CN107192343B - Six-degree-of-freedom displacement measuring device and method for suspension characteristic test wheel - Google Patents

Six-degree-of-freedom displacement measuring device and method for suspension characteristic test wheel Download PDF

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Publication number
CN107192343B
CN107192343B CN201710537263.XA CN201710537263A CN107192343B CN 107192343 B CN107192343 B CN 107192343B CN 201710537263 A CN201710537263 A CN 201710537263A CN 107192343 B CN107192343 B CN 107192343B
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wheel
binocular vision
measuring instrument
vision measuring
plane
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CN107192343A (en
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张云清
徐鹏举
吕天启
卓凯敏
孙海华
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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Priority to PCT/CN2018/093425 priority patent/WO2019007259A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/03—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring coordinates of points
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention discloses a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel, which mainly comprise a first binocular vision measuring instrument (41), a second binocular vision measuring instrument (42), an optical target, a data exchange device (5), an upper computer (6), a wheel positioning clamp (3) and a reference clamp (2); the vehicle (8) to be tested is fixed on the test bench (7), the wheel positioning clamp and the reference clamp are respectively arranged on the wheel and the frame, the optical targets are distributed on the measuring plane of the clamp and the vehicle body, the upper computer is connected with the binocular vision measuring instrument through the data exchange device, the spatial coordinate change of the optical targets is controlled to be measured, and the six-degree-of-freedom displacement of the wheels under the automobile coordinate system is calculated; according to the invention, the six-degree-of-freedom displacement of the wheel under the automobile coordinate system is solved through the spatial coordinate transformation of the optical target, so that accurate non-contact measurement can be realized; the invention has the advantages of convenient and flexible measurement, wide test range, high precision and good application prospect.

Description

Six-degree-of-freedom displacement measuring device and method for suspension characteristic test wheel
Technical Field
The invention belongs to the technical field of automobile suspension performance test, and particularly relates to a six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel.
Background
Since most suspension parts are connected to the vehicle body through rubber bushings while moving relative to the vehicle body, the suspension is often characterized in an automotive coordinate system, and the effects of vehicle body movement and tire forces on wheel alignment parameters are studied. The traditional automobile suspension characteristic test bed adopts a quasi-static loading mode, the stress and displacement movement of a vehicle when the vehicle runs on a road surface are simulated on the test bed, the mode of loading wheels by fixing the vehicle body on the test bed is generally adopted, and the six-degree-of-freedom displacement measuring device and method for the wheels are used for measuring the movement of the wheels or the change of part of wheel positioning parameters under an automobile coordinate system when the wheels are loaded.
Wheel of vehicleThe positioning parameters mainly comprise: wheel center space coordinates, wheel camber angle λ, wheel rotation angle θ, and wheel steering angle δ. The suspension is typically characterized in an automotive coordinate system, with the result that the displacement of the wheel relative to the body varies. As shown in fig. 1, the vehicle coordinate system (X V 、Y V 、Z V ) Is based on the sprung mass center (O) V ) Right-hand rectangular coordinate system as origin, which moves and rotates along with the sprung mass, X in stationary state V The axis pointing forward in the horizontal plane, Y V The axis pointing to the left in the horizontal plane, Z V The shaft points upwards; the vehicle body coordinate system (X, Y, Z) is a right-hand rectangular coordinate system taking the wheel center (O) of the wheel as an origin, the X axis and the Z axis are in the middle plane of the wheel, the X axis is horizontally forward, the Y axis is the center line of the wheel rotating shaft, and the Z axis is upward. As shown in fig. 2, the wheel coordinate system (X W 、Y W 、Z W ) Is based on the center (O) W ) Right-hand rectangular coordinate system with origin X W Axis and Z W The axis being in the mid-plane of the wheel, X W The axis is horizontally forward, Y W The axle is the center line of the wheel rotating axle, Z W In the axial direction. The steering angle delta of the wheel is the coordinate system X of the automobile V Axle and wheel coordinate system X W The included angle between the axles, the camber angle lambda is the coordinate system Z of the automobile V Axis and wheel coordinate system Z W The included angle between the axles, the rotation angle theta of the wheels is X W Axis and Z W The axle being about the wheel axis of rotation Y W The angle through which the shaft rotates. The six-degree-of-freedom displacement measuring device and the method for the wheels measure the change rule of main wheel positioning parameters along with test loading under an automobile coordinate system.
In the prior art, the six-degree-of-freedom displacement measuring device for the wheels of the suspension characteristic test bed mainly has two forms. In the form of a measuring arm, six degrees of freedom displacement of the wheel is measured by 6 rotation axes and corresponding angle sensors. The folding state of the measuring arm is a mechanical zero position, which is the zero position of each joint angle sensor, the state that each joint of the measuring arm is mutually perpendicular is a measuring zero position, and a six-degree-of-freedom displacement solving formula of the wheel is usually deduced according to the position.
The method needs to identify the relative position of the tail end axis of the measuring arm and the rotation axis of the wheel, correct the parameter of the measuring arm resolving model to ensure the six-degree-of-freedom displacement resolving precision of the wheel, and the measuring arm mechanisms are connected in series, so that accumulated errors exist; in the test, each coordinate axis of the measuring arm coordinate system is required to be parallel to each coordinate axis of the automobile coordinate system, and the requirement on the installation precision 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 can influence the dynamic feedback of the corner at the joint; the other end of the measuring device is fixed with the test bed, and the movement is inconvenient.
The other type adopts a stay wire type displacement sensor to measure six degrees of freedom displacement change of the wheel, and mainly comprises 5 stay wires and a measuring disc for fixing the stay wires, the wheel can rotate around a Y axis relatively in a measuring mode, a photoelectric encoder arranged on the measuring disc measures the rotation angle of the wheel to obtain the rotation angle of the wheel, the longitudinal displacement and the vertical displacement of the wheel center are respectively measured along the stay wires of a X, Z axis, the lateral displacement, the toe angle and the camber angle of the wheel center are measured along 3 stay wires of the Y axis, and the problem that the resolution of an early angle sensor is insufficient is well solved by adopting the stay wire type displacement sensor, but the measurement accuracy is reduced when the movement of a vehicle body is faster.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a six-degree-of-freedom displacement measuring device and a six-degree-of-freedom displacement measuring method for a wheel in a suspension characteristic test, which enable the measurement of wheel positioning parameters in the test to be more convenient, flexible and accurate.
