Method and system for aligning the wheels of a vehicle while temporarily covering a target on a rear wheel

Abstract

A method according to the invention for aligning the wheels of a vehicle (14) while temporarily covering a target (20) on a rear wheel comprises the following method steps: a) taking images of targets (16, 18) on the front wheels and both rear wheels of the vehicle (14) by means of measuring cameras (10) which are positioned in front of the vehicle (14); b) determining the geometrical reference between the positions and the alignments of the targets (18) on the rear wheels of the vehicle (14); c) covering a target (20) on a first rear wheel, in particular by an operator or some other means for obscuring it; d) taking images of the targets (16) on the front wheels and the target (18) on the second, non-covered rear wheel of the vehicle (14) by means of the measuring cameras (10); e) reconstructing the position and the alignment of the covered target (20) on the first rear wheel from the position of the target (18) on the second, non-covered rear wheel and from the previously determined geometrical reference between the positions and the alignments of the targets (18) on the rear wheels; and f) determining the geometric centre line as the bisector of the total toe angle of the rear axle and at least one parameter dependent on the geometric centre line, in particular the individual toe in the forward direction, as the parallel position of the front wheels in relation to the geometric centre line.

Description

[0001] Method and system for measuring the chassis of a vehicle when a measuring panel on a rear wheel is temporarily covered

[0002] The present invention relates to a method and a system for measuring the chassis of a vehicle when a measuring panel on a rear wheel is temporarily covered.

[0003] With measuring plate or target-based wheel alignment systems, measuring cameras are often used. These cameras are positioned in front of the vehicle and capture images of measuring plates on the front and / or rear wheels. Various chassis-specific parameters can be determined from the images acquired in this way.

[0004] When a vehicle is parked at a measuring station, situations often arise in which a measuring plate is obscured. With conventional wheel alignment devices, such obscured measuring plates often lead to inaccurate or even incorrect measurement values.

[0005] It is therefore an object of the present invention to provide a method and a system for measuring the chassis of a vehicle, in which correct measured values ​​are determined even if a measuring panel is covered.

[0006] Such a method and such a system should always provide correct measured values, even in different measuring station situations, and they should be easy and reliable to implement.

[0007] This problem is fully solved by the subject matter of the independent patent claims. Advantageous further developments arise from the dependent patent claims.

[0008] A method according to the invention for measuring the chassis of a vehicle with a measuring plate on a rear wheel temporarily obscured comprises the following method steps: a) Recording images of measuring plates on the front wheels and on both rear wheels of the vehicle using measuring cameras positioned in front of the vehicle; b) Determining the geometric relationship between the positions and the orientations of the measuring plates on the rear wheels of the vehicle; c) Obscuring a measuring plate on a first rear wheel, in particular by an operator or another obstacle; d) Recording images of the measuring plates on the front wheels and the measuring plate on the second, uncovered rear wheel of the vehicle using the measuring cameras;e) reconstructing the position and orientation of the concealed measuring plate on the first rear wheel from the position of the measuring plate on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring plates on the rear wheels, and f) determining the geometric driving axis as the bisector of the total toe angle, in particular the total toe-in angle of the rear axle and at least one parameter dependent on the geometric driving axis, in particular the individual toe at the front, as the parallel position of the front wheels to the geometric driving axis;

[0009] A system according to the invention for measuring the chassis of a vehicle with a measuring panel on a rear wheel temporarily obscured comprises the following features:

[0010] Measuring panels on the front and rear wheels of the vehicle

[0011] Measuring cameras arranged in front of the vehicle and designed such that images of measuring plates on the front wheels and on the rear wheels of the vehicle can be recorded; an evaluation device for determining measured values ​​for the chassis by evaluating the recorded images of the measuring plates; wherein the measuring cameras and the evaluation device are designed such that a) images of measuring plates on the front wheels and on both rear wheels of the vehicle can be recorded by measuring cameras; b) the geometric relationship between the positions and the orientations of the measuring plates on the rear wheels of the vehicle can be determined and the geometric driving axis can be determined; c) after a measuring plate on a first rear wheel has been covered, in particular by an operator or another obstacle; d) images of the measuring plates on the front wheels and the measuring plate on the second, uncovered rear wheel of the vehicle can be recorded by the measuring cameras;e) the position and orientation of the concealed measuring plate on the first rear wheel can be reconstructed from the position of the measuring plate on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring plates on the rear wheels; and f) the geometric driving axis can be determined as the bisector of the overall toe angle, in particular the overall toe-in angle of the rear axle, and at least one parameter dependent on the geometric driving axis, in particular the individual toe at the front, as the parallel position of the front wheels to the geometric driving axis.

