Method and control unit for operating a vehicle

Abstract

The present invention relates to a method for operating a vehicle (300), wherein a required full braking torque (100) at at least one wheel (302) of the vehicle (300) is summed using a slow dynamic brake actuator (304) of the vehicle (300) and a high dynamic control actuator (308) of the vehicle (300), the brake actuator (304) providing a slow dynamic braking torque (102) and the control actuator (308 applying a control torque (104) to the braking torque (102).

Description

[Technical Field]

[0001] The present invention relates to a method for operating a vehicle, a corresponding control unit and a corresponding computer program product. [Background technology]

[0002] The vehicle's brake control system can adjust the brake pressure individually and dynamically via an intake valve, a discharge valve, and at least one pump. For example, at a locked wheel, the brake pressure can be reduced briefly below the brake pressure applied by the vehicle driver via the vehicle's brake pedal in order to restart the locked wheel. The brake pressure can then be increased again by the pump until the wheel begins to lock again. This reduction and increase in brake pressure can be repeated to prevent locking over a relatively long time period.

[0003] For example, when the vehicle skids, at least one wheel can be braked independently of the driver by applying brake pressure using a pump to create a stable yawing moment on the vehicle. Summary of the Invention

[0004] Against this background, the proposed method provides a method for operating a vehicle as set forth in the independent claims, a corresponding control unit and a corresponding computer program product. Preferred developments and improvements of the proposed method can be taken from the description and are set forth in the dependent claims. [Effects of the Invention]

[0005] In the proposed method, the full braking torque at at least one wheel of a vehicle is generated by adding up a plurality of partial braking torques. The partial braking torques are generated by actuators that respond or can be changed at different speeds. These actuators have different operating principles. For example, one partial braking torque can be provided by a mechanical brake, while another partial braking torque can be provided by an electric drive.

[0006] A faster actuator may in particular provide full braking torque at a lower rate than a slower actuator, so that fast modulation of the full braking torque may be adjusted by varying the partial braking torque of the faster actuator in particular.

[0007] The proposal presented here allows the use of less expensive mechanical actuators with particularly slower response times as conventional ESPs for braking the vehicle, since the required fast adaptation of the full braking torque is carried out by an electric actuator with particularly fast response times.

[0008] A method is proposed for operating a vehicle, in which a required full braking torque at at least one wheel of the vehicle is summed using a slow dynamic brake actuator of the vehicle and a high dynamic control actuator of the vehicle, the brake actuator providing the slow dynamic braking torque and the control actuator applying a control torque to the braking torque.

[0009] The ideas of the embodiments of the present invention may be considered to be based in particular on the ideas and knowledge set out below.

[0010] The full braking torque required at one wheel of the vehicle can be adjusted by the vehicle driver via the vehicle's brake pedal, or it can be calculated and requested by the vehicle's control unit.

[0011] The slow-dynamic brake actuator may be a hydraulic brake system. Alternatively, the slow-dynamic brake actuator may be an electromechanical brake. The slow-dynamic brake actuator has reduced complexity compared to a conventional brake control system, e.g., with ASR or ESP functionality. The slow-dynamic brake actuator can adjust the brake torque individually to each wheel, but does not allow for rapid changes in brake torque.

[0012] The high dynamic control actuator may be an electric drive for the wheel or wheel axle. The high dynamic control actuator can change the control torque quickly and precisely. The high dynamic control actuator can provide a negative or positive control torque. That is, the high dynamic control actuator can brake or accelerate the wheel or axle. The high dynamic control actuator can provide a smaller power output than a slow dynamic brake actuator.

[0013] The high-dynamic modulation of the full brake torque may be applied to the slow-dynamic brake torque using a high-dynamic control torque. The slow-dynamic brake torque can be changed only slowly compared to the high-dynamic control torque. Thus, fast changes in the full brake torque can be controlled specifically using a high-dynamic control actuator. The slow-dynamic brake torque can follow the changes in the full brake torque slowly with a gentle gradient.

[0014] The slow modulation of the full braking torque may be performed using a slow dynamic braking torque.

[0015] The brake torque can be adjusted lower than the maximum value of the full brake torque by the rated value of the control torque. The rated value of the control torque can approximately correspond to the maximum value of the control torque. The rated value can be slightly lower than the maximum value. By using the rated value, the service life of the control actuator can be extended. The control actuator is always utilized to its maximum extent approximately as specified by the reduced brake torque. Thus, a high regenerative power can be obtained and as little energy as possible can be released as heat.

