Method for operating steering-by-wire system of motor vehicle, steering-by-wire system and motor vehicle

Abstract

The invention relates to a method for operating a steer-by-wire system of a motor vehicle, according to which a steering command input via a steering control device is acquired, a control signal for a steering gear actuator is generated by means of an adjusting control unit depending on the steering command, the steering gear actuator is mechanically separated from the steering control device, and an actuating signal is generated by means of the adjusting control unit and is used for exciting a force feedback actuator associated with the steering control device to apply haptic feedback on the steering control device. The method according to the invention is characterized in that at least one natural frequency of the steering control device is determined, and the control signal generated by means of the control unit is coordinated with the determined at least one natural frequency, so that excitation in the natural frequency range of the steering control device is avoided.

Description

Technical Field

[0001] The invention relates to a method for operating a steer-by-wire system of the type specified in the preamble of claim 1 , a steer-by-wire system according to claim 6 , and a motor vehicle according to claim 7 . Background Art

[0002] In the prior art, steer-by-wire systems are known, which are distinguished in particular by the fact that no steering column is provided, that is, the steering device and the steering gear actuator are mechanically separated from each other and are controlled in a completely electronic manner via force control and travel control. For electronic regulation / control, the steering system has a regulation control unit, which detects the steering desire or steering command given by the driver and generates control signals for controlling the steering gear actuator based on this. In order to provide tactile feedback to the driver, the steering device is also equipped with an electromechanical force feedback actuator, which generates corresponding tactile feedback. The tactile feedback includes steering feedback, in which a steering reaction torque is applied to the steering device as a function of the steering force that occurs, and lane feedback, which is associated with a disturbance excitation acting on the lane of the vehicle. Reference is made to DE 10 2015 005 020 A1 merely as an example.

[0003] A method described in the introduction for operating a steer-by-wire system is disclosed in DE 10 2016 009 684 A1. Summary of the invention

[0004] The object of the present invention is therefore to improve a method for operating a steer-by-wire system of a motor vehicle of the type specified in the preamble of claim 1 in such a way that steering vibrations which are unpleasant to the driver are prevented.

[0005] This object is achieved by the characterizing features of claim 1 in combination with the preamble.

[0006] Dependent claims 2 to 5 are advantageous developments of the method according to the invention.

[0007] According to the method for operating a steer-by-wire system, a steering command input via a steering device is detected in a known manner and a control signal for actuating a steering gear actuator, which is mechanically decoupled from the steering device, is generated based on the steering command by means of a control control unit. Furthermore, a control signal for actuating a force feedback actuator associated with the steering device is generated by means of the control control unit in order to apply haptic feedback to the steering device.

[0008] According to the invention, it is provided that at least one natural frequency of the steering device is determined.

[0009] An actuation signal generated by means of the control unit for actuating the force feedback actuator is adapted to at least one determined natural frequency of the steering device so that excitations in the region of the natural frequency of the steering device are avoided when applying haptic feedback by the force feedback actuator.

[0010] The method according to the invention can advantageously ensure that—due to the excitation not being within the natural frequency range of the steering device—vibrations of the steering device are effectively prevented, thereby providing the driver with a comfortable driving experience.

[0011] A further advantage is that the method requires only a corresponding activation of the force feedback actuator, ie no separate vibration damper is required for damping or avoiding vibrations of the steering device.

[0012] To this end, preferably, according to the method, body vibrations of the motor vehicle body generated or caused by interference excitations from the road surface and / or the motor vehicle body are acquired, an excitation frequency based on the body vibrations is determined, and an excitation frequency is determined that is within the range of a predetermined natural frequency of the steering control device.

[0013] A preferred embodiment of the invention is characterized in that the determined excitation frequencies, ie the frequencies in the range of the natural frequencies of the steering device, are filtered out.

[0014] This excitation frequency is not taken into account in the generation of the control signal for controlling the force feedback actuator or for the generation of the control signal. In other words, potential frequencies that cause vibrations of the steering device are filtered out in advance, so that the control signal does not contain the corresponding frequencies. This can advantageously ensure that only haptic feedback that is not within the natural frequency range of the steering device is applied by means of the force feedback actuator, so that vibrations of the steering device are avoided.

[0015] As an alternative or in addition to the above-described embodiment, another embodiment of the method according to the invention provides that the control signal for controlling the force feedback actuator is generated taking into account a predetermined excitation frequency, so that the excitation in the natural frequency range of the steering wheel actuator is cancelled by the force feedback actuator by applying a vibration in the opposite phase to the determined excitation frequency. In other words, the force feedback actuator is used as a vibration damping device for attenuating frequencies in the natural frequency range of the steering device.