[0012] According to one of the findings underlying the invention, vehicles parked at a measuring station often move by moving their wheels, for example, on the turntables at the front and the sliding plates at the rear, which is also referred to as the vehicle floating. According to another finding underlying the invention, such floating movements are often included in the calculation of the chassis parameters, resulting in imprecise or incorrect measured values.

[0013] According to a basic concept of the invention, the measuring cameras positioned in front of the vehicle capture images of measuring plates on the front wheels and both rear wheels of the vehicle, as long as they are not yet obscured, and the geometric relationship between the positions and orientations of the measuring plates on the rear wheels of the vehicle is determined. After a measuring plate on a first rear wheel has been obscured, in particular by an operator or another obstacle, another image of the measuring plates is captured by the measuring cameras. However, the obscured measuring plate on the first rear wheel cannot be "seen" or reconstructed.The position and orientation of the concealed measuring plate on the first rear wheel are therefore reconstructed according to the invention, specifically from the position of the measuring plate on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientation of the measuring plates on the rear wheels. Thus, according to the invention, the geometric driving axis can be determined as the angle bisector of the total toe angle, in particular the total toe-in angle or total toe-in angle of the rear axle, and at least one parameter dependent on the geometric driving axis, in particular the individual toe-in at the front, can be determined as the parallel position of the front wheels to the geometric driving axis. The terms total toe-in angle and total toe-in angle are considered synonymous with one another in the context of this patent application.

[0014] The geometric driving axis represents the direction in which the vehicle travels without steering.

[0015] This ensures that any floating movement of the vehicle, especially between the first and second image acquisitions, is not included in the calculation of the geometric driving axis and the parameters dependent on the geometric driving axis. Therefore, obscuring the measurement panel at the first rear wheel has no influence on the quality of the determined chassis parameters.

[0016] During wheel alignment, there are various situations in which, for example, an operator, especially a technician, or another obstacle is in the way, i.e., in the optical field of view between a measuring camera in front of the vehicle and a measuring plate on a rear wheel of a vehicle, thus obscuring the measuring plate. This happens, for example, when performing a steering angle. The operator often stands next to the vehicle and turns the steering wheel through the open window.

[0017] The method and system according to the invention offer a significant advantage over wheel alignment methods and systems in which the image of the concealed measuring plate on the first rear wheel, taken once, especially before the cover is covered, is memorized and used for subsequent calculations. Such methods and systems deliver imprecise or incorrect measurement values, particularly if the vehicle performs a floating movement after such an initial image capture.

[0018] In particular, if after such a first image recording a steering angle is carried out while obscuring a measuring panel on the first rear wheel, a twisting of the vehicle caused by floating can be interpreted and displayed as a steering movement or as part of a steering movement.

[0019] The method and the system according to the invention thus ensure that correct measurement values ​​are generated even if the vehicle orientation changes while a measuring panel is obscured.

[0020] When reconstructing the position and orientation of the concealed measuring plate on the first rear wheel from the position of the measuring plate on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring plates on the rear wheels, the method and system according to the invention assume that this geometric relationship has not changed during the image acquisition. This is particularly the case during the steering angle, since the rear axle is not changed during this time.

[0021] By reconstructing the position and orientation of the hidden measuring panel according to step (e), the geometric driving axis can be correctly determined in step (f) and at least one parameter dependent on the geometric driving axis, in particular the single track at the front, can be correctly determined.

[0022] The reconstructed hidden measuring panel on the first rear wheel thus rotates with the vehicle and does not produce false measured values.

[0023] The method and the system according to the invention thus always provide correct measured values ​​even in different measuring station situations and can be carried out easily and reliably.

[0024] According to a first embodiment of the method according to the invention, this further comprises the following method steps:

[0025] Performing a steering turn, in particular before or during step c); and

[0026] Determining the track change as the actual steered angle of the front wheels by relating the images of the measuring panels on the front wheels taken in step d) with the individual front track determined in step f).

