Method for operating an electromechanical steering assistance device for a vehicle

Abstract

This invention relates to a method for an electromechanical steering assist device for operating a vehicle: - the steering assist device operates via a battery charged by means of a generator-type motor; and - predictively detects that the steering assist device will operate at a future time (AP). 未来 It has more than the current (AP) 当前 The higher power requirement for charging the battery; and immediately following the detection, at a future time (AP) 未来 A higher voltage will be applied to the battery, so that the steering assist device will be able to apply a higher voltage at a future time (AP). 未来 ) Utilize the predicted higher power – only when detected in the predictive investigation at a future time (AP) 未来 A higher voltage is applied to the battery only when the steering assist device reaches and / or exceeds its design limits.

Description

Method for electromechanical steering assist device for operating vehicle Technical Field

[0001] This invention relates to a method for an electromechanical steering assist device for operating a vehicle and a computer program product. For prior art, see, for example, document DE 10 2015 2018 167 A1. Background Technology

[0002] The onboard electrical network in a vehicle includes cable bundles, energy storage devices, power sources, and electrical loads. Multiple energy storage devices or power sources can also be used in principle. In conventional vehicles with a 12V onboard electrical network, a generator is used as the power source, while in hybrid or electric vehicles, power is supplied by a DC / DC converter, which is connected to a high-voltage onboard electrical network with a high-voltage battery. The peak power of this energy source is typically determined to be large enough to cover the average power of all systems installed in the vehicle. However, the peak power of the installed systems may be many times greater than the average power. DC / DC converters have high dynamism, while generators in vehicles are limited in their dynamism due to installation techniques. Currently, for energy efficiency reasons, there is an increasing number of running gear components being electrified in vehicles, thus significantly increasing the load on the 12V onboard electrical network. Electric servo steering systems (also known as steering assist) are also supplied with current and voltage through the 12V onboard electrical network.

[0003] Electric servo steering systems, acting as dynamic peak power loads, exhibit greater dynamism than generators. This presents a problem: generators may fail to provide the desired current under dynamic load conditions, necessitating the use of batteries or other energy storage devices to cover the demand. Due to the battery's internal resistance, additional voltage disturbances occur at the battery terminals during current output. This can be particularly pronounced with dynamic peak power loads, such as electric servo steering systems, potentially leading to severe voltage fluctuations. This problem can also arise in onboard electrical systems where DC / DC converters are used as energy sources. However, in the presence of dynamic loads in the onboard electrical system, batteries are only necessary as energy buffers when the DC / DC converter approaches its power limit, even if the DC / DC converter's regulation is faster than that of the generator.

[0004] To optimize the performance of steering systems, particularly electric servo steering systems, under power-intensive driving conditions, software-based functions are now available for boosting voltage, for example, by switching on a generator. Exemplary methods are available in document DE 10 2015 218 167 A1.

[0005] Generally, measures known from the prior art are classified into reactive measures and predictive measures. Reactive measures increase voltage based on current driver input, such as steering angle, steering angular velocity, or steering torque, or utilize steering system data, such as current energy consumption or current mechanical and / or electrical power consumption.

[0006] Predictive measures (as illustrated in document DE 10 2015 218 167 A1) result in the identification of power-intensive driving conditions based on experience-based usage examples.

[0007] Reactive measures have the drawback that they intervene too late in time. Due to computation time, signal processing time, and physical inertia, voltage boosts in such systems often occur too late. Vehicle occupants then experience a brief stiffening of the steering handle during steering, which disappears once the voltage in the 12V onboard electrical grid is boosted. This "stiffening" can be perceived as uncomfortable by the occupants. Predictive measures, on the other hand, boost voltage promptly, but due to their inaccuracy, they also trigger unnecessary voltage boosts that are not needed by the steering system. Predictive measures therefore adversely affect CO2 emissions, energy consumption, and the potential electric range of electric vehicles. Summary of the Invention

[0008] Therefore, the objective of this invention is to provide a method for operating an electromechanical steering assist device that ensures the highest possible driver comfort while simultaneously ensuring the lowest possible energy consumption.

[0009] The solution to this task is derived through a method for operating an electromechanical steering assist device according to the invention and a computer program product according to the invention.

[0010] A method for a steering assist device for operating electromechanical systems is proposed here.

