Method, control arrangement, trailer and vehicle combination

Abstract

Method (300) for use in a trailer (120), operable to be part of a vehicle combination (100) together with a towing vehicle (110). The trailer (120) comprises an electric machine (140) configured to create a regenerative braking force and to store electrical energy in an electrical energy storage (150). The method (300) comprises detecting (301) a brake force requirement of the vehicle combination (100); estimating (302) regeneration capacity of the towing vehicle (110); obtaining (303) a parameter related to current driving conditions of the trailer (120); determining (304) a maximum allowed braking force of the trailer (120), based on the obtained (303) parameter; and applying (305) a regenerative braking force of the electric machine (140) while not exceeding the determined (304) maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated (302) regeneration capacity of the towing vehicle (110).

Description

[0001] METHOD, CONTROL ARRANGEMENT, TRAILER AND VEHICLE COMBINATION

[0002] TECHNICAL FIELD

[0003] This document relates to a method, a control arrangement, a trailer and a vehicle combination according to the appended claims.

[0004] BACKGROUND

[0005] A towing vehicle and a trailer are together forming a vehicle combination.

[0006] The vehicle combination may for example comprise a tractor and a connected semi-trailer, a tractor and a connected trailer, an articulated bus, a vehicle train comprising a towing vehicle and a plurality of trailers connected to each other via a respective connection, etc.

[0007] For vehicle combinations, it is typically desired to have the trailer independent of the towing vehicle; i.e., that a particular trailer is possible to combine with any towing vehicle. The propulsion technology of the towing vehicle pulling the trailer could thereby be different in different vehicle combinations, such as for example Internal Combustion Engine (ICE), Battery Electric Vehicle (BEV), Hybrid Electric Vehicle (HEV), Plug-in Hybrid Vehicle (PHEV), etc.

[0008] On vehicles, in particular heavy vehicles it is desired to avoid using wheel brakes of the vehicle combination when decreasing speed, for example when driving downhill. Retarder and / or engine braking of the towing vehicle may be applied (when having combustion engine), regeneration may be applied by the towing vehicle when being a Battery Electric Vehicle (BEV). The reason is to avoid unnecessary wear of the wheel brakes, but also to charge the vehicle battery (for BEV towing vehicles).

[0009] An emerging concept is usage of electric trailers having their own electric motor, electrical energy storage, drive line etc., which may operate independently from propulsion technology of the towing vehicle. Thus, the electric trailer may assist the towing vehicle during takeoff and acceleration by adding driving torque. Thereby, fuel / energy of the towing vehicle is saved. Also, driving properties on a low friction surface such as ice, snow, mud, terrain, etc. is improved as the driving torque is distributed over more driving axles than on conventional vehicle combinations.

[0010] The regenerative capacity of the electric trailer may hypothetically be used for braking the vehicle combination. However, the electric trailer may sometimes form a vehicle combination together with a towing vehicle having a combustion engine, sometimes with a BEV towing vehicle, leading to different requirements.

[0011] Currently, the communication and coordination of actions between the towing vehicle and the electric trailer is not solved in a satisfying way due to the modularity of vehicle combinations.

[0012] It is desired to achieve further improvements concerning vehicle combinations comprising an electric trailer having its own electric motor and electrical energy storage, in particular when it comes to braking properties of the vehicle combination.

[0013] SUMMARY

[0014] It would be advantageous to achieve a solution overcoming, or at least alleviating, at least some of the above-mentioned drawback(s). It would be desirable to convert requested / required braking torque of the vehicle combination into generated electric energy, in a trailer of a vehicle combination. To better address one or more of these concerns, a method, a control arrangement, a trailer and a vehicle combination are provided.

[0015] According to a first aspect, this objective is achieved by a method for use in a trailer. The trailer is operable to be part of a vehicle combination together with a towing vehicle connected to the trailer via a joint. The trailer comprises an electric machine configured to create a regenerative braking force by converting mechanical energy into electrical energy for storage in an electrical energy storage or battery of the trailer.

[0016] The method comprises the step of detecting a brake force requirement of the vehicle combination. Also, the method comprises the step of estimating regeneration capacity of the towing vehicle. The method in addition comprises obtaining a parameter related to current driving conditions of the trailer. Additionally, the method also comprises the step of determining a maximum allowed braking force of the trailer, based on the obtained parameter. The method comprises applying a regenerative braking force of the electric machine while not exceeding the determined maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated regeneration capacity of the towing vehicle.

[0017] Thanks to the disclosed method, it is assured that the electric machine of the trailer regenerate as much braking force as possible, of the brake force required by the vehicle combination, in case the towing vehicle cannot regenerate, either due to being a combustion engine vehicle or a BEV with fully charged batteries. Usage of service brakes and / or secondary brake of the towing vehicle, are thereby saved, while energy generated during the regenerative braking of the trailer is stored. Regenerative braking of the vehicle combination is maximised. Yet, safe braking is assured as the regenerated braking force of the trailer is adapted to the current driving conditions.

