WO2024251625A1 - Procédé de fonctionnement d'un système de direction à commande électrique d'un véhicule, et système de direction à commande électrique - Google Patents

Procédé de fonctionnement d'un système de direction à commande électrique d'un véhicule, et système de direction à commande électrique Download PDF

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Publication number
WO2024251625A1
WO2024251625A1 PCT/EP2024/065050 EP2024065050W WO2024251625A1 WO 2024251625 A1 WO2024251625 A1 WO 2024251625A1 EP 2024065050 W EP2024065050 W EP 2024065050W WO 2024251625 A1 WO2024251625 A1 WO 2024251625A1
Authority
WO
WIPO (PCT)
Prior art keywords
vehicle
steering
lrw
actuator
threshold value
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2024/065050
Other languages
German (de)
English (en)
Inventor
Florian Weigt
Johannes Lampe
Christoph Juritsch
Philipp Kamps
Sebastian Bextermöller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF Friedrichshafen AG
Original Assignee
ZF Friedrichshafen AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ZF Friedrichshafen AG filed Critical ZF Friedrichshafen AG
Priority to CN202480036977.0A priority Critical patent/CN121263349A/zh
Publication of WO2024251625A1 publication Critical patent/WO2024251625A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D7/00—Steering linkage; Stub axles or their mountings
    • B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
    • B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
    • B62D7/148—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering provided with safety devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D7/00—Steering linkage; Stub axles or their mountings
    • B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
    • B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
    • B62D7/15—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels
    • B62D7/159—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6/04—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel

Definitions

  • the present invention relates to a method for operating a steer-by-wire steering system of a vehicle according to the preamble of claim 1, to a device for carrying out such a method, to a steer-by-wire steering system for a vehicle which is operated according to such a method by means of such a device, to a computer program with program code means which is set up to carry out such a method and to a machine-readable storage medium on which such a computer program is stored.
  • mechanically decoupled steer-by-wire steering systems which can adjust a wheel steering angle on an axle of a vehicle, from a steering handle that maps a driver's request for a direction of travel or a route.
  • Actuators are used to actually adjust the wheel steering angle, e.g. on a rear axle, e.g. as known from DE 10 2014206 934 A1.
  • These comprise an electric motor, by means of which a rotation-Z-translation gear is driven in order to translationally displace a steering rod in the form of a spindle, which is articulatedly coupled to wheel supports, in order to rotate these and thus the wheels rotatably mounted on them about their vertical axis.
  • the wheel supports or wheels that are at least indirectly coupled to the steering rod can thus be steered by moving the steering rod.
  • a wheel steering angle on an axle of the vehicle can thus be adjusted.
  • an actuator can adjust the wheel steering angle on both wheels of an axle at the same time. It is also possible for a single actuator to adjust the wheel steering angle for each wheel.
  • the position of the spindle or steering rod is always known.
  • This position can be determined using a rotor position sensor, which counts the angle of rotation or the revolutions of the rotor of the electric motor, as well as using the known transmission of the rotation-to-translation gear.
  • the rotor position sensor is designed in a known manner as a so-called multi-turn sensor as is known from DE 10 2018 213 112 A1 or DE 10 2020 114 871 A1.
  • an additional linear displacement sensor is also used, which enables the determination of the absolute position of the steering rod or at least a specific position, usually the zero position.
  • the rotor position sensor can be initialized to this value, if necessary after a loss of position.
  • environmental sensors can be used, as can be seen from the generic DE 10 2017 209 231 A1, which discloses a method for operating a steer-by-wire steering system of a vehicle for steering wheels of at least one rear axle.
  • the unequivocal function of an actuator of a steer-by-wire steering system for the precise adjustment of the wheel steering angles on the wheels of a vehicle is important in order to be able to drive an intended path, also called trajectory, as expected and safely.
  • the present invention provides a method for operating a steer-by-wire steering system of a vehicle, a device for carrying out the method, a steer-by-wire steering system for a vehicle, a computer program with program code means and a machine-readable medium, which emerge from the independent claims.
  • Advantageous embodiments emerge from the subclaims and the following description.
  • the invention relates to a method for operating a steer-by-wire steering system of a vehicle for steering wheels of at least one rear axle.
  • the steering movement is carried out by means of at least one actuator.
  • the actuator can have a spindle drive.
