Patent ID: 12220960

DETAILED DESCRIPTION

In the exemplary embodiments below, the described components of the embodiments each represent individual features that should be considered independently of one another, and that each also develop the invention independently of one another and can therefore also be considered to be part of the invention individually or in a combination other than that shown. Furthermore, the embodiments described can also be supplemented by further features that have already been described.

In the figures, elements with the same function are each provided with the same reference signs.

FIG.1shows a vehicle1with the active suspension2. The vehicle1may be a truck or a passenger car. The vehicle1with the active suspension2may be a manually controlled vehicle or an autonomously controlled vehicle. The active suspension2may be set up to take into account unevenness of a road surface in order to thus reduce vertical accelerations of the vehicle. The active suspension2may comprise one or more shock absorbers3, which can be set up to dampen shocks occurring on a vehicle axle. The shock absorber3may have a shock absorber sensor system4which can record the respective position of the shock absorber SD. The position of the shock absorber SD may vary due to the action of unevenness of the road surface. The active suspension2may comprise a tire5which has a tire sensor system6. The tire sensor system6may for example record a pressure of the tire or a deformation of the tire. The recorded values can provide that the tire sensor system6determines a vertical and/or horizontal deformation of the tire SR. The vertical deformation of the tire SR may occur due to unevenness of the road. The deflection of the shock absorber and the deformation of the tire can be transmitted to the control unit7. The control unit7may be set up to activate the active suspension by means of adjustment values in order to be able to compensate preventively for surface unevenness. For this purpose, the surface profile8can be stored in the control unit7. The surface profile8may comprise the respective height values for a section of road to be driven along.

The adjustment values for the shock absorber3, for example, may be created according to the predetermined transfer function9or the adapted transfer function10. The activation of the shock absorber3by the control unit7may for example bring about a change in the height of the wheel or an adjustment of the damping strength of the shock absorber3. The surface profile8may be provided for example by a sensor device11of the vehicle1. This may be for example a lidar system, a radar system or an optical recording system which is set up to record the surface of the section of road.

FIG.2describes an external central computer. The external central computer12may for example have a microprocessor and be arranged outside the vehicle1. The external central computer12may be set up to carry out data transfers with the vehicle1. For example, it may be provided that the external central computer12provides surface profiles8for vehicles1, or receives surface profiles8recorded by the sensor devices11of the vehicle1. The task of the external central computer12may be to provide a requested surface profile8to a vehicle1. The external central computer12may be set up to receive an adjustment value18of a vehicle1in order to evaluate it. The evaluation of the adjustment value18may have the purpose of replacing the transfer function9of a vehicle1with an adapted transfer function10. This may be necessary for example if an aging process of components of the active suspension2requires a change in the adjustment value18of the vehicle1.

The external central computer12can receive the adjustment value18received from the vehicle with input variables and output variables from the control unit7of the vehicle1. To make a comparison possible, a reference transfer function14may be stored in the external central computer12. This may for example be identical to the predetermined transfer function of the vehicle1. By means of the reference model14, the external central computer12can calculate the expected vertical accelerations15. The expected vertical accelerations15for the section of road can thus be calculated.

In an ideal case, the expected vertical accelerations would have to match the recorded vertical accelerations. Due to manufacturing fluctuations or wear processes, there may be deviations16between expected vertical accelerations and recorded vertical accelerations. The deviation may thus indicate that the predetermined transfer function9used by the control unit of the vehicle1is incorrect and must be replaced by the adapted transfer function10. The adapted transfer function10may be generated by the external central computer for example by means of a fit process, with individual parameters being able to be fitted in order to reduce the deviation16.

It may be provided that the method described is carried out by the external central computer12for a number of vehicles1. The deviations16between the expected vertical accelerations15and the vertical accelerations recorded by the individual vehicles1can be determined. If there are deviations16that exceed a predetermined threshold value, this may indicate that the reference model14is unsuitable. In this case, the fit method may be carried out on parameters of the reference model14in order to minimize the deviations16.

