Methods for monitoring drives

Abstract

Method for monitoring moments in a vehicle, comprising the following steps in a first computing unit (100): Receiving a delta moment (110) that describes a difference in longitudinal moments for a left and a right side of the vehicle; in a first calculation process (120) calculating a first target torque (111) and a second target torque (112) from the delta torque (110); in a second calculation process (130) check whether the difference between the first target torque (111) and the second target torque (112) is less than or equal to the delta torque (110), wherein the second calculation process (130) is executed independently of the first calculation process (120); and Output of the first target torque (111) and the second target torque (112) only if the difference between the first and second target torques is less than or equal to the delta torque (110).

Description

[0001] The present invention relates to a method for monitoring moments, in particular delta moments. State of the art

[0002] Modern vehicles use engine control units (ECUs) for combustion engines that include monitoring according to the so-called "standardized e-gas monitoring concept for gasoline and diesel engine control units." This monitoring is intended to prevent unintended vehicle behavior.

[0003] The principle of functional monitoring is as follows: A permissible torque is calculated, taking into account numerous influencing factors such as driver input, internal friction torques, and external consumers. Conversely, an actual torque is calculated based on current engine parameters. These parameters can include, among others, the throttle valve angle, intake manifold pressure, injection timing, pressure, and angle.

[0004] The goal of functional monitoring is to keep the actual torque below the permissible limit to prevent unintended acceleration. Therefore, certain requirements are placed on the monitoring concept, including adherence to a specific fault response time, so that faulty vehicle reactions, such as unintended acceleration, remain controllable. This means that a fault must be detected and debounced within a specific time. After unambiguous fault detection, the vehicle must then be brought to a safe state.

[0005] Reading back actual values ​​requires a certain amount of time for the engine control unit: For example, the actual torque must first build up before corresponding actuator values ​​can be read back. For gasoline and diesel engines, this permissible fault reaction time is generally 500 ms. This fault reaction time is generally sufficient for monitoring vehicle dynamics along the direction of travel. The electronic throttle monitoring concept has been adapted accordingly for electric motors.

[0006] Hybrid vehicles, which combine combustion and electric motors, are increasingly being manufactured. In hybrid vehicles, the combustion engine's control unit is often used to determine the torque distribution between the combustion and electric motors. The target and actual torque of the electric motor must be integrated into the functional monitoring system. This is done according to the same principle as with a single combustion engine: From a total target torque, the control unit calculates the target torque and control parameters for the combustion engine and the target torque for the electric motor. The actual values ​​are then read back to calculate the actual torque. Here, the control unit for the electric motor calculates its actual torque from its actuator values ​​and sends this information to the combustion engine's control unit.

[0007] Recently, vehicles have also been developed that use electric motors to implement individual wheel drives, both on the front and rear axles. If the electric motors on one axle provide different torques for the right and left wheels, a torque perpendicular to the direction of travel is generated. These torque requirements can originate, for example, from an ESP control unit for regulating vehicle stability and be routed via the motor control unit.

[0008] This lateral moment can be used to assist the steering, making the vehicle more agile in curves. However, incorrectly applied moments can lead to unintended lateral dynamics, i.e., unintended changes in direction, potentially resulting in skidding. This is considered more dangerous than unintended longitudinal dynamics, and errors in lateral dynamics must be detected more quickly, as driving tests have shown that such errors can lead to skidding even after times of less than, for example, 100 ms.

[0009] DE 10 2005 062 870 A1, WO 2007 / 025 840 A1 and DE 10 2010 020 518 A1 represent the relevant state of the art.