[0011] Here, such an electromechanical steering assist device can be specifically configured as a so-called servo motor or servo steering device. The servo steering device is used to reduce the force necessary for steering wheel operation of the motor vehicle when stationary, maneuvering, or turning at low speeds. The servo steering device assists the driver during steering by amplifying the steering force applied by the driver through a motor.

[0012] The steering assist device here operates via a battery charged by a generator-type motor.

[0013] Particularly preferably, the steering assist device is supplied with current and voltage via an on-board power grid, which consists of a storage battery or battery (especially a 12V battery) and a generator.

[0014] Alternatively, a so-called DC / DC converter can be connected between the voltage level of the steering system and the voltage level of the generator-type motor, which supplies current and voltage to the steering assist system via a charged battery.

[0015] The so-called energy-powered on-board electrical network—on which the electromechanical steering assist device is connected—particularly preferably relates to a so-called 12V energy-powered on-board electrical network. In particular, the method is applicable to low-voltage on-board electrical networks. However, the method can also be implemented using other energy-powered on-board electrical networks, such as 24V or 48V on-board electrical networks.

[0016] Preferably, the charging and discharging of the battery, and the resulting power, as well as the voltage on the battery, are predetermined by means of the vehicle's energy and power management system design.

[0017] The voltage is predetermined by the power management system, and is variably designed in relation to the current driving conditions, the current energy and power consumption of the electrical loads present in the vehicle, and the state of the battery.

[0018] Based on the predetermined variable voltage on the battery, the following voltage can appear at the terminals of the electromechanical steering assist device, which can be below the design voltage of the electromechanical steering assist device.

[0019] Therefore, it is further stipulated that the steering assist device will have a higher power demand in the future than the current power required for charging the battery, especially through the power required by the energy and power management system.

[0020] In particular, it is necessary to detect and determine the future voltage requirements at the terminals of the steering assist device.

[0021] The predictive determination of power demand, or in particular voltage demand, is achieved, for example, by means of mathematical extrapolation or by one or more neural networks or similar prediction or estimation mechanisms.

[0022] If it is detected or calculated that the steering assist device will have a higher power demand or, in particular, a higher voltage demand in the future, then a higher voltage will be applied to the battery at that time. This is preferably achieved by the energy and power management system requesting a correspondingly higher voltage upon detection of a higher voltage demand, so that the higher voltage exists in the future. This voltage increase exists only briefly for the corresponding situation and is then immediately withdrawn, preferably when the increased voltage is no longer needed.

[0023] This provision states that the increase in voltage on the battery or the preference for a higher voltage through the energy and power management system is achieved only if the steering assist device reaches or exceeds its design limits at a future time.

[0024] The electromechanical steering assist device is preferably designed based on a curve of steering angular velocity with respect to rack travel or steering angle and steering torque (also known as so-called hand torque) with respect to rack travel or steering angle.

[0025] The steering unit in a vehicle is therefore preferably a so-called rack and pinion steering system, in which a rack is engaged by a gear connected to the steering handle, for example, via a steering shaft. The rack is moved by the rotation of the steering handle by the vehicle occupant (with so-called hand torque), and the rack oscillates the steering wheels with a defined rack travel.

[0026] The steering assist device assists the driver in such a way that it applies at least partially a force to the driver via a motor to move the steering handle, so that the driver only needs to apply a reduced hand torque.

[0027] Hand torque is described here as the torque that vehicle occupants must apply to the steering handle (e.g., to the steering wheel) in order to steer the vehicle.

[0028] The rack travel describes the path of the rack's translational motion, which helps in representing the steering angle determined at the vehicle wheels.

[0029] The design limits of the steering assist device are therefore preferably predetermined by the steering angular velocity characteristic curve and the hand torque characteristic curve. The two characteristic curves are plotted with respect to the rack travel (or steering angle) of the steering unit. That is, according to the characteristic curves, at a given rack travel, the maximum hand torque is always predetermined for the maximum steering angular velocity (and vice versa, the maximum hand torque is always the maximum steering angular velocity).