  • the spindle is displaced translationally by means of a rotary drive and a stationary spindle nut.
  • the rotary drive is preferably designed as an electric motor and drives the spindle nut either directly, e.g. by means of a hollow rotor electric motor or, in a preferred variant, indirectly by means of a gear, preferably a toothed belt gear.
  • the electric motor is arranged parallel to the longitudinal axis, preferably the common longitudinal axis of the spindle and the spindle nut, and is connected to the housing of the Actuator connected, preferably screwed. If the spindle nut is turned in one direction or the other or set in rotation, the spindle, which with its external thread is permanently in engagement with the internal thread of the spindle nut, is translationally displaced in one direction or the other along its longitudinal axis.
  • the movement thread consisting of the external and internal thread can be designed as a self-locking thread, preferably as a trapezoidal thread or as a thread with less self-locking or no self-locking.
  • the pitch of the thread can be varied accordingly or recirculating ball or roller screw drives or similar with little or no self-locking can be used.
  • the spindle is at least indirectly coupled to the wheels, more precisely to wheel supports that can pivot about their vertical axis.
  • the wheels are rotatably mounted on the wheel supports that can pivot about their vertical axis.
  • a wheel steering angle can be set on the relevant vehicle axle.
  • an actuator on the rear axle may set a wheel steering angle that does not lead to the expected trajectory.
  • the basic consideration here is that the driver intends the vehicle to drive straight ahead because the route corresponds to a straight section of road.
  • the vehicle When driving straight ahead, the vehicle usually moves along the vehicle's longitudinal axis and the longitudinal axis essentially follows the trajectory.
  • the wheel steering angles on both the front and rear axles correspond to an angle of 0°.
  • the steering wheel angle i.e. the angle of the steering handle, e.g. a steering wheel for entering the desired route, is also 0°.
  • the wheel steering angle set by the actuator does not match the expected or required wheel steering angle.
  • the driver who intends to drive straight ahead, will try to countersteer using the steering wheel on the front axle in order to continue the intended straight ahead journey. can.
  • the actuator can actually set the wheel steering angle on the rear axle to 1° to the right instead of 0°. The driver would notice that the vehicle is not driving straight ahead, but in this example is yawing to the left.
  • the method according to the invention is intended to reliably detect a fault in the actuator of the rear axle steering. There should be a robust function that only detects a fault in the actuator with great certainty if one actually exists. Influences such as those mentioned above should be masked out so that only actual misalignments in the actuator of the rear axle steering are detected.
  • the current rotational speeds of the wheels (wheel speeds) on the front and rear axles are recorded.
  • Wheel speeds can be recorded easily, for example, using the ABS speed sensors on the wheel carriers of a vehicle.
  • the speed of the vehicle can be determined from the rotational speeds.
  • the rotational speeds can be compared with one another. This can, for example, involve comparing the left and right wheels of an axle, the wheels by axle or by side (left wheels and right wheels of a vehicle), or even all wheels with one another.
  • straight-ahead travel is present when the wheels have the same rotational speed. Deviations can be tolerated here, which are within the scope of the measurement accuracy or also with regard to a road surface that is not exactly level.
  • the recorded state can be a This means driving straight ahead along the vehicle's longitudinal axis, with the wheels having the same steering angle of around 0°, preferably exactly 0°.
  • a vehicle can offer a special driving mode to move the vehicle diagonally or sideways, for example to drive out of a parking space or deliberately in a diagonal driving mode, also known as a crab walk. Even with this special form of driving straight ahead, the wheels should have the same speed within a tolerance and the front and rear axles should also have the same steering angle.
  • the current steering wheel angle is recorded. Based on a fixed gear ratio, a wheel steering angle is set on the respective axle. For example, turning the steering wheel by around 10° can result in a change in the wheel steering angle of around 1°.
  • a current vehicle movement can be determined in a further step. If the wheel speeds are the same and the LRW corresponds to 0°, the vehicle should be driving straight ahead along the longitudinal axis. It can therefore be assumed that the actuator for setting the wheel steering angle on the rear axle is working correctly and that the zero position of the spindle or steering rod in the actuator is in line with the actual 0° position of the wheel steering angle. It can also be assumed that the position determination of the actuator or its steering rod using the rotor position sensor is working perfectly. In the aforementioned case, the steering rod is in the “zero” position and the actuator has set a wheel steering angle of 0°.
