DE102022120842B3 - Method and device for computer-implemented control of a drive system of a rail vehicle - Google Patents

Abstract

The invention relates to a method for the computer-implemented control of a drive system of a rail vehicle with a control loop (10), the drive system comprising individual wheel drives assigned to the wheels of a pair of individual wheels. During operation of the rail vehicle, the control circuit (10) processes a requested tracking torque (My,soll) and a requested traction or braking torque (Mx,soll) and outputs a tracking torque (My) at a first output (13) and a tracking torque (My) at a second output ( 14) a traction or braking torque (Mx), which are fed to the individual wheel drives as input variables. During operation of the rail vehicle, a physically possible maximum torque (Mmax) of the wheels of the single wheel pair is output by a torque allocation unit (50) of the control circuit (10), which, depending on a specified operating state, is output at the first output as a tracking torque (My) for lateral control or at is determined at the second output as traction or braking torque (Mx) for longitudinal control on the individual wheel drives of the individual wheel pair.

Description

The present invention relates to a method for the computer-implemented control of a drive system of a rail vehicle with a control loop, the drive system comprising individual wheel drives assigned to the wheels of a pair of individual wheels. The invention also relates to a computer program product with software code sections for executing the steps of the aforementioned method on a computer system.

Rail and railway vehicles are designed in such a way that they can safely bring the large moving masses to a standstill within the framework of specified distances. In the case of railway vehicles, the aim is generally to achieve the shortest possible braking distances in the event of emergency braking.

In rail vehicles, there is generally a need to minimize wear in the longitudinal dynamics by avoiding sliding and skidding wheels. Wheel slip occurs when the wheels lock during braking. Skidding wheels are the result of the wheels spinning when the rail vehicle starts to move. In addition, rail vehicles with driven individual wheel bogies, such as trams, have the option of improving wear and tear on wheels and rails as well as driving comfort by implementing a suitable and efficient lane control system, regardless of the currently prevailing conditions.

In the case of rail vehicles with driven individual wheel bogies, the regulation of the drive system generally includes a control loop that includes a path for lateral control (so-called tracking control) and a path for longitudinal control (so-called braking/traction control). This is an example in 1 shown.

1 shows a control circuit 10, which includes a path 20 for transverse control and a path 30 for longitudinal control. Path 20 for lateral control includes lane guidance control 21, which performs the actual control task, and a lateral torque allocation unit 22. Path 30 for longitudinal control includes brake/traction control 31, which performs the actual control method for brake/traction control, and a braking torque allocation unit 32 The term “braking torque allocation unit” is to be understood here in such a way that a torque with a negative sign corresponds to a braking torque and a torque with a positive sign corresponds to a traction torque.

A lateral setpoint position LSP is fed to tracking control 21 as an input variable. The lateral target position LSP is present at a first input 11 of the control loop 10 . From the lateral setpoint position LSP, tracking control 21 determines a requested tracking torque M _y,setpoint and feeds this to lateral torque allocation unit 22 for further processing. The lateral torque allocation unit 22 determines from the requested tracking torque M _y,soll a tracking torque M _y , which is present at a first output 13 of the control loop 10 . The tracking torque M _y is determined from the requested tracking torque M _y,soll by a comparison with a fixed, predetermined first limit value M _y,max , the minimum of the predetermined first limit value M _y,max and the requested tracking torque M _y,soll being the the tracking torque M _y is used.

The brake/traction controller 31 determines a requested traction or braking torque M _x,soll from a braking/acceleration request BBA supplied to it as an input variable. The braking/acceleration request BBA is made available at a second input 12 of the control loop 10 . The requested traction or braking torque M _x,soll determined by the braking/traction control 31 is supplied to the braking torque allocation unit 32 . The braking torque allocation unit 32 determines a traction torque or braking torque M _x from the requested traction torque or braking torque M _x ,setpoint, by carrying out a comparison with a permanently specified second limit value M _x,max . The lower value from the predetermined second limit value M _x,max and the requested traction or braking torque M _x,soll is selected as the _traction or braking torque M x . The traction or braking torque M _x is made available at a second output 14 of the control loop 10 for further processing.

