Vehicle dynamics control with alternating side-specific steering pulses (tactos-l) and torque engagement (tactos-m) in a synchronized actos cycle

Abstract

The invention relates to a method and a control system for improving vehicle stability and traction on extremely low-friction or asymmetrical road surfaces. The method combines two coordinated actions within a recurring cycle: a steering-based lateral load-shift impulse (TACTOS-L), generated by small alternating steering angle pulses, and a torque-based drive impulse (TACTOS-M), applied through a controllable coupling. Both actions are activated sequentially or with partial overlap to increase available wheel friction and stabilise yaw behaviour. In a neutral phase, the steering returns to zero, the coupling opens, and vehicle dynamics parameters are measured to adapt the next cycle. Depending on the driving situation, the system prioritises traction improvement, braking stability or a hybrid mode. The method compensates for disadvantages of passive differentials, enhances acceleration and directional control on ice, snow or μ-split surfaces, and can be integrated into existing control units without additional hardware.

Description

DescriptionVehicle dynamics control with alternating side-specific steering pulses (TACTOS-L) andtorque engagement (TACTOS-M) in a synchronized ACTOS cycleTechnical Field

[0001] The invention relates to vehicle-dynamics control systems for motor vehicles,particularly for improving traction and stability on slippery or u-split road surfaces, by meansof alternating steering-pulse control (TACTOS-L) and torque-engagement control (TACTOS-M) executed within a synchronized ACTOS cycle.Background / Continuation of Prior Developments

[0002] This international application continues and extends the developments of the TACTOScontrol concept previously described in TACTOS-2.0 and TACTOS-3.0.These earlier versions disclosed the principle of alternating side-specific steering impulses(TACTOS-L) for improving traction and stability on slippery or asymmetric road surfaces.The present invention, designated as TACTOS-4.0, combines these principles with anadditional torque-engagement control (TACTOS-M) in a synchronized ACTOS cycle.Both subsystems operate together or in direct sequence within defined pulse and neutralphases, forming a unified control method that enhances driving stability and traction beyondthe prior developments.Preferred Embodiment (opening transition)

[0003] The control concept comprises two subsystems: the lateral impulse controlTACTOS-L (T-L) and the torque-engagement control TACTOS-M (T-M), which operatetogether within the synchronized ACTOS cycle.Further embodiments of the invention include adaptive operation modes, variable phaselengths, and hybrid control sequences allowing automatic transition between steering-dominant and torque-dominant modes, as defined in the following description.Background Art

[0004] Background of the InventionVarious approaches for improving driving stability and traction are known:- DE 10 2024 001 244 A1 (D1) discloses a driving function for vehicles with steer-by-wiresteering, in which continuous sinusoidal steering movements are applied on lose ground(especially sand) to prevent the vehicle from getting stuck. A sequential impulse control withneutral phases and algorithmic evaluation is not disclosed.

[0005] DE 10 2005 019 339 A1 (D2) describes a vehicle control system that initiates steeringoscillations when off-road obstacles are detected, in order to maintain the desired drivingpath. A pulse-based, side-specific steering impulse control for stability is not shown.- DE 10 2015 224 760 A1 (D3) relates to active steering support for vehicles stuck in softground, where periodic steering angle variations are applied automatically to enable rockingfree. This disclosure addresses standstill situations, not dynamic braking or accelerationevents.

[0006] DE 11 2020 004 314 T5 (D4) shows a steering control device that, in slip situations,determines the current steering angle as a reference and actuates a road wheel within a definedangle range. A combination of steering impulses with torque application in synchronizedcycles is not disclosed.- DE 11 2019 002 782 T5 (D5) concerns an adaptive rear-wheel steering system, in whichphase-shifted rear steering angles are implemented depending on the driving situation. Acoordinated control of side-specific steering impulses and torque application with neutralphases is not described.Known vehicle dynamics systems such as ABS, ASR and ESP mainly operate throughindividual braking interventions or torque distribution.Object of the Invention

[0007] Distinction over the Prior ArtIn contrast to the cited documents, the present invention provides a combined control in whichside-specific steering impulses (T-L system initiates steering impulses) and torqueapplications (T-M subsystem reduces torque engagement) are executed in a commonsynchronized cycle. Essential is that in each impulse phase both principles act together, and ineach neutral phase both are completely deactivated, allowing for an unbiased evaluation ofvehicle dynamics parameters.