The invention is realized by the following technical scheme:
the six-degree-of-freedom displacement measuring device for the suspension characteristic test wheel comprises a binocular vision measuring instrument, an optical target, a data exchange device, an upper computer, a wheel positioning clamp and a reference clamp; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the measured vehicle is fixed on a test bench, the wheel positioning clamps are used for being installed on left and right wheels of the measured vehicle, the reference clamps are used for being installed on the measured vehicle and are fixed with the measured vehicle, the optical targets are multiple, one part of the optical targets are distributed on measuring planes of the wheel positioning clamps and the reference clamps, and the other part of the optical targets are distributed on a vehicle body of the measured vehicle; the first binocular vision measuring instrument and the second binocular vision measuring instrument are respectively used for being placed on the left side and the right side of a vehicle body of a tested vehicle to measure the space coordinate change of the optical target; the upper computer is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument through the data exchange device at the same time, and is used for controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to measure and obtain measurement data, and can calculate and obtain six-degree-of-freedom displacement of the wheels under the automobile coordinate system according to the measurement data.
Specifically, the wheel positioning clamp comprises a disc, a nut and an inner hexagon bolt; the disc is provided with straight slot openings which are circumferentially distributed and extend along the radial direction, a gap exists between the straight slot openings and the inner hexagon bolts, one ends of the inner hexagon bolts are connected with the wheel bolts of the tested vehicle, the other ends of the inner hexagon bolts penetrate through the straight slot openings which are circumferentially distributed on the disc, nuts are arranged on two sides of the disc through the inner hexagon bolts, and the nuts on two sides of the disc are identical in rotation direction.
And the two planes perpendicular to each other at the short end of the T-shaped plate are respectively used for being respectively bonded with the upper plane and the side plane of the frame longitudinal beam and connected with the frame through bolts, the long end of the T-shaped plate extends 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 plate through bolts.
In particular, the three optical targets are uniformly distributed circumferentially on the measurement plane of the wheel alignment jig for mounting on the left wheel, the three optical targets are uniformly distributed circumferentially on the measurement plane of the wheel alignment jig for mounting on the right wheel, the interval between each of the optical targets distributed on the measurement plane of the wheel alignment jig is 120 °, and the shape of each of the optical targets distributed on the measurement plane of the wheel alignment jig is circular.
And then specifically, three optical targets are distributed on the measuring plane of the reference fixture, the three optical targets are an upper target, a middle target and a right target respectively, the three optical targets are sequentially distributed in an L shape, the connecting line of the middle target and the upper target is perpendicular to the horizontal plane, the connecting line of the middle target and the right target is parallel to the advancing direction of the automobile, and the upper target, the middle target and the right target are round.
More specifically, the first binocular vision measuring instrument is used for being placed on the left side of the vehicle body and facing the left wheel, and the optical targets distributed on the measuring plane of the wheel positioning clamp of the left wheel and the optical targets on the measuring plane of the reference clamp are arranged in the view field of the first binocular vision measuring instrument; the second binocular vision measuring instrument is used for being placed on the right side of the automobile body and right facing the right wheel, and the optical targets distributed on the measuring plane of the wheel positioning clamp of the right wheel are arranged in the field of view of the second binocular vision measuring instrument; round optical targets with certain intervals are continuously distributed on the vehicle body from right above the left wheel to right wheel, a part of targets distributed on the vehicle body at one end of the left wheel are in the view of the first binocular vision measuring instrument, and a part of targets distributed on the vehicle body at one end of the right wheel are in the view of the second binocular vision measuring instrument.
The invention also comprises a six-degree-of-freedom displacement measuring method for the suspension characteristic test wheel, which comprises a binocular vision measuring instrument, an optical target, a data exchange device, an upper computer, a wheel positioning clamp and a reference clamp; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning clamp comprises a disc, the reference clamp comprises a flat plate, and the measuring method comprises the following steps:
e1: fixing the tested vehicle on a test bench, mounting a wheel positioning clamp on a wheel of the tested vehicle, enabling a disc to be parallel to the middle plane of the wheel and coaxial with the wheel, mounting a reference clamp on a frame of the tested vehicle, and enabling a flat plate to be parallel to the longitudinal symmetry plane of a vehicle body of the tested vehicle;
e2: the method comprises the steps that optical targets are distributed at intervals from the left side to the right side of a vehicle body of a tested vehicle, and the relative position relationship among the optical targets on the vehicle body is measured;
e3: the method comprises the steps that optical targets are distributed on a wheel positioning clamp and a reference clamp, so that a first binocular vision measuring instrument is opposite to a left wheel, a second binocular vision measuring instrument is opposite to a right wheel, the distance between the binocular vision measuring instrument and the wheels is adjusted, the optical targets distributed on the left side of a vehicle body are located in the view field of the first binocular vision measuring instrument, and the optical targets on the right side of the vehicle body are located in the view field of the second binocular vision measuring instrument;
E4: one end of the data exchange device is connected with the upper computer, the other end of the data exchange device is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument, the upper computer is started, and the coordinate conversion relation between the first binocular vision measuring instrument and the second binocular vision measuring instrument is established through the relative position relation between the optical targets on the vehicle body;
e5: and selecting an optical target on the wheel positioning clamp, loading the tested vehicle, and simultaneously controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to synchronously measure the spatial coordinate change of the selected target, and calculating the spatial angle change of the wheel middle plane and the spatial coordinate change of the wheel center under the automobile coordinate system through the spatial coordinate change of the three optical targets on the wheel positioning clamp and the distance between the disc measuring plane and the wheel middle plane to obtain the six-degree-of-freedom displacement of the left and right wheels under the automobile coordinate system.
Specifically, the relative positional relationship between the optical targets on the vehicle body in the step E2 is established by the following method:
the optical targets are continuously distributed from the left side to the right side of the vehicle body at certain intervals, the first binocular vision measuring instrument is continuously moved to measure the relative position relationship between the targets on the vehicle body, wherein part of old optical targets remained in the last step and new optical targets which just enter the field of view of the first binocular vision measuring instrument are arranged in the field of view of each step after each step of movement to ensure the continuous transition of the relative position relationship.
More specifically, establishing the coordinate conversion relationship between the first binocular vision measuring instrument and the second binocular vision measuring instrument in the step E4 includes:
measuring the spatial coordinates of the optical targets on the right side of the vehicle body in the second binocular vision meter vision field under the second binocular vision meter coordinate system, measuring the spatial coordinates of the optical targets on the left side of the vehicle body in the first binocular vision meter vision field under the first binocular vision meter coordinate system,
the spatial coordinates of the targets on the right side of the vehicle body which are not in the view of the first binocular vision measuring instrument in the first binocular vision measuring instrument coordinate system are obtained through the relative position relation among the targets on the vehicle body,
and the number of targets on the right side of the vehicle body is greater than or equal to the unknown number of the transformation matrix T, so that the transformation matrix T of the second binocular vision measuring instrument coordinate system relative to the first binocular vision measuring instrument coordinate system is obtained.
