Method for generating roadway feedback for a steer-by-wire steering system, steer-by-wire steering system and vehicle

Abstract

The invention relates to a method for generating roadway feedback for a steer-by-wire steering system for a vehicle driver, wherein the roadway feedback is provided by a feedback torque at a steering handle by means of a steering wheel actuator, comprising the following steps: detecting a driver's manual torque applied to the steering handle; generating the feedback torque according to the detected driver's manual torque.

Description

[0001] Description

[0002] Method for generating road feedback from a steer-by-wire steering system, steer-by-wire steering system and vehicle

[0003] The invention relates to a method for generating road feedback for a steer-by-wire steering system for a vehicle driver according to claim 1, as well as a steer-by-wire steering system of a vehicle according to dependent claim 7 and a vehicle according to dependent claim 8. For the prior art, reference is made, by way of example, to DE 10 2014 211 815 A1.

[0004] So-called steer-by-wire systems for vehicles are already known in various forms from the prior art. Such a system differs from conventional steering systems in that the steering of the wheels is completely decoupled from the driver's mechanical steering movements, or rather, occurs solely through a purely electronic transmission. The conventional mechanical transmission devices are eliminated; instead, the driver generates data through their steering movements at the steering handle or steering wheel, which is then fed into an electronic control unit. This control module evaluates the data and translates it into corresponding steering commands. These commands then control the steering gear, which executes the desired steering movement.

[0005] To provide the driver with a steering feel comparable to that of conventional steering systems in a steer-by-wire system, a steering wheel actuator, force simulator, steering wheel motor, or feedback actuator is typically integrated into the steering wheel module. Based on the available sensor data, a control unit calculates a setpoint for the feedback actuator, which then translates into steering resistance at the steering wheel. Ideally, this resistance should reflect the friction between the tires and the road surface at an appropriate force level. Furthermore, it should simulate the inertia, friction, and hysteresis of the steering system, actively return the steering to straight-ahead driving, and replicate the forces acting on the tie rods of the front axle steering.

[0006] Such a steer-by-wire steering system is described in DE 10 2014 211 815 A1. These road feedback systems provide the driver with information about the vehicle's dynamics. However, the intensity and duration of such information or feedback can be disruptive to the driver and lead to a loss of comfort. Furthermore, the intensity of such road feedback can be too high or too low, making it difficult or disruptive for the driver to perceive.

[0007] The object of the invention is to demonstrate a method for generating road feedback for a steer-by-wire steering system, which is designed to be as comfortable as possible.

[0008] The solution to the problem is achieved by a method for generating road feedback for a steer-by-wire steering system for a vehicle driver with the features of claim 1, a steer-by-wire steering system of a vehicle according to the features of dependent claim 7, and a vehicle according to the features of dependent claim 8. Advantageous further developments are the subject of the dependent claims.

[0009] A method for generating road feedback from a steer-by-wire system for a vehicle driver is proposed. This road feedback is achieved by generating a feedback torque at a steering handle of the vehicle or steering system. This feedback torque is generated by a steering wheel actuator on the steering handle (specifically, the steering wheel).

[0010] A steering wheel actuator, also known as a feedback actuator, is an actuator typically located on the steering handle to initiate a steering maneuver by the driver of a vehicle. It generates, for example, the return force or torque for the steering handle (especially the steering wheel) to provide a haptic feel similar to conventional steering systems. Such a steering wheel actuator generates feedback, based on wheel-road forces, which is transmitted to the driver or the steering handle in the form of a feedback torque. This feedback is subsequently referred to as road feedback.

[0011] The aforementioned road feedback at the steering wheel actuator can, in certain cases, lead to a change in the wheel angle (i.e., actual wheel steering), depending on whether and with what force the driver holds the steering handle. The proposed invention is therefore based, in particular, on the consideration that a change in the steering wheel angle of the steering handle, potentially caused by a specific feedback torque, depends significantly on the opposing torque of the driver's hand and thus on the driver's hand position.

