RAILBORNE DRIVER ASSISTANCE DEVICE AND METHOD FOR SUPPORTING OR AUTOMATING THE LATERAL CONTROL OF A VEHICLE

Abstract

A railborne driver assistance device for supporting or automating the lateral control of a vehicle includes a first processing unit configured to control a steering torque intervention by establishing a steering angle with a stationary control accuracy of an electrically supported steering system. A second processing unit is configured to adjust the stationary control accuracy of the steering angle via the output of an accuracy request signal to the first processing unit in such a way that there is a scaling of the control accuracy between a lower and an upper threshold value. The second processing unit includes a control unit having an integrator with an input and an output, wherein the output of the integrator is connected to the input in a closed-loop manner with a weighting dependent on the accuracy request signal.

Claims

1. A railborne driver assistance device for supporting or automating the lateral control of a vehicle, comprising: a first processing unit configured to control a steering torque intervention by establishing a steering angle with a stationary control accuracy of an electrically supported steering system, and a second processing unit configured to adjust the stationary control accuracy of the steering angle via the output of an accuracy request signal to the first processing unit in such a way that there is a scaling of the control accuracy between a lower and an upper threshold value, wherein the second processing unit has a control unit having an integrator comprising an input and an output, wherein the output of the integrator is connected to the input in a closed-loop manner with a weighting dependent on the accuracy request signal.

2. The railborne driver assistance device according to claim 1, wherein the upper threshold value leaves the stationary control accuracy of the electrically supported steering system unchanged and wherein the lower threshold value implements a maximum predetermined attenuation of the stationary control accuracy.

3. The railborne driver assistance device according to claim 1, wherein the accuracy request signal is specified between the upper and lower threshold value, wherein a stationary control_error approaches zero at the upper threshold value and wherein the maximum permissible control_error is present at the lower threshold value.

4. The railborne driver assistance device according to claim 1, wherein the second processing unit is designed to adjust the control accuracy of the steering angle utilizing temporal cross-fading.

5. The railborne driver assistance device according to claim 4, wherein the accuracy request signal is designed quasi-continuously, wherein the second processing apparatus is designed to interpolate or to cross-fade between the upper and lower threshold value.

6. The railborne driver assistance device according to claim 1, wherein the weighting dependent on the accuracy request signal is a gain factor.

7. The railborne driver assistance device according to claim 1, wherein the first processing unit comprises a controller having a disturbance variable feedforward, wherein the proportional feedforward of the disturbance variable to the actuating torque is executed in accordance with a weighting that is dependent on the accuracy request signal.

8. The railborne driver assistance device according to claim 1, wherein a degree of attenuation of the control accuracy to be adjusted is established by a or multi-stage cascade control unit.

9. The railborne driver assistance device according to claim 1, wherein the first processing unit comprises a steering angle control unit for establishing a steering angle with a stationary control accuracy as well as a feedforward control unit for the feedforward control of the steering angle, wherein a contribution of the feedforward control unit is scaled as specified by the accuracy request signal prior to the proportional feedforward to the actuating torque.

10. The railborne driver assistance device according to claim 1, wherein the stationary control accuracy has a predetermined output value until it is adjusted by the second processing unit.

11. The railborne driver assistance device according to claim 1, wherein the second processing apparatus is designed to adaptively attenuate the control accuracy when wheel fight occurs and/or when a driver intervention is recognized.

12. The railborne driver assistance device according to claim 1, wherein during a dynamic driving maneuver, when entering and/or exiting a curve, the control accuracy is established with an accuracy request signal of at least 70 per cent.

13. The railborne driver assistance device according to claim 1, wherein a stronger or weaker recommended torque is obtained by the accuracy specification when the driver steers, depending on an established driving mode or as a function of driver-specific driving behavior.

14. A vehicle having a railborne driver assistance device comprising: a first processing unit configured to control a steering torque intervention by establishing a steering angle with a stationary control accuracy of an electrically supported steering system, and a second processing unit configured to adjust the stationary control accuracy of the steering angle via the output of an accuracy request signal to the first processing unit in such a way that there is a scaling of the control accuracy between a lower and an upper threshold value, wherein the second processing unit has a control unit having an integrator comprising an input and an output, wherein the output of the integrator is connected to the input in a closed-loop manner with a weighting dependent on the accuracy request signal.

15. A method for supporting or automating the lateral control of a vehicle, comprising: controlling a steering torque intervention with a first processing unit by establishing a steering angle with a stationary control accuracy of an electrically supported steering system; and adjusting the stationary control accuracy of the steering angle with a second processing unit via the output of an accuracy request signal to the first processing unit in such a way that there is a scaling of the control accuracy between a lower and an upper threshold value, wherein the second processing unit has a control unit having an integrator comprising an input and an output, wherein the output of the integrator is connected to the input in a closed-loop manner with a weighting dependent on the accuracy request signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Further features, advantages and effects are set out in the following description of exemplary embodiments, wherein:

[0036] FIG. 1 shows a schematic representation of a railborne driver assistance device having a first and second processing unit;

[0037] FIG. 2 shows an exemplary implementation of the railborne driver assistance device from FIG. 1 when using a traditional PID steering angle controller having a feedforward control;

[0038] FIG. 3 shows an example of an extension of a PD steering angle controller with disturbance value feedforward to include the path of an accuracy specification; and

[0039] FIG. 4 shows an example of an extension of a P-PI cascade controller to include the accuracy specification path.