FIG.3shows a surface profile. The surface profile8may have been generated by the control unit7of the vehicle1on the basis of the shock absorber position SD, the tire deformation SR and/or recorded values of the sensor device11. The surface profile8may have a coordinate system, where x indicates a direction along the direction of travel, y the width of the road and z the height. The surface profile8shown shows unevenness17in the form of bumps which occur along a section of road. The position of the unevennesses17may be described for example within the x-y plane. A distance Sx may be present between two of the unevennesses17shown along the x direction and a distance Sy in the y direction. The distances Sx and Sy may also be used by the vehicle1to synchronize the current geographical position. Therefore, the number of operating data and geographical positions by means of a suitable predetermined compression are reduced. In this way, straight or neutral sections of road that have no relevant effect on the feedback control can be bridged or compressed in an appropriate way. The distance to the next distinctive point in the x and y directions can thus be stored.

FIG.4shows a surface profile. The figure shows a temporal progression of the shock absorber position SD over time. The shock absorber position SD may be for example a deflection of the shock absorber3from a central position that was recorded by the shock absorber sensor system4. The vehicle1may have driven over two unevennesses17along the section of road. This may have resulted in a vertical acceleration13of the vehicle1. The progression of the line shows an undershoot at a point in time t1and an overshoot at a point in time t2due to the unevennesses17. The control unit7can determine the progression of the surface profile8from the progression of the shock absorber position SD. It may be provided that the geographical position and the shock absorber position SD are recorded at predetermined points in time. This means that a respective geographical position can be assigned to a respective value of the shock absorber position SD over time. It is thus possible that a local assignment of the unevennesses17can take place from the temporal progression of the shock absorber position SD.

FIG.5shows a possible sequence of a method. In a first step S1, it may be provided that the surface profile8is transferred to the vehicle1by the external central computer12. This may take place for example on the basis of a request from the vehicle1to the external central computer12, the surface profile8being requested for a section of road lying in front of the vehicle1. As an alternative to this, the surface profile8of the section of road may be recorded by the sensor device11of the vehicle1prior to driving along it and transferred to the control unit7. The recording may take place for example by means of lidar or a camera. The surface profile8may also be known from a previous trip by the vehicle1. During the previous trip, the shock absorber position SD and the tire deformation SR may have been recorded and evaluated by the control unit7to determine the surface profile8.

If the vehicle1drives along the section of road, the control unit7can activate the active suspension2on the basis of the surface profile8stored in the control unit7in order to be able to compensate for unevenness (S2). The adjustment values18can be generated by the control unit7according to the predetermined transfer function9. For example, depending on the surface profile8, a damping strength of the shock absorber3can thus be increased or reduced. In the feedback control, it may be provided that a respective tire pressure is taken into account in order to take into account the damping caused by the tires5. From a current geographical position of the vehicle1, the wheel positions and a current speed of the vehicle1, the control unit7can predict a trajectory of a respective wheel. The height profile driven along by the wheel can thus be determined and a respective level feedback control of the wheels can be carried out by the active suspension2in order to compensate for unevenness7and/or to minimize vertical accelerations. The adjustment values required for this can be calculated by the control unit7by means of the transfer functions9,10. To check the transfer functions9,10, the shock absorber position SD can be recorded by the shock absorber sensor system4and/or the tire deformation SR by the tire sensor system6, whereby the vertical acceleration of the vehicle1can be determined while driving along the section of road.

In a step S3, it may be provided that the vehicle1transfers the adjustment values and the recorded vertical acceleration to the external central computer.

The external central computer12can receive and store the received adjustment values18and the recorded vertical accelerations of the vehicle1. In order to make an evaluation of the adjustment value18possible, and possibly an adaptation of the transfer function9stored in the vehicle, it may be provided that the external central computer12calculates the adjustment values18according to a reference model14. The external central computer can determine the deviations16between the recorded vertical acceleration and the expected vertical acceleration. On the basis of the deviations16, the predetermined transfer function9can be replaced by the adapted transfer function10, for which a smaller deviation16is predicted according to a predetermined method by evaluating the adjustment values and the recorded vertical accelerations. In a step S5, the adapted transfer function10can be sent to the vehicle. In the control unit7of the vehicle1, the predetermined transfer function9can be replaced by the adapted transfer function10. The future adjustment values18are thus generated according to the adapted transfer function10.

A stability system with an active suspension has already been available in series for several years. The system tries to create optimal comfort by compensating for bumps and unevenness in roads with an air suspension system. For this purpose, the bumps directly in front of the vehicle1are measured with a 3D camera. In addition, with the help of hydraulic cylinders on the suspension struts, the system can reduce body tilts when cornering and pitching movements when braking and starting.