  • a momentary vehicle movement is determined, which is recognized as a first vehicle state of a compensated straight ahead driving.
  • the currently recorded steering wheel angle is added up over time, preferably at intervals, preferably intervals of 5 to 50 ms, most preferably 10 to 20 ms. This happens depending on the first vehicle state detected during compensated straight-ahead driving, i.e. as long as this state exists.
  • An offset integral is thus formed which fills up with the steering wheel angles recorded at intervals during compensated straight-ahead driving.
  • the offset integral is compared with a first threshold value. Only when this first threshold value is reached is a status of the actuator set which represents an error state. It is therefore advantageously possible for a wheel steering angle incorrectly set by the actuator to be detected if the wheel steering angle set on the rear axle does not correspond to the expectation, but is incorrect repeatedly and over a certain period of time.
  • the first threshold value is an empirically determined value, which is determined depending on the vehicle type, steering ratio on the front axle and on the rear axle, taking into account the actuator used on the rear axle. If counter-steering on the front axle of 10° is necessary for a given steering ratio and this corresponds to a wheel steering angle of 1° on the front axle, then a wheel steering angle on the rear axle of also 1° can be compensated. This counter-steering on the front axle causes the vehicle to move straight ahead with a wheel steering angle of 1° at the front and rear, pushing and compensating (direction of travel straight ahead).
  • the steering wheel angle is added up at intervals as long as the compensated straight-ahead driving is detected.
  • the first threshold is reached, the incorrect position is recognized without a doubt and a status of the actuator is set accordingly.
  • This status represents an error state of the actuator - in this case on the rear axle.
  • a control system can output this error state as a warning and/or change a steering function of the affected actuator. If the threshold is 300, for example, the condition of straight-ahead driving with a 10° steering wheel angle for compensation must be present for at least 30 seconds, so that the error can also be detected by counter-steering during this time. Based on real or realistic driving path or roadway situations, However, it has been shown that there is a constant change in the road surface and route or trajectory.
  • the condition of actually driving straight ahead is only present for a short time.
  • the offset integral is therefore realistically only filled for a short time when the aforementioned conditions are present. It has been shown that short-term disruptive influences such as crosswinds etc. can be masked out in this way. Surprisingly, it has been found that by checking at least the aforementioned conditions and forming the offset integral, it is unlikely that a fault in the actuator or steering on the rear axle will be falsely detected.
  • the method presented here is intended to advantageously detect an incorrect wheel steering angle on a vehicle axle or an incorrect position of at least one actuator on at least one rear axle of a vehicle in a cost-effective manner. This eliminates the need for an additional, complex and expensive linear displacement sensor for the spindle or steering rod of the vehicle steering system or the steer-by-wire steering.
  • Steps such as recording the wheel speeds and the steering wheel angle can also be carried out at very short intervals or simultaneously.
  • the specified steps are also carried out continuously and thus repeatedly, with the data or signals being recorded and processed temporarily and/or at intervals.
  • a status signal can be displayed to the vehicle driver, e.g. in the cockpit as an acoustic and/or optical signal in the sense of a warning.
  • a display for displaying status messages can be arranged on a dashboard (cockpit) in the vehicle.
  • a corresponding warning can be displayed.
  • This can advantageously warn a driver of the vehicle and, for example, take countermeasures, such as reducing speed, to increase safety for the vehicle and its occupants.
  • the status message can come in different variants, for example depending on the current speed of the vehicle.
  • Information can also be displayed when the vehicle is at a standstill, for example "Initialization of the rear axle steering is in progress". At a speed of 20 to 50 km/h, for example, this information can be linked to the message "Please drive slowly". At a speed of over 50 km/h, for example, the warning message can be visually prominent to make the danger warning clear.
  • a steering function of the actuator can be changed. For example, the actuator can be temporarily switched off or the actuating speed can be limited.
  • the vehicle can be, for example, a passenger car, which can have an electric or hybrid drive, for example.
  • the vehicle can comprise a device in the form of a control unit, which can be designed to detect or read in various signals, such as sensor signals, and to control various vehicle functions directly or indirectly using the signals.
  • a sensor signal representing the expected wheel steering angle can be read in within the actuator.
  • the sensor signal can be provided, for example, by a sensor unit, which can comprise at least one so-called multi-turn sensor.