The invention also comprises a six-degree-of-freedom displacement measuring method for the suspension characteristic test wheel, which comprises a binocular vision measuring instrument, an optical target and a plane clamp; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, and the measuring method comprises the following steps:
F1: the plane clamp is arranged in front of the head of a tested vehicle, extends from right to left wheels, distributes optical targets on the clamp plane fixed on a test bench, respectively places a first binocular vision measuring instrument and a second binocular vision measuring instrument on the left side and the right side of the body of the tested vehicle, establishes a coordinate conversion relation between the first binocular vision measuring instrument and the second binocular vision measuring instrument according to the relative position relation between the optical targets on the body, and converts the space coordinates of the optical targets measured in the field of view of the second binocular vision measuring instrument into the coordinate system of the first binocular vision measuring instrument;
f2: establishing a six-degree-of-freedom displacement measurement reference coordinate system of the wheel parallel to an automobile coordinate system through the space coordinates of three optical targets on the reference fixture;
f3: according to the principle of 'three-point determination of one plane', the spatial angle change of the middle plane of the wheel under the automobile coordinate system and the spatial coordinate change of the wheel center are calculated through the spatial coordinate change of the three optical targets on the wheel positioning clamp and the distance between the disc measuring plane and the middle plane of the wheel, so that the six-degree-of-freedom displacement of the left and right wheels under the automobile coordinate system is obtained.
The invention also comprises the following calculation method of six-degree-of-freedom displacement of the wheel:
T31: the first binocular vision measuring instrument is used for directly measuring the space coordinates of coordinate points A4, A5 and A6 of the optical target on the left wheel positioning clamp disc under the coordinate system of the first binocular vision measuring instrumentIndirectly measuring spatial coordinates of coordinate points A7, A8 and A9 of an optical target on a right wheel positioning clamp disc under a first binocular vision measuring instrument coordinate system>
T32: the rotation axis vectors and the wheel center coordinates of the left and right wheels can be expressed as follows in a first binocular vision measuring instrument coordinate system according to vector operation:
wherein, I WL For measuring the distance between the plane and the middle plane of the left wheel for the left disc, l WR The distance between the plane and the middle plane of the right wheel is measured for the right disc.
T33: the rotation axis vectors and the wheel center coordinates of the left and right wheels can be transferred from the first binocular vision measuring instrument coordinate system to the automobile coordinate system according to the cosine law, and the rotation axis vectors and the wheel center coordinates are expressed as:
t34: the three-degree-of-freedom linear displacement of the left and right wheels in the automobile coordinate system is measured according to the spatial coordinate change of the wheel centers of the left and right wheels in the automobile coordinate system, the three-degree-of-freedom angular displacement of the left and right wheels in the automobile coordinate system is measured according to the change of the included angle between the vector of the connecting line of the targets on the left and right wheel rotating axes and the automobile coordinate system in the automobile coordinate system, the calculation methods of the left and right wheel angular displacement are the same, the change amounts of the toe angle, the camber angle and the rotating angle of the left and right wheels are the same, and the toe angle delta and the camber angle lambda of the wheels are calculated by using the wheel rotating axis vector under the automobile coordinate system as an example of the left wheel.
Using the car coordinate systemVector solution wheel rotation angle θ:
optionally, the invention relates to a multi-degree-of-freedom displacement measuring device for a wheel in a suspension characteristic test, which is characterized by comprising a binocular vision measuring instrument, an optical target, a data exchange device, an upper computer, a wheel positioning clamp and a reference clamp; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the measured vehicle is fixed on a test bench, the wheel positioning clamp is used for being installed on left and right wheels of the measured vehicle, the reference clamp is used for being installed on a frame of the measured vehicle, the optical targets are multiple, one part of the optical targets are distributed on measuring planes of the wheel positioning clamp and the reference clamp, and the other part of the optical targets are distributed on a vehicle body of the measured vehicle; the first binocular vision measuring instrument and the second binocular vision measuring instrument are respectively used for being placed on the left side and the right side of a vehicle body of a tested vehicle to measure the space coordinate change of the optical target; the upper computer is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument through the data exchange device at the same time, and is used for controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to measure and obtain measurement data, and calculating and obtaining the multi-degree-of-freedom displacement of the wheels under the automobile coordinate system according to the measurement data.
The invention also comprises a multi-degree-of-freedom displacement measuring method for the wheel of the suspension characteristic test, which is characterized by comprising a binocular vision measuring instrument, an optical target, a data exchange device, an upper computer, a wheel positioning clamp and a reference clamp; the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning clamp comprises a disc, the reference clamp comprises a flat plate, and the measuring method comprises the following steps:
e1: fixing the tested vehicle on a test bench, mounting a wheel positioning clamp on a wheel of the tested vehicle, enabling a disc to be parallel to the middle plane of the wheel and coaxial with the wheel, mounting a reference clamp on a frame of the tested vehicle, and enabling a flat plate to be parallel to the longitudinal symmetry plane of a vehicle body of the tested vehicle;
e2: the method comprises the steps that optical targets are distributed at intervals from the left side to the right side of a vehicle body of a tested vehicle, and the relative position relationship among the optical targets on the vehicle body is measured;
e3: the method comprises the steps that optical targets are distributed on a wheel positioning clamp and a reference clamp, so that a first binocular vision measuring instrument is opposite to a left wheel, a second binocular vision measuring instrument is opposite to a right wheel, the distance between the binocular vision measuring instrument and the wheels is adjusted, the optical targets distributed on the left side of a vehicle body are located in the view field of the first binocular vision measuring instrument, and the optical targets on the right side of the vehicle body are located in the view field of the second binocular vision measuring instrument;
E4: one end of the data exchange device is connected with the upper computer, the other end of the data exchange device is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument, the upper computer is started, and the coordinate conversion relation between the first binocular vision measuring instrument and the second binocular vision measuring instrument is established through the relative position relation between the optical targets on the vehicle body;
e5: and selecting an optical target on the wheel positioning clamp, loading the tested vehicle, and simultaneously controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to synchronously measure the spatial coordinate change of the selected target, and calculating the spatial angle change of the wheel middle plane and/or the spatial coordinate change of the wheel center under the automobile coordinate system through the spatial coordinate change of the three optical targets on the wheel positioning clamp and the distance between the disc measuring plane and the wheel middle plane to obtain the wheel multi-degree-of-freedom displacement under the automobile coordinate system.
