Method for operating steer-by-wire device

Abstract

The invention relates to a method for operating a steering-by-wire device in a vehicle, said steering-by-wire device comprising a feedback actuator, which is associated with a steering handle, and a steering actuator, in which a first signal carrying information about the operating state is generated during the operation of the vehicle and a second signal carrying information about the operating state is generated during the operation of the vehicle. The first signal is transmitted to the steering handle as a feedback to the driver by means of a feedback actuator, and a second signal carrying information about the responsibility of the driver for operation is generated, which is likewise transmitted to the steering handle as a feedback to the driver by means of the feedback actuator.

Description

Technical Field

[0001] The invention relates to a method for operating a steer-by-wire device and to an arrangement for carrying out the method. Background Art

[0002] A steer-by-wire system provides for the steering command to be transmitted from a sensor via one or more controllers only electrically to an electromechanical actuator, which implements the steering command. Such a steering system usually comprises a feedback unit (e.g. a steering wheel actuator), a steering actuator (e.g. in the form of a rack actuator) and a unit for evaluating and calculating the signals, which is implemented, for example, in software or software functions.

[0003] The method presented is used in particular in vehicles which are capable of implementing different automation levels as specified, for example, in SAE International J3016.

[0004] In vehicles, a distinction is typically made between assisted driving, automated driving and autonomous driving. The degree of automation is determined by the degree of automation or automation level. These levels are:

[0005] Level 0: Owner-driver, the driver drives the car himself;

[0006] Level 1: Assistance mode, specific assistance systems help vehicle operation, such as a speed controller for pitch adjustment;

[0007] Level 2: Assisted mode, using partially automated functions such as automatic parking and lane keeping;

[0008] Level 3: Automated mode, where the driver does not have to constantly monitor the system and the vehicle independently performs functions such as lane changing and lane keeping.

[0009] Level 4: Autonomous mode, highly automated, with the system permanently taking over the guidance of the vehicle;

[0010] Level 5: Autonomous mode, full automation, no driver required.

[0011] When implementing different degrees or levels of automation, it should be noted that the driver should have an appropriate degree of trust in the automated functions. Too much trust can lead to an increased risk of accidents, too little trust can lead to too little system utilization and may even lead to no utilization of the system. It is necessary to take into account that the driver should be prepared to at least temporarily hand over control of the vehicle at an automation level greater than or equal to 3 (≥L3). For this purpose, the driver must be able to identify or distinguish which level the driver or vehicle is at. It must also be possible to clearly identify the transition of the levels. In the absence of these prerequisites, the driver cannot exert appropriate trust in order to use the corresponding functions in accordance with regulations.

[0012] Basically, the goal is to provide the driver with information about current or immediately upcoming driving situations as quickly as possible, independently of the use in the automated vehicle. Summary of the invention

[0013] Against this background, a method according to claim 1 and an arrangement having the features of claim 11 are described. Embodiments are derived from the dependent claims and from the description.

[0014] A method for operating a steer-by-wire device in a vehicle is described, wherein the steer-by-wire device comprises a feedback actuator, such as a steering wheel actuator, which is associated with the steering wheel, and a steering actuator, such as a rack actuator. During operation of the vehicle, a first signal is generated, which carries information about at least one operating state, such as a lane state and / or a steering state, and is transmitted to a steering handle, such as a steering wheel, as feedback to the driver via the feedback actuator. In this way, the driver receives the same lane feel as he is accustomed to from conventional steering devices.

[0015] In addition, a second signal is generated, which carries information about the driver's responsibility for the operation. This second signal is also transmitted to the steering handle, for example the steering wheel, as feedback to the driver via the feedback actuator. The second signal is thus added to the first signal, wherein the second signal does not necessarily have to be continuous, but can also be generated as required. As an alternative, the generation of the first signal can be stopped at least temporarily while, before or after, or immediately before the generation of the second signal.

[0016] The feedback actuator generates the steering feel and transmits the driver's steering signal by wire or via a wire to the steering actuator which steers the wheels, depending on the driving speed and driving conditions.

[0017] The use of the presented method is discussed below in connection with driving at different levels of automation. The level of automation has a direct influence on the degree of responsibility of the driver for the operation of the vehicle. However, the method is not limited to use within the scope of assisted or automated driving, but can also be used in vehicles without additional driver assistance systems, provided that these vehicles have steer-by-wire.