[0012] Therefore, it is designed so that the driver's hand torque present at the steering handle is first detected. This is because simply holding the steering handle with one or both hands (or just fingers) already creates a counter-torque at the steering handle to the feedback torque of the steering wheel actuator.

[0013] Such measurement of the driver's hand torque can be achieved through suitable sensors, estimation, or calculation. This measurement is preferably taken at regular intervals (for example, 100 times per second).

[0014] Furthermore, the system is designed to generate the aforementioned feedback torque based on the detected driver hand torque. For example, if the driver hand torque is found to be particularly low (e.g., below a defined threshold), the feedback torque can be adjusted accordingly and, for instance, made weaker. This is because the weaker the driver hand torque, the greater the impact of the feedback torque on the actual steering of the vehicle wheel. Conversely, if the driver hand torque is higher (e.g., above a defined threshold), the feedback torque can be correspondingly stronger.

[0015] In a preferred embodiment of the invention, the inertia of the system “driver-arm-hand-steering handle” can be estimated, calculated or recorded using or instead of the driver's hand torque.

[0016] The driver's hand torque or a so-called system inertia can then be used to predict the steering angle change and thus also the wheel angle change resulting from the feedback torque.

[0017] It is therefore preferably provided that such a change in wheel angle of at least one vehicle wheel is determined or predicted as a result of a change in the steering handle angle generated by the feedback moment at the steering handle, depending on the driver's hand torque.

[0018] In addition to the wheel steering angle or the change in wheel steering angle, the steering hand angle or the change in steering hand angle can alternatively or additionally be used as a reference value.

[0019] Furthermore, a predefined maximum wheel angle change or a predefined maximum wheel steering angle can be determined. This maximum wheel angle change or maximum wheel steering angle can either be determined situationally or stored in the system and thus be predefined.

[0020] The maximum wheel angle change or the maximum wheel steering angle can represent a value beyond which the resulting vehicle steering becomes uncomfortable or even disturbing for a driver.

[0021] The aforementioned feedback torque is then preferably generated or limited in such a way that this maximum wheel angle change is not exceeded.

[0022] For example, if it is determined that the feedback torque, in combination with the current driver hand torque, leads to a change in the steering angle that would exceed the maximum wheel angle change or steering angle, the feedback torque is accordingly limited or generated at a lower intensity. The feedback torque can preferably be scaled or adjusted so that a defined angle change (either wheel steering angle change or steering angle change) is achieved and corresponding comfort and safety limits are maintained even with a low opposing driver hand torque.

[0023] In a preferred embodiment of the invention, the maximum wheel angle change, the maximum wheel angle itself, the maximum steering angle change, or the maximum steering angle can be determined depending on the current vehicle environment, the current driving situation, or the current vehicle state. For example, certain angle limits or angle change limits, above which an uncomfortable driving condition exists, can vary depending on the driving situation, vehicle environment, or vehicle state.

[0024] For example, suitable sensors (especially sensors already present in the vehicle) can detect the vehicle's surroundings (e.g., the lane width or lateral distances of the vehicle from a road boundary) and, depending on this, set the aforementioned limit value for the wheel angle change or the wheel angle or the steering angle or the steering angle change.

[0025] For example, if the vehicle is using appropriate sensors, navigation data, or similar technologies, and is in a construction zone or has only small lateral distances with a narrow lane and correspondingly little space perpendicular to the direction of travel, the feedback signal can be reduced (depending on the driver's hand torque) to limit potential lane deviation. Conversely, if a wide lane with ample space is detected, the feedback signal can be increased.

[0026] It is also preferred that the aforementioned limit value for the wheel angle change, or the steering angle, or the steering angle change, be determined depending on the driving and vehicle situation (e.g., driving dynamics data), and that the feedback torque is adjusted accordingly. For example, if a sporty driving situation is detected via vehicle data or corresponding vehicle sensors, the limit values ​​can be widened and the feedback torque correspondingly stronger. A sporty driving situation can be indicated, for example, by correspondingly high longitudinal and lateral accelerations measured or recorded over a certain period (e.g., determined as an average of absolute acceleration values).

[0027] It is also preferably provided that the feedback moment is generated depending on a detected attention state of the driver.