[0016] The full brake torque per wheel at multiple wheels of at least one axle of the vehicle can be summed using the individual wheel brake torques and the control torque per axle. The control actuator can act on multiple wheels simultaneously. In particular, the control actuator can act on two wheels of one axle. In this case, the vehicle can have one control actuator on one axle and no control actuator on the other axle. The vehicle can also have one control actuator per axle. The same control torque can be applied to multiple wheels of an axle based on the axle differential.

[0017] The differential full braking torque of the wheels of an axle can be adjusted using various slow dynamic braking torques. The differential full braking torque of the wheels of an axle generates a yawing moment of the vehicle. Because a vehicle has a very large inertial mass due to its mass, the vehicle's reaction to the yawing moment is significantly slower than the reaction of the wheels to the applied full braking torque and actual static friction.

[0018] Alternatively, the full brake torque per wheel at multiple wheels of an axle may be summed using the wheel individual brake torque and the wheel individual control torque. Each wheel of an axle may have its own control actuator.

[0019] The method may be computer-implemented in any suitable form, for example in software or hardware, or a mixture of software and hardware, for example in a driver assistance system.

[0020] The proposal presented here further provides a control unit in the form of a driver assistance system for a vehicle, where the driver assistance system is configured to implement, control or execute the steps of the method variants presented here in a corresponding device.

[0021] The control unit or driver assistance system may be an electrical device comprising at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, and at least one interface and / or communication interface for reading or outputting data, embedded in a communication protocol. The processing unit may be, for example, a signal processor, a so-called system ASIC, or a microcontroller for processing sensor signals and outputting data signals depending on the sensor signals. The storage unit may be, for example, a flash memory, an EPROM, or a magnetic storage device. The interface may be configured as a sensor interface for reading sensor signals from sensors and / or as an actuator interface for outputting data signals and / or control signals to actuators. The communication interface may be configured for reading or outputting data wirelessly and / or via wired induction. The interface may be, for example, a software module located in the microcontroller next to other software modules.

[0022] Also advantageous is a computer program product or computer program having a program code which may be stored on a machine-readable carrier or storage medium, such as a semiconductor memory, a hard disk or an optical memory, and which is used to execute, perform and / or control the steps of the method according to any one of the embodiments, in particular when the program product or program is run on a computer or device.

[0023] It is noted that some of the possible features and advantages of the present invention have been described in relation to various embodiments, and those skilled in the art will recognize that the features of the control unit and method can be combined, adapted or exchanged in any suitable manner to arrive at other embodiments of the present invention. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 10 illustrates total summed full brake torque according to one embodiment. [Figure 2] FIG. 10 illustrates a modulation applied to the total full brake torque according to one embodiment. [Figure 3a] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3b] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3c] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3d] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3e] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3f] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3g]1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. [Figure 3h] 1A-1C illustrate vehicles with various brake configurations for using a method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, in which neither the drawings nor the description should be interpreted as limiting the present invention.

[0026] The drawings are only schematic and not to scale. The same reference numerals represent the same features or features with the same effect.

[0027] 1 shows the full braking torque 100 at one wheel of a vehicle, summed according to one embodiment. The course of the full braking torque 100 is plotted on a graph with time on the abscissa and torque on the ordinate.

[0028] The full brake torque 100 is the sum of the brake torque 102 of the slow dynamic brake actuator at one wheel and the control torque 104 of the high dynamic control actuator at one wheel. The progression of the brake torque 102 and the progression of the control torque 104 are also shown in the graph.

[0029] The control actuator may provide a lower output than the brake actuator. The rated value 106 of the control torque 104 is less than the full brake torque 100. If the requested full brake torque 100 is greater than the rated value 106, the brake actuator's brake torque 102 is greater, while the control torque 104 is the same as its rated value 106.

[0030] In one embodiment, braking is only performed using the control actuator if the full braking torque 100 is less than the rated value 106 of the control torque 104. If the full braking torque 100 is greater than the rated value 106, the brake actuator is used to generate as much additional braking torque 102 as necessary to achieve the full braking torque 100.

[0031] In one embodiment, the brake torque 102 and the control torque 104 are increased in a predetermined proportion until the nominal value 106 of the control torque 104 is reached. Then, only the brake torque 102 is increased.