The invention has the beneficial effects that:
(1) The binocular vision measuring instrument is adopted to carry out non-contact measurement on the multi-degree-of-freedom displacement of the wheel in the suspension characteristic test, so that the arrangement, the installation, the adjustment and the measurement of the measuring device are more convenient and quicker;
(2) The coordinate conversion relation between the two binocular vision measuring instruments is established, so that six-degree-of-freedom displacement of the left and right wheels is unified under one coordinate system, and the movement relation between the left and right wheels is more convenient and accurate in analysis;
(3) An automobile coordinate system fixed on the automobile body is established through target coordinates on the reference fixture, and six-degree-of-freedom displacement of the left and right wheels to be measured is converted into the automobile coordinate system, so that the measurement reference and the measurement displacement are more accurate in definition;
(4) The six-degree-of-freedom displacement of the wheel is solved through the change of the target coordinates on the positioning clamp, the mathematical model is simple and accurate, and the installation error of the measuring mechanism when the measuring mechanism is connected with the positioning clamp during contact measurement is eliminated;
(5) The upper computer program controls the two binocular vision measuring instruments to carry out synchronous tracking measurement, thereby facilitating the integration of a test bed system and enabling the six-degree-of-freedom displacement of the left and right wheels to be accurately corresponding to the excitation of the test bed at each moment.
Drawings
FIG. 1 is a schematic diagram of an automotive coordinate system;
FIG. 2 is a schematic illustration of a wheel coordinate system;
FIG. 3 is an overall schematic of the present invention;
FIG. 4 is a left side wheel measurement schematic of the present invention;
FIG. 5 is a right side wheel measurement schematic of the present invention;
FIG. 6 is a wheel alignment jig structure of the present invention;
FIG. 7 is a reference fixture structure of the present invention;
FIG. 8 is a measurement schematic of the present invention;
FIG. 9 is a schematic view of a wheel space angle;
Fig. 10 is a schematic diagram of another embodiment of the present invention.
In the figure:
11. 12, 13, reference jig optical targets, 14, 15, 16, left wheel alignment jig optical targets, 17, 18, 19, right wheel alignment jig optical targets; 2. the device comprises a reference clamp, 21. A connecting bolt, 22. A T-shaped plate, 23. An L-shaped plate and 24. A flat plate; 3. wheel alignment fixture, 31, left wheel alignment fixture disc, 32, nut, 33, socket head cap bolt, 34, right wheel alignment fixture disc; 41. a first binocular vision measuring instrument 42; 5. a data exchange device; 6. an upper computer; 7. a test bed; 8. the vehicle under test, 81, left side wheels, 82, right side wheels, 83, frame.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Fig. 3 is an overall schematic diagram of the six-degree-of-freedom displacement measuring device and method for suspension characteristic test wheels according to the present invention, which mainly includes a first binocular vision measuring instrument 41, a second binocular vision measuring instrument 42, a data exchange device 5, an upper computer 6, a wheel positioning jig 3, and a reference jig 2. As shown in fig. 3 to 7, the vehicle 8 to be tested is fixed to the test stand 7, the wheel alignment jig 3 is mounted on left and right wheels 81, 82 of the vehicle 8 to be tested, and the reference jig 2 is mounted on and fixed to the vehicle to be tested, preferably, a frame 83 of the vehicle to be tested; one part of the optical targets are distributed on the measuring planes of the wheel positioning clamp 3 and the reference clamp 2, the other part of the optical targets are distributed on the vehicle body, and the relative position relationship between the targets on the vehicle body is measured by continuously moving the first binocular vision measuring instrument 41, so that a transformation matrix T between the coordinate systems of the two binocular vision measuring instruments is solved; the two binocular vision measuring instruments 41 and 42 are respectively placed on two sides of a vehicle body of the tested vehicle 8, the spatial coordinate change of the optical target on the plane of the measuring fixture is unified under the coordinate system of the first binocular vision measuring instrument, the upper computer 6 is connected with the binocular vision measuring instrument through the data exchange device 5, the binocular vision measuring instrument is controlled to measure and obtain measurement data, and the six-degree-of-freedom displacement of the wheels under the coordinate system of the vehicle is calculated according to the measured data.
As shown in fig. 6, the structure diagram of the left wheel alignment fixture of the six-degree-of-freedom displacement measuring device for the suspension characteristic test wheel of the invention comprises a disc 31, six nuts 32 and three inner hexagon bolts 33, wherein one end of each inner hexagon bolt 33 is connected with the corresponding wheel bolt, the other end of each inner hexagon bolt passes through a straight slot 35 radially distributed on the disc 31, the diameter of each inner hexagon bolt is smaller than the width of the corresponding straight slot 35, a certain adjusting gap exists between each inner hexagon bolt and the corresponding straight slot, the disc 31 can move along the axial direction of the corresponding inner hexagon bolt 33 and the radial direction of the disc 31 through the corresponding straight slot, the nuts 32 with the same rotation direction are screwed on the inner hexagon bolts 33 on two sides of the disc plane, the posture of the disc 31 is adjusted to be parallel and coaxial with the middle plane of the left wheel 81, the posture of the disc 31 is determined by opposite jacking of the nuts 32 on two sides, and the disc 31 is fixed, and the structure and the installation requirements of the wheel alignment fixture 3 on the left wheel 81 and the right wheel 81 are the same. The stability of the clamp is guaranteed by screwing the nuts with the same screwing direction on the inner hexagon bolts on two sides of the plane, and the straight notch is convenient to install, convenient to adjust, applicable to various wheel models and high in applicability.
As shown in FIG. 7, the reference clamp of the six-degree-of-freedom displacement measuring device for the suspension characteristic test wheel of the invention is a structure diagram of the reference clamp, the reference clamp can be arranged on any side of a vehicle body, the reference clamp comprises a connecting bolt 21, a T-shaped plate 22, an L-shaped plate 23 and a flat plate 24, two ends of the T-shaped plate 22 are asymmetric, planes perpendicular to each other at the short ends of the T-shaped plate 22 are respectively bonded with the upper plane and the side plane of a longitudinal beam of a frame 83 and are connected with the frame 83 through the bolt 21, the long ends of the T-shaped plate 22 extend out of the vehicle body, two ends perpendicular to each other of the L-shaped plate 23 are respectively connected with the long ends of the T-shaped plate 22 and the flat plate 24 through the bolt 21, the flat plate plane is parallel to the longitudinal symmetry plane of the vehicle, and the reference clamp is directly arranged on the frame through the structure, so that the reference clamp is simple in structure, convenient and stable to install, and high in applicability.