[0008] This achieves active stability control and braking distance reduction beyond thedisclosures of D1 – D5. Neither the continuous sinusoidal steering variations of D1 and D3,nor the off-road oscillations of D2, nor the reference-angle based control of D4, nor theadaptive rear-wheel steering of D5, disclose such a synchronized combination of twofundamentally different control principles with neutral phasesSolution of the Object

[0009] An essential feature of the method is that, in each pulse phase of the ACTOS cycle,both systems - the steering-pulse principle (T-L) and the torque-engagement principle(T-M) - are obligatorily executed together, either simultaneously or in direct temporalsequence, and that during the neutral phase both systems are completely deactivated, in orderto allow an uninfluenced re-evaluation of the sensor data.This principle of combined activation during the pulse phase and simultaneous, completedeactivation during the neutral phase is not applied in known vehicle dynamics systems, sincetheir control impulses overlap without genuine evaluation pauses.Decision Logic

[0010] The decision logic provides that, in the standard mode, both systems are always activeduring each pulse phase of the ACTOS cycle. This constitutes a central distinguishing featurecompared to known systems. The temporal sequence of the standard mode is illustrated inFIG. 3. Claim 9 describes an optional operating mode in which, within a pulse phase, eitheronly T-L or only T-M is activated, whereby the selection is adaptive but always within thefixed cycle structure. An embodiment with adaptive activation is shown in FIG. 4.Neutral Phase

[0011] The term “neutral phase" refers to a time-limited interval (for example 0.5 s to 1.0 s),as illustrated in the embodiments, during which both the T-L system (steering pulses) and theT-M subsystem (torque engagement) are simultaneously and completely deactivated.During this phase, no steering pulses and no additional drive torque are introduced.This fundamentally differs from known control systems, which either provide no neutralphase at all or deactivate only a partial system during pauses.The technical advantage of the complete simultaneous deactivation is that the vehicledynamics sensors can capture measurement values in a stable, uninfluenced state.

[0012] This enables an exact re-evaluation of the current driving situation, without themeasurement being distorted by control signals.As a result, the response accuracy in the next pulse step is significantly improved andconstitutes a key distinguishing feature compared with overlapping control systems.ACTOS Cycle Definition

[0013] The term ACTOS cycle (see FIG. 3) includes both fixed and adaptive phase lengths,as long as the fundamental structure of pulse phase and neutral phase is preserved. The variantwith variable phase lengths and braking dominance is shown in FIG. 5.Safety Criteria

[0014] The amplitude and frequency of the steering pulses, as well as the duration of thetorque engagement, are selected such that comfort and safety limits are not exceeded. In caseof exceeding such limits, deactivation occurs automatically.Implementation

[0015] The method can be integrated in a software-based manner into existing control unitswithout requiring additional hardware. The system architecture is illustrated in FIG. 1,showing the essential input and output signals between sensors, control unit, and actuators.The positioning of the relevant sensor and actuator components in the vehicle is schematicallyshown in FIG. 2.Extended Embodiments

[0016] In a further embodiment consistent with the same ACTOS cycle, the control algorithmmay be extended to adapt the pulse-phase duration or the torque amplitude based on estimatedfriction or vehicle response. These adaptations remain parameter adjustments within theTACTOS-4.0 control framework and do not introduce a separate control concept. Optionalrefinements with prediction logic may be implemented without departing from the combinedsteering- and torque-impulse principle defined in this invention.

[0017] FIG. 4 illustrates the adaptive activation mode within the synchronized ACTOS cycle.In this configuration, the control of steering pulses (T-L) and torque engagement (T-M) iscoordinated by an adaptive mode selector (38).

