System for stabilizing a motor vehicle during acceleration in straight-line travel and in cornering

Abstract

The invention relates to a method and a system for stabilizing a motor vehicle during an acceleration maneuver. A slip condition of one or more wheels is detected on the basis of vehicle dynamics variables, including wheel speeds, yaw rate and lateral acceleration. Depending on the detected slip, alternating micro-steering impulses or micro-steering torque impulses are automatically applied to a steering system, the impulses having sub-degree steering angle variations and generating a lateral micro-movement of the tire contact patch. The micro-impulses serve to stabilize lateral forces and are executed in two operating modes: a symmetric mode for acceleration in substantially straight-line travel and an asymmetric mode with an impulse-time bias for acceleration in cornering. The impulse parameters are adapted to steering angle, yaw rate and lateral acceleration. The invention further comprises a system with sensors, a control unit and an actuator for generating the micro-steering impulses.

Description

00347484-0011 11.12.2025 PCT / DE0S£^ / |SQffi12711-12-2025-003 743 -0011TACTOS-7.0 - PCT Description Date: 09.12.2025DescriptionTACTOS-7.0 - System for Stabilizing a Motor Vehicle During Acceleration in Straight-Line and Cornering ManeuversTechnical Field

[0001] The invention relates to vehicle dynamics control of motor vehicles and concerns a system and a method for stabilizing a vehicle during acceleration maneuvers, both in straight-line travel and in cornering. The invention in particular relates to the generation of microsteering impulses or steering torque impulses for controlling slip and lateral force conditions.Re -la - -t -io -n t.o. t.he - Prio -rit.v An M-nlic >ation[0001a] This application claims the priority of German patent application DE 10 2024 004 430.2 of 17 December 2024, the entire disclosure of which is incorporated herein by reference.[0001b] The embodiments described herein are based on the same fundamental principle of contact-patch-modulating micro-steering impulses and constitute a single general inventive concept.Background of the Invention

[0002] DE 10 2024 001 244 A1 (DI) discloses a method for improving traction on loose ground, in which steering oscillations are used to avoid becoming stuck. Application during dynamic acceleration is not disclosed.

[0003] DE 10 2005 019 339 A1 (D2) describes steering oscillations at low speeds in off-road start-up situations. Reference to higher-dynamics driving states is missing.

[0004] DE 10 2015 224 760 A1 (D3) shows steering impulses for rocking free a stuck vehicle. The impulses are not intended for acceleration or cornering.

[0005] DE 11 2020 004 314 T5 (D4) relates to steering logic under slip conditions but without micro-steering impulses or friction- value regeneration.

[0006] DE 11 2019 002 782 T5 (D5) describes adaptive rear-wheel steering without reference to acceleration maneuvers or lateral contact-patch modulation.Page 1 to 500347484-0012 11.12.2025 PCT / DE0S£^ / |SQffi127TACTOS-7.0 -PCT Description Date: 09.12.2025

[0007] None of documents D1-D5 discloses micro-steering impulses in the sub-degree range (below 2°) at frequencies from 3 to 7 Hz for lateral migration of the tire contact patch during an acceleration maneuver, either in symmetric or asymmetric form.Object of the Invention

[0008] It is an object of the invention to stabilize a motor vehicle during an acceleration maneuver and to reduce undesired driving states, in particular when slip occurs on individual wheels or when increased lateral force demand exists during cornering.Extended Technical Problem

[0009] During rapid acceleration, changes in vehicle dynamics often occur earlier than perceived by the driver. An unstable slip distribution leads to delays in lateral force build-up and may cause understeer or oversteer before the driver can react.

[0010] As driver reactions typically occur with delays exceeding 200 ms, macroscopic counter-steering movements arise which may further amplify the unstable condition.

[0011] Micro-steering impulses with frequencies above the reaction dynamics controllable by the driver enable early correction of slip and lateral force distribution. Stabilization is thereby achieved at a stage in which macroscopic deviations of the vehicle trajectory are not yet visible.Summary of the Invention

[0012] The object is achieved by a method in which a slip condition of one or more wheels is detected during an acceleration maneuver and, depending thereon, alternating micro-steering impulses and / or micro-steering torque impulses are automatically applied to a steering system to generate stabilizing lateral forces. The impulses are generated depending on vehicle speed, yaw rate, lateral acceleration and / or road curvature.

[0013] A TACTOS sensor system detects friction-value variations on the basis of thermal, structural-mechanical, vibration-based and walk-dynamics features. Micro-steering impulses are understood as small, alternating steering-angle variations in the sub-degree range.