[0016] Preferably, disturbance excitations to the vehicle body with respect to the road surface and / or with respect to the vehicle body are detected by means of sensors.

[0017] A further object of the present invention is to provide a steer-by-wire system for a motor vehicle which is designed—with little effort—to prevent undesired vibrations of the steering device.

[0018] This object is achieved by the characterizing features of claim 6 in combination with the preamble.

[0019] To this end, the steer-by-wire system comprises in a known manner a steering control device, a steering sensor for acquiring a steering command implemented on the steering control device, a steering gear actuator mechanically separated from the steering control device, a force feedback actuator associated with the steering control device, and a regulating control device, which is designed to generate a control signal for the steering gear actuator as a function of the acquired steering command, and which is designed to generate a control signal for the force feedback actuator in order to apply tactile feedback to the steering control device.

[0020] The steer-by-wire system according to the invention is distinguished in that the regulating control unit is also designed to execute the method according to any one of claims 1 to 5 .

[0021] Since—as described above—unwanted vibrations of the steering device are avoided by carrying out the method according to the invention, the steer-by-wire system according to the invention advantageously does not require additional components, such as a special steering wheel damper for eliminating or damping unwanted vibrations.

[0022] The object of the present invention is also to further improve a motor vehicle, which includes a steer-by-wire system and at least one sensor for detecting interference excitations of the motor vehicle body with respect to the lane and / or the motor vehicle body, which is improved to avoid undesirable vibrations of the steering control device during driving operation.

[0023] This object is achieved by a steer-by-wire system according to claim 6 .

[0024] All statements regarding the steer-by-wire system according to the invention and all statements regarding the method according to the invention for operating a steer-by-wire system apply analogously to the motor vehicle according to the invention, so that the advantages described above can also be achieved with this motor vehicle.

[0025] Preferably, at least one sensor is designed in the form of an acceleration sensor. Since such sensors are installed in motor vehicles in a standardized manner, the function of "detecting disturbance excitations in relation to the road surface and / or the vehicle body" can be realized cost-effectively and simply. However, it is also conceivable to calculate the required disturbance excitations by means of an evaluation device.

Claims

1. A method for operating a steer-by-wire system of a motor vehicle, according to which a steering command input via a steering device is detected, a control signal for a steering gear actuator is generated based on the steering command by means of a control control unit, the steering gear actuator being mechanically decoupled from the steering device, according to which a control signal is generated by means of the control control unit, the control signal being used to actuate a force feedback actuator associated with the steering device in order to apply haptic feedback to the steering device, It is characterized in that At least one natural frequency of the steering device is determined, and the control signal generated by means of the control control unit is adapted to the at least one determined natural frequency, so that excitations in the region of the natural frequency of the steering device are avoided.

2. The method according to claim 1, It is characterized in that Disturbance excitations from the road and / or the motor vehicle body and resulting body vibrations of the motor vehicle body are detected, an excitation frequency based on the body vibrations is determined, and the excitation frequency is determined to be within the range of a natural frequency of the steering wheel actuator.

3. The method according to claim 2, It is characterized in that The determined excitation frequency is filtered out so that it is not taken into account in the generation of the actuation signal for exciting the force feedback actuator.

4. The method according to claim 2, It is characterized in that Taking the determined excitation frequency into account, an actuation signal is generated such that excitations in the natural frequency range of the steering device are cancelled at the steering wheel actuator by applying a vibration in phase opposition to the determined excitation frequency.

5. The method according to claim 2, It is characterized in that Disturbance excitations to the vehicle body in relation to the lane and / or in relation to the vehicle body are detected by means of sensors.

6. A steer-by-wire system for a motor vehicle, the steer-by-wire system comprising a steering control device, a steering sensor for acquiring a steering command implemented on the steering control device, a steering transmission mechanism actuator mechanically separated from the steering control device, a force feedback actuator assigned to the steering control device, and a regulating control device, the regulating control device being designed to generate a control signal for the steering transmission mechanism actuator according to the acquired steering command, the regulating control device being designed to generate a control signal for the force feedback actuator to apply tactile feedback to the steering control device, It is characterized in that The regulating control device is further configured to execute the method according to any one of claims 1 to 6.

7. A motor vehicle comprising a steer-by-wire system and at least one sensor for detecting disturbance excitations to the vehicle body with respect to the lane and / or the vehicle body, It is characterized in that The steer-by-wire system is designed according to claim 6 .

8. The motor vehicle according to claim 7, It is characterized in that The sensor is designed in the form of an acceleration sensor.