[0027] The lane change can be determined from the beginning of the steering angle and / or independently of a complete movement of the vehicle.

[0028] This ensures that the track change of the front wheels is determined correctly. A change in the overall position of the motor vehicle, in particular due to a floating or rotating movement of the motor vehicle, is not reflected. According to a further finding of the inventors, when the steering is manually performed by an operator, there is often a change in the overall position of the motor vehicle, even if only a small one. According to the invention, this is calculated out and is not included in the calculation of the geometric driving axis or the parameters dependent on it, and not in the determined track change. This prevents a change in position or a rotation of the vehicle as a whole, e.g. when a steering angle is manually performed by an operator, from being interpreted and displayed as a steering movement.

[0029] Such a steering angle is usually performed by an operator, for example, by turning the steering wheel through the driver's door window. According to the invention, very precise measurement values ​​are thus obtained.

[0030] The measuring panel can be obscured by an operator during a program-guided manual movement of the steering wheel to perform the steering angle. The operator's body is located in the field of vision between the measuring camera, especially the measuring camera in front of the vehicle on the driver's side, and the measuring panel on the rear wheel of the vehicle on the driver's side.

[0031] A complete movement of the vehicle can take place before step d), so that the position of the vehicle on the measuring station changes overall.

[0032] According to a further embodiment of the method according to the invention, if the correlation of the images of the measuring panels on the front wheels taken in step d) with the individual front track determined in step f) shows that no steering movement / steering angle has been carried out, but only the position of the vehicle on the measuring station has changed overall, an indication is given that no steering angle has taken place or a steering progress indicator shows no steering progress.

[0033] In this case, in particular, the angle between the geometric driving axis and the vertical direction of the measuring plates on the front wheels of the motor vehicle has remained unchanged.

[0034] According to a further embodiment of the method according to the invention, when determining the track change by relating the images of the measuring panels on the front wheels recorded in step d) with the individual track at the front determined in step f), the portion of the change in the alignment of the front wheels that is attributable to the complete movement of the vehicle is not taken into account.

[0035] According to a further embodiment of the method according to the invention, the vehicle is mounted in a floating manner on the measuring station. The front wheels can be mounted on turntables, and the rear wheels on sliding plates that have been previously released.

[0036] A vehicle that is mounted in such a floating manner on the measuring station can be moved and its position changed, in particular rotated, by an operator, intentionally or unintentionally, in a simple manner and with little effort.

[0037] According to a further embodiment of the method according to the invention, the geometric relationship from step b) between the positions and the orientations of the measuring panels on the rear wheels of the vehicle is determined in the form of a 3-D transformation with six degrees of freedom.

[0038] According to a further embodiment of the method according to the invention, at least one of the following characteristic values ​​is / are determined as further measured value(s) for the chassis: a caster; a spread; and a track difference angle.

[0039] For the system according to the invention for measuring the chassis of a vehicle when a measuring panel on a rear wheel is temporarily covered, the same advantages and embodiments arise as have been explained above with reference to the method according to the invention.

[0040] These embodiments will not be repeated again with reference to the measuring system according to the invention.

[0041] However, the applicant expressly reserves the right to make claims directed to a system for measuring the chassis of a vehicle with a measuring plate temporarily obscured at a rear wheel, and which include the above-mentioned method features in a functional equivalent. According to a first embodiment of the system according to the invention, the measuring cameras and the evaluation device are further configured such that a steering angle can be performed; and the track change can be determined as the actually steered angle of the front wheels by relating the recorded images of the measuring plates on the front wheels to the determined individual track at the front.

[0042] According to a further embodiment of the system according to the invention, this further comprises at least one of the following features: two or more measuring cameras per vehicle side, which are positioned in front of the vehicle;

[0043] Running rails with front turntables and rear sliding plates; wherein the vehicle is mounted in a floating manner on the running rails, in particular on the front turntables and on the rear sliding plates; and / or wherein the front wheels are on the previously released turntables and the rear wheels are on the previously released sliding plates.

[0044] In practice, it is easy to verify whether a measurement method or system implements the method / system according to the invention. To do so, the overall position of the vehicle on the measuring station must be changed; in particular, the entire vehicle must be rotated while the measurement panel on the first rear wheel is covered.

[0045] Based on the resulting measured values ​​for the geometric driving axis and the parameters dependent on it, in particular the single track at the front, the caster, the spread and the track difference angle, it can be deduced whether compensation of the vehicle rotation has taken place or not.