The first limit value M _y,max and the second limit value M _x,max are predetermined maximum values, which are determined, for example, by tests or simulations.

$$M_x=M_{x,links}=M_{x,rechts}.$$

The control tasks carried out by the control circuit 10, namely tracking control and braking/traction control, are implemented by the same actuator, namely the individual wheel drives of the individual wheels of the individual wheel chassis, in the case of driven pairs of individual wheels. In other words, a respective individual wheel drive is assigned to the left and the right wheel. The following applies to the two actuating torques M _i,j (i=x, y, j=left, right) of the left-hand and right-hand single-wheel drives of a single-wheel pair $$M_y=M_{y,links}=-M_{y,\mathrm{right}ecHts},$$

$$M_x=M_{x,links}=M_{x,\mathrm{right}ecHts}.$$

The tracking torque M _y is applied to the left and right wheels of the pair of single wheels with different signs, ie in opposite torque directions. The traction or braking torque M _x is set in the same direction (ie with the same sign) and identically on the left and right wheels. This is realized by a first adder 41, which is assigned to the left single wheel drive, and a second adder 42, which is assigned to the right single wheel drive. While the first and second adders 41, 42 are supplied with the tracking torque M _y with a different sign, the adders 41, 42 are supplied with the traction or braking torque M _x with the same sign. This then results in the moment M _left to be generated by the left single wheel drive, which is provided at the output of the first adder 41 , and the moment M _right to be generated by the right single wheel drive, which is provided at the output of the second adder 42 .

The control processes executed by tracking control 21 and braking/traction control 31 are known in principle from the prior art. For example, in the brake/traction control 31, an anti-skid method can be implemented to reduce the braking distance in the event of poor adhesion conditions between the wheel and the rail. Existing control concepts, such as in [1] and the DE 10 2015 116 862 A1 described, are based on a slip-based approach. They differ in terms of specific implementation steps.

When using the slip as a controlled variable within the framework of a wheel slide protection control, it is not always ensured that an optimal adhesion is achieved, since depending on the wheel-rail contact conditions, a maximum adhesion can occur with other slip values, as is the case, for example, in 2 is illustrated. 2 shows the adhesion f _x depending on the slip s _x . The dashed line shows the connection between adhesion and slip when the rails are wet, and the solid line shows the connection between adhesion and slip when there are leaves on the rails.

An approach that enables adhesion-based brake control based on estimated adhesion coefficients is described in [2]. The approach described in [2] regulates a braking/traction signal in such a way that the traction currently being used between the wheel and the rail tends towards the currently maximum transferrable traction. The estimation of the adhesion coefficients can, for example, according to the DE 10 2017 213 970 A1 described procedures.

A disadvantage of the above in connection with 1 The procedure described for the fixed allocation of predefined maximum torques M _y,max and M _x,max can lead to safety and/or wear-related disadvantages in certain critical situations.

It is the object of the present invention to specify a method and a device for controlling a drive system of a rail vehicle with independent wheel drive with a control circuit that is functionally improved.

This object is achieved by a method according to the features of claim 1, a computer program product according to the features of claim 15 and a device according to the features of claim 16. Advantageous refinements result from the dependent claims.

A method for the computer-implemented control of a drive system of a rail vehicle with a control loop is proposed, the drive system comprising individual wheel drives assigned to the wheels of a pair of individual wheels. During operation of the rail vehicle, the control loop processes a requested tracking torque and a requested traction or braking torque. The requested tracking torque and the requested traction or braking torque represent setpoint torques. The control loop outputs a tracking torque at a first output and a traction or braking torque at a second output, which are fed to the individual wheel drives as input variables. At any point in time of one or more points in time during the operation of the rail vehicle, a physically possible maximum torque of the wheels of the single wheel pair is determined by a torque allocation unit of the control circuit depending on a predetermined operating state at the first output as tracking torque for lateral control or at the second output as traction or braking torque output to the single wheel drives of the single wheel pair for longitudinal control.