DETAILED DESCRIPTION

[0040] FIG. 1 shows a schematic representation of a railborne driver assistance device 1 for a vehicle 2. The driver assistance device 1 includes a first processing unit 3 which is designed to control a steering torque intervention by establishing a steering angle with a stationary control accuracy of an electrically supported steering system. For example, the first processing unit 3 is a control unit of an electric power steering EPS for controlling steering torque interventions.

[0041] The driver assistance device 1 includes a second processing unit 4 which is designed to adjust the stationary control accuracy of the steering angle via the output of an accuracy request signal to the first processing unit 3 in such a way that there is a scaling of the control accuracy between a lower and an upper threshold value.

[0042] FIG. 2 shows an exemplary implementation of the railborne driver assistance device 1 from FIG. 1 when using a traditional PID steering angle controller with feedforward control. Purely by way of example, the second processing unit 3 here includes a control unit having an integrator I comprising an input and an output, wherein the output of the integrator I is connected to the input in a closed-loop manner with a weighting dependent on the accuracy request signal G.

[0043] An aspect according to the disclosure is that the component of the feedforward control is scaled with the value range [0% . . . 100%] depending on the specification of an externally specified continual accuracy specification G.

[0044] A further aspect according to the disclosure is that the integrator output of the controller, likewise scaled by way of the accuracy request signal G, is fed back to the integrator input in the sense of a connection in a closed-loop manner. In the case of an accuracy specification of 100%, the loop gain is 0, in the case of an accuracy specification of 100%, this is a specifiable maximum gain M.

[0045] The transfer function of the integrator block having a connection branch in a closed-loop manner is:

G(s)=1/(s+Max return factor M*(1−Accuracy specification G/100))

It can be seen that, depending on the value of the accuracy specification G, the pure integrator results in a PT1 element with a predefinable steady component gain.

[0046] These two measures can, on the one hand, effectively prevent the continuous integration of the integrator I when the driver intervenes. When the driver deflects the steering wheel, if an accuracy request signal G is 0% and a high value is selected for max. return factor M, there is practically only one PD controller present that generates an EPS engine superposition torque of the size EPS_engine torque_superposition=control_error*(s*kd+kp) which corresponds to the system equation of a damped spring, which behavior is comprehensible to the driver.

[0047] Without scaling the feedforward control component, an additional, deflection-dependent additional torque would result which, depending on the level of the feedforward control, can be perceived as being implausible for the driver.

[0048] By converting the pure integrator I into a PT1 element, limit cycles of the steering angle control variable are prevented at the same time, since the controller is now no longer striving for exact stationary control accuracy, which is the main cause for the stick-slip in connection with the static and dynamic friction of the system. This increases the smoothness of the steering wheel and the driving comfort felt by the driver.

[0049] In the event that the first processing unit 3, in particular a steering angle controller of the first processing unit 3, e.g., on the EPS is not based on a PI(D) approach, the method can nevertheless be implemented in a similar manner, cf. FIG. 3.

[0050] FIG. 3 shows, by way of example, an extension of a PD steering angle controller having disturbance variable feedforward control to include the path of the accuracy specification. The first processing unit 3 is shown with a controller having disturbance value feedforward, wherein the proportional feedforward of the disturbance variable to the actuating torque is executed in accordance with a weighting that is dependent on the accuracy request signal.

[0051] In the case of a controller approach which is based on a disturbance variable estimation and feedforward, the estimated disturbance variable Disturbance torque_raw is scaled with the accuracy signal prior to the feedforward thereof.

Disturbance torque=Disturbance torque_raw*(Accuracy specification G/100))

[0052] FIG. 4 shows, by way of example, an extension of a P-PI cascade controller to include the accuracy specification path. In this exemplary embodiment, the degree of attenuation of the control accuracy to be adjusted is established by means of a multi-stage cascade control unit, consequently multiple controllers having different parameterizations and different controller structures (designs) are implemented, between which the second processing unit 4 is designed to switch over, to cross-fade and/or to interpolate.

[0053] The exemplary cascade control comprises a P controller for the steering angle and a PI controller for the steering angle speed, wherein the integrator I of the inner cascade is limited to how it is implemented in the case of the PID controller in FIG. 2.

[0054] In the case of state controller or cascade controller approaches having an I component, the integrator I is to correspondingly be connected in a closed-loop manner (cf. exemplary embodiment in FIG. 4).

[0055] In general, irrespective of the controller approach, the effect of that path which is responsible for the stationary control accuracy is to be attenuated in a scaled manner.

[0056] It should be noted that the two-stage cascade control shown in FIG. 4 is exemplary and not restrictive, so that additional controllers and controller types to a P and a PI controller are also conceivable.

[0057] The adaptive controller accuracy interface can be operated when required or always. In this way, the accuracy can be adaptively reduced when wheel fight occurs. The accuracy can also be reduced in order to adjust the steering torque when a driver intervention is recognized. During dynamic driving maneuvers or when entering or exiting curves, a high accuracy of at least 70 percent is preferably selected.