At the same time, high-precision maps for autonomous driving are now being created by various providers, by recording the lane or the surroundings with the vehicle's own sensor system (cameras, lidar, etc.). The maps offer inter alia: the number and width of the lanes, details such as the gradient and curve of the road, and lane markings and objects at the edge of the lane such as traffic signs and their information.

The accuracy is under 0.5 m in the longitudinal direction of a section of road and under 15 centimeters laterally. With stereo camera variants, the recording accuracy is up to 3 mm.

The stereo camera variants only work during the day and in good weather, since the recording has to meet very demanding requirements. A dedicated stereo camera is also required for the front area directly in front of the vehicle. Due to the contrary requirements, this cannot be used, or can be used only to a very limited extent, at the same time for a medium distance and the far range.

Therefore, almost perfect feedback control of the suspension is possible. This is of interest in particular for autonomous vehicles, since the free time available for the driver and other occupants can then be used for other purposes and “motion sickness” or travel sickness (kinetosis) can easily occur.

On the one hand, the system presented is intended to make highly accurate recording of the road profile possible via the suspension or tire sensor system with other existing sensors. In addition, the profile of the road is intended to be recorded with the highest resolution and as completely as possible, and continuously kept up to date. Furthermore, almost perfect feedback control is to be achieved through the collaborative recording and adaptation of the control deviation of the damping and/or feedback control system.

Various aspects are intended to lead in combination to an optimal feedback control of the suspension, such as a robust, accurate and always up-to-date recording of the road.

For this purpose, the vehicles are to access highly accurate map data, but also deliver updates back to the cloud or the backend. The highly accurate recording of the road can use the previously known sensor systems (3D stereo camera, surround cameras, lidar, inertial sensor system, inclination and tilt sensor systems, GPS/GNSS, etc. and corresponding merging of all the sensors). In addition, the position/movement of the shock absorbers, the damping system or the adjustment values or position of the active damping system of each individual damper can be used as a sensor for recording the road or the exact road profile.

Instead of the previous sensor data given, the suspension information (used as a sensor) can also be sent back to the cloud. In one variant, the tire can also be used as a sensor. Together with the damper system, this forms contact with the road. Together with the actuator system (active suspension), the vehicle parameters and the sensor systems already mentioned above, this control loop can be fully or at least largely described. The tire deforms according to the forces acting on it (acceleration, depending on the course of the road/slope/height profile, vehicle weight, occupants or load, current damper characteristics).

The deformation of the tires can be determined in different ways. It is conceivable to measure the tire pressure by means of strain gages or piezo sensors by means of ultra-sound (height measurement, for example within the tire), see alsoFIG.1. This can be carried out because of the continuous data acquisition and wireless transmission.

The localization of the vehicle1in the environment model can be achieved with the usual sensors provided for this purpose (lidar, radar, surround cameras, GPS, V2X). In addition, the localization may take place via synchronization with the mapped bumps or unevenness. A correlation of the different positions of the bumps in relation to one another or, with a corresponding extent or accuracy of the system, also characteristic features, such as for example the beginning or apex of the bump, can be determined itself, see alsoFIG.3.

Taking into account further parameters, such as vehicle type and design and the corresponding deviations between the vehicles, the data can be brought together by being collaboratively gathered in the external central computer12and evaluated.

In addition, the parameter drift due to aging of the sensor systems4,6or other elements that influence the recording may be determined. This can be recognized in the external central computer12by means of deviations16from the data record stored in the central computer12. The external central computer12can determine correction factors in order to compensate for the individual deviations. These can be stored in the adapted transfer function10for the respective vehicle1and be transferred to the vehicle. In this step it is also possible to compensate for deviations16in the actuator system of the active suspension2.

Adjustment values18can be made possible by means of a collaborative optimization of the reference model14. In addition to the exact recording of the surface profile8of a road and the determination of possible deviations of the sensor systems4,6,11, in a further step the adapted reference model14determined and/or learned or trained in the external central computer12is to be used (similar to autonomous driving) to generate the adapted transfer function10for a respective vehicle1. For the distance to be covered, the respective surface profile8and the adapted transfer function10can be transmitted to the vehicle1as a precaution. The resulting deviation16of the recorded vertical accelerations of the vehicle1from the expected vertical accelerations15is then to be checked for plausibility and/or analyzed by the external central computer12. As part of this process, the external central computer12can examine whether the deviation16is attributable to disturbance variables or has occurred in the vehicle1due to a not yet “perfectly” adapted transfer function10. If the recorded vertical acceleration of the adapted transfer function10still deviates, this is stored in the external central computer12, and an attempt is made in the external central computer12to optimize the adapted transfer function10or the adjustment values calculated with it.