[0014] Two operating modes are distinguished:- symmetric mode for acceleration in substantially straight-line travel,- asymmetric mode for acceleration during cornering.Page 2 to 500347484-0013 11.12.2025 PCT / DE0S£ / |SQffi127TACTOS-7.0 - PCT Description Date: 09.12.2025lateral micro-migration of the tire contact patch.The TACTOS sensor system detects thermally overloaded contact regions, slip variations, or friction-value reductions. FIG. 3 shows a typical impulse profile.

[0020] FIG. 2 illustrates the detection of an incipient slip condition based on vehicle dynamics variables supplied by the sensors, including wheel speeds, yaw rate and lateral acceleration. The slip detection serves as a triggering criterion for the micro-steering impulses generated in the symmetric or asymmetric mode.Mode B - Cornering Acceleration

[0021] With increasing steering angle, the impulse mode is continuously adapted toward an asymmetric mode. FIG. 5 illustrates the transition.Dynamic Transition Mode

[0022] If the steering angle exceeds a vehicle-specific threshold (e.g. 1.5°), the system detects variations in slip, lateral acceleration and yaw-rate deviation.

[0023] The asymmetric mode generates micro-steering impulses having an amplitude of 0.5° to 2.0° and an impulse-time bias of > 60% in the direction of the outer side of the curve. The frequency typically lies in the range of 3 - 5 Hz.Example 1 - Straight-Line Acceleration

[0024] FIG.4 illustrates an example of full acceleration on a straight road section.

[0025] Micro-impulses (± 0.3° to ± 1.5°, 3 -7 Hz) are activated within the first 50 - 100 ms following the increase in drive torque.

[0026] The TACTOS system detects slip, thermal hotspots and friction- value drops.

[0027] An impulse phase of 300 - 800 ms leads to periodic engagement of adhesionproviding contact regions and stabilizes the frictional contact.Example 2 - Cornering Acceleration

[0028] FIG. 6 shows the stabilized vehicle trajectory in a long, constant-radius curve.Page 4 to 500347484-0014 11.12.2025 PCT / DE0S£ / |& Qffi127TACTOS-7.0 - PCT Description Date: 09.12.2025

[0029] At a speed of approximately 60 km / h and an acceleration of 4 - 5 m / s2, TACTOS detects slip variations, an increase in lateral acceleration and deviations between nominal and actual yaw rate.

[0030] The system activates the asymmetric mode and generates micro-impulses with amplitudes of 0.7° to 1.8° and an impulse-time bias of 60 - 75% toward the outer side of the curve.

[0031] The laterally load-bearing contact regions are enlarged so that the lateral guiding force is maintained even under high longitudinal drive forces.This effect is attributable to the fact that the asymmetric micro-impulses generate a controlled lateral migration of the effective contact zone and thereby activate the load-bearing outercurve tire flank, which provides the predominant portion of the lateral guiding force.

[0032] FIG.7 illustrates the resulting stabilized vehicle trajectory during acceleration in cornering, as achieved by the asymmetric micro-steering impulses described in paragraphs

[0028] to

[0031] ,Variants and Extensions

[0033] For acceleration from standstill or at very low vehicle speed,the micro-impulse amplitude may be larger than in deceleration from higher speeds.In.such start-up situations,, amplitudes in the range of ±0.5° to ±2.5°,and in particular cases up to ±3.0°, may be used without generating aperceptible or unstable steering response, since the lateral stiffness of the tireis significantly lower at low vehicle speed.

[0034] The impulse frequency may lie in an extended range between 1 Hz and 12 Hz.

[0035] The micro-impulses may exhibit non-linear impulse shapes, including step-shaped, exponential or adaptively modulated profiles.Conclusion

[0036] The invention operates not by brake interventions or drive-torque reduction, but by modulation of the contact-patch conditions, and constitutes an independent vehicle-dynamics control system.Page 5 to 500347484-0015 11.12.2025 PCT / DE0S^ / |»Qffi1271Reference Signs ListVehicle and contact10- Vehicle11 - Tire-road contact patchSteering and motion12 - Steering-angle change14 - Unstable vehicle trajectory30 - Vehicle acceleration / driving-force direction Sensor and trigger28 - Trigger point in the sensor signalAxes and signal quantities16 -Time axis18 - Steering-angle / signal axisMicro-steering impulses20 - Steering-signal / impulse sequence22 - Upper signal component / signal level24 - Positive micro-impulses26 - Negative micro-impulsesContact zones / lateral shift32 - Contact-zone segment34 - Lateral migration of the contact patch Trajectories40 - Unstabilized vehicle trajectory42 - Stabilized vehicle trajectory

