Patent Description:
For some tractor-trailer combinations, trailers are at least partly controlled by use of a Power Line Communication (PLC). This means that data is signaled to and from the trailers in the same wire that is supplying electrical power to the trailers. The data may be signaled by modulating a carrier signal providing electrical power in a wiring between the trailers and tractors.

When PLC is used, communication between the tractor and trailer is limited and thereby, the status of the trailer is unknown and/or uncertain. Due to the unknown or uncertain status, when an external brake request (XBR) is obtained, e.g., any of emergency braking, Cruise Control (CC), Adaptive Cruise Control (ACC), or a combination thereof, the tractor will apply brakes by use of a conservative approach.

In tractor-trailer combinations, when braking of the combination is desired, brakes on the trailers are then typically applied in a pulsed fashion, such as by being applied for <NUM> seconds, then released for <NUM> seconds, and so on according to this cycle, regardless of the pressure applied to the brakes. This is done to minimize the possibility of the trailer wheels locking up or loss of stability of the trailer or trailers.

Because the brakes of a trailer or trailers are typically only applied for a fraction of many braking operations, the brakes of a tractor of a tractor-trailer combination have to perform substantially more of the braking force than the brakes of the trailer or trailers. For example, where the brakes of the trailer are only applied <NUM> seconds and then released for <NUM> seconds, i.e. a <NUM>/<NUM> of the time, the brakes of the tractor will ordinarily be required to provide at least about <NUM>/<NUM> of the braking force. This often results in the brakes of the tractor being caused to perform braking for a total combination load that is greater than the load that the tractor brakes are designed to handle, and can lead to high temperatures at the brake pads and damage to the brakes. Additionally, because the length of time that the brakes are applied and released is not adjusted, the effectiveness of the braking operation can be compromised.

It is desirable to improve the manner in which trailer brakes are applied during a braking operation in a tractor-trailer combination.

A method for controlling the brake of a tractor-trailer combination is known from <CIT>.

According to a first aspect of the invention, a method for braking one or more trailers in a tractor-trailer combination is provided.

The method comprises measuring or estimating a load of the one or more trailers. The method further comprises measuring a speed of the tractor-trailer combination. The method further comprises determining an understeer or oversteer gradient for the tractor-trailer combination.

The method further comprises establishing a maximum continuous brake pressure for trailer brakes of wheels of the one or more trailers of the tractor-trailer combination that can be continuously applied over a range of braking parameters without causing the wheels to lock up or the one or more trailers to lose stability. The range of braking parameters includes the load of the one or more trailers, the speed of the tractor-trailer combination, and the understeer or oversteer gradient for the tractor-trailer combination.

The method further comprises establishing an on-off cycling frequency for pulsing of the trailer brakes of the one or more trailers of the tractor-trailer combination at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels to lock up or the one or more trailers to lose stability.

The method further comprises applying the brakes of the one or more trailers continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure.

The first aspect of the invention may seek to improve the use of trailer brakes in the tractor-trailer combination. A technical benefit may include that the trailer brakes can be used more often than as they are applied constantly up to the maximum continuous brake pressure, and above the maximum continuous brake pressure they are applied in a pulsing manner using the established on-off cycling frequency.

Since the maximum continuous brake pressure is established based on the range of brake parameters, the trailer brakes of the one or more trailers is used more often than for legacy trailer brakes. This is since a constant braking of the trailers can be performed up to the maximum continuous brake pressure and no pulsation is necessary to ensure that the brakes of the trailers are not locking up or losing stability.

Since the on-off cycling frequency is established based on the range of brake parameters, the trailer brakes of the one or more trailers is used more often than for legacy trailer brakes where pulsation is performed conservatively as the range of brake parameters are not known and cannot be used to control the pulsation. This means that on-off frequency ensures an increased trailer brake usage while ensuring that the trailer brakes of the trailers will not lock up and that the one or more trailers will not lose stability.

In some examples, establishing the maximum continuous brake pressure and establishing the on-off cycling frequency is based on whether or not Anti-lock Braking System, ABS, is present or absent in the one or more trailers.

In this way, the on-off cycling frequency and the maximum continuous brake pressure can be more accurately established which allows an increased usage of the trailer brakes.

It should further be noted that when the one or more trailer brakes are applied, a respective ABS may be used for each respective trailer based on the applied brake pressure. For trailers with ABS, ABS may take priority over brake pressures established of examples herein.

In some examples, whether or not ABS is present or absent in the one or more trailers is established using a Power Line Communication, PLC, with the one or more trailers.

In this way, whether or not ABS is present can be automatically detected based on the PLC communication.

In some examples, the maximum continuous brake pressure and/or the on-off cycling frequency are established as a function of a number of trailers in the one or more trailers.

In this way, the on-off cycling frequency and the maximum continuous brake pressure can be more accurately established which allows an increased usage of the trailer brakes. For example, an increase in number of trailers may increase the maximum continuous brake pressure. Furthermore for the on-off cycling frequency, the on-time in the on-off cycling frequency may be decreased when the number of trailers are increased.

The on-off cycling frequency and the maximum continuous brake pressure may further depend on whether or not the one or more trailers have installed ABS or not. In some examples, a higher number of trailers, e.g., above a threshold, in the one or more trailers may lead to a higher risk of instability and/or brakes locking up, and for a lower number of trailers, e.g., below the threshold, there is a lower risk of instability and/or brakes locking up. Hence, the higher number of trailers may mean less continuous pressure, i.e. a lower maximum continuous brake pressure and/or longer off-durations of the on/off cycling frequency, than for the lower number of trailers.

Since ABS configurations takes priority over brake pressures established herein, more trailers with ABS in the one or more trailers, e.g., above an ABS threshold, may mean that there is a lower risk of instability and/or brakes locking up than when there is a lower number of trailers with ABS in the one or more trailers, e.g., below the ABS threshold. Hence, higher number of trailers with ABS, e.g., above the ABS threshold, may mean a higher continuous pressure i.e. a higher maximum continuous brake pressure and/or longer on-durations of the on/off cycling frequency, compared to a lower number of trailers with ABS, e.g., below the ABS threshold.

In some examples, the method further comprises estimating the number of trailers in the one or more trailers based on an obtained plurality of PLC signals transmitted via PLC signalling from each one of the one or more trailers.

In this way, the number of trailers can be detected in an automatic manner, and thereby the maximum continuous brake pressure and the on-off cycling frequency can be established accurately for ensuring an increased trailer usage.

In some examples, estimating the number of trailers is performed by using a machine learning model and the obtained plurality of PLC signals. In these examples, the machine learning model is trained on a plurality of different numbers of trailers signalling using PLC.

In this way, the number of trailers can be estimated automatically, thereby the maximum continuous brake pressure and the on-off cycling frequency can be established accurately for ensuring an increased trailer usage.

In some examples, establishing the maximum continuous brake pressure and establishing the on-off cycling frequency comprises producing the maximum continuous brake pressure and the on-off cycling frequency based on a maximum allowed brake pressure that can be applied prior to pulsing, and based on a maximum allowed pulse.

In this way, the maximum continuous brake pressure and the on-off cycling frequency will be saturated to be within limits of the maximum allowed brake pressure and the maximum allowed pulse.