Fig. 4 is a left side schematic view of the six-degree-of-freedom displacement measuring device and method for a suspension characteristic test wheel according to the present invention, taking the reference fixture installed on the left side of the vehicle body as an example, as shown in fig. 3-4, the device mainly comprises a first binocular vision measuring instrument 41, a left side wheel 81, a wheel positioning fixture 3, a reference fixture 2, and an optical target; wherein, three optical targets 14, 15, 16 are uniformly distributed along the circumference on the measuring plane of the positioning fixture disc 31 fixed with the left wheel 81, and the targets are spaced by 120 degrees; three optical targets 11, 12 and 13 are distributed on the measuring plane of the reference clamp flat plate 24 fixed with the frame 83 in an L shape, the target 11 is above the target 12, the target 13 is on the right side of the target 12, the connecting line of the target 12 and the target 11 is perpendicular to the horizontal plane, and the connecting line of the target 12 and the target 13 is parallel to the advancing direction of the automobile; the first binocular vision measuring instrument 41 is opposite to the wheel positioning jig 3 and the reference jig 2, is about 2 meters from the measuring plane of the disc 31, measures the spatial coordinate changes of the targets 11, 12, 13, 14, 15, 16 on the jig measuring plane in the field of view thereof under the first binocular vision measuring instrument coordinate system, and transmits the measured data to the upper computer 6 through the data exchange device 5.
Fig. 5 is a right side schematic view of the six-degree-of-freedom displacement measuring device and method for suspension characteristic test wheels according to the present invention, including a second binocular vision measuring instrument 42, a right side wheel 82, a wheel positioning jig 3, and an optical target; wherein, three optical targets 17, 18, 19 are uniformly distributed along the circumference on the measuring plane of the positioning fixture disc 34 fixed with the right wheel 82, and the target intervals are 120 degrees; the second binocular vision measuring instrument 42 is opposite to the wheel alignment jig disc 34, is about 2 meters from the measuring plane thereof, measures the spatial coordinate change of the targets 17, 18, 19 on the jig measuring plane in the field of view thereof under the coordinate system of the first binocular vision measuring instrument, and transmits the measured data to the upper computer 6 through the data exchange device 5.
As shown in fig. 8, which is a measurement schematic diagram of a six-degree-of-freedom displacement measurement method for a wheel for suspension characteristic test according to the present invention, the coordinate of the target in the second binocular vision measuring apparatus in the field of view under the coordinate system can be converted into the coordinate system of the first binocular vision measuring apparatus by the conversion matrix T, and the spatial coordinates of the coordinate points A1, A2, A3, A4, A5, A6 of the optical targets 11, 12, 13, 14, 15, 16 on the reference jig plate 24 and the left wheel positioning jig disc 31 under the coordinate system of the first binocular vision measuring apparatus can be directly measured by the first binocular vision measuring apparatus 41 Spatial coordinates +_ of coordinate points A7, A8, A9 of the optical targets 17, 18, 19 on the right wheel alignment jig disc 34 under the first binocular vision measuring instrument coordinate system can be indirectly measured>
Automobile coordinate system X V 、Y V 、Z V The vector of axes can be expressed as:
the vector between the optical targets on the left wheel alignment jig disc 31 can be expressed as:
the vector between the optical targets on the right wheel alignment jig disc 34 can be expressed as:
the left and right wheel axis of rotation vectors can be expressed as:
wherein, I WL For the distance between the left wheel alignment jig disc measurement plane and the left wheel intermediate plane, l WR The distance between the plane and the right wheel center plane is measured for the right wheel alignment jig disc.
Origin O of automobile coordinate system V The vector to the left and right side hubs can be expressed as:
left and right wheel axis vector sum vectorExpressed in the car coordinate system as:
the coordinates of the left and right wheel center points in the automobile coordinate system are as follows:
according to the displacement diagram of six degrees of freedom of the right wheel in fig. 9, it can be seen that 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 that the wheel center W is along the vehicle coordinate system X V 、Y V 、Z V Displacement of the shaft, namely spatial coordinate change of the wheel center W under an automobile coordinate system; the rotational displacement of the wheel under the automobile coordinate system is the wheel coordinate system X W 、Z W Shaft and automobile coordinate system X V 、Z V Variation of the angle between the axes and X W 、Z W Around axis Y W A change in the shaft rotation angle;
it can be seen that the wheel axis of rotation vectorAnd Y is equal to W Axis of coincidence, X W The axis is X V -Y V On plane, X W Axis and X V The angle of the axle is the toe angle delta of the wheel, the tangent of which is equal to +.>Vector at X V Axes and Y V Ratio of components on the axis. Z is Z V The axis is at Y W -Z W On plane, Z V Axis and Z W The angle of the axes being equal to Y W Axis and X at V -Y V The included angle between the projections on the plane is the camber angle lambda, and the sine value of the included angle lambda is equal to +.>Vector at Z V The ratio of the component on the axis to its mode. The rotation angle theta of the wheel is X W Axis and Z W The axle being about the wheel axis of rotation Y W The angle of rotation of the shaft is also Y due to the measurement point P of the wheel center W On the shaft, the rotation angle of the wheel is the same as the angle of the vector between the targets of the wheel positioning clamp rotating around the point P, and is approximately equal to the vector between the targets of the wheel positioning clamp and Z in the automobile coordinate system V The change of the included angle between the axles, the sine value of the included angle is equal to the vector between the targets of the wheel positioning clamp under the automobile coordinate system at Z V The ratio of the component on the axis to its mode.