  • Multi-turn sensors offer the advantage, particularly over linear position sensors, that they can detect rotation of the motor when switched off even without power or with extremely low power consumption, or can count and store the number of revolutions. This allows the steering system to be checked once, for example during production, when adjusting the track or when the vehicle is first put into operation (for example via approaching the end stops). Each time the rear axle steering is started, for example, the absolute position of the steering rod, e.g. in the form of a spindle, can be calculated from the number of revolutions of the multi-turn sensor on the motor.
  • the method mentioned can also be used, for example, if there are doubts about the value of the multi-turn sensor when the vehicle is started.
  • a possible reason for the spindle to wander away from a previous, saved position when switched off is conceivable in exceptional cases, for example when the vehicle is subject to dynamic influences, e.g. a rough stretch of road, e.g. when it is being towed, or when the actuator of the rear axle steering issues an error while driving.
  • the actuator of the rear axle steering could initially be deactivated and only released again when the absolute position of the spindle has been confirmed or determined by the method.
  • An absolute position is understood to be an actual position, so that the actuator actually sets the expected wheel steering angle, e.g. when driving straight ahead it actually sets 0°.
  • the expected wheel steering angle can be determined using a sensed rotation of the rotor of the rear axle steering motor in conjunction with a known gear ratio of a transmission into an expected wheel rotation angle of the rear axle.
  • Determining the vehicle movement can be further improved if additional vehicle parameters are taken into account.
  • it can be taken into account whether the wheels are being accelerated.
  • a tolerance range is also allowed here.
  • a reasonable threshold value can be in the range of 4.5 to 6 m/s 2 , whereby a threshold value of 5.5 m/s 2 is most preferably taken into account. Below this threshold value, negligible acceleration is assumed.
  • a threshold value is also taken into account for the detection of the steering wheel angle. It can be assumed with sufficient certainty that the steering wheel is actually being turned to compensate if the steering wheel angle exceeds the threshold value of 3° to 6°, preferably 5°, starting from the zero position of the steering wheel. It can therefore be assumed with increasing accuracy that the vehicle movement corresponds to a compensated straight-ahead movement.
  • Angular velocity of the steering wheel in particular above a threshold value, preferably less than or equal to 507s and/or
  • Yaw rate of the vehicle in particular below a threshold value, preferably less than or equal to 2 m/s 2 and/or
  • ABS anti-lock braking system: consideration of “brake of individual wheels not applied” or ABS not engaged) and/or the status of an ESP (electronic stability control) can be advantageously taken into account.
  • Program Consideration of “vehicle is not subject to yaw” and/or braking of individual wheels or ESP intervention).
  • Determining the vehicle movement should enable a precise determination of the first vehicle state of a compensated straight-ahead journey. It has been shown that the determination becomes more and more precise the more of the above-mentioned parameters or states are recorded.
  • An evaluation is carried out in a corresponding unit of a control unit after an AND link of the existing states and parameters. If all states apply (all threshold values are met and the queried states apply), compensated straight-ahead journey and thus the first vehicle state is reliably detected. A summation to form the offset integral is then carried out in a corresponding unit of the control unit. This ensures that an offset integral is only formed in the case of compensated straight-ahead journey.
  • the method is intended to detect a misalignment in at least one actuator of the rear axle steering.
  • the method is intended to be robust against influences that can make evaluation difficult. It is intended to prevent a misalignment from being falsely detected or indicated due to transverse influences, as described above, e.g. crosswinds or similar.
  • additional measures can be taken to further rule out misinterpretation depending on a further vehicle state that is different from the first vehicle state (compensated straight-ahead driving).
  • a decay value is advantageously subtracted from the current offset integral.
  • This subtraction is preferably carried out at intervals, in particular cyclically, preferably at intervals of 5 to 40 ms, most preferably 10 to 20 ms.
  • a compensated straight-ahead journey is added up and a decay value is gradually subtracted during the sections driven that differ from the recorded compensated straight-ahead journey, e.g. cornering or similar.
  • the decay value is determined empirically depending on the vehicle fleet or vehicle. For example, a decay value of 3 to 6, preferably 4, was determined for conventional cars, which is cyclically subtracted from the current offset integral. It has It has also been shown that it is advantageous if the decay value is reduced the closer the offset integral approaches the first threshold.