In some examples, the maximum allowed brake pressure and the maximum allowed pulse is established by the use of one or more datamaps. In these examples, at least a number of trailers of the one or more trailers is used as input.

In this way, the number of trailers limits the maximum allowed brake pressure and the maximum allowed pulse, and the maximum continuous brake pressure and the on-off cycling frequency can be accurately established up until these limits. This ensures that the brakes of the one or more trailers will not lock up and/or that the one or more trailers will not lose stability by swaying out.

In some examples, the maximum allowed brake pressure and the maximum allowed pulse are further established based on whether the one or more trailers have ABS or not. In this way, the limits of the maximum allowed brake pressure and the maximum allowed pulse can be established more accurately. For example, when the one or more trailers has an increased number of trailers, e.g., above a threshold, with ABS installed, the maximum allowed brake pressure and the maximum allowed pulse can be increased compared to when the one or more trailers does not have ABS. An increased maximum allowed pulse may mean an increased maximum "on"-time when pulsing the brake pressure.

In some examples, applying the trailer brakes of the one or more trailers continuously at brake pressures up to the established maximum continuous brake pressure and pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure are based on the measured or estimated load of the one or more trailers, the measured speed of the tractor-trailer combination, and the determined understeer or oversteer gradient for the tractor-trailer combination. In other words, applying the trailer brakes of the one or more trailers continuously at brake pressures up to the established maximum continuous brake pressure and pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure are based at least on the range of braking parameters.

In this way, the on-off cycling frequency and the maximum continuous brake pressure can be more accurately established which allows an increased usage of the trailer brakes. For example, an increase in load, e.g., a load loaded on the one or more trailer and/or a load exerted by the one or more trailers to a ground surface, may lead to an increase in the maximum continuous brake pressure, an increase in speed may decrease an on-time of the on-off cycling frequency, i.e. how long the trailer brakes of the one or more trailers is to be applied, and the understeer or oversteer gradient may decrease the maximum continuous brake pressure and/or increase an on-time of the on-off cycling frequency when the gradient indicate an oversteer or understeer by more than a threshold.

According to a second aspect of the invention, a system for braking one or more trailers in a tractor-trailer combination is provided. The system comprises a brake Electronic Control Unit (ECU) comprising a database. The database contains a maximum continuous brake pressure established for brakes of wheels of the one or more trailers of the tractor-trailer combination that can be continuously applied over a range of braking parameters without causing the wheels to lock up or the one or more trailers to lose stability. The database further contains an on-off cycling frequency established for pulsing of the brakes of the one or more trailers of the tractor-trailer combination at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels to lock up or the one or more trailers to lose stability. The range of braking parameters includes load of the one or more trailers, speed of the tractor-trailer combination, and an understeer or oversteer gradient for the tractor-trailer combination. The system comprises means for measuring or estimating a load of the one or more trailers. The system comprises means for measuring speed of the tractor-trailer combination. The system comprises means for determining an understeer or oversteer gradient for the tractor-trailer combination. The system comprises trailer brakes of the one or more trailers. The brake ECU is arranged to control application of the trailer brakes of the one or more trailers continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure.

The second aspect of the invention may seek to improve the use of trailer brakes in the tractor-trailer combination. A technical benefit may include that the trailer brakes can be used more often than as they are applied constantly up to the maximum continuous brake pressure, and above the maximum continuous brake pressure they are applied in a pulsing manner using the established on-off cycling frequency.

The system of the second aspect may be configured to perform the method according to the first aspect.

Advantages and effects of the system of the second aspect are largely analogous to the advantages and effects of the method of the first aspect. Further, all embodiments of the system of the second aspect are applicable to and combinable with all embodiments of the method of the first aspect, and vice versa.

According to a third aspect of the invention, a computer program product is provided. The computer program product comprises program code which, when the program is executed by a processor device, cause the processor device to perform the method of the first aspect.

According to a fourth aspect of the invention, a non-transitory computer-readable storage medium provided. The non-transitory computer-readable storage medium comprises instructions, which when executed by a processor device, cause the processor device to perform the method of the first aspect.

Advantages and effects of the third and fourth aspects are largely analogous to the advantages and effects of the method of the first aspect. Further, all embodiments of the third and fourth aspects are applicable to and combinable with all embodiments of the method of the first aspect, and vice versa.

For the above aspects, the trailer brakes of the one or more trailers may be applied in response to receiving an XBR, e.g., from a control unit controlling a CC mode and/or an ACC mode of the vehicle, due to an emergency braking, autonomous vehicle braking control, or a combination thereof. While XBR may be a most common scenario, manual braking as applied from a driver may also use any of the examples or embodiments herein.

Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the invention as described herein.

With reference to the appended drawings, below follows a more detailed description of aspects of the invention cited as examples.

Aspects set forth below represent the necessary information to enable those skilled in the art to practice the invention.

<FIG> is an exemplary trailer-tractor combination <NUM> according to one example. The trailer-tractor combination <NUM> comprises a tractor <NUM> and one or more trailers <NUM>.

While <FIG> only depicts one trailer, any multiple number of trailers are also possible and can be part of embodiments herein, e.g., the trailer-tractor combination <NUM> may comprise two or three trailers pulled by the tractor <NUM>.

The trailer-tractor combination <NUM> comprises trailer brakes <NUM> for each of the one or more trailers <NUM>. The trailer brakes <NUM> are arranged to brake one or more respective trailer wheels <NUM>.

Embodiments herein may be performed at least partly by a system <NUM>, and in particular a brake ECU <NUM> comprised therein. The brake ECU <NUM> may be a processor device. The system <NUM> may be any suitable system such as a computer system or a control system. The system <NUM> may be comprised in the trailer-tractor combination <NUM>, or may be at a remote location communicatively coupled to the trailer-tractor combination <NUM>, e.g., comprised in a server or control station which may be arranged to remotely control the trailer-tractor combination <NUM>. The system <NUM> and/or the brake ECU <NUM> comprised therein may be able to control the trailer brakes <NUM> of the one or more trailers <NUM>, directly or indirectly via communication with one or more brake control units <NUM>, e.g., of each respective trailer in the one or more trailers <NUM>. The respective one or more brake control units <NUM> may be arranged to control the trailer brakes <NUM>, e.g., by applying a respective brake pressure to the respective trailer brakes <NUM>. In some examples, there is a pneumatic control pressure line from the tractor <NUM> to all trailers in the one or more trailers <NUM>, one by one. The control line pressure on the tractor <NUM> may have a pressure control valve which may modulate the brake pressures for each respective trailer in the one or more trailers <NUM>.

The respective one or more brake control units <NUM> may be powered using a powerline <NUM>, e.g., one for all trailers in the one or more trailers <NUM>. The one or more brake control units <NUM> may be controlled by the brake ECU <NUM> directly or indirectly by signalling over the powerline <NUM>. The one or more brake control units <NUM> and the brake ECU <NUM> may communicate, e.g., sending and receiving data, using signalling over the powerline <NUM>, e.g., by modulating a pulse or wave over the powerline <NUM> and/or supplying a certain current and/or voltage on the powerline <NUM>.