The calculation methods of the left and right wheel angular displacements are the same, and are the variation of the toe-in angle, the camber angle and the rotation angle of the left and right wheels, taking the left wheel as an example, and calculating the toe-in angle delta and the camber angle lambda of the wheels by using the wheel rotation axis under the automobile coordinate system:
vector between targets of wheel positioning fixture under automobile coordinate systemAnd (3) calculating a wheel rotation angle theta:
one embodiment of the invention comprises the following test steps:
s1: the test vehicle 8 is fixed on the test bed 7, and the reference jig 2 and the wheel alignment jig 3 are installed:
s11: the wheel positioning clamp 3 is arranged on a wheel, one end of three inner hexagon bolts 33 are connected with the wheel through bolts, the other end of the three inner hexagon bolts passes through straight notches distributed in the radial direction on the disc 31, the posture of the disc 31 is determined by opposite jacking of nuts 32 on two sides of the disc and is fixed, the wheel is rotated after the wheel is suspended, the dial indicator is used for measuring the runout of the disc plane during rotation, if the runout of a certain position of the edge of the disc is large, the spatial posture of the disc plane is adjusted by adjusting the front-back position of the disc on the bolt axis until the requirement is met, the disc axis is considered to be parallel to the wheel rotation axis, the wheel is rotated as well, the rotation offset of the disc cylindrical surface is measured by using the dial indicator, and the spatial position of the disc axis is adjusted by adjusting the position of the disc along the radial direction of the disc in a chute, so that the disc coincides with the wheel rotation axis;
S12: the standard fixture 2 is arranged on the frame 83, the planes of the short ends of the T-shaped plates 22 which are mutually perpendicular are respectively bonded with the upper plane and the side plane of the longitudinal beam of the frame 83 and are connected with the frame 83 through bolts 21, and the two ends of the L-shaped plates 23 which are mutually perpendicular are respectively connected with the long ends of the T-shaped plates 22 and the flat plates 24 through bolts 21, so that the flat plates are parallel to the longitudinal symmetry plane of the vehicle body;
s2: continuously distributing optical targets 1 (shown in fig. 3) at intervals of about 0.5 m from the left side to the right side of the vehicle body, measuring the relative position relationship between targets on the vehicle body by continuously moving a first binocular vision measuring instrument, requiring part of old targets remained in the last step and new targets just entering the field in the field of view after each step to ensure continuous transition of the relative position relationship, for example, measuring the space coordinates of optical targets a and b in the field of view at the ith step of the first binocular vision measuring instrument movement to obtain the relative position relationship between targets a and b, measuring the space coordinates of optical targets b and c in the field of view at the (i+1) th step of the first binocular vision measuring instrument movement to obtain the relative position relationship between targets b and c, calculating the relative position relationship between targets a and c by the target b, and obtaining the relative position relationship between targets distributed on the vehicle body in the same way;
S3: optical targets are distributed on the wheel positioning clamp 3 and the reference clamp 2 according to requirements, so that targets on two sides of a vehicle body are respectively positioned in the fields of view of the first binocular vision measuring instrument and the second binocular vision measuring instrument:
s31: three circular optical targets 14, 15 and 16 are uniformly attached to the measuring plane of the left wheel alignment jig disc 31 along the circumference, three circular optical targets 17, 18 and 19 are uniformly attached to the measuring plane of the right wheel alignment jig disc 34 along the circumference, and the two targets are spaced by 120 degrees;
s32: three circular optical targets 11, 12 and 13 are attached to the measuring plane of the reference clamp flat plate 24 in an L shape, wherein the target 11 is above the target 12, the target 13 is on the right side of the target 12, the connecting line of the target 12 and the target 11 is perpendicular to the horizontal plane, and the connecting line of 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 measured and facing the measuring plane of the wheel positioning jig disc 31 and the reference jig flat plate 24 (taking the reference jig on the left side of the vehicle body as an example), and adjusting the distance between them so that the optical targets 11, 12, 13, 14, 15, 16 are distributed in the field of view of the first binocular vision measuring instrument;
s34: placing a second binocular vision measuring instrument 42 on the right side of the body of the measured vehicle 8 and facing the measuring plane of the wheel positioning clamp disc 34, and adjusting the distance between the two to enable the optical targets 17, 18 and 19 to be distributed in the field of vision of the second binocular vision measuring instrument;
S4: one end of the data exchange device 5 is connected with the upper computer 6, the other end of the data exchange device is connected with the two binocular vision measuring instruments, the upper computer 6 is started, a measuring instrument control program is operated, the relative position relation between targets on a vehicle body is imported to establish the coordinate conversion relation between the two binocular vision measuring instruments, the optical targets on the clamp are selected, the two binocular vision measuring instruments are controlled to synchronously track and measure the spatial coordinate change of the selected targets while the test bed starts to be loaded, the measurement is stopped when the test is finished, and the measuring instrument control program stops operating.
The invention comprises the following calculation steps:
t1: establishing a coordinate conversion relation between the two binocular vision measuring instruments according to the relative position relation between targets on the vehicle body, and converting the spatial coordinate points of the optical targets measured in the field of view of the second binocular vision measuring instrument into the coordinate system of the first binocular vision measuring instrument:
t11: the spatial coordinates of targets on the right side in the visual field of the second binocular vision measuring instrument under the second binocular vision measuring instrument coordinate system and the spatial coordinates of targets on the left side in the visual field of the first binocular vision measuring instrument under the first binocular vision measuring instrument coordinate system are known, the spatial coordinates of targets on the right side not in the visual field of the first binocular vision measuring instrument under the first binocular vision measuring instrument coordinate system can be obtained through the relative position relation among the targets on the vehicle body, and the number of the targets on the right side is larger than or equal to the unknown number of the conversion matrix T, so that the conversion matrix T of the second binocular vision measuring instrument coordinate system in the first binocular vision measuring instrument coordinate system can be obtained;
T12: multiplying the coordinate points B7, B8, B9 of the optical targets 17, 18, 19 on the disc 34 under the second binocular vision measuring instrument coordinate system by the transformation matrix T to obtain the space coordinates of the coordinate points A7, A8, A9 of the optical targets 17, 18, 19 under the first binocular vision measuring instrument coordinate system
T2: the spatial coordinates of the three optical targets 11, 12, 13 on the reference jig 2 in its field of view, measured by the first binocular vision meter 41, establish a six degree-of-freedom displacement measurement reference coordinate system of the wheel parallel to the vehicle coordinate system:
t21: the first binocular vision measuring instrument 41 can measure the space coordinates of the coordinate points A1, A2 and A3 of the optical targets 11, 12 and 13 on the reference fixture flat plate 24 under the coordinate system of the first binocular vision measuring instrument(Vector)With the car coordinate system Z V Axis parallel, vector->With the automobile coordinate system X V Axis parallel, vector->And->Is the outer product of (2) and the automobile coordinate system Y V Parallel axes, automobile coordinate system X V The vector of the axis can be expressed as +.>Automobile coordinate system Z V The vector of the axis can be expressed as +.>Automobile coordinate system Y V The vector of axes can be expressed as
T3: according to the principle of 'three-point determination of one plane', the spatial angle change of the middle plane of the wheel under the automobile coordinate system and the spatial coordinate change of the wheel center are calculated through the spatial coordinate change of three optical targets on the wheel positioning clamp and the distance between the disc measuring plane and the middle plane of the wheel, so that six-degree-of-freedom displacement of the left and right wheels under the automobile coordinate system is obtained:
T31: the first binocular vision measuring instrument 41 can directly measure the space coordinates of coordinate points A4, A5 and A6 of the optical targets 14, 15 and 16 on the left wheel positioning clamp disc 31 under the coordinate system of the first binocular vision measuring instrument Spatial coordinates +_ of coordinate points A7, A8, A9 of the optical targets 17, 18, 19 on the right wheel alignment jig disc 34 under the first binocular vision measuring instrument coordinate system can be indirectly measured>
T32: the rotation axis vectors and the wheel center coordinates of the left and right wheels can be expressed as follows in a first binocular vision measuring instrument coordinate system according to vector operation:
wherein, I WL For measuring the distance between the plane and the middle plane of the left wheel for the left disc, l WR The distance between the plane and the middle plane of the right wheel is measured for the right disc.