[0032] FIG. 2 illustrates modulation applied to the total full brake torque 100 according to one embodiment. Here, similar to FIG. 1, the progression of the full brake torque 100, the brake torque 102, and the control torque 104 is shown in a graph. Unlike the graph in FIG. 1, the full brake torque 100 is not constant here, for example, based on periodic ABS control. Here, a roughly constant share of the full brake torque 100 is provided by the brake torque 102. A varying share of the full brake torque 100 is provided by the varying control torque 104.

[0033] By adding together the torques in this way, the high dynamic behavior of the control actuator and the slow dynamic behavior of the brake actuator are combined in an advantageous manner.

[0034] 3a-3h show diagrams of a vehicle 300 having various braking configurations for using a method according to one embodiment.

[0035] In all figures, the vehicle 300 has one slow dynamic brake actuator 304 for each wheel 302. The brake actuators 304 can provide wheel-specifically adapted braking torque to each wheel 302. The brake actuators 304 are, for example, hydraulic brake systems of the vehicle 100.

[0036] 3a to 3c, the vehicle 300 has, in addition to the brake actuator 304, one high-dynamic control actuator 308 for two wheels 302 on at least one axle 306. The control actuator 308 provides the same control torque per axle to both wheels 302. The control actuator 308 is, for example, an electric drive motor for the axle 306.

[0037] In Figure 3a, the control actuators 308 act on the rear axle 306. In Figure 3b, the control actuators 308 act on the front axle 306. In Figure 3c, one control actuator 308 each acts on the front axle 306 and the rear axle 306.

[0038] 3d to 3f, a vehicle 300 has a respective individual control actuator 308 for each of a plurality of wheels 302 of at least one axle 306. The plurality of control actuators 308 can provide wheel-independent, adapted control torques to each of the connected wheels 302. The plurality of control actuators 308 can be, for example, electric individual wheel drives for the wheels 302.

[0039] In Figure 3d, multiple control actuators 308 are located on the rear axle 306. In Figure 3e, multiple control actuators 308 are located on the front axle 306. In Figure 3f, two control actuators 308 are located on each of the front and rear axles 306.

[0040] In Figures 3g and 3h, the vehicle 300 has one axle 306 with one control actuator 308 each for providing control torque to the two wheels 302 of the axle 306, and one axle 306 with one control actuator 308 each for each wheel 302 of the axle 306.

[0041] In Figure 3g, one control actuator 308 acts on two wheels 302 on the front axle 306, while two control actuators 308 act on multiple wheels 302 on the rear axle 306. In Figure 3h, one control actuator 308 acts on two wheels 302 on the rear axle 306, while two control actuators 308 act on multiple wheels 302 on the front axle 306.

[0042] In the following, possible embodiments of the present invention will be summarized again or described in slightly different terms.

[0043] A hybrid brake modulation based on the interaction of several individual systems is presented. This proposal is particularly relevant for future brake control system configurations for electric or hybrid vehicles.

[0044] Modern brake control systems, apart from stable characteristics, for example in the form of classic ESP / ABS, also include an increasingly expanded range of functions, for example by means of an eBKV (electromechanical brake booster) to introduce force into the brake pedal or assist the driver during braking, or also assisted or partially assisted functions (e.g. ESP, eBKV, boost unit, etc.) by units for actively modulating the hydraulic brake pressure without active driver involvement. In vehicles with electric or partly electric drives, an electric drive motor can be used for deceleration modulation. The braking power depends on the power of the electric motor.

[0045] Here, a brake modulation function is described in which the ability for brake force modulation is achieved by the interaction of at least two individual components. Each individual component may not only perform the appropriate brake pressure modulation for, for example, ABS, VDC, etc. Such interaction may also realize known brake force modulations for hydraulic brake control systems such as ESP, IPB, etc.

[0046] The modulation unit is a deceleration unit which generates a deceleration force by means of friction wheel modulation, for example a hydraulic or electromechanical brake control system, which will be referred to below as Type A.

[0047] Other modulation units are units with deceleration and acceleration modulation properties on one wheel, one axle or two axles or a combination thereof, such as the drive motor of an electric vehicle. The drive motor or motors are hereinafter referred to as Type B.

[0048] Changing requirements and boundary conditions will alter the possibilities and capabilities of deceleration modulation and (wheel-specific) brake modulation in future vehicles. Vehicles will become increasingly electrified, thereby offering the possibility of deceleration modulation by one or more electric motors. Electromechanical braking systems of various forms may also become increasingly common.