<FIG> is another view of the trailer-tractor combination <NUM> shown in <FIG>, according to another example. <FIG> illustrates the system <NUM>. The system <NUM> is configured to brake the one or more trailers <NUM> using the trailer brakes <NUM>. The one or more trailers <NUM> is comprised in the trailer-tractor combination <NUM>. The system <NUM> comprises the brake ECU <NUM>. The brake ECU <NUM> comprises a database. The database contains a maximum continuous brake pressure established for brakes <NUM> of wheels <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> that can be continuously applied over a range of braking parameters without causing the wheels <NUM> to lock up or the one or more trailers <NUM> to lose stability. The database further contains an on-off cycling frequency established for pulsing of the brakes <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels <NUM> to lock up or the one or more trailers <NUM> to lose stability. The range of braking parameters includes load of the one or more trailers <NUM>, speed of the tractor-trailer combination <NUM>, and an understeer or oversteer gradient for the tractor-trailer combination <NUM>.

The database may be represented by any suitable computer-readable storage medium or storage device. The established on-off cycling frequency established and maximum continuous brake pressure contained in the database may be established by using any of the embodiments or examples herein.

The system <NUM> further comprises means for measuring or estimating a load of the one or more trailers <NUM>.

The system <NUM> further comprises means for measuring speed of the tractor-trailer combination <NUM>.

The system <NUM> further comprises means for determining an understeer or oversteer gradient for the tractor-trailer combination <NUM>.

The system <NUM> further comprises the brakes <NUM> of the one or more trailers <NUM>. The brake ECU <NUM> is arranged to control application of the brakes <NUM> of the one or more trailers <NUM> continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure.

<FIG> is a flow chart of an exemplary method for braking one or more trailers <NUM> in a tractor-trailer combination <NUM>. The method may for example be performed by the system <NUM> and/or the brake ECU <NUM>. The method may comprise one or more out of the following actions, which actions can be taken in any suitable order.

The method comprises, measuring or estimating a load of the one or more trailers <NUM>. The load of the one or more trailers <NUM> may comprise a load, e.g., a weight, loaded on the one or more trailer and/or may comprise a load exerted by the one or more trailers <NUM> to a ground surface, e.g., on one or more axles of each trailer in the one or more trailers <NUM>. The load of the one or more trailers <NUM> may be individual for each trailer in the one or more trailers <NUM> or may be a total load for the one or more trailers <NUM>.

Measuring or estimating a load of the one or more trailers <NUM> may be performed in many different manners which can be performed in combination. For example, measuring or estimating a load of the one or more trailers may comprise:.

In some example embodiments, measuring or estimating the load of the one or more trailers <NUM> may comprise measuring or estimating the load of a first trailer in the one or more trailers <NUM> and estimating at least one second trailer in the one or more trailers <NUM> to have the same load as the first trailer.

The method comprises, measuring or estimating a speed of the tractor-trailer combination <NUM>. Measuring or estimating a speed of the tractor-trailer combination <NUM> may comprise any one or more out of:.

The method comprises, determining an understeer or oversteer gradient for the tractor-trailer combination <NUM>. Alternatively, instead of determining the understeer or oversteer gradient, it may be sufficient to obtain any suitable indication of an understeer or oversteer of the tractor-trailer combination <NUM>.

An oversteer or understeer gradient as used herein may mean a derivative of one or more front wheels steer angle, e.g., average steer angle for a predefined period of time, with respect to a lateral acceleration imposed to the tractor-trailer combination <NUM>, e.g., at the center of gravity of the tractor <NUM> or tractor-trailer combination <NUM>. The one or more front wheels may be e.g., one or more wheels on a front axle of the tractor <NUM>, the front axle being in the front of the tractor <NUM> with respect to a driving direction of the tractor <NUM>.

In other words, the oversteer or understeer gradient may be any suitable indication of a steering wheel angle of the one or more front wheels in relation to a lateral acceleration of the tractor-trailer combination <NUM>.

In some examples, an understeer is, if the yaw rate of the tractor-trailer combination <NUM> is lesser than a desired yaw rate, e.g., an absolute yaw rate and ignoring sign convention for clockwise and anticlockwise,.

In some examples, an oversteer is, if the yaw rate of the tractor-trailer combination <NUM> is greater than the desired yaw rate, e.g., an absolute yaw rate and ignoring the sign convention for clockwise and anticlockwise,.

In some examples, the desired yaw rate is when the tractor-trailer combination <NUM> has no side slip angle. This means that the driving direction of the tractor-trailer combination <NUM> is in a desired driving direction.

As an example, similar to the side slip angle on tires, if a front wheel loses grip and ploughs, it is an understeer. If the rear loses grip and swings out, it is an oversteer.

Determining the oversteer or understeer gradient may comprise measuring or estimating the oversteer or understeer gradient by any one or more out of: using the desired yaw rate and a measured yaw rate. The desired yaw rate may be estimated through a wheelbase of the tractor-trailer combination <NUM>, a steering wheel angle, and a vehicle speed of the tractor-trailer combination <NUM>.

In some example embodiments, the method further comprises estimating the number of trailers in the one or more trailers <NUM> based on an obtained plurality of PLC signals transmitted via PLC signalling from each one of the one or more trailers <NUM>.

In other words, estimating the number of trailers in the one or more trailers <NUM> may comprise obtaining a plurality of PLC signals transmitted via PLC signalling from each one of the one or more trailers <NUM>. The PLC signals may be signaled from a respective control unit <NUM> of each respective trailer, e.g., by modulating power on the powerline <NUM>, e.g. Alternating Current (AC) or Direct Current (DC).

The PLC signalling may be any suitable signalling made over the powerline <NUM>.

Each trailer may for example perform signalling over the powerline <NUM>, continuously, periodically or based on an event. The signalling may be indicative of any one or more signalling parameters such as any one or more out of:.

Obtaining the plurality of PLC signals may comprise listening on the powerline <NUM>, and identifying the one or more signals made over the powerline <NUM>.

As an example, when a plurality of trailers communicate using PLC, many signals may be sent simultaneously over the powerline <NUM>, which, in addition to the normal modulation necessary for electrical power, e.g., AC or DC, on the powerline <NUM>, may cause what appears to be a random noise due the plurality of PLC signals mixing modulation on the powerline <NUM>. However, while the plurality of PLC signals may appear random, the signals will follow a certain characteristics and/or pattern, e.g., defined by the number of trailers communicating, and/or the types of the one or more trailers <NUM>.

In other words, estimating the number of trailers in the one or more trailers <NUM> based on the obtained plurality of PLC signals transmitted via the PLC signalling from each one of the one or more trailers <NUM> may comprise estimating the number of trailers based on a predefined model and/or heuristics by comparing the obtained plurality of PLC signals.

The plurality of PLC signals may be obtained over a predefined time period, e.g., defined by the model or heuristics. In some example embodiments, multiple different time periods or measuring events may be performed to ensure that a correct number of trailers is estimated.

In some example embodiments, estimating the number of trailers is performed by using a machine learning model and the obtained plurality of PLC signals. The PLC signals may be achieved continuously, periodically, or under a predefined time period. The machine learning model is trained on a plurality of different numbers of trailers signalling using PLC. The machine learning model may be trained using any suitable statistical model, e.g., a neural network by inputting training PLC signalling and a corresponding number of trailers performing said training PLC signalling.