[0010] It is therefore desirable to specify a way to reduce the error response time for specifications relating to the lateral dynamics of a vehicle compared to the state of the art. Disclosure of the invention

[0011] According to the invention, a method with the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description. Advantages of the invention

[0012] In a method according to the invention for monitoring torques, a first computing unit, in particular a control unit, receives a delta torque. Subsequently, in a first calculation process, a first and a second target torque are calculated from the delta torque. In a second calculation process, it is checked whether the difference between the first and the second target torque is less than or equal to the delta torque, the second calculation process being carried out independently of the first. If the difference is less than or equal to the delta torque, the first and second target torques are output. This allows the calculation of target torques based on a given delta torque to be verified by means of a second, independent calculation; that is, the first calculation is monitored, by means of which errors can be detected.Since the monitoring is performed in the same processing unit as the calculation, no transfer times between multiple processing units or the reading back of values ​​need to be considered, resulting in a short monitoring time and thus a short fault tolerance time.

[0013] This advantageous type of functional monitoring can be used in particular for delta moments in the lateral direction of a vehicle, i.e. for lateral dynamics, resulting in faster monitoring than, for example, for longitudinal dynamics.

[0014] Preferably, the first and second target torques are calculated from the delta torque and a third target torque, the third of which is calculated from required values. This is useful when, as is often the case in practice, the delta torque needs to be combined with another specified torque. For example, two electric motors may have identical longitudinal torques, but differing torques for a lateral torque. For instance, there might be one electric motor on the left side and one on the right side of a vehicle, with a higher torque specified for the right electric motor to generate a lateral torque to the left. This can assist with cornering.

[0015] Advantageously, the second calculation process takes into account the sign of the delta moment, the first and / or the second target moment during the check. This allows for even more precise error monitoring, since, depending on the driving situation, moments in different directions can have varying degrees of criticality.

[0016] It is advantageous to output the first and second target torque values ​​to a second processing unit, where the implementation of these values ​​is verified against the resulting actual torque values. This is done by reading back the actual torque values ​​after the target torque values ​​have been implemented and comparing them to the target torque values. Typically, the second processing unit is a control unit for electric motors. Any necessary corrections can be made quickly here, as an electric motor's target torque can be regulated more rapidly than target torque values ​​for internal combustion engines.

[0017] It is further advantageous if the delta torque is specified by a third processing unit. A delta torque is frequently required for vehicle dynamics control, so that a torque acts perpendicular to the direction of travel to assist the steering. It is therefore sensible for the delta torque to be specified by a different control unit, one that is dedicated to vehicle dynamics control.

[0018] Preferably, in the first processing unit, a fourth target torque is calculated from the required values, and from this fourth target torque, setpoint values ​​for actuators, which are to implement the fourth target torque, are calculated and output. In addition to target torques for electric machines, target torques for an internal combustion engine are also usually required or calculated, which are then output as setpoint values ​​to the internal combustion engine or associated actuators. The calculation of all required target torques can thus be performed in a single processing unit.

[0019] It is also advantageous if actual values ​​resulting from the implementation of the target values ​​and / or an actual moment resulting from the implementation of the first and second target moments are received by the first processing unit and compared with a permissible moment calculated from the required values. This allows for an additional check of the further target moments and contributes to safety. This is particularly useful for moments in the longitudinal direction, i.e., for longitudinal dynamics.

[0020] A computing unit according to the invention, e.g. a control unit, in particular an engine control unit, of a motor vehicle, is, in particular in terms of programming, equipped to carry out a method according to the invention.

[0021] Implementing the process in software form is also advantageous, as this incurs particularly low costs, especially if the executing control unit is already used for other tasks and is therefore already present. Suitable data carriers for providing the computer program include floppy disks, hard drives, flash memory, EEPROMs, CD-ROMs, DVDs, etc. Downloading the program via computer networks (Internet, intranet, etc.) is also possible.

[0022] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0023] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0024] The invention is schematically illustrated in the drawing using exemplary embodiments and is described in detail below with reference to the drawing. Brief description of the drawings Fig. Figure 1 shows a schematic representation of a process according to the state of the art. Fig. Figure 2 shows a schematic representation of a further method according to the state of the art. Fig. Figure 3 shows a schematic representation of a method according to the invention in a preferred embodiment. embodiment(s) of the invention

[0025] In Fig. Figure 1 schematically illustrates a method for functional monitoring of an internal combustion engine according to the state of the art.