The method enables an improvement in the dynamic behavior of the rail vehicle with individual wheel drives, since lane guidance control (lateral control) and braking/traction control (longitudinal control) are taken into account together. The mutual influence is taken into account, which results from the tangential contact between wheel and rail in the lateral and longitudinal direction, both with regard to adhesion and slip.

Due to the situation-dependent torque distribution, safety and/or wear-related disadvantages can be reduced in critical driving situations. These driving situations arise specifically when the setpoint torques of the lane guidance control and/or the brake/traction control required by the regulations (lane guidance control (lateral control) and brake/traction control (longitudinal control)) cannot be provided to the full extent. For example, in the case of non-critical lateral behavior and simultaneous braking with low or changing adhesion conditions, the braking distance can be reduced by assigning a higher traction or braking torque. Likewise, in the case of critical lateral behavior with no or an uncritical braking process, the lateral dynamics can be improved with regard to wear and comfort through a higher tracking torque.

This procedure is based on the consideration that, due to the fixed assignment of predefined maximum torques for lane guidance control and braking/traction control provided in the prior art, torque reserves that are not required in one control system cannot be made available to the other control system.

An expedient embodiment provides that the physically possible maximum torque is determined from the engine torque that can be physically provided by the single wheel drives of the single wheel pair and a maximum torque that can be transmitted between at least one wheel of the single wheel pair and an assigned rail on which the rail vehicle moves, depending on environmental conditions. The maximum moment that can be transmitted between the wheel and the rail can, for example, be calculated using a method known from the prior art, such as, for example, in DE 10 2017 213 970 A1 described, to be determined.

In particular, the minimum value from the engine torque and the transmittable torque is processed as the physically possible maximum torque. In other words, with this configuration, the calculation of a maximum possible frictional connection between wheel and rail takes place. The maximum torque that can be transmitted can be determined, for example, from an estimated vertical wheel force and a generally known wheel radius.

According to a further expedient refinement, the maximum torque that is physically possible is compared with a requested total torque, with a first torque control or a second torque control being carried out depending on the result of the comparison. The first torque control includes normal operation, in which the sum of the tracking torque and the traction or braking torque can be transmitted by the wheels of the single wheel pair. The second torque control includes emergency operation, in which the sum of the tracking torque and the traction or braking torque cannot be transmitted by the wheels of the single wheel pair. Emergency operation can be braking operation, for example. Emergency operation can also be traction operation.

The requested total torque is expediently determined from the sum of the absolute values of the requested tracking torque and the requested traction or braking torque. In particular, the first torque regulation is carried out when the result of the comparison includes that the maximum torque that is physically possible is greater than the requested total torque. To carry out the first torque control, the requested tracking torque is expediently output as tracking torque at the first output and the requested traction or braking torque is output as traction or braking torque at the second output.

The first torque control represents normal operation. In normal operation, the two controls (tracking control and braking/traction control) are not restricted in any way, as long as the total of the tracking torque and the traction or braking torque (i.e. the control torques) can be transmitted. Since the predefined maximum torques that have been customary up to now are not taken into account in the regulation according to the invention, any performance restrictions that may occur can be avoided. If, on the other hand, the sum of the two control torques exceeds the torque available from a respective single-wheel drive and/or a maximum transmissible torque, control takes place in accordance with the second torque control.

According to an expedient embodiment, the second torque control is carried out when the result of the comparison includes that the maximum torque that is physically possible is less than the requested total torque. When executing the second torque control, it is determined whether emergency braking is present or not. If it is determined that there is no emergency braking, a third torque control is carried out, and otherwise a fourth torque control is carried out. The third torque control and the fourth torque control are therefore alternative variants of the second torque control.