[0018] Optionally, the regeneration capacity of the towing vehicle may be estimated by detecting that the towing vehicle cannot perform regenerative braking and / or has insufficient regeneration capacity and / or energy storage capacity to meet the detected brake force requirement of the vehicle combination by regenerative braking.

[0019] In case the towing vehicle has capacity to perform regenerative braking, it is preferred to apply regenerative braking on the towing vehicle instead of the trailer for extending the driving range of the vehicle combination. By detecting that the towing vehicle cannot perform regenerative braking before applying regenerated braking of the trailer, it is avoided that the towing vehicle runs out battery power while the battery of the trailer is fully charged.

[0020] Optionally, the step of detecting the brake force requirement of the vehicle combination may comprise a sensor detection of a force caused by the trailer pushing on the joint in the driving direction of the vehicle combination.

[0021] By sensor detection, the brake force requirement of the vehicle combination could be obtained also when there is no communication of brake force requirement between the towing vehicle and the trailer.

[0022] Optionally, the detection of the brake force requirement of the vehicle combination and the estimation of the regeneration capacity of the towing vehicle may be made based on information obtained via a communication interface between the towing vehicle and the trailer.

[0023] By communicating brake force requirement of the vehicle combination via a communication interface, a safe braking of the vehicle combination is assured.

[0024] Optionally, the obtained parameter related to current driving conditions of the trailer may comprise speed and / or acceleration of the trailer, and / or a parameter related to friction between the tyres of the trailer and the road, and / or a parameter related to a longitudinal alignment between the towing vehicle and the trailer.

[0025] By detecting various parameters which may affect stability of the trailer during regenerative braking, adaption of the regeneration to the current driving conditions is enabled, leading to increased safety.

[0026] Optionally, the step of determining the maximum allowed braking force of the trailer may comprise estimating a risk of having a friction between the tyres of the trailer and the road, lower than a threshold friction; and / or estimating an ongoing curve passage. The maximum allowed braking force of the trailer may be reduced or inhibited when any one of these conditions is fulfilled.

[0027] By detecting and adapting the allowed braking force of the trailer to the current driving conditions, traffic safety is enhanced.

[0028] Optionally, the regenerative braking force applied by the electric machine may depend on the detected brake force requirement of the vehicle combination with reduction of the estimated regeneration capacity of the towing vehicle, while not exceeding the determined maximum allowed braking force of the trailer.

[0029] Thereby, an efficient yet safe regenerative braking is assured.

[0030] According to a second aspect, this objective is achieved by a control arrangement for use in a trailer operable to be part of a vehicle combination together with a towing vehicle connected to the trailer via a joint. The trailer comprises an electric machine configured to create a regenerative braking force by converting mechanical energy into electrical energy, for storage in an electrical energy storage of the trailer.

[0031] The control arrangement is configured to detect a brake force requirement of the vehicle combination. The control arrangement is also configured to estimate regeneration capacity of the towing vehicle. In addition, the control arrangement is configured to obtain a parameter related to current driving conditions of the trailer. The control arrangement is configured to determine a maximum allowed braking force of the trailer, based on the obtained parameter. The control arrangement is additionally configured to provide an instruction to the electric machine, to apply the regenerative braking force while not exceeding the determined maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated regeneration capacity of the towing vehicle.

[0032] Thanks to the disclosed solution, it is assured that the electric machine of the trailer regenerate as much braking force as possible, of the brake force required by the vehicle combination, in case the towing vehicle cannot regenerate, either due to being a combustion engine vehicle or a BEV with fully charged batteries. Usage of service brakes and / or sec- ondary brake of the towing vehicle, are thereby saved, while energy generated during the regenerative braking of the trailer is stored. Yet, safe braking is assured as the regenerated braking force of the trailer is adapted to the current driving conditions.

[0033] According to a third aspect, this objective is achieved by a trailer suitable for forming a vehicle combination together with a towing vehicle via a joint. The trailer comprises an electric machine configured to create a regenerative braking force by converting mechanical energy into electrical energy. The trailer also comprises an electrical energy storage configured to store electrical energy. In addition, the trailer comprises a control arrangement according to the second aspect.

[0034] According to a fourth aspect, this objective is achieved by a vehicle combination, comprising a towing vehicle. The vehicle combination also comprises a trailer according to the third aspect. In addition, the vehicle combination also comprises a joint, configured to connect the trailer to the towing vehicle.

[0035] According to a fifth aspect, this objective is achieved by a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to the first aspect.