Furthermore, when estimating the number of trailers in the one or more trailers <NUM> based on the obtained plurality of PLC signals, any one or more out of the above-mentioned signalling parameters may be estimated for the one or more trailers <NUM>, e.g., whether or not the one or more trailers <NUM> have an absence or presence of ABS and/or a number of trailers in the one or more trailers <NUM> that have ABS installed.

Estimating the number of trailers in the one or more trailers <NUM> may further comprise estimating a confidence in the estimated number of trailers and/or a confidence in the estimated above-mentioned signalling parameters such as the absence or presence of ABS.

The method comprises, establishing a maximum continuous brake pressure for the trailer brakes <NUM> of the wheels <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM>. The maximum continuous brake pressure is a brake pressure that can be continuously applied over a range of braking parameters without causing the wheels <NUM> to lock up or the one or more trailers <NUM> to lose stability.

The range of braking parameters includes the measured or estimated load of the one or more trailers <NUM>, the measured or estimated speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>, e.g., as in actions <NUM>-<NUM>. The load of the one or more trailers <NUM> may comprise a load, e.g., a weight, loaded on the one or more trailer and/or may comprise a load exerted by the one or more trailers <NUM> to a ground surface, e.g., on one or more axles of each trailer in the one or more trailers <NUM>. The load of the one or more trailers <NUM> may be individual for each trailer in the one or more trailers <NUM> or may be a total load for the one or more trailers <NUM>.

In some example embodiments, establishing the maximum continuous brake pressure is based on whether or not ABS is present or absent in the one or more trailers <NUM>.

In some example embodiments, whether or not ABS is present or absent in the one or more trailers <NUM> is established using a Power Line Communication, PLC, with the one or more trailers <NUM>. Whether or not ABS is present or absent in the one or more trailers <NUM> may be estimated as in action <NUM> based on the communication of the signalling parameters over the powerline <NUM>.

As an example, when ABS is present in the one or more trailers <NUM> or there is an increased presence of ABS in the one or more trailers, the established maximum continuous brake pressure can be decreased. This is since brakes applies brake pressures beyond an ABS pressure limit and thus there may be an increased risk of instability or brakes locking up.

In some example embodiments, establishing the maximum continuous brake pressure comprises producing the maximum continuous brake pressure based on a maximum allowed brake pressure that can be applied prior to pulsing. The maximum allowed brake pressure may be a maximum brake pressure used for saturation, i.e. an upper limit or a constraint, for when establishing the maximum continuous brake pressure.

In some example embodiments, the maximum allowed brake pressure is established by the use of a first datamap. The first datamap may be a predefined data structure, such as a lookup table, for mapping the maximum allowed brake pressure based on one or more inputs. The one or more inputs comprises at least the number of trailers of the one or more trailers <NUM> and optionally whether the one or more trailers <NUM> have ABS or not, e.g., a number of trailers in the one or more trailers <NUM> that have ABS present.

In other words, based on the number of trailers in the one or more trailers <NUM>, and optionally whether they have ABS installed or not, the maximum allowed brake pressure is established to serve as an upper limit for the establishment of the maximum continuous brake pressure.

The first datamap may be comprised in the system <NUM>, e.g., as part of the database stored in the system <NUM>.

The method comprises, establishing an on-off cycling frequency for pulsing of the brakes <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> at brake pressures above the maximum continuous brake pressure, over the range of braking parameters without causing the wheels <NUM> to lock up or the one or more trailers <NUM> to lose stability.

The on-off cycling frequency may be a frequency of switching between indicating to the trailer brakes <NUM> of the one or more trailers <NUM>, to supply a brake pressure, e.g., by signalling the brake control units <NUM> over the powerline <NUM>. The brake pressure, when applied, may be higher than the established maximum continuous brake pressure. Such high brake pressure which cannot be sustained for more than a period of time without risking locking up the wheels <NUM>, therefore the brake pressure need to be pulsated on and off repeatedly using the on-off cycling frequency. Applying or indicating to apply brake pressure may be referred to as an on-state, and not applying or indicating to not apply brake pressure may be referred to as an off-state The on-off cycling frequency may define any one out of:.

While the above frequencies are typically the same or associated, they may differ slightly as the duration of the on-state and the duration of the off-state may be different durations.

In some example embodiments, establishing the on-off cycling frequency is based on whether or not ABS is present or absent in the one or more trailers <NUM>.

In some example embodiments, whether or not ABS is present or absent in the one or more trailers <NUM> is established using a PLC with the one or more trailers <NUM>. Whether or not ABS is present or absent in the one or more trailers <NUM> may be estimated as in action <NUM> based on the communication of the signalling parameters over the powerline <NUM>.

As an example, when ABS is present in the one or more trailers <NUM> or there is an increased presence of ABS in the one or more trailers <NUM>, the on-off frequency can be modified for the trailers with ABS, such that any one or more out of:.

This is since this ensures that the trailer brakes <NUM> are used more, and when ABS is more prevalent, there is less risk of the trailer brakes <NUM> locking up.

In some example embodiments, the on-off cycling frequency is established as a function of a number of trailers in the one or more trailers <NUM>.

In some example embodiments, establishing the on-off cycling frequency comprises producing the on-off cycling frequency based on a maximum allowed pulse.

The maximum allowed pulse may be a pulse frequency constraint used for saturation for when establishing the on-off cycling frequency, e.g., for limiting a lowest and/or highest frequency and/or for limiting longest and/or shortest durations of on/off states. The maximum allowed pulse may be a maximum or minimum allowable cycling frequency, e.g., for pulsating the trailer brakes <NUM>.

In some example embodiments, the maximum allowed pulse is established by the use of a second datamap. The second datamap may be a predefined data structure, such as a lookup table, for mapping the maximum allowed pulse based one or more inputs. The one or more inputs comprises at least the number of trailers of the one or more trailers <NUM> and optionally whether the one or more trailers <NUM> have ABS or not, e.g., a number of trailers in the one or more trailers <NUM> that have ABS present.

The second datamap may be the same as the first datamap, i.e. the first datamap of action <NUM> may be used to establish both the maximum allowed pulse and the maximum continuous brake pressure using the same input of at least the number of trailers of the one or more trailers <NUM> and optionally whether the one or more trailers <NUM> have ABS or not.

In other words, based on the number of trailers in the one or more trailers <NUM>, and optionally whether they have ABS or not, the maximum allowed pulse is established to serve as a constraint for limiting the establishment of the on-off cycling frequency. For example, the maximum allowed pulse may limit the frequency and/or duration of the on-state such as to ensure that the trailer brakes <NUM> does not lock up and that the tractor-trailer combination <NUM> does not lose stability.

The second datamap may be comprised in the system <NUM>, e.g., as part of the database stored in the system <NUM>.

In some example embodiments, actions <NUM> and <NUM> are performed in combination, e.g., to establish both the on-off cycling frequency for pulsing of the brakes <NUM> and the maximum continuous brake pressure for brakes <NUM> as one joint action.

The method comprises, applying the brakes <NUM> of the one or more trailers <NUM> continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure, e.g., as established in actions <NUM>-<NUM>.