When executing the third torque control, a first selection torque is expediently determined, which is output at the first output as tracking torque for lateral control. The first selection torque is the smaller value of the physically possible maximum torque and the requested tracking torque in terms of absolute value. The first selection moment corresponds to the tracking moment.

Another expedient embodiment provides that a first differential torque, which is calculated from the difference between the physically possible maximum torque and the absolute value of the first selected torque not used for lateral control, is provided as traction or braking torque for longitudinal control. If the required tracking torque exceeds the physically possible maximum torque, the traction or braking torque is set to zero.

If no braking torque is requested, it is expedient if the first differential torque is set to zero.

In a further expedient refinement, when the fourth torque control is carried out, a second selection torque is determined, which is output at the second output as traction torque or braking torque for longitudinal control. The second selection torque corresponds to the traction or braking torque. The second selection torque is the lower value of the physically possible maximum torque and the requested traction or braking torque.

In particular, it can be provided that a second differential torque, which is calculated from the difference between the physically possible maximum torque and the absolute value of the second selected torque that is not used for control, is provided as tracking torque for lateral control. It is provided in particular that the determination of the second differential torque takes place under the condition that lateral slip is minimized. A slip control method known from the prior art can be used for this purpose. An example of this is in the DE 10 2020 212 544 A1 procedure described. Alternatively, a suitable method is shown in [3].

The invention further proposes a computer program product that can be loaded directly into the internal memory of a digital control unit and comprises software code sections with which the steps according to one or more embodiments of the method according to the invention are carried out when the product runs on the control unit.

Finally, the invention proposes a device for computer-implemented control of a drive system of a rail vehicle with a control loop as described above. The device includes a computing unit for implementing the control loop and is designed to carry out one or more specific embodiments of the method according to the invention. The device has the same advantages as those explained above in connection with the method according to the invention.

• 1 einen aus dem Stand der Technik bekannten Regelkreis zur Regelung einer Antriebsanlage eines Schienenfahrzeugs, bei dem die Antriebsanlage den Rädern eines Einzelradpaars zugeordnete Einzelradantriebe umfasst;
• 2 ein Diagramm, das den bekannten Zusammenhang zwischen Kraftschluss und Schlupf bei unterschiedlichen Rad-Schiene Kontaktbedingungen illustriert;
• 3 einen erfindungsgemäß ausgebildeten Regelkreis zur Regelung einer Antriebsanlage eines Schienenfahrzeugs, bei dem die Antriebsanlage den Rädern eines Einzelradpaars zugeordnete Einzelradantriebe umfasst;
• 4 ein Kennfeld, das den Zusammenhang zwischen einem Längs-Kraftschluss und dem Schlupf in Längs- und Querrichtung zeigt;
• 5 ein Kennfeld, das den Zusammenhang zwischen Lateral-Kraftschluss und Längs- und Querschlupf zeigt;
• 6 nummerische Simulationen eines ersten Ausführungsbeispiels; und
• 7 nummerische Simulationen eines zweiten Ausführungsbeispiels.

The invention is explained in more detail below using an exemplary embodiment in the drawing. Show it:

• 1 a control loop known from the prior art for controlling a drive system of a rail vehicle, in which the drive system comprises individual wheel drives assigned to the wheels of a pair of individual wheels;
• 2 a diagram that illustrates the known relationship between adhesion and slip under different wheel-rail contact conditions;
• 3 a control loop designed according to the invention for controlling a drive system of a rail vehicle, in which the drive system comprises individual wheel drives assigned to the wheels of a pair of individual wheels;
• 4 a map that shows the relationship between a longitudinal adhesion and the slip in the longitudinal and transverse directions;
• 5 a map showing the relationship between lateral adhesion and longitudinal and lateral slip;
• 6 numerical simulations of a first embodiment; and
• 7 numerical simulations of a second embodiment.