[0030] Therefore, according to the steering angular velocity characteristic curve, if the driver turns, for example, at a certain rack travel point, then the hand torque must not exceed the hand torque characteristic curve. Conversely, it must be possible for the driver to apply hand torque according to the hand torque characteristic curve, thus reaching the maximum steering angular velocity according to the steering angular velocity characteristic curve. In both of the above cases, the operation of the steering assist device is thus still within the design limits.

[0031] The voltage increase is preferably caused or required only when it is detected that two characteristic curves are reached or exceeded at a future time, thereby reaching or exceeding the design limits of the steering assist device.

[0032] This additional condition—related to the voltage increase—avoids unnecessary voltage increases. This is because reaching the design limits of the steering assist is a more accurate measure of the actual occurrence of the driver's steering "hardening" than interpolated or estimated data. The voltage increase only occurs when the design limits of the steering assist are actually reached or exceeded.

[0033] At the same time, by predictively forecasting the power demand that will increase in the future, it is ensured that the voltage increase is implemented only when the driver turns so quickly or so sharply that the driver will feel the stiffening without the voltage increase; and that the increase is implemented early enough to prevent such a short-term stiffening from starting.

[0034] This can greatly reduce or completely avoid the adverse effects of past predictive measures described in the prior art on carbon dioxide emissions, energy consumption, or electric driving range.

[0035] For example, when turning quickly with a small amount of hand torque, the steering assist does not force the vehicle to its design limits. Similarly, in the case of a vehicle with an unloaded front axle on an uphill slope, a high steering angular velocity can be achieved with a small steering torque. Furthermore, even in slow turns with a high steering torque, the steering assist does not force the vehicle to its design limits. For this purpose, for example, consider a situation where the steering return of the front wheels is located at a so-called end stop, which causes mechanical resistance and thus increases the steering torque.

[0036] In other words, by understanding the relationship between voltage increases and the design limits of the steering assist device, the accuracy can be improved to determine whether a higher power requirement for the steering assist device will actually be needed in the future. This can help avoid unnecessary voltage increases in the future.

[0037] Furthermore, it is possible to avoid installing costly multi-voltage vehicle electrical systems (400V, 60V, 48V, 24V, or 12V) and instead use low-voltage vehicle electrical systems. This can save on manufacturing costs. In particular, in lower or mid-range vehicles, it is also possible to install steering systems with smaller power ratings, which further contributes to cost reduction.

[0038] In a preferred embodiment of the claimed method, it is repeatedly determined at time intervals whether the steering assist device will have a higher power demand at another future time than is currently required, particularly by the power required for charging the battery through the energy and power management system. This determination is particularly performed every 1 to 15 milliseconds, and especially preferably every 10 milliseconds.

[0039] Such a high-frequency detection process ensures that it can be determined at almost every moment whether an increased power demand should be required in the future.

[0040] Here, the prediction time for determining whether the steering assist device will have a higher power demand in the future is preferably selected such that the steering assist device operates with increased power, and in particular increased voltage, at the respective detected future time. The prediction time is therefore selected in a timely manner, so that the vehicle driver does not feel a so-called "stiffening" when steering.

[0041] Preferably, the prediction time is in the range of approximately 100 to 2000 milliseconds, and particularly preferably in the range of 500 to 1500 milliseconds.

[0042] The aforementioned and other features are further known from the specification and the accompanying drawings, wherein each feature is implemented individually or in combination in one embodiment of the invention and may represent advantageous and insurable embodiments, for which protection is claimed herein. Attached Figure Description

[0043] The invention is further illustrated below with reference to one embodiment. Importantly, all the features further described herein are relevant to the invention.

[0044] The accompanying diagram illustrates an exemplary design limit with steering assist. Detailed Implementation

[0045] The design limit of the steering assist device is therefore preferably determined by the steering angular velocity characteristic curve v. 转向角 And through the hand torque characteristic curve M 手 Pre-order. Two characteristic curves regarding the rack travel of the steering unit (Hub). ZGS The curve is depicted. The design limit is therefore specified as follows: according to the characteristic curve at a given rack travel, the maximum steering angular velocity is always the predetermined maximum hand torque (and vice versa, the maximum hand torque is always the maximum steering angular velocity).

[0046] For example, it can be seen that the rack travels forward from the hub. ZGS Initially, the hand torque increases significantly, while the steering angular velocity decreases. This is possible, for example, during vehicle parking maneuvers at speeds close to a standstill, where the steering mechanism is almost at its end stop and the steering angular velocity is only very slow.