[0018] Based on this evaluation, the selector determines whether the following pulse phaseshall be executed by T-L alone or switched to T-M.The selector thus governs the temporal sequence and ensures that within each pulse phaseonly one subsystem is active, while both remain deactivated during the neutral phase.This configuration allows the system to adapt between steering-dominant and torque-dominant control depending on the detected road condition or vehicle response.

[0019] Curved-Road and µ-split Operation (Interpretation within the existing ACTOS cycle)In another embodiment consistent with the same ACTOS cycle described above, the controlof steering pulses (T-L) and torque engagement (T-M) can also be applied when the vehicletravels along a curved path or when the friction coefficient differs between the left and rightsides of the vehicle (u- split). In such conditions, the same alternating pulse and neutralphases of the ACTOS cycle remain valid. The side-specific steering pulses and torqueimpulses are adaptively balanced so that the combined control maintains directional stabilityand steering response without exceeding the available tire-road friction.

[0020] During the neutral phase, the yaw rate and lateral acceleration values are evaluated toadjust the amplitude of the following pulse phase, whereby the principle of temporarydeactivation and unbiased re-evaluation of vehicle dynamics sensors remains unchanged. Thisinterpretation does not introduce new control elements beyond those already defined forTACTOS-4.0 but specifies that the same pulse-based synchronization can stabilize the vehicleduring curved-road motion or asymmetric friction conditions.Advantages

[0021] The invention overcomes the weaknesses of differentials, enables adaptiveintervention, relieves the driver, stabilizes the vehicle on slippery surfaces, and requires noadditional hardware.Brief Description of the DrawingsFIG. 1 shows the system architecture of the TACTOS control unit with sensors, actuators, andvehicle wheels.FIG. 2 shows a schematic representation of the synchronized ACTOS cycle, consisting ofpulse phases and neutral phases.FIG. 3 shows the standard mode of the synchronized ACTOS cycle, in which TACTOS-L andTACTOS-M are simultaneously active during each pulse phase.FIG. 4 shows the adaptive activation mode, in which the control sequence proceeds from thesensor block to TACTOS-L, then to the adaptive mode selector, and finally to TACTOS-M.FIG. 5 shows a schematic comparison of vehicle acceleration over time on a dry road and ona slippery road, illustrating the stabilizing effect of TACTOS modulation.FIG. 6 shows an overview of the embodiments, including the standard mode, adaptive mode,and variable phase-length mode of the ACTOS cycle.Reference Signs List per Figure (TACTOS-4.0 – PCT Version)FIG. 1 - System ArchitectureNo.Description10 Control unit (TACTOS electronic controller)12 Vehicle wheels / wheel assemblies14 Steering actuator (EPAS)16 Yaw-rate sensor18 Lateral-acceleration sensor20 Wheel-speed sensors22 Friction estimator μ24 Pulse generator (TACTOS-L steering-pulse control)26 Torque-engagement module (TACTOS-M)28 Drive-torque limiter / clutch actuator30 Guardrail logic / safety control32 Driver-information / HMI moduleFIG. 2 - Synchronized ACTOS Cycle34 Pulse phase of ACTOS cycle36 Neutral phase of ACTOS cycle(t) Time axis (s)FIG. 3 - Standard Mode of ACTOS Cycle34 Pulse phase (TACTOS-L and M active)36 Neutral phase (systems off)48 Desired yaw rate r(des)50 Actual yaw rate rFIG. 4 - Adaptive Activation Mode38Adaptive mode selector42Sensor interface lines44 Output control lines to actuatorsTACTOS-L Steering-pulse moduleTACTOS-M Torque-engagement moduleFIG. 5- Vehicle Acceleration over Time46 Friction coefficient μ / µ-split indicator56 Drive-torque amplitude curve60 Pulse frequency f and amplitude A parameters(1) icy roads(2) dry road(t) Time axis (s)FIG. 6- Overview of Embodiments34 Pulse phase (hatching " / / ")36 Neutral phase (dotted "...")62 Mode logic states (standard, adaptive, variable phase length)