[0028] Using appropriate data and sensors (e.g., vehicle interior sensors, driver observation cameras, vital signs measurements, etc.), driver attention data can be collected, providing insights into the driver's level of attention. This recorded level of attention can then be assessed and classified, and, depending on the system's logic, the level of feedback can be adjusted accordingly.

[0029] The functional logic might, for example, require that a driver be "awakened" by a correspondingly high level of feedback when low attention is detected. Conversely, the feedback level can be lower if a low level of attention is detected, so as not to startle the driver. Depending on the severity and intensity of the driver's attention, the feedback level can thus be adjusted.

[0030] In a further preferred embodiment of the invention, the feedback moment is generated or adjusted depending on steering wheel touch detection (also known as "hands-on detection"). For this purpose, a capacitive sensor element for occupancy detection or so-called hands-on detection can be arranged on the steering handle. The capacitive sensors are used to detect a hand or finger by its influence on an electric field generated by the sensor, i.e., the capacitive change. In this way, a release or even a very light touch of a finger or hand with the steering handle can be detected.

[0031] If a corresponding steering wheel touch detection system detects that the steering handle is not being touched at all or only minimally by a driver (for example, because the vehicle is currently being steered at least partially autonomously), the feedback signal can be set accordingly weak or even omitted completely.

[0032] In a preferred embodiment of the invention, the method comprises a machine learning process such that the feedback torque is adjusted based on trained or learned data, depending on the driver's hand torque. The method is designed to train or validate machine learning or artificial intelligence algorithms with features from measurement data, calculation data, and optionally other data.

[0033] Furthermore, a steer-by-wire steering system for a vehicle to carry out the procedure, as well as a vehicle with such a steer-by-wire steering system, is proposed.

[0034] The steer-by-wire system includes a steering handle that the driver can operate to steer the wheels. The steering handle is mechanically completely decoupled from the steered wheels.

[0035] The steering system further includes at least one wheel actuator for adjusting a wheel steering angle of at least one wheel of the vehicle in response to the input of the steering request at the steering handle.

[0036] Furthermore, the steer-by-wire steering system includes at least one computing unit, sensor unit, or control unit for detecting a driver hand torque applied to the steering handle.

[0037] To inform the driver about the current wheel-road forces or road feedback, as he is used to, these are synthetically generated or simulated by a single steering wheel actuator, for example in the form of torques at the steering handle (= feedback torque).

Claims

Patent claims 1. Method for generating road feedback from a steer-by-wire steering system for a vehicle driver, wherein the road feedback is provided by a feedback moment at a steering handle by a steering wheel actuator, comprising the steps: - Detecting a driver hand torque applied to the steering handle; - Generating the feedback moment depending on the detected driver hand torque.

2. The method of claim 1, further comprising the following steps: - Determining a change in wheel angle of at least one vehicle wheel due to a change in steering handle angle generated by the feedback torque at the steering handle, depending on the detected driver hand torque; - Determining a specified maximum wheel angle change, - Generating the feedback torque in such a way that the determined maximum wheel angle change is not exceeded.

3. Method according to claim 1, wherein the maximum wheel angle change is determined depending on the current vehicle environment and / or depending on the current driving situation and / or depending on a current vehicle state.

4. Method according to claim 1 or 2, wherein the feedback moment is generated depending on a detected attention state of the driver.

5. Method according to one of the preceding claims, wherein the feedback moment depends on steering wheel touch detection.

6. A method according to any of the preceding claims, comprising a machine learning method. . Steer-by-wire steering system of a vehicle for carrying out the method according to one of claims 1 to 6, comprising - a steering handle for a vehicle occupant to input a steering request, - at least one wheel actuator for adjusting the steering angle of at least one wheel of the vehicle in response to the steering request input at the steering handle - at least one computing unit and / or sensor unit and / or control unit for detecting a driver hand torque applied to the steering handle - as well as a steering wheel actuator controllable by a control unit to generate a feedback moment at the steering handle to a vehicle occupant.

8. Vehicle comprising a steer-by-wire steering system configured according to claim 7.