[0046] The invention is explained in more detail below using exemplary embodiments with reference to the attached figures.

[0047] Figure 1 shows a schematic side view of a motor vehicle measuring station with a vehicle parked thereon, with measuring panels on the front and rear wheels, an operator standing next to the vehicle, and a measuring camera mounted on a frame in front of the vehicle, along with its fields of view to the measuring panels on the front and rear wheels. Figure 2 shows plan views of the measuring station 2 according to Figure 1 in four different situations, which are illustrated in sub-figures 2(a), 2(b), 2(c), and 2(d).

[0048] Figure 1 shows the measuring station 2 as seen from the left side of the vehicle, the driver's side. A left measuring camera 10 is mounted on a frame 12 at a height above the vehicle 4 and is aligned such that a measuring plate 16 is located on the front wheel of the motor vehicle in its first field of view 28 and a measuring plate 18 is located on a rear wheel of the motor vehicle in its second field of view 30.

[0049] On the right side of the vehicle (not shown here), a right measuring camera 10 is arranged analogously, and on the right side of the vehicle, the passenger side, measuring panels 16 and 18 are also attached to the front and rear wheels and are located in the fields of view 28 and 30 of the right measuring camera 10.

[0050] The system for measuring the chassis of a vehicle 14 while temporarily obscuring a measurement panel 20 on a rear wheel also includes a computing unit (not shown) and a display unit (not shown), which are designed and arranged in a conventional manner. The system for measuring the chassis of a vehicle 14 is also referred to as a chassis measurement system.

[0051] From the images recorded by the measuring cameras 10 from the measuring panels 16 and 18, the wheel alignment system can thus determine and display corresponding measured values ​​such as the geometric driving axis, the individual front track, the caster, the spread or the track difference angle.

[0052] Figure 1 shows an operator 26 standing on or next to the measuring station 2, reaching for the steering wheel through the open window of the driver's door and, in particular, performing a program-controlled steering turn by following a corresponding display on the display unit. As can be clearly seen in Figure 1, the operator 26 is located in the field of view 30 between the measuring camera 10 and the measuring plate 18 on the rear wheel of the vehicle 4, so that the measuring plate 18 on the rear wheel of the vehicle 4 is hidden from the measuring camera 10. In the top views of Figures 2 (a), (b), (c), and (d), the left and right rails 4 with the front turntables 6 and the rear sliding plates 8 are clearly visible. The vehicle 14 to be measured is positioned with its front wheels on the turntables 6 and its rear wheels on the sliding plates 8.

[0053] The front measuring panels 16 and the rear measuring panels 18 are also clearly visible, which are each attached to the front wheels and the rear wheels of the motor vehicle 14 in a suitable manner, for example by means of wheel holders.

[0054] The measuring panels 16 and 18 each have a pattern of geometric marks on their front sides. Left and right measuring cameras 10 are arranged on the frame 12 in front of the measuring station 2.

[0055] The geometric driving axis of the motor vehicle 14, defined as the bisector of the total toe angle of the rear axle, is shown as a dotted line in Figures 2 (a), (b), (c), and (d). For most motor vehicles with positive toe / toe-in, this corresponds to the bisector of the total toe angle of the rear axle.

[0056] The vertical direction of the front left measuring plate 16 is shown in Figures 2 (a), (b), (c), and (d) as a dashed line 24. It should be noted that this representation is simplified. In practice, the rotational axis of the front wheel or the perpendicular to it is used.

[0057] In Figure 2 (a), the vehicle 14 to be measured is in its starting position. The geometric driving axis 22 lies in the longitudinal center plane of the measuring station 2, and the vertical direction 24 of the front measuring panel 16 is parallel to the geometric driving axis 22. The steering angle is therefore zero.

[0058] The front measuring cameras 10 have both the front measuring panels 16 and the rear measuring panels 18 in their field of view.

[0059] In Figure 2 (b), the position of vehicle 14 on measuring station 2 is rotated to the left, its rear end is shifted to the right, and its front end is shifted to the left. The geometric driving axis 22 forms an angle to the front left with the longitudinal center plane of measuring station 2. The vertical direction 24 of the front measuring plate 16 is parallel to the geometric driving axis 22. The steering angle is thus zero.