Applying may be performed based on a requested brake pressure, e.g., from an XBR, wherein the brake pressure is modified to be constantly applied to the trailer brakes <NUM> up to the established maximum continuous brake pressure and, when above the established maximum continuous brake pressure, applied to the trailer brakes <NUM> in a pulsating manner according to the established on-off cycling frequency.

In some example embodiments, applying the brakes <NUM> of the one or more trailers <NUM> continuously at brake pressures up to the established maximum continuous brake pressure and pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure are based on the measured or estimated load of the one or more trailers <NUM>, the measured speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>. This means that the trailer brakes <NUM> will be applied differently based on the on the measured or estimated load of the one or more trailers <NUM>, the measured or estimated speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>. This is since depending on the measured or estimated load of the one or more trailers <NUM>, the measured or estimated speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>, the brake pressure will change from a constant applied brake pressure to a pulsating brake pressure at different thresholds, and the pulsation of the trailer brakes <NUM> will be different based on the measured or estimated load of the one or more trailers <NUM>, the measured or estimated speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>.

Applying the brakes <NUM> of the one or more trailers <NUM> may be performed in response to receiving an XBR, e.g., from other ECUs in the tractor-trailer combination <NUM>, such as from any of: an Advanced Driver-Assistance System (ADAS) ECU, an Engine ECU, a vehicle master controller, etc..

While XBR may be a most common scenario for when to apply the brakes of the one or more trailers <NUM>, manual braking as applied from a driver may also use any of the examples or embodiments herein, e.g., if explicitly set to be safe by a driver or user.

<FIG> illustrates an example scenario of embodiments herein. <FIG> schematically shows the brake ECU <NUM> and tractor and trailer brake solenoids. When braking of the tractor-trailer combination <NUM> is desired, an XBR is sent <NUM> to the brake ECU <NUM>. The sent XBR may trigger any one or more out of the actions <NUM>-<NUM> above.

The brake ECU <NUM> may estimate <NUM> a required deceleration for the tractor-trailer combination's axles based on one or more first parameters e.g., as part of the range of braking parameters including load, speed, and configuration of the combination.

The configuration may for example comprise any one or more out of:.

The brake ECU <NUM> may then estimate <NUM> a required torque to perform the required deceleration based on one or more second parameters e.g., including tire radius and brake factor, and, in an open loop system. The one or more second parameters may or may not be part of the range of braking parameters.

The brake ECU <NUM> may then estimate <NUM> a required brake pressure based on one or more predetermined pneumatic response parameters e.g., including a pressure gradient and a pressure delay. The one or more predetermined pneumatic response parameters may or may not be part of the range of braking parameters.

The brake ECU <NUM> may then send <NUM> DO signals to the tractor solenoids <NUM> to apply the brakes of the tractor and to the trailer solenoids <NUM> to apply the brakes <NUM> of the one or more trailers <NUM> based on the estimated required deceleration, estimated required torque, and estimated required brake pressure. DO signals as user herein means a Digital Output to open the respective solenoids <NUM>, <NUM>, or to close the respective solenoids <NUM>, <NUM>.

In embodiments herein, the sending <NUM> of DO signals to the trailer solenoids <NUM> to apply the brakes <NUM> of the one or more trailers <NUM> may be controlled by action <NUM> above.

<FIG> illustrates an example scenario of embodiments herein. <FIG> may illustrate a graph of pressure versus time during a braking operation according to an aspect of the present invention as will be explained.

The Y-axis <NUM> may represent a trailer pressure, e.g., in a number of Bar, to be applied to the trailer brakes <NUM>, e.g., by communicating the trailer pressure using PLC signalling to the brake control units <NUM>. The X-axis <NUM> may be time, e.g. in seconds.

In the example scenario, a no pulse threshold <NUM> is illustrated which represents the maximum continuous brake pressure and/or the maximum allowed brake pressure, e.g., as established in action <NUM>. Up to the no pulse threshold <NUM>, the trailer brakes <NUM> may be applied using a constant brake pressure. When a brake pressure to be applied, e.g., as in action <NUM>, and the brake pressure is above the no pulse threshold <NUM>, the trailer brakes <NUM> may need to be pulsated to ensure that the trailer brakes <NUM> do not lock up and/or to ensure stability of tractor-trailer combination <NUM>, as illustrated as a pulse wave <NUM>. The pulsation of the pulse wave of the brake pressure may be controlled by the on-off cycling frequency and/or the maximum allowed pulse, e.g., as established in action <NUM>. The pulsation of the pulse wave <NUM> may have an on-state when the brake pressure is to be applied to the trailer brakes <NUM> and an off-state when the brake pressure is not applied to the trailer brakes <NUM>. The pulsation of the pulse wave <NUM> may define a frequency of switching between the on-state and the off-state, or alternatively frequencies of when to initiate on-states and/or when to initiate off-states. Any of the frequencies may be part of the on-off cycling frequency as established in action <NUM>. Furthermore, the pulsation of the pulse wave <NUM> may define a duration for each on-state and/or for each off-state, e.g., as part of the on-off cycling frequency as established in action <NUM>.

<FIG> illustrates a flowchart showing steps, e.g., performed in the brake ECU <NUM>, in a method for braking one or more trailers <NUM> in the tractor-trailer combination <NUM> according to an example.

The method may be adapted to be performed via the system <NUM>. At step <NUM>, whether a trailer is attached to a tractor, e.g., and a number of trailers in the one or more trailers <NUM>, is detected and this information is transmitted to the brake ECU <NUM>.

Step <NUM> may be performed based on PLC communication <NUM>, e.g., as in action <NUM> above.

If a trailer is detected then, at step <NUM>, whether more than one trailers are attached is determined and this information is transmitted to the brake ECU <NUM>. Any existing trailer detection algorithm may be used to estimate the number of trailers connected.

At step <NUM>, a powerline communication (PLC) is provided, e.g., as in action <NUM>. This PLC may include information regarding whether the one or more trailers <NUM> have ABS and whether the ABS is being operated, e.g., a frequency of operation. This information is transmitted to the brake ECU <NUM>. In other words at step <NUM>, whether or not the trailers in the one or more trailers <NUM> have ABS present, is detected and this information is transmitted to the brake ECU <NUM>.

Using the information from steps <NUM>, <NUM>, and <NUM>, the brake ECU <NUM> may include one or more datamaps <NUM>, <NUM> that output, as seen at step <NUM>, a maximum no pulse threshold, and a maximum pulse frequency permitted, e.g., as illustrated in <FIG>. The one or more datamaps <NUM>, <NUM> may correspond to the first datamap and second datamap of actions <NUM>-<NUM>.

The maximum no pulse threshold may be a maximum pressure that can be applied prior to pulsing, e.g., the maximum allowed brake pressure, e.g., as established in action <NUM>.

The maximum no pulse threshold may be output by the datamap <NUM>.

The maximum pulse frequency permitted may be most pulses and maximum length of time for brake application and minimum length of time for brake release. The maximum pulse frequency permitted may be the maximum allowed pulse established in action <NUM>.

The maximum pulse frequency permitted may be output by the datamap <NUM>.