3 shows the structure of the control circuit 10 according to the invention, which has a path 20 for lateral control (tracking control) and a path 30 for longitudinal control (brake/traction control), as already described in connection with 1 was described. The control circuit 10 according to the invention 3 differs from the known control loop 10 1 in that a torque allocation unit 50 takes the place of the lateral torque allocation unit 22 of the path 20 for lateral control and the braking torque allocation unit 32 of the path 30 for longitudinal control.

The moment allocation unit 50 has a first input 51 to which you, from the tracking control 21 provided, requested tracking torque M _y,soll is supplied. At a second input 52 it is supplied with a requested traction or braking torque M _x,soll , which is provided by the braking/traction controller 31 . The requested tracking torque M _y,soll and the requested traction or braking torque M _x,soll are desired torques. The torque allocation unit 50 processes these two requested setpoint torques as input variables in a common manner and outputs a tracking torque M _y determined according to the invention at a first output 53 and a traction or braking torque M _x determined according to the invention at a second output 54 . The first output 53 of the torque allocation unit 50 is connected to the first output 13 of the control circuit 10 or corresponds to it. In a corresponding manner, the second output 54 of the torque allocation unit 50 is connected to the second output 14 of the control circuit 10 or corresponds to it.

The rest of the structure of the control circuit according to the invention corresponds to that in connection with 1 described structure. The method described below is carried out in the moment allocation unit 50 .

In a first step, a requested total torque M set _is determined. The requested total torque M _set is determined from the sum of the absolute values of the requested tracking torque M _y, set fed to the torque allocation unit 50 at the first input 51 and the requested traction or braking torque M _x, set fed at the second input 52 . The determination is made according to: $$M_{sOll}=\left|M_{y,sOll}\right|+\left|M_{x,sOll}\right|.$$

In a next step, a physically possible maximum torque M _max is determined. The physically possible maximum torque M _max is determined from the engine torque M _motor that can be physically provided by the individual wheel drives of the individual wheel pair and a maximum torque M _fmax that can be transmitted between at least one wheel of the individual wheel pair and an assigned rail on which the rail vehicle is moving, depending on environmental conditions. The minimum value from the engine torque M _Motor and the transmissible torque M _fmax is processed as the physically possible maximum torque M _max : $$M_{max}=min\left(M_{MOtO\mathrm{right},}{M}_{ƒmax}\right).$$

For this purpose, the maximum usable adhesion f _x is first calculated in the braking/traction control 31 . This is only possible under the restriction that the frictional connection is also achieved. For example, the adhesion can be converted into a maximum torque M _fmax that can be transmitted between the wheel and the rail using information about a wheel contact force, which can be estimated using known methods, and a generally known wheel radius.

If the required total torque M _set and the physically possible maximum torque M _max are available, the two variables are compared. Depending on the result of the comparison, a first torque control or a second torque control is then carried out.

The first torque regulation is carried out when the result of the comparison includes that the maximum torque M _max that is physically possible _is greater than the requested total torque M setpoint , ie M _setpoint <M _max . Otherwise, the second torque control is carried out.

The first torque control includes normal operation, in which the sum of the tracking torque M _y and the traction or braking torque M _x can be transmitted through the wheels of the single wheel pair. In this case, the torque allocation unit 50 outputs the requested tracking torque M _{y,soll as the tracking torque M y} at the first output 53 (and thus at the first output 13 of the control loop) and at the second output 54 (and thus at the second output 14 of _the control loop) the requested traction or braking torque M _x,soll is output as traction or braking torque M _x : M _y = M _y,soll , M _x = M _x,soll . In other words, there is no restriction of the two controls (lane guidance control or braking/traction control) as long as the sum of both control torques can be transmitted. In contrast to the in 1 The methods described above eliminate the limitations by means of the maximum torques M _y,max , M _x,max specified in advance, as a result of which any performance restrictions that may occur are avoided.