[0018] The method presented is essentially based on calibrating trust in the automation system by achieving a clear distinction between different automation levels through the familiar tactile sensation that can be felt at the feedback actuator. Insufficient use of system functions can be prevented in this way.

[0019] The arrangement described is designed to carry out a method of the type described here. The arrangement can be implemented in hardware and / or software. In addition, the arrangement can be integrated in a control unit of a vehicle or designed as such a control unit. A typical evaluation unit is provided in the arrangement, which is designed, for example, to acquire and output signals based on the received information. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further advantages and embodiments of the invention are apparent from the description and the drawings.

[0021] It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the present invention. Among them:

[0022] Figure 1 A possible sequence of the method described is shown in a flow chart.

[0023] Figure 2 A schematic, highly simplified illustration shows a vehicle having an embodiment of the described arrangement for carrying out the presented method. DETAILED DESCRIPTION

[0024] The invention is schematically illustrated on the basis of embodiments in the drawings and is described in detail below with reference to the drawings.

[0025] In the method described, it is provided in the design that feedback about the activation of a driving function with a level greater than or equal to L3 is provided to the driver via a feedback actuator, such as a steering wheel actuator, as a feedback unit. This can mean that mechanical properties are specifically simulated to the driver via the feedback actuator. For example, a familiar, intuitively recognizable feeling, such as a click or bite, which can be clearly felt at the steering handle, can be provided to the driver. In this way, the driver is clearly informed of the change of driving mode and is reassured to allow the transfer of responsibility from that moment on or to assume responsibility again if necessary.

[0026] Proper driver trust and calibration of the vehicle's automation capabilities are facilitated by higher resolution accuracy between automation levels.

[0027] Figure 1 A possible sequence of the method described is shown in a flow chart. In a first step 50, driving of a vehicle is started, which is equipped with a steer-by-wire system and which can assume different automation levels. The driving begins at a level lower than L3. At a later time, in step 52, the vehicle assumes level L3. In step 54, the driver is informed of this change in automation level by means of a feedback actuator. This information is conveyed to the driver in a haptic manner by the sensation provided. The driver can adapt to the new situation and trust in the reliable operation of the vehicle.

[0028] The torque required for synthetically generating the sensation is output only to the feedback actuator, but is not transmitted to the wheels via the steering actuator.

[0029] The haptic of the simulated sensation can be varied and adapted via a software menu. The effect can be calculated in a control unit of the vehicle, for example a steering control unit, based on the current driving situation and superimposed on conventionally provided feedback or feedback signals. If, for a corresponding functionality greater than or equal to L3, it is provided that the steering handle is stationary or retracted, for example folded or lowered, the sensation generated can also limit the reproduction of conventional feedback signals.

[0030] Concrete possible effects for modifying the motion of the feedback actuator are, for example:

[0031] As soon as the automation function is activated, and if necessary with a delay of 0.5s to 1s, the feedback actuator:

[0032] 1) Follow the click-in feel, like a door lock,

[0033] 2) According to the feeling when approaching the magnet,

[0034] 3) according to the feel during locking by means of a spring pressure element, as is known, for example, from lockable telescopic rods,

[0035] Come bite in position.

[0036] Other features associated with snapping in, snapping in or screwing in are also conceivable. These provide a generally familiar tactile press-in effect to support the intuitive use of the automation functions and unconsciously (subconsciously) calibrate trust in the system based on its efficiency.

[0037] When the automated function is terminated by the planned handover scenario, a similar or opposite effect can be output by the feedback actuator. In this way, it can be clearly indicated to the driver that he is again in charge from this point on. If necessary, the transition can be supported during the assisted transition period by a subsequent gradual change or phased implementation of the conventional steering feel.

[0038] In addition to the switching between automation levels, it is also conceivable to use corresponding effects in other, fundamentally different types of use of the feedback actuator. An example of this is the switch between a game function and normal driving operation. When switching between driving operation and game operation, the driver's responsibility also changes.

[0039] The characteristics of the aforementioned effects or the angle-torque characteristic curve can be detected by means of a torque / angle sensor which is installed in a device equipped with the aforementioned components.