The one or more datamaps <NUM>, <NUM> of step <NUM> may have been prepared beforehand such that, for X number of trailers and depending on whether the trailers have ABS or not the trailer or trailers can consistently be braked without pulsing until a particular pressure, e.g., <NUM> Bar, and above which pulsing of the brake will occur at a particular rate, such as at <NUM> sec. of brake application with l second of no brake application. This one or more datamap will ensure that the trailer or trailers in the particular configuration of tractor-trailer will be stable but will not provide excessively conservative braking.

At step <NUM>, a load of the one or more trailers <NUM> may be measured or estimated, e.g., as in action <NUM>, and this information may then be transmitted to the brake ECU <NUM>. The load may be measured or estimated <NUM> by any one or more out of:.

At step <NUM>, speed of the tractor-trailer combination <NUM> may be determined, e.g., as in action <NUM>, and this information is transmitted to the brake ECU <NUM>. The speed of the tractor-trailer combination <NUM> may be determined e.g., by using a speedometer in the tractor <NUM>.

At step <NUM>, an understeer or oversteer gradient for the tractor-trailer <NUM> combination is determined, e.g., as in action <NUM>, based on, e.g., steering wheel angle <NUM>, lateral acceleration <NUM>, and yaw rate <NUM>, and this information is transmitted to the brake ECU <NUM>.

By testing or modeling, the brake ECU <NUM> may include a third datamap <NUM> of a maximum continuous brake pressure, e.g., a threshold brake pressure, for the trailer brakes <NUM> that can be continuously applied over a range of braking parameters without causing the wheels to lock up or the one or more trailers <NUM> to lose stability is established. The range of braking parameters may be e.g., the load of the one or more trailers <NUM>, e.g., as step <NUM> and/or action <NUM>, the speed of the tractor-trailer combination <NUM>, e.g., as in step <NUM> and/or action <NUM>, and the understeer or oversteer gradient for the tractor-trailer combination <NUM>, e.g., as in step <NUM> and/or action <NUM>.

Also by testing or modeling, the brake ECU <NUM> may include a fourth datamap <NUM> of an on-off cycling frequency for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels to lock up or the one or more trailers <NUM> to lose stability is established. The range of braking parameters may be e.g., the load of the one or more trailers <NUM>, e.g., as step <NUM> and/or action <NUM>, the speed of the tractor-trailer combination <NUM>, e.g., as in step <NUM> and/or action <NUM>, and the understeer or oversteer gradient for the tractor-trailer combination <NUM>, e.g., as in step <NUM> and/or action <NUM>.

As part of a step <NUM>, the information third datamap <NUM> outputs a maximum continuous brake pressure, and the information fourth datamap <NUM> outputs an on-off cycling frequency, e.g., a maximum cycling frequency.

The trailer brakes <NUM> of the one or more trailers <NUM> may then be continuously applied at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure based on the measured or estimated load of the one or more trailers <NUM>, the measured speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination.

The maximum continuous brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM>, the length of an on cycle of the established on-off cycling frequency for pulsing of the brakes, and/or the length of an off cycle of the established on-off cycling frequency for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> may further be established in response to whether the PLC communication indicates that ABS braking is present on the one or more trailers <NUM>, e.g., from step <NUM>, and/or as a function of the number trailers attached to the tractor <NUM>, e.g., from step <NUM>. For example, the established maximum continuous brake pressure and the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure may be calculated/determined based on the measured or estimated load of a single trailer that is supplied with ABS. The presence of a second or more trailer and/or the absence of an ABS system may affect the established values and the confidence in the ability of the brakes to stop the tractor- trailer combination <NUM>. For example, if the established maximum continuous brake pressure is <NUM> bar and the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure is <NUM> seconds braking and <NUM> seconds no braking calculated based on the measured or estimated load of a single trailer supplied with ABS, if a second trailer is present, the parameters may need to be adjusted to, e.g., <NUM>% of the originally calculated brake pressure / cycling, e.g., <NUM> bar and <NUM> seconds braking. If, in addition, no ABS is provided, the parameters may need to be adjusted to, say <NUM>% of the originally calculated numbers, say <NUM> bar and <NUM> seconds braking.

The input of the information from the datamaps <NUM>, <NUM> from step <NUM> and the information from the datamaps <NUM>, <NUM> at step <NUM> establishes saturation values of maximum constant pressure and maximum cycling frequency for the particular configuration and produces, at step <NUM>, a saturated maximum continuous brake pressure <NUM> and a saturated on-off cycling frequency <NUM> for the trailer brakes <NUM> of the tractor-trailer combination <NUM>.

In a step <NUM> the saturated maximum continuous brake pressure <NUM> and the saturated on-off cycling frequency <NUM> may be sent to the brake ECU <NUM> to be used for defining and/or limiting a brake pressure <NUM> and an on-off cycling frequency <NUM>, e.g., as requested by a brake request, such as an XBR request, e.g., as applied in action <NUM>.

The exemplary embodiments herein may also involve a machine learning function. Particularly, the maximum allowed brake pressure for the brakes of the one or more trailers <NUM> and/or the maximum allowed pulse may be changed in response to whether the PLC communication indicates that ABS braking has occurred during a braking operation, and/or as a function of the number trailers attached to the tractor <NUM>. The maximum allowed pulse may for example change, based on the machine learning function, the duration and/or length of an on cycle of the established on-off cycling frequency for pulsing of the brakes, and/or a duration or length of an off cycle of the established on-off cycling frequency.

Changing maximum allowed brake pressure for the brakes of the one or more trailers <NUM> and/or the maximum allowed pulse may mean to establish them respectively in a different manner, or dynamically, e.g.,, based on the PLC communication.

The brake ECU <NUM> may be configured to make incremental adjustments up or down to the maximum continuous brake pressure for the brakes of the one or more trailers <NUM>, the length of an on cycle of the established on-off cycling frequency for pulsing of the brakes, and/or the length of an off cycle of the established on-off cycling frequency in response to inputs such as whether the ABS is applied during a braking operation, or whether a trailer is added or removed from the tractor-trailer combination <NUM>.

The incremental adjustments may be part of establishing any one or more out of: the maximum continuous brake pressure, the maximum allowed brake pressure, the on-off cycling frequency, and the maximum allowed pulse.

As one example (A), the established maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM> may be changed as a function of operation of the ABS for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the brakes of the one or more trailers <NUM>. For example, if the ABS does not operate, then that means that the maximum continuous brake pressure or the maximum allowed brake pressure may be increased. If the ABS does operate, then that may mean that the maximum continuous brake pressure or the maximum allowed brake pressure should be decreased. The brake ECU <NUM> may be configured to make incremental adjustments up or down.

In addition to (A) or alternatively, (B) a length of an on cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> may be changed as the function of operation of the anti-lock braking system for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the trailer brakes <NUM> of the one or more trailers <NUM>. For example, if the ABS does not operate, then that means that the length of time that the trailer brakes <NUM> can be applied, i.e., an on-state duration, may be increased, e.g. for the trailer which does not have ABS.

If the ABS does operate, then that may mean that the length of time that the brake can be applied should be decreased. The brake ECU <NUM> may be configured to make incremental adjustments up or down, e.g., as part of establishing the maximum continuous brake pressure or the maximum allowed brake pressure in action <NUM>, and/or as part of establishing the on-off cycling frequency or the maximum allowed pulse in action <NUM>.