[0060] The measuring plate 20 on the left rear wheel of the vehicle 14 is shown somewhat brighter. This is intended to visualize that the rear left measuring plate 20 is obscured and not in the field of view of the front left measuring camera 10. This can be caused by an operator standing on the driver's side next to the vehicle 14 at the measuring station 2 and, for example, making a steering turn through the open window of the driver's door of the vehicle 14, as shown in Figure 1.

[0061] In Figure 2 (c), the position of vehicle 14 on measuring station 2 is rotated to the right, with its rear end shifted to the left and its front end shifted to the right. The geometric driving axis 22 forms an angle to the front right with the longitudinal center plane of measuring station 2. The vertical direction 24 of the front measuring plate 16 is parallel to the geometric driving axis 22. The steering angle is thus zero.

[0062] Again, the measuring panel 20 on the left rear wheel, which is covered by an operator, for example, is shown somewhat brighter.

[0063] Figures 2 (b) and (c) show a purely floating movement of the vehicle. The turntables 6 and sliding plates 8 have been previously released. Therefore, even a small force acting on the vehicle 14, for example, when an operator performs a steering turn, is sufficient to change the position of the vehicle 14 as a whole.

[0064] Figure 2 (d) shows the vehicle 14 on the test site 2 during a steering maneuver. In Figure 2 (d), the position of the vehicle 14 on the test site 2 is rotated to the right, its rear end is shifted to the left, and its front end to the right. Furthermore, the front wheels 16 have been steered with a steering angle to the right.

[0065] By comparing the geometric travel axis 22 to the vertical direction 24 of the front left measuring panel 16, it is clearly visible that these are not parallel, as in Figures 2 (a), (b), and (c), but rather that they are at an angle to each other. The rear left measuring panel 20 is again obscured, for example, by an operator standing in the field of view between the front left measuring camera 10 and the rear left, obscured, first measuring panel 20.

[0066] The implementation of the method according to the invention for measuring the chassis of the vehicle 14 with the measuring panel 20 on the left rear wheel temporarily obscured and the functioning of the system according to the invention for measuring the chassis of the vehicle 14 with the measuring panel 20 on the left rear wheel temporarily obscured will now be explained as follows.

[0067] In the starting position shown in Figure 2 (a), the front turntables 6 and the rear sliding plates 8 are first released from their locking positions. Images of the two front measuring plates 16 and the two rear measuring plates 18 are captured by the front measuring cameras 10. The geometric relationship between the positions and the orientation of the rear measuring plates 18 is then determined.

[0068] Now, according to one of the illustrations in Figures 2 (b), (c) and (d), the left rear measuring panel 20 is covered, for example by an operator or another obstacle.

[0069] Now, images of the front measuring panels 16 and the right rear, uncovered, second measuring panel 18 are again taken by the measuring camera 10.

[0070] The position and orientation of the concealed first measuring plate 20 on the left rear wheel is reconstructed from the position of the non-concealed second measuring plate 18 on the right rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring plates 18 on the rear wheels.

[0071] Now, the geometric driving axis 22 is determined as the bisector of the total track angle / total toe-in angle of the rear axle, and at least one parameter dependent on the geometric driving axis, in particular the individual front track, is determined as the parallel position of the front wheels to the geometric driving axis 22. The geometric driving axis 22 is thus correctly determined, which also correctly determines at least one parameter dependent on the geometric driving axis.

[0072] If a steering angle is now carried out, as shown in Figure 2 (d), and before or during this the measuring panel 20 is covered and in addition a change in position of the vehicle 14 as a whole occurs, as shown in Figure 2 (d), the track change is determined as the actually steered angle of the front wheels by relating the recorded images of the front measuring panels 16 with the determined individual track at the front.

[0073] The lane change can be determined from the beginning of the steering angle and independently of a complete movement of the vehicle. The operator can cover the measuring panel 20 himself, for example, during a program-guided manual movement of the steering wheel.

[0074] If the correlation of the recorded images of the front measuring panels 16 with the determined individual front track shows that no steering movement and no steering angle has been carried out, but only the position of the vehicle 14 as a whole on the measuring station 2 has changed, as is visualized with reference to Figures 2 (b) and (c), an indication is given on the display unit (not shown here) that no steering angle has taken place or the steering progress indicator shows no steering progress.