[0040] A purely synthetic mapping by mathematical derivation and / or reading from a mechanical device is also conceivable. In practice, a hybrid approach can prove useful, namely reading by means of a torque sensor and mapping the existing characteristic curve into a mathematical function. For this purpose, a known mathematical function can be selected which reproduces the entire characteristic curve as well as possible.

[0041] The characteristic curve created in this way can be varied and optimized via a number of parameters. A number of selection options are also available to the end user, which can be selected, for example, via an app or a vehicle menu, such as:

[0042] a) the angular range through which the occlusion is carried out,

[0043] b) the intensity of the effect or the magnitude of the torque,

[0044] c) The hardness of the effect, ie, a soft or hard engagement, can optionally be achieved by a change in the first or second derivative of the torque function.

[0045] It is important that the feedback actuator provides feedback as torque for the change in automation level, wherein a familiar haptic sensation is generated. It is also important that the wheel deflection is not changed in this process. This allows the sensation to be provided to be represented significantly more precisely than has been achieved so far, for example, by vibrations.

[0046] The method described has a number of advantages at least in some embodiments:

[0047] The potential for savings due to the avoidance of additional feedback actuators, such as vibrations, can be implemented cost-effectively in software alone;

[0048] Improvements to driving comfort, which can be flexibly changed and individually customized, for example via an app;

[0049] Develop new business models, such as follow-up opening and leasing models;

[0050] About competitive differentiation;

[0051] Modifiability (Firmware Over the Air: FOTA);

[0052] The clear demarcation of automation levels leads to a build of confidence in the end user, thereby increasing the frequency of use of auxiliary automation functions / increasing the attractiveness of the system.

[0053] The method can basically be used in all steer-by-wire systems which have a feedback unit, such as, for example, a feedback actuator, and which are installed in vehicles which have, for example, an automated function of level 3 or higher.

[0054] Figure 2 A schematic diagram shows a vehicle, which is generally designated by reference numeral 100. The vehicle has a steer-by-wire system 102, which has a feedback actuator 104 and a steering actuator 106, which is associated with a steering handle 105, and an arrangement 108 for carrying out the described method. The arrangement 108 is implemented, for example, by a software function.

[0055] Furthermore, vehicle 100 is designed to assume different automation levels. Arrangement 108 can now generate a signal as a function of the applied automation level or, if necessary, an upcoming change of the automation level, which carries information for this purpose and is transmitted to feedback actuator 104, which takes the signal or the information transmitted by the signal into account when providing feedback to the driver.

[0056] This feedback can provide a positional locking, ie, locking or releasing, of the steering handle 105 .

Claims

1. A method for operating a steer-by-wire device (102) in a vehicle (100), wherein: The wire-controlled steering device comprises a feedback actuator (104) and a steering actuator (106), wherein the feedback actuator is assigned to a steering handle (105). wherein a first signal carrying information about at least one operating state is generated during operation of the vehicle (100), and the first signal is transmitted to the steering handle (105) via the feedback actuator (104) as feedback to the driver, and generating a second signal carrying information about the driver's responsibility for the operation, The second signal is also transmitted to the steering handle (105) via the feedback actuator (104) as feedback to the driver.

2. The method according to claim 1, wherein: The first signal carries information about the steering state and / or lane state of the vehicle (100).

3. The method according to claim 1 or 2, wherein: The second signal carries information about the automation level of the vehicle (100).

4. The method according to claim 3, wherein: The second signal carries information about a change in the automation level.

5. The method according to claim 4, wherein: The signal carries information that the automation level has become greater than or equal to L3.

6. The method according to claim 4, wherein: The second signal carries information that the automation level has become less than L3.

7. The method according to any one of claims 1 to 6, wherein: The feedback provides a positional locking of the steering handle (105), for example, locking in or releasing it.

8. The method according to any one of claims 1 to 7, wherein: The feedback is adapted.

9. The method according to any one of claims 1 to 8, wherein: The feedback is calculated in a vehicle control unit, for example a steering control unit, and is superimposed on a feedback signal of the feedback actuator (104).

10. The method according to any one of claims 1 to 9, wherein: Synthetic mapping of features representative of the second signal is performed by mathematical derivation and / or reading from a mechanical device.

11. An arrangement for operating an automated vehicle (100), which is designed to carry out a method according to claim 1 and has an evaluation unit.

Images