In addition to (A) and/or (B) or alternatively, (C) a length of an off cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> can be changed, e.g., as part of action <NUM>, as the function of operation of the anti-lock braking system for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the trailer brakes <NUM> of the one or more trailers <NUM>. For example, if the ABS does not operate, then that means that the length of time that the brake can be released can be decreased. If the ABS does operate, then that may mean that the length of time that the brake can be released should be increased. The brake ECU <NUM> may be configured to make incremental adjustments up or down, e.g., as part of establishing the maximum continuous brake pressure or the maximum allowed brake pressure in action <NUM>, and/or as part of establishing the on-off cycling frequency or the maximum allowed pulse in action <NUM>.

In addition to (A) and/or (B) and/or (C) or alternatively, (D) the established maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM> may be changed, e.g., as part of action <NUM>, as a function of a number of trailers in the tractor-trailer combination <NUM>. For example, if more than one trailer is present in the tractor-trailer combination <NUM>, it may be desirable to decrease the maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM>. The brake ECU <NUM> may be configured to make incremental adjustments up or down, e.g., as part of establishing the maximum continuous brake pressure or the maximum allowed brake pressure in action <NUM>, and/or as part of establishing the on-off cycling frequency or the maximum allowed pulse in action <NUM>.

In addition to (A) and/or (B) and/or (C) and/or (D) or alternatively, (E) the length of an on cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> may be changed, e.g., as part of action <NUM>, as the function of the number of trailers in the tractor-trailer combination <NUM>. For example, if only one trailer is present, it may be possible to increase the length of an on cycle, or the cycle might be set to a maximum. The brake ECU <NUM> may be configured to make incremental adjustments up or down, e.g., as part of establishing the maximum continuous brake pressure or the maximum allowed brake pressure in action <NUM>, and/or as part of establishing the on-off cycling frequency or the maximum allowed pulse in action <NUM>.

In addition to (A) and/or (B) and/or (C) and/or (D) and/or (E), (F) the length of an off cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> can be changed e.g., as part of action <NUM>, as the function of the number of trailers in the tractor-trailer combination <NUM>. For example, if more than one trailer is present in the tractor-trailer combination <NUM>, it may be desirable to decrease the length of an off cycle of the established on- off cycling frequency for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM>. The brake ECU <NUM> may be configured to make incremental adjustments up or down, e.g., as part of establishing the maximum continuous brake pressure or the maximum allowed brake pressure in action <NUM>, and/or as part of establishing the on-off cycling frequency or the maximum allowed pulse in action <NUM>.

In the system <NUM>, e.g., for braking one or more trailers <NUM> in a tractor-trailer combination <NUM>, the brake ECU <NUM> may be provided. The brake ECU <NUM> may comprise a database containing a maximum continuous brake pressure established for trailer brakes <NUM> of wheels <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> that can be continuously applied over a range of braking parameters without causing the wheels to lock up or the one or more trailers <NUM> to lose stability, and an on-off cycling frequency established for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> of the tractor-trailer combination <NUM> at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels to lock up or the one or more trailers <NUM> to lose stability. The range of braking parameters includes load of the one or more trailers <NUM>, speed of the tractor-trailer combination <NUM>, and an understeer or oversteer gradient for the tractor-trailer combination <NUM>, e.g., as in actions <NUM>-<NUM>. Means is provided for measuring or estimating a load of the one or more trailers <NUM>, such as via measurement of a drive axle load, measurement of a vehicle load, and measurement of an inclination of the one or more trailers <NUM>. Means such as a speedometer for measuring speed of the tractor-trailer combination <NUM> is also provided. Means is provided for determining an understeer or oversteer gradient for the tractor-trailer combination <NUM> using devices such as sensors for steering wheel angle, lateral acceleration, and yaw rate.

The system <NUM> may further include the one or more respective trailer brakes <NUM> of the one or more trailers <NUM> (which will ordinarily be connected to a source of pneumatic pressure via tractor solenoids <NUM> and trailer solenoids <NUM> of <FIG>. The brake ECU <NUM> may be arranged to control application of the trailer brakes <NUM> of the one or more trailers <NUM> continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure based on the measured or estimated load of the one or more trailers <NUM>, the measured speed of the tractor-trailer combination <NUM>, and the determined understeer or oversteer gradient for the tractor-trailer combination <NUM>.

The brake ECU <NUM> may, in addition, be arranged to establish the maximum continuous brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM>, the length of an on cycle of the established on-off cycling frequency for pulsing of the brakes, and/or the length of an off cycle of the established on-off cycling frequency for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> in response to whether the PLC communication indicates that ABS braking is present on the trailers, e.g., from step <NUM> or action <NUM>, and/or as a function of the number of trailers attached to a tractor, e.g., from step <NUM>, <NUM> or action <NUM>. For example, the established maximum continuous brake pressure and the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure may be calculated based on the measured or estimated load of a single trailer that is supplied with ABS. The presence of a second (or more) trailer and/or the absence of an ABS system may affect the established values and the confidence in the ability of the brakes to stop the tractor-trailer combination <NUM>. For example, if the established maximum continuous brake pressure is <NUM> bar and the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure is <NUM> seconds braking and <NUM> seconds no braking calculated based on the measured or estimated load of a single trailer supplied with ABS, if a second trailer is present, the numbers may need to be adjusted to, say <NUM>% of the originally calculated numbers, say <NUM> bar and <NUM> seconds braking. If, in addition, no ABS is provided, the numbers may need to be adjusted to, say <NUM>% of the originally calculated numbers, say <NUM> bar and <NUM> seconds braking. The input of the information from step <NUM> and the information from step <NUM> establishes saturation values of maximum constant pressure and maximum cycling frequency for the particular configuration and produces. In other words, the maximum continuous brake pressure may be limited to the maximum allowed brake pressure, both established in action <NUM>, and/or the on-off cycling frequency may be limited by the maximum allowed pulse, both established in action <NUM>.

At step <NUM>, the saturated maximum continuous brake pressure and established on-off cycling frequency may be used for the trailer brakes <NUM> of the tractor-trailer combination <NUM>.

The system <NUM> may comprise a machine learning function. Particularly, the maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM>, the length of an on cycle of the established on-off cycling frequency or maximum allowed pulse for pulsing of the brakes, and/or the length of an off cycle of the established on-off cycling frequency for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> may be changed, e.g., as part of actions <NUM>-<NUM>, in response to whether the PLC communication indicates that ABS braking has occurred during a braking operation, and/or as a function of the number trailers attached to the tractor <NUM>. The brake ECU <NUM> may be configured to make incremental adjustments up or down to the maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM>, the length of an on cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the brakes, and/or the length of an off cycle of the established on-off cycling frequency in response to inputs such as whether the ABS is applied during a braking operation, or whether a trailer is added or removed from the tractor-trailer combination <NUM>, e.g., as part of actions <NUM>-<NUM>,.