  • a model with three thresholds is preferable, whereby when a second threshold is reached with respect to the offset integral, the decay value is further reduced, preferably halved, and when a third threshold is reached, the decay value is reduced again, preferably halved again. If the first threshold is exceeded, the decay value is reduced to a value close to zero, e.g. 0.05. This can further improve the detection of only actual errors without reducing the sensitivity of the method.
  • the offset integral then fills up more quickly and a large deviation or misalignment of the actuator is detected more quickly.
  • this embodiment can be used to reset the actuator so that the actuator can again set the intended or expected steering wheel angle.
  • This process is also referred to as (re-)initialization.
  • information from so-called vehicle level sensors can be used to detect a tilt (driving on an inclined surface, tilt of the body, e.g. different spring deflection on the left and right sides) and the influences this has on the process.
  • the deviation determined based on the recorded steering wheel angle can be fed back into a control loop in order to slowly, i.e.
  • an observer/model can also be used here, which can detect the deviation in addition to or as an alternative to the method presented.
  • the model would calculate the required wheel steering angle on the rear wheel axle based on the individual wheel speeds and the wheel steering angle on the front axle, among other things. If this deviates from the value set by the rear axle steering actuator, a safety status can be set and, if necessary, a warning can be issued to the driver. The unexpected wheel steering angle on the rear axle can then be returned to a reasonable value.
  • the spindle or steering rod can be returned in sensible small steps of, for example, 0.1 ° per return interval.
  • the actuator of the rear axle steering is reset so that its zero position corresponds to the actual wheel steering angle of 0° for normal straight-ahead driving along the longitudinal axis of the vehicle.
  • the actuator can be re-initialized when the zero position is reached. This can be particularly important for steer-by-wire steering, especially when starting the system after the vehicle has been switched off and restarted, as well as in the event of errors, e.g. in the power supply, and in emergency operation.
  • the approach presented here further provides a device that is designed to carry out and control or implement the steps of the method presented here in corresponding devices.
  • a device can be an electrical device that processes electrical signals, for example sensor signals, and outputs control signals depending on them.
  • the device can have one or more suitable interfaces that can be designed as hardware and/or software.
  • the interfaces can be part of an integrated circuit in which the functions of the device are implemented.
  • the interfaces can also be separate integrated circuits or at least partially consist of discrete components.
  • the Interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.
  • Such a device can be a control unit as part of at least one actuator or at least part of a central control unit of a vehicle.
  • a steer-by-wire steering system for a vehicle in particular a rear-axle steering system
  • the steer-by-wire steering system has a device presented above.
  • a computer program product with program code means which can be stored on a machine-readable carrier such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out the method according to one of the embodiments described above when the program is executed on a computer or a device.
  • a machine-readable carrier such as a semiconductor memory, a hard disk memory or an optical memory
  • Fig. 1 is a schematic representation of a vehicle with a steer-by-wire steering system
  • Fig. 2 is another view of the vehicle as in Fig. 1 driving straight ahead;
  • FIG. 3 another representation of the vehicle like Fig.1 or 1 with a positioning error on the rear axle
  • FIG. 4 another representation of the vehicle like Fig. 2 with compensated straight-ahead driving
  • Fig. 5 is a flow chart of a method for operating a steer-by-wire steering system of a vehicle
  • Figure 1 shows a schematic of a vehicle 1 with steer-by-wire steering with a steerable front axle 21 and a steerable rear axle 31.
  • An actuator 4 is provided for steering the wheels 2 on the front axle 21, which can set or change a wheel steering angle via a steering linkage 41.
  • a set wheel steering angle 6vi is shown as an example on the right wheel 2 in Figure 1.
  • an actuator 5 uses a steering linkage 51 to set or change the wheel steering angle 6h on the rear wheels 3 (shown as an example on the left rear wheel).
  • the actuator 5 shown in detail in Fig. 1 as an example has a housing 56 in which a spindle 52 is mounted so as to be translationally displaceable in the function of a steering rod.
  • a spindle nut 53 is driven in a rotating or rotational manner by an electric motor 54 and is rotatably mounted in a fixed position in the housing 56.
  • the spindle nut 53 has an internal thread (not shown) which engages with an external thread (not shown) of the spindle 52 and forms a movement thread.
  • the rotary motion of the electric motor 54 is converted by the movement thread into the translational displacement or movement of the spindle 52.
  • the spindle 52 is coupled to the above-mentioned steering linkage 51 and, when it is displaced, causes a change in the wheel steering angle 6h.