If the sum of the requested torques M _y,soll , M _x,soll exceeds the available physically possible maximum torque M _max , the second torque control is carried out, which includes emergency operation, which can be divided into two cases. A first case is taken into account in a third torque control and a second case in a fourth torque control.

A prerequisite for carrying out the second torque control is therefore that the result of the comparison includes that the maximum torque M _max that is physically possible _is less than the requested total torque M setpoint (ie M _setpoint >M _max ). Whether then the third or the fourth moments control is executed depends on whether emergency braking is present or not. The third torque control includes the case that there is no emergency braking. The fourth torque control includes the case that emergency braking is present.

If there is no emergency braking and the third torque control is carried out, a tracking torque referred to as the first selection torque is determined, which is output at the first output 53 or 13 as the tracking torque M _y for lateral control, with the first selection torque being the smaller value of the physically possible maximum torque M _max and the requested tracking torque M _y,soll is: $$M_y=min\left(M_{max},M_{y,sOll}\right)$$

This is the case when there is a driving situation that is critical in terms of lateral dynamics but not critical in terms of longitudinal dynamics. The entire torque range is made available to the tracking control. Consequently, in this driving state, the traction control only has the remaining torque portion not requested by the tracking control, possibly no portion at all. Due to the non-critical braking request, however, there is no critical lengthening of the braking distance and thus no impairment of driving safety.

If, on the other hand, there is emergency braking, the fourth torque control is carried out. Here, a traction or braking torque referred to as the second selection torque is determined, which is output at the second output 54 or 14 as traction or braking torque M _x for longitudinal control, with the second selection torque being the lower value of the physically possible maximum torque M _max and the requested one Traction or braking torque M _x,set is: $$M_x=min\left(M_{max},M_{x,sOll}\right)$$

In the event of emergency braking, the primary function is to operate the brake control. As a result, the entire physically possible maximum torque M _max is made available for brake control. If the entire physically possible maximum torque M _max is not used by the brake control, an attempt is made to minimize the lateral slip s _y according to: $$s_y\cdot v=\dot{y}+v\cdot \text{sin}\phi \text{.}$$

This equation reflects the simplified relationship between lateral slip s _y , driving speed v, lateral speed y and the set steering angle φ.

In the well-known map of 4 the relationship between longitudinal adhesion f _x , lateral slip s _y and longitudinal slip s _x is described. 5 shows the lateral adhesion f _y as a function of lateral slip s _y and longitudinal slip s _x in another known map. Out of 4 it is easy to see that the longitudinal adhesion f _x is at its maximum when the lateral slip s _y is zero: $$s_y=0$$

The method described was tested in numerical simulations and a system with previous torque allocation in two test scenarios that are presented in the 6 and 7 are shown, compared. Both cases describe braking (no emergency braking) with simultaneous lane guidance, ie carry out the torque control. The prevailing frictional connection is sufficient in each case to transfer the required tracking torque M _y,soll . However, the tracking torque M _{y,soll is} higher than the maximum torque M _ymax allocated in the reference control, which is used in the prior art.

in the in 6 In the test scenario shown, good adhesion conditions prevail throughout. At time t = 4 seconds, there is a brief disturbance in the lateral dynamics (see moment-time diagram in the middle). With the reference controller, which is shown in the two lower moment-time diagrams with a dot-dash line, this means that the tracking control is limited and the setpoint position can no longer be optimally followed for a short time (see upper diagram). Another disadvantage of the reference control is a braking distance that is approx. 10% longer in this scenario. The shortening of the braking distance by the method according to the invention comes about because a higher torque is available during the lateral dynamically less critical phases of the brake control due to the lack of lane guidance allocation according to the specified maximum torques M _y,max , M _x,max . The present due to the method according to the invention behavior is in the moment-time diagrams 6 shown with a solid line.