The system <NUM> may further comprise an ABS for the trailer brakes <NUM> of the one or more trailers <NUM>, and the brake ECU <NUM> may be arranged to change, e.g., as part of actions <NUM>-<NUM>, the established maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM> as a function of operation of the ABS for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the trailer brakes <NUM> of the one or more trailers <NUM>, and/or to increase a length of an on cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> as a function of operation of an anti-lock braking system for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the trailer brakes <NUM> of the one or more trailers <NUM>, and/or to decrease a length of an off cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> as a function of operation of an anti-lock braking system for the trailer brakes <NUM> of the one or more trailers <NUM> during application of the trailer brakes <NUM> of the one or more trailers <NUM>, and/or to change the established maximum continuous brake pressure or the maximum allowed brake pressure for the trailer brakes <NUM> of the one or more trailers <NUM> as a function of a number of trailers in the tractor-trailer combination <NUM>, and/or to increase a length of the on cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> as the function of the number of trailers in the tractor-trailer combination <NUM>, and/or to decrease a length of the off cycle of the established on-off cycling frequency or the maximum allowed pulse for pulsing of the trailer brakes <NUM> of the one or more trailers <NUM> as the function of the number of trailers in the tractor-trailer combination <NUM>.

<FIG> illustrates an example scenario of embodiments herein.

In the example scenario, the tractor-trailer combination <NUM> comprises three trailers in the one or more trailers <NUM>. The brake ECU <NUM> is in the example scenario comprised in the tractor <NUM>. The brake ECU <NUM> and the brake control units <NUM> communicates over the powerline <NUM>. To estimate the number of trailers in the one or more trailers <NUM>, e.g., as in action <NUM>, the brake ECU <NUM> may use a machine learning model. The machine learning model may be trained using an intensity of PLC communication for different number of trailers. In this way, the machine learning model may map an intensity of PLC traffic to the number of trailer in the one or more trailers <NUM>.

The machine learning model may have been trained at a previous time using all applicable combination of trailers with their communication over a powerline such as the powerline <NUM>.

The brake ECU <NUM> may also utilize the machine learning model to estimate how many and/or which trailers in the one or more trailer <NUM> have ABS, e.g., trained at a previous time with all applicable and/or suitable combination of trailers communicating ABS signals over the powerline <NUM>.

The machine learning model may, e.g., as part of action <NUM>, estimate a confidence in its above-mentioned estimations. Establishing the maximum continuous brake pressure or the maximum allowed brake pressure, and/or establishing the on-off cycling frequency or the maximum allowed pulse, e.g., in action <NUM>-<NUM>, may further be based on the estimated confidence.

<FIG> is a schematic diagram of the system <NUM> for implementing examples disclosed herein. The system <NUM> may be a computer system or a control system, or comprise any one or both thereof. The system <NUM> is adapted to execute instructions from a computer-readable medium to perform these and/or any of the functions or processing described herein. The system <NUM> may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the system <NUM> may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and/or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processor device, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc..

The system <NUM> may comprise at least one computing device or electronic device capable of including firmware, hardware, and/or executing software instructions to implement the functionality described herein. The system <NUM> may include the brake ECU <NUM> (may also be referred to as a control unit or a processor device), a memory <NUM>, and a system bus <NUM>. The system <NUM> may include at least one computing device having the brake ECU <NUM>. The system bus <NUM> provides an interface for system components including, but not limited to, the memory <NUM> and the brake ECU <NUM>. The brake ECU <NUM> may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory <NUM>. The brake ECU <NUM> (e.g., control unit or processor device) may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The brake ECU <NUM> may further include computer executable code that controls operation of the programmable device.

The system bus <NUM> may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and/or a local bus using any of a variety of bus architectures. The memory <NUM> may be one or more devices for storing data and/or computer code for completing or facilitating methods described herein. The memory <NUM> may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory <NUM> may be communicably connected to the brake ECU <NUM> (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory <NUM> may include non-volatile memory <NUM> (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory <NUM> (e.g., random-access memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with an ECU, such as the brake ECU <NUM>. A basic input/output system (BIOS) <NUM> may be stored in the non-volatile memory <NUM> and can include the basic routines that help to transfer information between elements within the system <NUM>.

The system <NUM> may further include or be coupled to a non-transitory computer-readable storage medium such as the storage device <NUM>, which may comprise, for example, an internal or external hard disk drive (HDD) (e.g., enhanced integrated drive electronics (EIDE) or serial advanced technology attachment (SATA)), HDD (e.g., EIDE or SATA) for storage, flash memory, or the like. The storage device <NUM> may represent or may comprise the database of the system <NUM> described with respect to <FIG>.

A number of modules can be implemented as software and/or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may be stored in the storage device <NUM> and/or in the volatile memory <NUM>, which may include an operating system <NUM> and/or one or more program modules <NUM>. All or a portion of the examples disclosed herein may be implemented as a computer program product <NUM> stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device <NUM>, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the brake ECU <NUM> to carry out the steps described herein. Thus, the computer-readable program code can comprise software instructions for implementing the functionality of the examples described herein when executed by the brake ECU <NUM>. The brake ECU <NUM> may serve as a controller or control system for the system <NUM> that is to implement the functionality described herein.

The system <NUM> also may include an input device interface <NUM> (e.g., input device interface and/or output device interface). The input device interface <NUM> may be configured to receive input and selections to be communicated to the system <NUM> when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the brake ECU <NUM> through the input device interface <NUM> coupled to the system bus <NUM> but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) <NUM> serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The system <NUM> may include an output device interface <NUM> configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The system <NUM> may also include a communications interface <NUM> suitable for communicating with a network as appropriate or desired.

The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the invention.

For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element.

It is to be understood that the present invention is not limited to the aspects described above and illustrated in the drawings; the invention is limited only within the scope of the appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the inventive concepts being set forth in the following claims.

Change or changing as used herein may mean that values and/or parameters are initially established in a different manner based on the changed valued and/or parameters.

In the present application, the use of terms such as "including" is open-ended and is intended to have the same meaning as terms such as "comprising" and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as "can" or "may" is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

Claim 1:
A method for braking one or more trailers (<NUM>) in a tractor-trailer combination (<NUM>), comprising:
- measuring or estimating (<NUM>) a load of the one or more trailers (<NUM>);
- measuring (<NUM>) a speed of the tractor-trailer combination (<NUM>);
- determining (<NUM>) an understeer or oversteer gradient for the tractor-trailer combination (<NUM>);
- establishing (<NUM>) a maximum continuous brake pressure for trailer brakes (<NUM>) of wheels (<NUM>) of the one or more trailers of the tractor-trailer combination (<NUM>) that can be continuously applied over a range of braking parameters without causing the wheels (<NUM>) to lock up or the one or more trailers (<NUM>) to lose stability, wherein the range of braking parameters includes the load of the one or more trailers (<NUM>), the speed of the tractor-trailer combination (<NUM>), and the understeer or oversteer gradient for the tractor-trailer combination (<NUM>);
- establishing (<NUM>) an on-off cycling frequency for pulsing of the trailer brakes (<NUM>) of the one or more trailers (<NUM>) of the tractor-trailer combination (<NUM>) at brake pressures above the maximum continuous brake pressure over the range of braking parameters without causing the wheels (<NUM>) to lock up or the one or more trailers (<NUM>) to lose stability;
- applying (<NUM>) the trailer brakes (<NUM>) of the one or more trailers (<NUM>) continuously at brake pressures up to the established maximum continuous brake pressure and by pulsing according to the established on-off cycling frequency at brake pressures above the established maximum continuous brake pressure.