  • the position of the spindle 52 can be detected by a rotor position sensor 55, knowing the ratio of the drive or transmission from the electric motor 54 by means of the spindle nut 53 to the spindle 52.
  • the set wheel steering angle can be calculated using the known transmission ratio and the rotation-to-translation converter by means of the rotor position sensor 55, which is preferably designed as a so-called multi-turn sensor on the rotor of the electric motor 54.
  • the details described for the actuator 5 also apply in principle to the actuator 4. In the other figures 2-4, the reference symbols for the above-mentioned components of the actuator 5 are not shown again for the same components.
  • the wheels on the front axle 21 and the rear axle 31 are steered in opposite directions, so that at low speeds of e.g. less than 50 km/h, a reduced turning circle and an improved Parking is possible compared to vehicles that only have one steered (front) axle.
  • Two steered axles also advantageously allow for more agile automated driving.
  • the driver generally enters his steering intention via a steering wheel 14, with the steering wheel angle LRW being recorded by a sensor unit and, after the wheel steering angle has been calculated by means of a control unit SG, is sent via a signal line to the actuator 4 and/or actuator 5, which sets the wheel steering angle on the front axle 21 and/or on the rear axle 31.
  • the sensor unit for transmitting the respective steering wheel angle LRW/LRW_mom is electrically connected via a bus system 10 to the control unit SG of the steer-by-wire steering or the actuators 4, 5.
  • the bus system 10 is, for example, a CAN bus or a Flexray bus or similar.
  • the bus system enables functions for a driver assistance system for autonomous driving (ADAS), correction functions for limiting a maximum steering angle, a parking assistant for automated parking or an electronic stability control ESP (shown here), etc. to be carried out electrically by means of the control unit SG and the steer-by-wire steering by means of the associated actuators 4, 5.
  • the control unit SG is provided with a unit which can execute a process by means of a computer program and control the actuators 4, 5 on the signal path, the computer program being stored on a machine-readable storage medium as part of the control unit SG.
  • a yaw rate yaw_v measured at the center of gravity G of the vehicle is determined using a suitable sensor (rotation rate sensor) in the center of gravity of the vehicle 1 and recorded or evaluated by the electronic stability control ESP.
  • Sensors S are arranged at the outer ends of the vehicle 1, which are assigned to a sensor system and which are used to detect the vehicle's surroundings. These can be temperature sensors, e.g. optical sensors that include a camera, or LiDAR or radar, which are suitable for temperature, distance or optical detection, for example of the road. Weather conditions such as humidity or the temperature on the road, etc. can thus be recorded and fed to the control unit SG.
  • trajectory T which is also shown schematically in Figure 1 at the front end of the vehicle in its direction of travel.
  • the trajectory T corresponds to a left turn.
  • the front wheels 2 are turned to the left and the rear wheels 3 to the right.
  • the actuators 4, 5 are functioning properly, the known zero position of the spindle 52 or handlebar is set by both actuators 4, 5 based on a control signal from the control unit SG. This corresponds to a wheel steering angle of 0° in each case.
  • the vehicle 1 can thus follow a trajectory T for straight ahead travel along the longitudinal axis a as intended and shown in Fig. 2.
  • a wheel steering angle 6h3 is set (for clarity, much greater) than 0°.
  • the driver will or must countersteer and use the steering wheel 14 on the front axle 21 to set a wheel steering angle 6v4 that corresponds to the wheel steering angle 6h4 on the rear axle 31.
  • a wheel steering angle 6v4 that corresponds to the wheel steering angle 6h4 on the rear axle 31.
  • Figure 4 In the situation shown, the driver has turned the steering wheel 14 to the right, as shown by the arrow, in order to turn the wheels in the same direction as the Wheels of the rear axle. This results in compensated straight-ahead travel, in which the incorrect position on the actuator 5 for steering the rear axle 31 is compensated.
  • the longitudinal axis a forms an acute angle TT with the actual direction of travel according to the trajectory T shown.
  • the vehicle 1 moves straight ahead with the set compensation.
  • the vehicle is now moving in a so-called crab walk (pushing movement). It is obvious that when driving straight ahead the wheels 2, 3 rotate at at least approximately the same speed.
  • the speeds can be detected, for example, using the ABS speed sensors on the wheel carriers.
  • the steering wheel angle LRW can be detected using a sensor in the steering column. The method according to the invention is described below using an exemplary embodiment.