[0047] In the first step, for example by extrapolation, estimation methods, or similar detection: the steering assist device at a future time AP 未来Or, in the case of a future operating point having a higher current AP than the current operating point of the steering assist device. 当前 The charging power required for the battery is even higher.

[0048] Therefore, the current operating point of the steering assist device is detected at the current moment, which is within the design limits, and in this case, below the design limits of both characteristic curves.

[0049] Next, the future operating point is predicted within the required prediction time using, for example, extrapolation (shown by dashed lines). In this case, the predicted operating point exceeds two design characteristic curves of the steering assist device (see arrows). This is achieved by exceeding the hand torque characteristic curve M at the future operating point. 手 and steering angular velocity characteristic curve v 转向角 The trigger voltage increases.

[0050] Here, a higher voltage is applied to the battery by the increased voltage requirement of the vehicle's energy and power management system, thereby enabling the steering assist to obtain a predicted higher voltage at the predicted operating point.

[0051] However, triggering only occurs under the following conditions: if the hand torque characteristic curve M... 手 and steering angular velocity characteristic curve v 转向角 There exists a quantity that exceeds or reaches the specified quantity.

[0052] If it only exceeds the hand torque characteristic curve M 手 and steering angular velocity characteristic curve v 转向角 If one of them is not exceeded, and the voltage does not exceed the other, then no voltage boost occurs because the design limit of the steering assist device has not been reached.

[0053] This effectively avoids unnecessary increases in battery voltage and thus unnecessary energy consumption. At the same time, if a voltage increase is actually necessary, it allows for a more comfortable steering experience for the vehicle driver.

Claims

1. A method for an electromechanical steering assist device for operating a vehicle: - The steering assist device operates by means of a battery charged by means of a generator-type motor; And - predictive detection: the steering assist device at a future time (AP) 未来 It has more than the current (AP) 当前 The higher power requirement for charging the battery; and immediately following the detection, at a future time (AP) 未来 A higher voltage will be applied to the battery, so that the steering assist device will be able to apply a higher voltage at a future time (AP). 未来 ) Utilizing the predicted higher power, it is characterized by, Only when detected in predictive identification: at a future time (AP) 未来 A higher voltage is applied to the battery only when the design limits of the steering assist device are reached and / or exceeded. The design limits of the steering assist device are expressed as per the steering angular velocity characteristic curve (v). 转向角 ) and the torque characteristic curve (M) of the hand torque applied to the steering handle by the vehicle occupants. 手 To determine; - The steering angular velocity characteristic curve (v) 转向角 According to the rack travel of the vehicle's steering system (Hub) ZGS To determine the limit steering angular velocity of at least one wheel of the vehicle; And - the hand torque characteristic curve (M) 手 When operating the vehicle's steering handle, the travel of the rack depends on the rack travel. ZGS To predetermine the ultimate hand torque of the vehicle occupants; and - only if it is detected in the predictive investigation that: at a future time (AP) 未来 Not only does it reach and / or exceed the steering angular velocity characteristic curve (v) of the steering assist device, but it also achieves and / or exceeds the steering angular velocity characteristic curve (v) of the steering assist device. 转向角 And it reaches and / or exceeds the hand torque characteristic curve (M). 手 Only then can a higher voltage be applied to the battery.

2. The method according to claim 1, characterized in that, The steering assist device is operated by means of a 12V battery.

3. The method according to claim 1 or 2, characterized in that, Repeatedly ascertaining at intervals: the steering assist device at a future time (AP) 未来 Does it have a higher power requirement than the current power required for charging the battery? 4. The method according to claim 1 or 2, characterized in that, Select the option to determine the steering assist device at a future time (AP) 未来 Does it have a higher power demand prediction time, so that at the detected future time (AP) 未来 The steering assist device operates with increased power.

5. The method according to claim 4, characterized in that, The prediction time is in the range of 150 to 2000 milliseconds.

6. The method according to claim 1 or 2, characterized in that, The power requirements of the steering assist device are predictively determined using extrapolation mathematical methods.

7. A computer program product that, when loaded into the memory of a computer having a processor, performs the method according to any one of claims 1 to 6.

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