In a second embodiment in the diagrams of 7 is shown, there are lower adhesion ratios between one second and four seconds. At the same time, the lateral dynamic disturbance is maintained at t = 4 seconds. In this scenario, the braking distance with the method presented here is 5% less than in the reference case, the conventional torque allocator tion process uses. However, differences in the sequence of the set position are all the greater (see diagram above). It can be clearly seen that under adverse track conditions, the allocated torque of the tracking controller with the conventionally implemented control method is not sufficient to stably follow the target position. This is evident from the strong deviation of the dot-dash line from the dark solid line in the upper diagram. The two examples show the advantage of the method according to the invention.

The method proposed here for the computer-implemented control of a drive system of a rail vehicle is intended specifically for use in running gear with driven individual wheels. For example, this can be used in trams, since many modern tram vehicles are equipped with single-wheel chassis. It can also be used in railway vehicles (express trains) with driven single-wheel chassis.

Reference List

10

control loop

11

first input of the control loop

12

second input of the control circuit

13

first output of the control circuit

14

second output of the control circuit

20

Path for lateral control (tracking control)

21

lane control

22

lateral moment allocation unit

30

Path for longitudinal control (brake/traction control)

31

Brake/Traction Control

32

braking torque allocation unit

41

first adder (to determine the moment of a left single wheel drive)

42

second adder (to determine the moment of a right independent wheel drive)

50

moment allocation unit

51

first input of the moment allocation unit

52

second input of the moment allocation unit

53

first output of the moment allocation unit

54

second output of the moment allocation unit

LSP

lateral target position

BBA

Brake/acceleration request

credentials

• [1] MAYER, Reinhold; RASEL, Thomas: Higher train frequency: Novel wheel slide protection for improved utilization of the rail infrastructure. In: ZEVrail 144 (2020), No. 11-12, pp. 438-442
• [2] Schwarz, Christoph; Posielek, Tobias; Goetjes, Björn: Adhesion-Based Maximum-Seeking Brake Control for Railway Vehicles. In: 27th IAVSD International Symposium on Dynamics of Vehicles on Roads and Tracks, Aug. 2021, St. Petersburg, Russia.
• [3] Daniel Frylmark and Stefan Johnsson: "Automatic Slip Control for Railway Vehicles", Master's thesis, 6 Feb. 2003, available at https://www.diva-portal.org/smash/get/diva2:19091/FULLTEXT01 .pdf

Claims (17)