[0075] When determining the track change by relating the recorded images of the front measuring panels 16 to the previously determined individual front track, the portion of the change in the alignment of the front wheels 16 is not taken into account, which is due to the complete movement of the vehicle 14 and thus to the change in the geometric driving axis 22 according to Figure 2 (d) to the geometric driving axis 22 according to Figure 2 (a).

[0076] According to Figure 2 (d), only the angle between the vertical direction 24 of the front measuring plates 16 and the geometric driving axis 22 is indicated as the steering angle. With other conventional chassis measurement methods, however, the vertical direction 24 of the front measuring plates 16 in Figures 2 (b) and (c) would be recognized as the steering angle. As additional measured values ​​for the chassis, at least one of the following parameters can also be correctly determined: caster, wheelbase, and track difference angle.

[0077] The angle of spread or spread angle is the angle between the projection of the inclined steering axis onto the plane perpendicular to the vehicle's longitudinal center plane and the axis perpendicular to the roadway in the vehicle's longitudinal center plane. Instead of the roadway, this can also refer to the horizontally forward direction of the vehicle. The angle is positive when the upper end of the steering axis is tilted inward. In a car, the angle of spread or spread angle is always positive. According to a more colloquial definition, the angle of spread is the angle between the inclined steering axis and a perpendicular to the roadway, as seen from the vehicle's longitudinal axis.

[0078] Caster angle is defined as the angle between the projection of the inclined steering axis onto the vehicle's longitudinal center plane and the axis perpendicular to the road surface in the vehicle's longitudinal center plane. The angle is positive when the upper end of the steering axis is tilted rearward. According to a somewhat more colloquial definition, caster is the angle between the inclined steering axis and a perpendicular to the road surface in the direction of the vehicle's longitudinal axis.

[0079] The toe difference angle is the angle between the wheel rotation axis of the inside wheel and the wheel rotation axis of the outside wheel when the steering angle (usually 20°) is applied to the inside wheel.

[0080] All three values ​​(spread / spread angle; caster / trail angle and track difference angle) are determined at a steering angle of usually 20 degrees, but there are also 10 degrees, for example.

[0081] The total toe-in angle is the sum of the toe angles of an axle.

[0082] Toe-in is essentially positive toe-in. Most motor vehicles have positive toe-in.

[0083] Instead of the term "steering axis," the terms "steering axis" or "pivot axis" can also be used. Thus, according to the invention, the geometric driving axis 22 is correctly determined for every situation of the vehicle 14 at the measuring station 2, with the rear measuring panel 20 concealed. From this correctly determined geometric driving axis 22, all other parameters dependent on the geometric driving axis 22 can be correctly determined.

[0084] List of reference symbols

[0085] 2 measuring stations

[0086] 4 running rails 6 front turntables

[0087] 8 rear sliding plates

[0088] 10 measuring cameras

[0089] 12 frame

[0090] 14 Vehicle 16 measuring panels on front wheels

[0091] 18 measuring panels on rear wheels

[0092] 20 hidden first measuring panel

[0093] 22 geometric driving axes

[0094] 24 vertical direction of the front measuring panels 26 operator

[0095] 28 first field of view between measuring camera and measuring panel on left front wheel

[0096] 30 second field of view between measuring camera and measuring panel on left rear wheel

Claims

Patent claims 1. A method for measuring the chassis of a vehicle (14) with a measuring plate (20) on a rear wheel temporarily obscured, comprising the following method steps: a) recording images of measuring plates (16, 18) on the front wheels and on both rear wheels of the vehicle (14) by measuring cameras (10) positioned in front of the vehicle (14); b) determining the geometric relationship between the positions and the orientations of the measuring plates (18) on the rear wheels of the vehicle (14); c) obscuring a measuring plate (20) on a first rear wheel, in particular by an operator or another obstacle; d) recording images of the measuring plates (16) on the front wheels and the measuring plate (18) on the second, uncovered rear wheel of the vehicle (14) by the measuring cameras (10);e) reconstructing the position and orientation of the concealed measuring plate (20) on the first rear wheel from the position of the measuring plate (18) on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring plates (18) on the rear wheels, and f) determining the geometric driving axis as the angle bisector of the total toe angle of the rear axle and at least one parameter dependent on the geometric driving axis, in particular the individual toe at the front, as the parallel position of the front wheels to the geometric driving axis; 2. The method according to claim 1, further comprising the steps of: Performing a steering maneuver, particularly before or during step c); and Determining the track change as the actual steered angle of the front wheels by relating the images of the measuring panels (16) on the front wheels taken in step d) with the individual front track determined in step f).