  • Figure 5 shows a flow chart of a method 200 for operating a steer-by-wire steering system of a vehicle (1) according to an embodiment.
  • the method 200 shown here can be carried out with a steer-by-wire steering system designed as a rear axle steering system using an actuator 5 in a vehicle 1.
  • a steer-by-wire steering system designed as a rear axle steering system using an actuator 5 in a vehicle 1.
  • further parameters are recorded using suitable sensors.
  • the longitudinal acceleration ax and the lateral acceleration ay of the vehicle are recorded, and the yaw rate of the vehicle yaw_v is recorded using the ESP.
  • the anti-lock braking system ABS is used to determine whether individual wheels are being braked, and the speed veh_v of the vehicle is determined, which is preferably calculated from the previously recorded wheel speeds.
  • the calculated position of the steering rod (spindle 52) is also recorded, which results from taking into account the rotor position sensor 55 of the electric motor 54 of the actuator 5. From this, an expected wheel steering angle on the rear axle can be calculated, which is to be set using the actuator 5 on the rear axle.
  • the determined signals or data are transmitted from corresponding sensors via the vehicle's bus system (e.g. CAN / Flexray or similar bus systems) to a control unit SG, or the control unit SG fetches the determined signals or data via the bus system used.
  • the vehicle's bus system e.g. CAN / Flexray or similar bus systems
  • the control unit SG is shown schematically with a dashed border. shown.
  • the currently existing steering wheel angle LRW_mom is summed up and an offset integral LRW_int is formed, which is filled at intervals with the currently existing steering wheel angle LRW_mom.
  • the status act_err therefore clearly represents an error state act_cond_err of the actuator 5 for steering the wheels 2, 3 on the rear axle 31.
  • the control unit SG shows the status act_err to the driver in a display in the cockpit of the vehicle.
  • the steering function of the actuator can be changed.
  • the performance (e.g. limiting the maximum possible setting angle) of the actuator 5 can be reduced or at least temporarily switched off.
  • a correction function Corr can also be triggered for the actuator 5.
  • the actuator 5 can be gradually reset or returned at intervals using the correction function Corr. After each reset, the vehicle movement and thus the wheel steering angle set by the actuator 5 and expected in this context are examined again using the aforementioned steps. A detected error of the actuator 5 can thus be automatically corrected within the scope of the method.
  • the control unit detects proper, i.e. normal, vehicle movement veh_norm. During this vehicle movement and also during cornering, a decay value is subtracted as part of the process. This subtraction is preferably carried out at intervals, in particular cyclically, preferably at intervals of 10 ms. In other words, during compensated straight-ahead travel, the values are added up and during the sections driven which differ from the detected compensated straight-ahead travel, e.g. cornering or similar, the decay value is subtracted.
  • a decay value of 4 determined empirically for a conventional car is therefore subtracted from the current offset integral.
  • Subtracting the decay value means that the offset integral is reduced during the current process.
  • the aim is to prevent the actuator from being incorrectly detected. This is effectively prevented by the step-by-step subtraction.
  • TT angle for compensated straight-ahead driving
  • veh_v vehicle speed veh_mv_mom current vehicle movement
  • veh_comp1 first vehicle state (compensated straight-ahead driving)
  • veh_norm further vehicle state yaw_v yaw rate

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)

Abstract

L'invention concerne un procédé (200) pour faire fonctionner un système de direction à commande électrique d'un véhicule (1) pour diriger des roues (2, 3) d'au moins un essieu arrière (31) au moyen d'au moins un actionneur (5). Le procédé (200) est caractérisé par au moins les étapes suivantes (205, 210, 215, 220, 225), consistant à : • détecter des vitesses de roue (RDZ_mom 2, 3) au niveau de roues (2, 3) de l'essieu avant (21) et/ou de l'essieu arrière (31) ; • détecter un angle de volant (LRW_mom) ; • déterminer un mouvement de véhicule (veh_mv_mom) en tenant compte au moins des vitesses de roue (RDZ_mom 2, 3) et de l'angle de volant de direction (LRW_mom) représentant un premier état de véhicule (veh_comp1) d'une conduite en ligne droite compensée du véhicule (1) ; • faire la somme des angles de volant détectés respectifs (LRW_mom) dans le temps (t) en fonction du premier état de véhicule (veh_comp1) pour former une intégrale de décalage (LRW_int), • comparer l'intégrale de décalage (LRW_int) à au moins une première valeur seuil (LRW_int_krit1), un état (act_err) dudit au moins un actionneur (5) de l'essieu arrière étant réglé lorsque la première valeur seuil (LRW_int_krit1) est atteinte, lequel état représente un état de panne (act_cond_err) de l'actionneur.