Claims

AMENDED CLAIMSreceived by the International Bureau on 25 June 2026 (25.06.2026)1. A method for stabilizing a motor vehicle during a traction-limited driving condition, comprising:- detecting a friction-limited operating state during simultaneous longitudinal force transmission and lateral-force demand;- generating a controlled lateral micro-migration of an effective tire-road contact zone by applying alternating sub-degree steering-related micro-actuation impulses via an electrically assisted steering system or a steer-by-wire system;- wherein the controlled lateral micro-migration dynamically incorporates laterally load-bearing tire-contact regions into a friction-transmitting contact region;- wherein the controlled lateral micro-migration cyclically redistributes locally friction-transmitting load zones within the tire-road contact interface;- wherein the controlled lateral micro-migration modifies a local friction-transmitting tire-road contact state such that stabilizing lateral forces are maintained during longitudinal tractive-force build-up;- thereby stabilizing combined longitudinal and lateral force transmission within the friction-limited operating state without initiating a brake intervention and without commanding a reduction of drive torque.

2. The method according to claim 1,wherein the controlled lateral micro -migration of the effective tire-road contact zone lies within a range from 0.1 mm to 5 mm.

3. The method according to claim 1 or 2,wherein the micro-actuation impulses generate steering variations below ±1.0° under nominal operating conditions.

4. The method according to any of the preceding claims,wherein the micro-actuation impulses are generated at a frequency between 1 Hz and 12 Hz, preferably between 3 Hz and 7 Hz.

5. The method according to any of the preceding claims,wherein the controlled lateral micro -migration periodically engages adhesionproviding tire-road contact regions during the traction-limited operating condition.

6. The method according to any of the preceding claims,wherein the controlled lateral micro -migration dynamically recruits laterally loadbearing tire-contact regions during a transient traction-instability condition.

97. The method according to any of the preceding claims,wherein transient unloading of locally overloaded tire-contact regions enables frictionstate restoration.

8. The method according to any of the preceding claims,wherein the controlled lateral micro-migration counteracts localized friction saturation during simultaneous longitudinal and lateral loading.

9. The method according to any of the preceding claims,wherein lateral guiding force is maintained during simultaneous longitudinal tractive-force transmission.

10. The method according to any of the preceding claims,wherein the friction-limited operating state includes at least one of:- acceleration-induced traction instability,- low-friction cornering,- combined longitudinal / lateral transient loading,- curve-exit acceleration.

11. The method according to any of the preceding claims,wherein during substantially straight-line operation a symmetric micro-actuation pattern is generated relative to a dynamic neutral steering position.

12. The method according to any of the preceding claims,wherein during cornering an asymmetric micro-actuation pattern is generated.

13. The method according to claim 12,wherein an impulse-time bias toward an outer side of a curve exceeds 60%.

14. The method according to any of claims 11 to 13,comprising a transition mode in which interpolation between symmetric and asymmetric micro-actuation patterns is performed as a function of at least steering angle and yaw-rate deviation.

15. The method according to any of the preceding claims,wherein the controlled lateral micro-migration is generated preemptively before a macroscopically perceptible vehicle-instability condition occurs.

16. The method according to any of the preceding claims,wherein stabilization is achieved prior to driver-perceptible trajectory deviation.

17. The method according to any of the preceding claims,wherein the friction-limited operating state is detected based on at least one of: - wheel-speed behavior,- yaw-rate deviation,- lateral acceleration,- wheel-speed asymmetry,- slip-gradient behavior.

18. The method according to claim 17,wherein friction-related detection further uses at least one of:- vibration-based features,- thermal features,- structural-mechanical features,- tire walk-dynamics features.

19. The method according to any of the preceding claims,wherein the controlled lateral micro -migration sequentially activates laterally displaced friction-transmitting contact subregions.

20. A system configured to carry out the method according to any ofclaims 1 to 19,comprising:- at least one sensor system,- an electronic control unit,- and a steering-system-based micro-actuation mechanism.

21. The system according to claim 20,wherein the steering-system-based micro-actuation mechanism comprises an electrically assisted steering system or a steer-by-wire system.

22. An electronic control unit configured to perform the method according to any of claims 1 to 19.

23. A motor vehicle comprising a system according to claim 20 or 21.

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