T33: the rotation axis vectors and the wheel center coordinates of the left and right wheels can be transferred from the first binocular vision measuring instrument coordinate system to the automobile coordinate system according to the cosine law, and the rotation axis vectors and the wheel center coordinates are expressed as:
t34: the three-degree-of-freedom linear displacement of the left and right wheels in the automobile coordinate system is measured according to the spatial coordinate change of the wheel centers of the left and right wheels in the automobile coordinate system, the three-degree-of-freedom angular displacement of the left and right wheels in the automobile coordinate system is measured according to the change of the included angle between the vector of the connecting line of the targets on the left and right wheel rotating axes and the automobile coordinate system in the automobile coordinate system, the calculation methods of the left and right wheel angular displacement are the same, the change amounts of the toe angle, the camber angle and the rotating angle of the left and right wheels are the same, and the toe angle delta and the camber angle lambda of the wheels are calculated by using the wheel rotating axis vector under the automobile coordinate system as an example of the left wheel.
Using the car coordinate systemVector solution wheel rotation angle θ:
optionally, although the invention relates to a device and a method for measuring six-degree-of-freedom displacement of a wheel in a suspension characteristic test, according to actual measurement needs, the invention can be used for measuring displacement of a certain degree of freedom or displacement of a certain degree of freedom of the wheel, namely the invention also relates to a device and a method for measuring multiple degrees of freedom displacement of the wheel in the suspension characteristic test, and the invention is not limited to measuring only six degrees of freedom.
As shown in fig. 10, another embodiment of the present invention is that the optical targets 111 for establishing the coordinate conversion relationship between the two binocular vision measuring instruments are distributed on the fixture plane of the plane fixture 9 fixed to the test bed, the plane fixture 9 is installed in front of the vehicle head, and extends from the right side wheel to the right side wheel, the distribution requirements of the optical targets 111 and the measurement method of the relative positional relationship are the same as those in the above embodiment, and the relative positional relationship between the optical targets can be used in the subsequent test after the first measurement.
The above embodiments are only preferred embodiments of the present invention, not limiting, and various changes and modifications can be made by one skilled in the relevant art without departing from the spirit and scope of the invention, so all equivalent technical solutions fall within the scope of the invention.

Claims (8)

1. The six-degree-of-freedom displacement measuring device for the wheel of the suspension characteristic test is characterized by comprising a binocular vision measuring instrument, an optical target, a data exchange device (5), an upper computer (6), a wheel positioning clamp (3) and a reference clamp (2); the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, a vehicle (8) to be measured is fixed on a test bench (7), the wheel positioning clamps are used for being installed on left and right wheels of the vehicle to be measured, the reference clamps are used for being installed on the vehicle to be measured and fixed with the vehicle to be measured, the optical targets are multiple, one part of the optical targets are distributed on measuring planes of the wheel positioning clamps and the reference clamps, and the other part of the optical targets are used for being distributed on a body of the vehicle to be measured; the first binocular vision measuring instrument and the second binocular vision measuring instrument are respectively used for being placed on the left side and the right side of a vehicle body of a tested vehicle to measure the space coordinate change of the optical target; the upper computer is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument through the data exchange device at the same time, and is used for controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to measure and obtain measurement data, continuously moving the first binocular vision measuring instrument to measure the relative position relation between targets on a vehicle body, solving a conversion matrix T between coordinate systems of the two binocular vision measuring instruments, and calculating according to the measurement data to obtain six-degree-of-freedom displacement of wheels under the coordinate system of the vehicle;
The wheel positioning clamp comprises a disc (31), a nut (32) and an inner hexagon bolt (33); the disc is provided with straight slot openings which are circumferentially distributed and extend along the radial direction, a gap is reserved between the straight slot openings and the inner hexagon bolts, one end of each inner hexagon bolt is connected with a wheel bolt of a tested vehicle, the other end of each inner hexagon bolt penetrates through the straight slot openings distributed on the disc, nuts are arranged on two sides of the disc through the inner hexagon bolts, and the nuts on two sides of the disc are identical in rotation direction;
the first binocular vision measuring instrument (41) is used for being placed on the left side of the automobile body and right facing the left wheel (81), and the optical targets distributed on the measuring plane of the wheel positioning clamp of the left wheel and the optical targets on the measuring plane of the reference clamp are arranged in the visual field of the first binocular vision measuring instrument; the second binocular vision measuring instrument (42) is used for being placed on the right side of the vehicle body and right facing the right wheel (82), and optical targets distributed on the measuring plane of the wheel positioning clamp of the right wheel are arranged in the view field of the second binocular vision measuring instrument; round optical targets with certain intervals are continuously distributed on the vehicle body from right above the left wheel to right wheel, a part of targets distributed on the vehicle body at one end of the left wheel are in the view of the first binocular vision measuring instrument, and a part of targets distributed on the vehicle body at one end of the right wheel are in the view of the second binocular vision measuring instrument;
Three optical targets (14, 15, 16) are uniformly distributed circumferentially on a measurement plane of a disc of a wheel alignment jig for mounting on a left wheel (81), and three optical targets (17, 18, 19) are uniformly distributed circumferentially on a measurement plane of a disc of a wheel alignment jig for mounting on a right wheel (81);
three optical targets (11, 12, 13) are distributed on the measuring plane of the reference fixture, the three optical targets are an upper target, a middle target and a right target respectively, the three optical targets are distributed in an L shape in sequence, a connecting line of the middle target (12) and the upper target (11) is perpendicular to a horizontal plane, a connecting line of the middle target (12) and the right target (13) is parallel to the advancing direction of an automobile, and the measuring plane of the reference fixture is parallel to the longitudinal symmetrical plane of a vehicle body of a tested vehicle.
2. A six degree of freedom displacement measuring apparatus for a wheel for a suspension characteristic test according to claim 1, wherein the reference jig comprises a connecting bolt (21), a T-shaped plate (22), an L-shaped plate (23), a flat plate (24), both ends of the T-shaped plate being asymmetric, having long and short ends, the vehicle being tested comprising a frame, the frame of the vehicle being tested having a longitudinal beam having an upper plane and a side plane, both planes of the short end of the T-shaped plate being mutually perpendicular for respectively engaging with the upper plane and the side plane of the longitudinal beam of the frame and being connected with the frame by bolts, the long end of the T-shaped plate extending outside the vehicle body, both ends of the L-shaped plate being mutually perpendicular being respectively connected with the long end of the T-shaped plate and the flat plate by bolts.