Claims

1. A method for controlling the vehicle dynamics of a motor vehicle on slippery orasymmetric road surfaces,characterized in that• the driving state is continuously monitored and intervention occurs only during anacceleration or braking process,• the control is performed according to a synchronized ACTOS cycle comprising cycle-bound pulse and neutral phases,• in each pulse phase of the ACTOS cycle, both principles are obligatorily executedeither simultaneously or in direct temporal sequence, wherein(i) TACTOS-L generates alternating side-specific steering pulses for side-specificwheel load transfer, and(ii) TACTOS-M introduces torque engagement impulses to a drive axle via acontrollable clutch,• and wherein during each neutral phase both systems are completely deactivated, thesteering angle is held at 0°, and the clutch is opened,in order to record and evaluate vehicle dynamics parameters in an uninfluencedmanner and to parameterize the next pulse phase,• wherein, in case of start-up dominance, TACTOS-L is controlled such that the wheelwith the lower adhesion is relieved to a wheel load of less than 5% of the static wheelload value and runs substantially slip-free with the road surface at a slip of less than5%, until drive torque is reapplied upon reversal of the steering angle,• and the cycle is continued until a stable driving state is detected and the system isdeactivated;2. The method according to claim 1,characterized in thatTACTOS-L executes steering pulses with amplitudes of ±3° to +12° and frequencies of 2 Hzto 6 Hz, and is always returned to a steering angle of 0°;3. The method according to one of the preceding claims,characterized in thatTACTOS-M executes torque engagement impulses with a duration of 0.3 s to 0.7 s, followedby observation phases of 0.5 s to 1.0 s;4. The method according to one of the preceding claims,characterized in thatactivation occurs only within a yaw rate window, preferably ±8° / s, and automatic deactivationtakes place if the limit is exceeded;5. The method according to one of the preceding claims,characterized in thatin the case of braking, the selection is prioritized in favor of TACTOS-L;6. The method according to one of the preceding claims,characterized in that• in a hybrid operating mode, both TACTOS-L and TACTOS-M are obligatorilyexecuted within the same pulse phase of the ACTOS cycle,• the execution of both systems occurs in a temporally coordinated manner, eithersimultaneously or in a predefined sequential order,• such that, within each pulse phase, combined influence of steering pulses and torqueengagement is applied, while in every neutral phase both systems are completelydeactivated;7. The method according to one of the preceding claims,characterized in thatno fixed maximum of pulse-neutral cycles is predetermined, and the cycle is continuouslyrepeated as long as instability is detected;8. A control unit for carrying out the method according to one of claims 1 to 7,comprising a processor, a memory with stored instructions, and interfaces to a steeringactuator, a clutch actuator, and vehicle dynamics sensors,wherein the processor is configured to execute TACTOS-L and TACTOS-M in each pulsephase according to the synchronized ACTOS cycle and to necessarily deactivate both systemscompletely in each neutral phase and to evaluate the vehicle dynamics parameters,and a vehicle comprising such a control unit;9. The method according to one of the preceding claims,characterized in thatwithin a pulse phase of the ACTOS cycle, exclusively either TACTOS-L or TACTOS-M isactivated,wherein the exclusive activation is determined by a selection logic evaluating current vehicledynamics parameters,and the selection is necessarily synchronized with the fixed ACTOS cycle structure,and wherein, in an exploratory sub-mode, TACTOS-L is executed with minimal steeringdeflections in order to detect road grip, the frequency and amplitude of the pulses beingsuccessively increased if no vehicle response is detected, until a stable response level isreached, at which point operation continues at an intermediate frequency and amplitude;10. The method according to one of the preceding claims,characterized in thatthe duration of the pulse phases and neutral phases is variably adapted to vehicle dynamicsparameters, while the temporal sequence of the phases within the ACTOS cycle is preserved.

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