[0026] In this process, a processing unit (100), typically an engine control unit (ECU), receives request values ​​(140). Such request values ​​can originate, for example, from an accelerator pedal through which a driver specifies a desired torque. Further torque requests from other processing units, such as control systems for safe driving operation or for the protection of components, are also conceivable.

[0027] At a functional level, the processing unit 100 calculates a target torque 114 for the internal combustion engine from the required values ​​140 in a calculation step 10. Subsequently, within the same functional level, output values ​​150 are calculated from the target torque 114 in a calculation step 20. These output values ​​are intended for actuators 30, which are responsible for controlling the internal combustion engine, such as the injection system. The processing unit 100 outputs these values ​​150 to the corresponding actuators 30, such as injectors, spark plugs, etc.

[0028] At a functional monitoring level, the processing unit 100 also calculates a permissible torque 118 from the received requirement values ​​140 in a calculation step 40. The permissible torque 118 represents a limit value that, due to safety requirements, for example, must not be exceeded by the target torque 114. The functional monitoring level performs calculations independently of the functional level.

[0029] Furthermore, actual values ​​161, i.e., the actual values ​​achieved by the actuators 30 when implementing the target values ​​150, are read back from the computing unit 100 via an interface 70. These actual values ​​161 can be measured using suitable sensors.

[0030] At the functional monitoring level, an actual torque 162, which is actually achieved by the internal combustion engine, is calculated from the received actual values ​​161 in a calculation step 60. Subsequently, the actual torque 162 is compared with the permissible torque 118 in a verification step 50 to check whether the actual torque 162 is within the required limit. If the actual torque 162 exceeds the permissible torque 118, appropriate countermeasures, such as reducing the torque of the internal combustion engine, can be taken.

[0031] However, this check involves a long error response time (approx. 500 ms) due to the output and subsequent rereading of the actual values ​​161.

[0032] In Fig. Figure 2 schematically illustrates a method for functional monitoring of an internal combustion engine and an additional electric machine according to the state of the art.

[0033] The difference to the one in Fig. The method shown in Figure 1 consists of calculating, at the functional level, a target torque 113 for an electric machine in addition to the target torque 114 for the internal combustion engine in a calculation step 10'. This target torque 113 is output by the processing unit 100 without further calculations and received by another processing unit 200, which is intended for controlling the electric machine. Any necessary further calculations regarding the target torque 113 for the electric machine and its implementation are performed by the other processing unit 200.

[0034] An actual electrical torque 160 achieved by the electric machine is, after being recorded by suitable means, read back by the computing unit 100 via a suitable interface and, at the functional monitoring level, combined with the actual torque of the internal combustion engine in a calculation step 60' to obtain a total actual torque 163. Subsequently, as also occurs at Fig. As described in section 1, in verification step 50 the comparison of the, in this case total, actual moment 163 with the permissible moment 118.

[0035] Here too, a long error response time (approx. 500 ms) is available for checking by outputting and rereading the actual values ​​161 and additionally the electrical actual torque 160.

[0036] In Fig. Figure 3 schematically illustrates a method according to the invention for monitoring moments in a preferred embodiment.

[0037] As in the prior art, the first computing unit receives 100 request values ​​140, from which a fourth target torque 114 for an internal combustion engine and a third target torque 113 for electric machines are calculated on a functional level in the calculation step 10'.

[0038] From the fourth target torque 114, output values ​​150 are calculated and output for the actuators 30.

[0039] Additionally, the first computing unit 100 receives a delta moment 110 from a third computing unit 300. While the required values ​​140 are intended for calculating moments in the longitudinal direction, i.e., for controlling longitudinal dynamics, the delta moment 110 is intended for controlling lateral dynamics.

[0040] The third control unit, 300, typically a vehicle dynamics control unit such as an ESP control unit, specifies a delta moment. This means that different longitudinal moments are to be specified for the left and right sides of the vehicle, differing by precisely this delta moment. This generates a lateral moment. As mentioned earlier, this allows for, for example, more stable and / or agile cornering. Such different specification of longitudinal moments is possible, for instance, when an electric motor is provided for propulsion on each side of the vehicle.