Method for the computer-implemented control of a drive system of a rail vehicle with a control loop (10), the drive system comprising individual wheel drives assigned to the wheels of a single wheel pair, the control loop (10) determining a requested tracking torque (M _y,soll ) and a requested traction torque during operation of the rail vehicle or braking torque (M _x,soll ) and outputs a tracking torque (M _y ) at a first output (13) and a traction or braking torque (M _x ) at a second output (14), which are fed to the individual wheel drives as input variables, at which at any time of one or more times during the operation of the rail vehicle by a torque allocation unit (50) of the control circuit (10) a physically possible maximum torque (M _max ) of the wheels of the single wheel pair depending on a predetermined operating state at the first output as tracking torque ( M _y ) for lateral control or at the second output as traction or braking torque (M _x ) for longitudinal control to the individual wheel drives of the individual wheel pair. procedure after claim 1 , at which the physically possible maximum torque (M _max ) is determined from the engine torque (M _motor ) that can be physically provided by the single wheel drives of the single wheel pair and a maximum between at least one wheel of the single wheel pair and an associated one depending on environmental conditions Rail on which the rail vehicle moves, transmittable torque (M _fmax ). procedure after claim 2 , at which the minimum value from the motor torque (M _motor ) and the transmissible torque (M _fmax ) is processed as the physically possible maximum torque (M _max ). Method according to one of the preceding claims, in which the physically possible maximum torque (M _max ) is compared to a requested total torque (M _desired ), a first torque control or a second torque control being carried out depending on a comparison result, the first torque control including normal operation , in which the sum of the tracking torque (M _y ) and the traction or braking torque (M _x ) can be transmitted by the wheels of the pair of single wheels, and the second torque control includes an emergency operation, in which the sum of the wheels of the pair of single wheels the tracking torque (M _y ) and the traction or braking torque (M _x ) are not transmitted. procedure after claim 4 , in which the requested total torque (M _set ) is determined from the sum of the absolute values of the requested tracking torque (M _{y, set} ) and the requested traction or braking torque (M _{x, set} ). procedure after claim 4 or 5 , in which the first torque control is carried out when the comparison result includes that the physically possible maximum torque (M _max ) is greater than the requested total torque (M _set ). procedure after claim 6 , in which, in order to carry out the first torque control, the requested tracking torque (M _{y, target} ) is fed to the first output (13) as tracking torque (M _y ) and the second output (14) receives the requested traction or braking torque (M _{x, target} ) be output as traction or braking torque (M _x ). Procedure according to one of Claims 4 until 7 , in which the second torque control is executed when the comparison result includes that the physically possible maximum torque (M _max ) is smaller than the _requested total torque (M set ), it being determined during the execution of the second torque control whether emergency braking is present or not , wherein in the case of the determination that there is no emergency braking, a third torque control and otherwise a fourth torque control is performed. procedure after claim 8 , in which when executing the third torque control, a first selection torque is determined, which is output at the first output (13) as tracking torque (M _y ) for lateral control, the first selection torque being the smaller value of the physically possible maximum torque (M _max ) and of the requested tracking torque (M _y,soll ). procedure after claim 9 , in which a first differential torque, which is calculated from the difference between the physically possible maximum torque (M _max ) and the absolute value of the first selected torque not used for lateral control, is provided as traction or braking torque (M _x ) for longitudinal control. procedure after claim 10 , at which the first differential torque is set to zero if no braking torque is requested. Procedure according to one of Claims 8 until 11 , in which a second selected torque is determined when executing the fourth torque control, which is output at the second output (14) as traction or braking torque (M _x ) for longitudinal control, the second selected torque being the smaller value of the physically possible maximum torque (M _max ) and the requested traction or braking torque (M _x,soll ). procedure after claim 12 , in which a second differential torque, which is calculated from the difference between the physically possible maximum torque (M _max ) and the absolute value of the second selection torque not used for traction or braking control, is provided as tracking torque (M _y ) for lateral control. procedure after Claim 13 , in which the second differential torque is determined under the condition that a lateral slip (s _y ) is minimized. A computer program product loadable directly into the internal memory of a digital control unit, comprising software code portions which, when run on the control unit, perform the steps of any preceding claim. Device for the computer-implemented control of a drive system of a rail vehicle with a control circuit (10), the drive system comprising individual wheel drives assigned to the wheels of a single wheel pair, the device comprising a computing unit for implementing the control circuit (10), which is designed to be activated during operation of the rail vehicle to process requested tracking torque (M _{y, target} ) and a requested traction or braking torque (M _{x, target} ) and at a first off gear (13) to output a tracking torque (M _y ) and at a second output (14) a traction or braking torque (M _x ), which are fed to the individual wheel drives as input variables, the computing unit also being designed to, at any time, from one or several points in time during the operation of the rail vehicle by a torque allocation unit (50) of the control circuit (10) a physically possible maximum torque (M _max ) of the wheels of the single wheel pair depending on a predetermined operating state at the first output (13) as tracking torque (M _y ) for Output transverse control or at the second output (14) as a traction or braking torque (M _x ) for longitudinal control of the individual wheel drives of the pair of individual wheels. device after Claim 16 , characterized in that the processing unit for carrying out the steps according to one of claims 2 until 14 is trained.

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