[0049] Additional systems can increase the cost and complexity of the vehicle. The proposal presented here describes the functional interaction of various individual components, so that together these individual components meet the existing demand for wheel-specific brake modulation possibilities. This allows the individual components to be constructed more cheaply.

[0050] In passenger cars, brake control systems are required to enable passive brake modulation acting on individual wheels, vehicle control indication (ABS, VDC, TCS), longitudinal dynamic active brake modulation on the vehicle plane to indicate deceleration functions within a comfort range and dynamic range, longitudinal dynamic active brake modulation on the axle plane to indicate a warning impact function, and coordination of regenerative braking using electric motors to avoid deceleration variations based on the deceleration characteristics of the electric motors.

[0051] Here, the functional interaction of two individual systems, Type A and Type B, is introduced. The combined individual systems can improve the characteristics described below by interacting with each other to obtain an improved braking system for a vehicle or to make conventional brake control systems less expensive, because the interaction of the individual systems provides the required capabilities and characteristics.

[0052] The system presented improves the maximum deceleration modulation capability, improves the maximum frequency of modulation variations with a given amplitude, and therefore improves the maximum deceleration modulation capability at an improved maximum frequency of modulation variations with a given amplitude.

[0053] Individual systems have the characteristics of wheel-specific modulation capability, axle-specific modulation capability, or vehicle-plane modulation capability.

[0054] In this case, ideally, at least one individual system is characterized by wheel-specific modulation capabilities.

[0055] The basic principle of interaction is the combined effect of the individual components in the wheel-road-friction value combination theory.

[0056] As individual components, one hydraulic modulation unit per wheel of Type A and at least one modulation unit per axle of Type B may interact.

[0057] In one embodiment, one wheel-specific modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts with one axle-specific modulation unit Type B, which is provided on the rear axle, for example on the electric drive unit of the rear axle (Figure 3a).

[0058] In one embodiment, one wheel-specific modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts with one axle-specific modulation unit Type B, which is provided on the front axle, for example on the electric drive unit of the front axle (Figure 3b).

[0059] In one embodiment, one wheel-specific modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with one axle-specific modulation unit Type B, which is provided on the front and rear axles, for example on electric drive units provided on the front and rear axles (Figure 3c).

[0060] As individual components, one hydraulic modulation unit for each wheel of Type A and multiple modulation units for each wheel of Type B may interact with each other.

[0061] In one embodiment, one wheel-specific hydraulic modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with several wheel-specific modulation units Type B provided on the rear axle, for example on the electric drive unit of the rear axle (Figure 3d).

[0062] In one embodiment, one wheel-specific hydraulic modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with several wheel-specific modulation units Type B provided on the front axle, for example on the electric drive unit of the front axle (Figure 3e).

[0063] In one embodiment, one wheel-specific hydraulic modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with several wheel-specific modulation units Type B provided on the front and rear axles, for example on the front and rear axle electric drive units (Figure 3f).

[0064] As individual components, one hydraulic Type A wheel-specific modulation unit may interact with multiple Type B axle-specific modulation units and multiple Type B wheel-specific modulation units.

[0065] In one embodiment, one wheel-specific hydraulic modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with several wheel-specific modulation units Type B on the rear axles, e.g. on the electric drive units of the rear axles, and one modulation unit per axle Type B on the front axles, e.g. on the electric drive units of the front axles (Figure 3g).

[0066] In one embodiment, one wheel-specific hydraulic modulation unit Type A, for example in the form of an ESP hydraulic brake modulation unit, interacts in conjunction with one axle-specific modulation unit Type B on the rear axle, e.g. on the electric drive unit of the rear axle, and several wheel-specific modulation units Type B on the front axle, e.g. on the electric drive unit of the front axle (Figure 3h).

[0067] A functional variant for pure deceleration capacity is total wheel modulation to obtain the maximum desired deceleration capacity in individual components that cannot provide the desired deceleration modulation alone.

[0068] The functional principle of the hybrid symbiotic proposal is a total modulation at several wheels with the intervention of several modulation units of type A and type B. For example, hydraulic modulation of type A is performed in conjunction with electric drive motors at several wheels of type B with the intervention of several modulation units, whereby relatively fast actuators control the target deceleration demand change.

