets are an upper target, an intermediate target, and a right target, respectively, which are sequentially distributed in an "L" shape, and the intermediate target (12) is connected with the superscript target (11). The horizontal plane is vertical, and the line connecting the intermediate target (12) and the right target (13) is parallel to the advancing direction of the automobile, and the superscript target, the intermediate target and the right target are circular in shape.
6. A six-degree-of-freedom displacement measuring device for a suspension characteristic test wheel according to any one of claims 1 to 3, wherein said first binocular vision measuring device (41) is placed on the left side of the vehicle body. For the left wheel (81), the optical target on the measuring plane of the wheel positioning fixture distributed on the left wheel and the optical target on the measuring plane of the reference fixture are placed in the field of view of the first binocular vision measuring instrument; A two-binocular vision measuring instrument (42) is placed on the right side of the vehicle body facing the right side wheel (82), and the optical target distributed on the measuring plane of the wheel positioning fixture of the right side wheel is set in the second binocular vision measurement Within the field of view of the instrument; a circular optical target with a constant spacing from the directly above the left wheel to the body directly above the right wheel, and a part of the target distributed on the body at the end of the left wheel in the first binocular vision measurement Within the field of view of the instrument, a portion of the target distributed on the body at one end of the right wheel is within the field of view of the second binocular vision meter.
7. Suspension characteristic test wheel six-degree-of-freedom displacement measuring method, which comprises a binocular vision measuring instrument, an optical target, a data exchange device (5), a host computer (6), a wheel positioning fixture (3) and a reference a fixture (2); the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning fixture comprising a disk, the reference fixture comprising a flat plate, the measuring method comprising The following steps:

   E1: Fix the vehicle to be tested on the test rig, install the wheel alignment clamp on the wheel of the vehicle to be tested, make the disc parallel to the intermediate plane of the wheel and coaxial with the wheel, and install the reference fixture on the vehicle to be tested. On the frame, the flat plate is parallel to the longitudinal symmetry plane of the vehicle body of the vehicle under test;

   E2: distributing optical targets from the left side to the right side of the vehicle body of the vehicle to be measured, and measuring the relative positional relationship between the optical targets on the vehicle body;

   E3: The optical target is distributed on the wheel alignment fixture and the reference fixture so that the first binocular vision measuring instrument is facing the left wheel, the second binocular vision measuring instrument is facing the right wheel, and the binocular vision measuring instrument and the wheel are adjusted. The distance between the optical targets on the left side of the vehicle body is in the field of view of the first binocular vision measuring instrument, and the optical target on the right side of the vehicle body is located in the field of view of the second binocular vision measuring instrument;

   E4: Connect one end of the data exchange device to the upper computer, the other end to the first and second binocular vision measuring instruments, start the upper computer, and establish the first and second pairs through the relative positional relationship between the optical targets on the vehicle body. The coordinate conversion relationship between the visual vision measuring instruments;

   E5: Select the optical target on the wheel alignment fixture to load the vehicle to be tested, and control the first and second binocular vision measuring instruments to simultaneously measure the spatial coordinate changes of the selected target target, and pass the three optics on the wheel positioning fixture. The spatial coordinate change of the target and the distance between the disc measurement plane and the intermediate plane of the wheel are used to solve the spatial angle change of the midplane of the wheel in the vehicle coordinate system and the spatial coordinate change of the wheel center, and the six-degree-of-freedom displacement of the wheel in the vehicle coordinate system is obtained. .
8. A six-degree-of-freedom displacement measuring method for a suspension characteristic test wheel according to claim 7, wherein the relative positional relationship between the optical targets on the vehicle body in the above step E2 is established by the following method:

   The optical target is continuously distributed from the left side to the right side of the vehicle body at regular intervals, and the first binocular vision measuring instrument is continuously moved to measure the relative positional relationship between the targets on the vehicle body, wherein the first binocular vision measurement after each step of movement The instrument's field of view has a portion of the old optical target remaining in the upper step and a new optical target that has just entered the field of view to ensure a continuous transition of the relative positional relationship.
9. The six-degree-of-freedom displacement measuring method for a suspension characteristic test wheel according to claim 7 or 8, wherein the coordinate conversion relationship between the first and second binocular vision measuring instruments in the step E4 is as follows:

   Measuring the spatial coordinates of the optical target on the right side of the body of the second binocular vision measuring instrument in the field of view of the second binocular vision measuring instrument, measuring the distribution in the field of view of the first binocular vision measuring instrument The spatial coordinates of the optical target on the side body in the coordinate system of the first binocular vision measuring instrument,

   Obtaining the spatial coordinates of the target on the right side body in the field of view of the first binocular vision measuring instrument in the coordinate system of the first binocular vision measuring instrument by the relative positional relationship between the targets on the vehicle body,

   The number of targets on the right side of the vehicle body is greater than or equal to the unknown number of the conversion matrix T, thereby obtaining a conversion matrix T of the second binocular vision measuring instrument coordinate system relative to the first binocular vision measuring instrument coordinate system.
10. A six-degree-of-freedom displacement measuring method for a suspension characteristic test wheel, comprising: a binocular vision measuring instrument, an optical target, a plane fixture (9); the binocular vision measuring instrument comprises a first binocular vision measuring instrument And a second binocular vision measuring instrument, the measuring method comprising the steps of:

    F1: The plane clamp is installed in front of the front of the vehicle to be tested, continuing from directly above the left wheel to directly above the right wheel, and distributing the optical target on the plane of the fixture fixed to the test bench, the first and the first Two binocular vision measuring instruments are respectively placed on the left and right sides of the vehicle body of the vehicle to be tested, and the coordinate conversion relationship between the first and second binocular vision measuring instruments is established according to the relative positional relationship between the optical targets on the vehicle body. The spatial coordinates of the optical targets (17, 18, 19) measured in the field of view of the binocular vision measuring instrument are converted to the coordinate system of the first binocular vision measuring instrument;

    F2: establishing a six-degree-of-freedom displacement measurement reference coordinate system parallel to the vehicle coordinate system by the spatial coordinates of the three optical targets (11, 12, 13) on the reference fixture;

    F3: According to the principle of “determining a plane at three points”, the space of the middle plane of the wheel in the car coordinate system is solved by the spatial coordinate change of the three optical targets on the wheel alignment fixture and the distance between the disk measurement plane and the intermediate plane of the wheel. The angle change and the spatial coordinate change of the wheel center obtain the six-degree-of-freedom displacement of the wheel in the vehicle coordinate system.

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