[0041] At the functional level, in a first calculation process 120, a first target torque 111 and a second target torque 112 are calculated from the third target torque 113 for the electric machines and the delta torque 110. For example, the first target torque 111 is intended for an electric machine for driving the left side of the vehicle, and the second target torque 112 is intended for an electric machine for driving the right side of the vehicle.

[0042] The first and second target torques 111 and 112 are not yet output by the processing unit 100, but are first passed to the function monitoring level. There, in a second calculation process 130, the difference between the first target torque 111 and the second target torque 112 is calculated. Subsequently, it is checked whether this difference is less than or equal to the received delta torque 110, or whether this difference is greater than the received delta torque 110. The signs of the delta torque, as well as the first and second target torques, are also taken into account during this check.

[0043] The first and second target torques 111, 112 are subsequently only output by the processing unit 110 and forwarded to a second processing unit 200 for controlling the electric machines if the check is successful, i.e., if the difference is less than or equal to the received delta torque 110. This ensures that no larger lateral moments than intended are generated, as the vehicle could otherwise go into a skid.

[0044] This type of verification allows for a significantly shorter fault tolerance time (approx. 100 ms) than the state-of-the-art verification method typically used for longitudinal dynamics, since no values ​​need to be output and then read back. Nevertheless, the two independent calculation processes 120 and 130, performed at the functional and functional monitoring levels respectively, ensure the necessary safety of the target torques.

[0045] Additionally, the second processing unit 200 can monitor the first and second target torques 111 and 112, thus ensuring extra safety. This means that the actual torques achieved by the electrical machines when implementing the first and second target torques 111 and 112 are recorded using suitable means, read back by the second processing unit 200, and compared there with the specified first and second target torques 111 and 112. Any deviation could then be corrected, as the electrical machines can be controlled relatively quickly.

[0046] As in the prior art, the actual values ​​161 and the electrical actual torque 160 are read back from the first computing unit 100 via the interface 70 and, at the functional monitoring level, a total actual torque 163 is calculated in a calculation step 60' and compared with a permissible torque 118, thus ensuring monitoring of the longitudinal dynamics.

[0047] For longitudinal dynamics, in contrast to lateral dynamics, a longer error tolerance time of approximately 500 ms is permissible, since no dangerous situations such as the vehicle skidding, which would no longer be controllable, can arise here.

Claims

[1] Method for monitoring moments in a vehicle, comprising the following steps in a first computing unit (100): Receiving a delta moment (110) that describes a difference in longitudinal moments for a left and a right side of the vehicle; in a first calculation process (120) calculating a first target torque (111) and a second target torque (112) from the delta torque (110); in a second calculation process (130) check whether the difference between the first target torque (111) and the second target torque (112) is less than or equal to the delta torque (110), wherein the second calculation process (130) is executed independently of the first calculation process (120); and Output of the first target torque (111) and the second target torque (112) only if the difference between the first and second target torques is less than or equal to the delta torque (110). [2] Method according to claim 1, wherein in the second calculation process (130) the sign of the delta moment (110), the first target moment (111) and / or the second target moment (112) is taken into account when checking. [3] Method according to one of the preceding claims, wherein the first target torque (111) and the second target torque (112) are output to a second computing unit (200), wherein in the second computing unit (200) a check of the first and the second target torque is carried out on the basis of the actual torques obtained therefrom. [4] Method according to one of the preceding claims, wherein the delta moment (110) is specified by a third computing unit (300). [5] Method according to one of the preceding claims, wherein the first and second target torque are assigned to at least two different electrical machines. [6] Computing unit configured to perform the steps of a method according to any of the preceding claims carried out by the first computing unit. [7] Computer program that causes a computing unit to perform the steps of a method according to any one of claims 1 to 5, as performed by the first computing unit, when executed on the computing unit according to claim 6. [8] Machine-readable storage medium with a computer program stored thereon according to claim 7.

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