This can then be made available to and used by the next vehicle1, which creates “stimulus data” under a corresponding setup, that is to say travels along the same position of the surface profile8. As long as the deviation16is not yet sufficiently small, this process is repeated, that is to say the adapted transfer function10or the adjustment value is adapted. If, when activated by the control unit7, the active suspension2works according to the adapted transfer function10for precisely this setup, i.e. under these input parameters for this position, so that the deviation16falls below a predetermined threshold value, the adapted transfer function10is retained in the control unit7.

Deviations16due to changes in the surface profile8can be detected by means of synchronizing the input values, which may comprise the shock absorber position SD and the tire deformation SR (position matching). These can be uploaded to the external central computer12for updating in order to update a surface profile8stored in the external central computer12. This only happens of course after a corresponding statistical and further plausibility check.

In one embodiment it is provided that a suitable compression is determined for the very large number of data. In this way, straight or neutral sections of road that have no relevant effect on the feedback control can be bridged or compressed in an appropriate way. The distance to the next distinctive point in the x and y directions can then be stored. The active suspension2may comprise a damping system, which may be purely passive (in the case of just recording) or an active damping system, for example with an adjustable rebound stage and compression stage, as an air pressure version or with additional hydraulic adjustment for level compensation. It may also be operated electrically/electromechanically and is not to be described any further here in a restrictive manner. At least it should be mentioned that the approach presented aims to achieve inter alia almost perfect feedback control for the active suspension2by means of providing an adapted transfer function10. The actuator system of the active suspension2ideally covers a broad dynamic range in order to be able to compensate for both large deflections and unevenness17in the surface profile8and for the smallest movements.

Compensation may cover low to the highest frequencies. When the surface profile8is provided by the external central computer12, the active suspension2is independent of the weather and also functions in rain, fog and in absolute darkness, because in this case it does not depend on a sensor device11in the vehicle itself. As with an exclusively camera-based system, the unevenness of roads (if they are completely recorded in the surface profile8that is provided to the control unit7) can be predicted and the active suspension2or damper system can be preventively activated or preconditioned accordingly by the control unit7.

The system can be implemented in a more cost-effective manner, since a separate 3D stereo camera which records the first 15 m in front of the vehicle1with high resolution does not have to be provided exclusively for recording the surface profile. The shock absorber sensor system4can give very sensitive feedback, since the individual shock absorbers (together with the tires5) are in direct contact with the road and the vehicle1with its relatively high mass is rather sluggish and “counteracts”. The gradients of the bumps may for example be recorded individually at the shock absorber sensor system4and/or the tire sensor system6of each wheel, thereby providing quasi-analog feedback (see alsoFIG.3).

The method can also be used for orientation itself (matching the measured surface profile8with the map data) and, depending on the quality, serve as an additional sensor for localization in the environment model.

By combining measurement data from the shock absorber sensor system, such as the shock absorber position SD, and the tire sensor system, such as the tire deformation SR, with measurement data from the sensor device, the accuracy of the surface profile8can be increased. The robustness of the recording can be increased because the measurement data from different sensors can be created independently of one another and compared. In case of doubt, the method can increase accuracy. A possible redundancy in the event of total failure of the sensor device11is thereby established.

Vehicles1that are used for an initial recording of the surface profile8may have the sensor device11, which comprises for example a 3D stereo camera, lidar scanner or laser scanner. Data recorded by the sensor device11in relation to surface profiles8can be supplemented by the shock absorber position SD and the tire deformation SR in order to increase the accuracy of the recorded surface profile8. The shock absorber sensor system4and the tire sensor system6can thus be used for the high-precision recording of surface profiles8.

This method could also be used for example in rail-road trains, especially high-speed trains. Here, of course, the lane width or variance to be sensed is significantly smaller. Synchronization is much easier here. Furthermore, the iterative adjustment is precise, since the train can be verified very well against the reference data while it is in motion (differentiation between disturbance variables and aging and parameter drift).

By mapping the unevenness or the entire surface profile8, other vehicles1or combinations could also be predictively stabilized by their active suspensions2.

The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the scope of the following claims.