3. A six degree-of-freedom displacement measuring apparatus for a wheel for a suspension characteristic test according to any one of claims 1 to 2, wherein the interval between each of the optical targets distributed on the measuring plane of the wheel alignment jig is 120 ° and the shape of each of the optical targets distributed on the measuring plane of the wheel alignment jig is circular.
4. A six degree of freedom displacement measuring apparatus for a wheel for a suspension property test according to any one of claims 1 to 2, wherein the upper target, the middle target and the right target are circular in shape.
5. A six-degree-of-freedom displacement measurement method for a wheel for a suspension characteristic test, characterized in that the measurement method is carried out according to the six-degree-of-freedom displacement measurement device for a wheel for a suspension characteristic test according to any one of claims 1 to 4, and comprises a binocular vision measuring instrument, an optical target, a data exchange device (5), an upper computer (6), a wheel positioning clamp (3) and a reference clamp (2); the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, the wheel positioning clamp comprises a disc, the reference clamp comprises a flat plate, and the measuring method comprises the following steps:
E1: fixing the tested vehicle on a test bench, mounting a wheel positioning clamp on a wheel of the tested vehicle, enabling a disc to be parallel to the middle plane of the wheel and coaxial with the wheel, mounting a reference clamp on a frame of the tested vehicle, and enabling a flat plate to be parallel to the longitudinal symmetry plane of a vehicle body of the tested vehicle;
e2: the method comprises the steps that optical targets are distributed at intervals from the left side to the right side of a vehicle body of a tested vehicle, and the relative position relationship among the optical targets on the vehicle body is measured;
e3: the method comprises the steps that optical targets are distributed on a wheel positioning clamp and a reference clamp, so that a first binocular vision measuring instrument is opposite to a left wheel, a second binocular vision measuring instrument is opposite to a right wheel, the distance between the binocular vision measuring instrument and the wheels is adjusted, the optical targets distributed on the left side of a vehicle body are located in the view field of the first binocular vision measuring instrument, and the optical targets on the right side of the vehicle body are located in the view field of the second binocular vision measuring instrument;
e4: one end of the data exchange device is connected with the upper computer, the other end of the data exchange device is connected with the first binocular vision measuring instrument and the second binocular vision measuring instrument, the upper computer is started, and the coordinate conversion relation between the first binocular vision measuring instrument and the second binocular vision measuring instrument is established through the relative position relation between the optical targets on the vehicle body; establishing a six-degree-of-freedom displacement measurement reference coordinate system of the wheel parallel to an automobile coordinate system through the space coordinates of three optical targets on the reference fixture;
E5: and selecting an optical target on the wheel positioning clamp, loading the tested vehicle, and simultaneously controlling the first binocular vision measuring instrument and the second binocular vision measuring instrument to synchronously measure the spatial coordinate change of the selected target, and calculating the spatial angle change of the wheel middle plane and the spatial coordinate change of the wheel center under the automobile coordinate system through the spatial coordinate change of the three optical targets on the wheel positioning clamp and the distance between the disc measuring plane and the wheel middle plane to obtain the six-degree-of-freedom displacement of the wheel under the automobile coordinate system.
6. The six-degree-of-freedom displacement measurement method of a wheel for suspension characteristics test according to claim 5, wherein the relative positional relationship between the optical targets on the vehicle body in the above step E2 is established by:
the optical targets are continuously distributed from the left side to the right side of the vehicle body at certain intervals, the first binocular vision measuring instrument is continuously moved to measure the relative position relationship between the targets on the vehicle body, wherein part of old optical targets remained in the last step and new optical targets which just enter the field of view of the first binocular vision measuring instrument are arranged in the field of view of each step after each step of movement to ensure the continuous transition of the relative position relationship.
7. The six degree-of-freedom displacement measurement method of a wheel for suspension characteristics test according to claim 5, wherein establishing the coordinate conversion relationship between the first and second binocular vision measuring instruments in the step E4 comprises:
Measuring the spatial coordinates of the optical targets on the right side of the vehicle body in the second binocular vision meter vision field under the second binocular vision meter coordinate system, measuring the spatial coordinates of the optical targets on the left side of the vehicle body in the first binocular vision meter vision field under the first binocular vision meter coordinate system,
the spatial coordinates of the targets on the right side of the vehicle body which are not in the view of the first binocular vision measuring instrument in the first binocular vision measuring instrument coordinate system are obtained through the relative position relation among the targets on the vehicle body,
and the number of targets on the right side of the vehicle body is greater than or equal to the unknown number of the transformation matrix T, so that the transformation matrix T of the second binocular vision measuring instrument coordinate system relative to the first binocular vision measuring instrument coordinate system is obtained.
8. A six-degree-of-freedom displacement measurement method of a suspension characteristic test wheel, characterized in that the measurement method is performed according to the six-degree-of-freedom displacement measurement device of a suspension characteristic test wheel according to any one of claims 1-4, comprising a binocular vision measuring instrument, an optical target, a planar clamp (9); the binocular vision measuring instrument comprises a first binocular vision measuring instrument and a second binocular vision measuring instrument, and the measuring method comprises the following steps:
F1: the method comprises the steps of installing a plane clamp in front of a head of a tested vehicle, continuing from right side wheel to right side wheel right side, distributing optical targets on a clamp plane of the plane clamp fixed on a test bench, respectively placing a first binocular vision measuring instrument and a second binocular vision measuring instrument on the left side and the right side of a body of the tested vehicle, establishing a coordinate conversion relation between the first binocular vision measuring instrument and the second binocular vision measuring instrument according to a relative position relation between the optical targets on the body, and converting space coordinates of the optical targets (17, 18 and 19) on the wheel positioning clamp measured in the view of the second binocular vision measuring instrument into a coordinate system of the first binocular vision measuring instrument;
f2: establishing a six-degree-of-freedom displacement measurement reference coordinate system of the wheel parallel to the automobile coordinate system through the space coordinates of three optical targets (11, 12, 13) on the reference fixture;
f3: according to the principle of 'three-point determination of one plane', the spatial angle change of the middle plane of the wheel under the automobile coordinate system and the spatial coordinate change of the wheel center are calculated through the spatial coordinate changes of three optical targets on the wheel positioning clamp and the distance between the disc measuring plane on the wheel positioning clamp and the middle plane of the wheel, so that the six-degree-of-freedom displacement of the wheel under the automobile coordinate system is obtained.
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