PCT/EP2024/065050 2023-06-06 2024-05-31 Procédé de fonctionnement d'un système de direction à commande électrique d'un véhicule, et système de direction à commande électrique Ceased WO2024251625A1 (fr)

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CN202480036977.0A CN121263349A (zh) 2023-06-06 2024-05-31 用于运行车辆的线控转向系统的方法以及线控转向系统

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DE102023205296.2A DE102023205296B3 (de) 2023-06-06 2023-06-06 Verfahren zum Betreiben einer Steer-by-wire-Lenkung eines Fahrzeugs sowie Steer-by-wire-Lenkung
DE102023205296.2 2023-06-06

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US20240166257A1 (en) * 2021-04-08 2024-05-23 Scania Cv Ab Control device and method for controlling a tag axle steering system
CN119389291A (zh) * 2025-01-02 2025-02-07 武汉普西芯电子技术有限责任公司 一种基于sbw系统的方向盘控制方法及装置

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US20090095562A1 (en) * 2007-10-16 2009-04-16 Yoshiyuki Yasui Steering control device for vehicle
DE102014117926A1 (de) 2013-12-11 2015-06-11 GM Global Technology Operations LLC Verfarhren und Systeme zum Ausrichten eines Lenksystems eines Fahrzeugs
DE102014206934A1 (de) 2014-04-10 2015-10-15 Zf Friedrichshafen Ag Stellmotor
DE102017209231A1 (de) 2017-05-31 2018-12-06 Zf Friedrichshafen Ag Verfahren und Anordnung zur Plausibilisierung und/oder (Re-) Initialisierung einer Hinterradlenkung
DE102018213112A1 (de) 2018-08-06 2020-02-06 Zf Friedrichshafen Ag Stellvorrichtung sowie Kraftfahrzeuglenkvorrichtung mit einem Elektromotor und einem Rotorlagesensor und einem Multiturnsensor
US20200377150A1 (en) * 2017-03-24 2020-12-03 Aisin Seiki Kabushiki Kaisha Vehicle
DE102020114871A1 (de) 2020-03-03 2021-09-09 Schaeffler Technologies AG & Co. KG Hinterachslenkungsanordnung und Verfahren zur Kalibrierung eines Hinterachslenkungsaktuators

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090095562A1 (en) * 2007-10-16 2009-04-16 Yoshiyuki Yasui Steering control device for vehicle
DE102014117926A1 (de) 2013-12-11 2015-06-11 GM Global Technology Operations LLC Verfarhren und Systeme zum Ausrichten eines Lenksystems eines Fahrzeugs
DE102014206934A1 (de) 2014-04-10 2015-10-15 Zf Friedrichshafen Ag Stellmotor
US20200377150A1 (en) * 2017-03-24 2020-12-03 Aisin Seiki Kabushiki Kaisha Vehicle
DE102017209231A1 (de) 2017-05-31 2018-12-06 Zf Friedrichshafen Ag Verfahren und Anordnung zur Plausibilisierung und/oder (Re-) Initialisierung einer Hinterradlenkung
DE102018213112A1 (de) 2018-08-06 2020-02-06 Zf Friedrichshafen Ag Stellvorrichtung sowie Kraftfahrzeuglenkvorrichtung mit einem Elektromotor und einem Rotorlagesensor und einem Multiturnsensor
DE102020114871A1 (de) 2020-03-03 2021-09-09 Schaeffler Technologies AG & Co. KG Hinterachslenkungsanordnung und Verfahren zur Kalibrierung eines Hinterachslenkungsaktuators

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240166257A1 (en) * 2021-04-08 2024-05-23 Scania Cv Ab Control device and method for controlling a tag axle steering system
US12473021B2 (en) * 2021-04-08 2025-11-18 Scania Cv Ab Control device and method for controlling a tag axle steering system
CN119389291A (zh) * 2025-01-02 2025-02-07 武汉普西芯电子技术有限责任公司 一种基于sbw系统的方向盘控制方法及装置

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