3. Method according to claim 2, wherein the determination of the lane change takes place from the beginning of the execution of the steering angle and / or independently of a complete movement of the vehicle (14).

4. The method according to claim 2 or 3, wherein the covering of the measuring panel (20) by an operator occurs during a program-guided manual movement of the steering wheel to carry out the steering angle.

5. Method according to one of claims 2 to 4, wherein before step d) a complete movement of the vehicle (14) takes place, so that the position of the vehicle (14) on the measuring station (2) changes overall.

6. The method according to claim 5, wherein if the correlation of the images of the measuring panels (16) on the front wheels taken in step d) with the individual front track determined in step f) shows that no steering movement / steering angle has been carried out, but only the position of the vehicle (14) on the measuring station (2) has changed overall, an indication is given that no steering angle has taken place or a steering progress indicator shows no steering progress.

7. The method according to claim 5, wherein when determining the track change by relating the images of the measuring panels (16) on the front wheels recorded in step d) with the individual track at the front determined in step f), the portion of the change in the alignment of the front wheels which is attributable to the complete movement of the vehicle (14) is not taken into account.

8. Method according to one of the preceding claims, wherein the vehicle (14) is mounted in a floating manner on the measuring station (2), wherein in particular the front wheels are mounted on turntables (6) and the rear wheels are mounted on sliding plates (8) which have been previously released.

9. Method according to one of the preceding claims, wherein the geometric reference from step b) between the positions and the orientations of the measuring panels (18) on the rear wheels of the vehicle (14) is determined in the form of a 3-D transformation with six degrees of freedom.

10. Method according to one of the preceding claims, wherein at least one of the following characteristic values is determined as a further measured value for the chassis: caster; spread; and Track difference angle.

11. System for measuring the chassis of a vehicle (14) with temporary obscuration of a measuring panel (20) on a rear wheel, comprising Measuring panels (16, 18) on the front wheels and on the rear wheels of the vehicle (14); Measuring cameras (10) arranged in front of the vehicle (14) and configured such that images of measuring panels (16, 18) on the front wheels and on the rear wheels of the vehicle (14) can be recorded; an evaluation device for determining measured values for the chassis by evaluating the recorded images of the measuring panels (16, 18); wherein the measuring cameras (10) and the evaluation device are configured such that a) images of measuring panels (16, 18) on the front wheels and on both rear wheels of the vehicle (14) can be recorded by measuring cameras (10); b) the geometric relationship between the positions and the orientations of the measuring panels (18) on the rear wheels of the vehicle (14) can be determined and the geometric driving axis can be determined; c) after a measuring panel (20) on a first rear wheel has been covered, in particular by an operator or another obstacle;d) images of the measuring panels (16) on the front wheels and the measuring panel (18) on the second, uncovered rear wheel of the vehicle (14) can be recorded by the measuring cameras (10); e) the position and orientation of the concealed measuring panel (20) on the first rear wheel can be reconstructed from the position of the measuring panel (18) on the second, uncovered rear wheel and from the previously determined geometric relationship between the positions and orientations of the measuring panels (18) on the rear wheels; and f) the geometric driving axis can be determined as the angle bisector of the total toe angle of the rear axle and of at least one parameter dependent on the geometric driving axis, in particular the individual toe at the front, as the parallel position of the front wheels to the geometric driving axis; 12. System according to claim 11, the measuring cameras (10) and the evaluation device are further configured such that a steering angle can be carried out; and the track change can be determined as the actually steered angle of the front wheels by relating the recorded images of the measuring panels (16) on the front wheels with the determined individual track at the front.

13. System according to claim 11 or 12, further comprising at least one of the following features: two or more measuring cameras (10) per vehicle side, positioned in front of the vehicle (14); Running rails (4) with front turntables (6) and rear sliding plates (8); wherein the vehicle (14) is mounted in a floating manner on the running rails (4), in particular on the front turntables (6) and on the rear sliding plates (8); and / or wherein the front wheels are on the previously released turntables (6) and the rear wheels are on the previously released sliding plates (8).

Images