[0069] The target demand increase can be controlled by increasing the brake torque of the relatively fast actuator Type B. Optionally, the target deceleration demand decrease can be controlled by decreasing the brake torque of the relatively fast actuator Type B. A rapid decrease in the target deceleration demand can be achieved by decreasing the brake torque and increasing the drive output of the fast actuator Type B, so that the total torque acting on the wheels decreases quickly. This means that the working point of the Type A actuator can be above the target deceleration level and can be corrected by applying the opposite torque of the Type B actuator. This allows the dynamic demand on the slower actuator to be reduced, which can lead to the actuator Type A being cheaper to design and manufacture.

[0070] A functional variant for wheel pressure modulation to provide ABS functionality for pure deceleration capacity is, for example, total wheel modulation to obtain the desired maximum deceleration capacity for individual components that are not capable of performing the desired deceleration modulation themselves. In this case, the Type A modulation unit applies brake torque without dynamic (alternating) distribution. The Type B modulation unit adjusts the high-speed dynamic distribution.

[0071] For example, a typical control strategy for vehicle controller intervention for ABS functionality is that the wheel with the lower wheel-road target force on one axle is controlled by an axle-specific modulation unit (e.g., an electric motor). If an axle does not have an axle-specific modulation unit, control is performed via a hydraulic brake control system. In an ideal case, frequent ABS unstable modulations are taken over by a more efficient actuator device in relation to modulation fluctuations. In a μ-split situation, delta value control is performed between the left and right wheels by actuator Type A. Here, the vehicle remains controllable, as the lift is essentially achieved by reducing the yawing moment.

[0072] For VDC and TCS functionality, the modulation unit Type B is selected during longitudinal dynamic vehicle controller intervention, so that the axle torque / axle slip can be adjusted more quickly, thereby achieving better vehicle stability. Depending on the topology, Type B intervention can be performed by reducing the deceleration modulation by Type B or by applying acceleration by Type B.

[0073] The different individual wheel brake interventions between the left and right wheels are essentially slow-dynamic. Since the yaw inertia is essentially larger than the wheel or axle inertia, here Type A actuators are used to adjust the delta value between the left and right wheels. Furthermore, an attempt is made to make such interventions slower-dynamic to keep the vehicle controllable.

[0074] Finally, it is to be pointed out that the words "comprise", "contain" etc. do not exclude other elements or steps, and the word "a" does not exclude a plurality. Claim signs are not to be considered limiting. [Explanation of symbols]

[0075] 100 full brake torque 102 Brake torque 104 Control Torque 106 Rated value 300 vehicles 302 Wheels 304 Brake Actuator 306 axle, rear axle, front axle 308 Control Actuator

Claims

1. A method for operating a vehicle (300), comprising: A method for driving a vehicle (300) comprising summing a required full brake torque (100) at at least one wheel (302) of the vehicle (300) using a slow dynamic brake actuator (304) of the vehicle (300) and a high dynamic control actuator (308) of the vehicle (300), such that the brake actuator (304) provides a slow dynamic brake torque (102) and the control actuator (308) applies a control torque (104) to the brake torque (102).

2. The method of claim 1 , further comprising applying a high dynamic modulation of the full braking torque (100) to the slow dynamic braking torque (102) using a high dynamic control torque (104).

3. 3. The method according to claim 1, wherein a slow modulation of the full braking torque (100) is performed with the slow dynamic braking torque (102).

4. 4. The method according to claim 1, further comprising adjusting the braking torque (102) to be lower than the maximum value of the full braking torque (100) by a rated value (106) of the control torque (104).

5. 5. The method according to claim 1, wherein the full brake torque per wheel (302) at a plurality of wheels (302) of at least one axle (306) of the vehicle (300) is summed using wheel-specific brake torques (102) and axle-specific control torques (104).

6. The method of claim 5, wherein the full braking torque (100) differential of the plurality of wheels (302) of the axle (306) is adjusted using a varying slow dynamic braking torque (102).

7. 7. The method according to claim 1, wherein the control torque (104) is adjustable to be negative or positive.

8. 8. A control unit configured to implement, execute and / or control a method according to any one of claims 1 to 7 in a corresponding device.

9. 10. A computer program product designed to cause a processor to implement, perform and / or control the method of any one of claims 1 to 7 when the computer program product is executed.

10. 10. A machine-readable storage medium having stored thereon the computer program product of claim 9.

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