[0036] According to a sixth aspect, this objective is achieved by a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to the first aspect.

[0037] Other advantages and additional novel features will become apparent from the subsequent detailed description.

[0038] FIGURES

[0039] Embodiments of the invention will now be described in further detail with reference to the accompanying figures, in which:

[0040] Figure 1A illustrates a vehicle combination comprising a towing vehicle and a trailer as regarded from a side view according to an embodiment of the invention.

[0041] Figure 1B illustrates a vehicle combination comprising a towing vehicle and a trailer as regarded from a side view according to an embodiment of the invention.

[0042] Figure 2 illustrates vehicle combination driving in a curve.

[0043] Figure 3 is a flow chart illustrating an embodiment of a method of a trailer. DETAILED DESCRIPTION

[0044] Embodiments of the solution described herein are defined as a method, a control arrangement, a trailer and a vehicle combination which may be put into practice in the embodiments described below. These embodiments may, however, be exemplified and realised in many different forms and are not to be limited to the examples set forth herein; rather, these illustrative examples of embodiments are provided so that this disclosure will be thorough and complete.

[0045] Still other objects and features may become apparent from the following detailed description, considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the herein disclosed embodiments, for which reference is to be made to the appended claims. Further, the drawings are not necessarily drawn to scale and, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

[0046] Figure 1A and 1 B illustrate embodiments of a vehicle combination 100. The vehicle combinations 00 comprise a towing vehicle 110 such as a tractor, a truck or similar, and a trailer 120 in form of a semi-trailer or similar arrangement (in Figure 1A) or trailer (in Figure 1B), on a road 105.

[0047] The expression “trailer” is consequently used herein for denoting the entity, which is pulled by the towing vehicle 110, irrespectively whether it is a trailer, a semi-trailer, or other similar entity.

[0048] The trailer 120 may normally / typically be unmanned. Further, the trailer 120 may be autonomous in some particular embodiments, configured for making at least minor position adjustments, e.g., adjusting the position at a loading bay and / or adjusting height of a coupling device, for example.

[0049] The vehicle combination 100 may comprise several instances of the trailer 120 (and / or possibly also several instances of the towing vehicle 110) in some embodiments, arranged sequentially after each other in a main driving direction of the vehicle combination 100.

[0050] However, subsequently, the vehicle combination 100 is described as comprising one towing vehicle 110 and one attached trailer 120. The towing vehicle 110 may be driver controlled or driverless (i.e., autonomously controlled) in different embodiments. However, for enhanced clarity, the towing vehicle 110 is subsequently described as having a driver.

[0051] The towing vehicle 110 comprises a first coupling device member 101 and the trailer 120 comprises a second coupling device member 111 , together forming a joint 101, 111. This joint 101 , 111 may alternatively be referred to as a towing coupling / towing eye / king pin / tow bar / trailer hitch, etc. Other similar mechanical arrangements may be used for attaching the trailer 120 to the towing vehicle 110 in other embodiments.

[0052] The vehicle combinationlOO is composed by attaching the first coupling device member 101 of the towing vehicle110 with the second coupling device member 111 of the trailer 120.

[0053] The trailer 120 comprises an electric machine 140 may be configured to convert electrical energy into mechanical energy thereby operate as an electric motor of the trailer 120. The electric machine 140 may be configured to propel the trailer 120 / vehicle combination 100 while driving; possibly also for moving independently from the towing vehicle 110 when disengaged from the towing vehicle 110.

[0054] The electric machine 140 is configured to operate in generator mode. The electric machine 140 is then operating with a reversed flow of power in comparison with the running in the electric motor mode, thereby converting mechanical energy of a rotor rotating around a stator into electrical energy. The electric machine 140 of the trailer 120 is enabled to create a regenerative braking force by converting mechanical energy into electrical energy, for storage in an electrical energy storage 150 / battery of the trailer 120.

[0055] In case an indication is perceived that the vehicle combination 100 is to reduce speed, for example when driving down-hill and / or braking for not exceeding a maximum allowed speed, the electric machine 140 may be set to operate as an electric generator, generating electricity which may be stored in the electrical energy storage 150 of the trailer 120.

[0056] The electrical energy storage 150 may comprise a rechargeable battery, e.g., based on lithium-ion and other lithium-based variants such as Lithium iron phosphate and Lithium- titanate. Lead acid batteries, Nickel metal hydride (NiMH) and / or zinc-air battery are other possible options. The trailer 120 and / or possibly the towing vehicle 110 may be propelled by electricity generated and stored in the electrical energy storage 150. The trailer 120 also comprises a control arrangement 130. The control arrangement 130 is configured to control application of the regenerative braking force of the trailer 120 in order to brake or assist the towing vehicle 110 in braking the vehicle combination 100. The control arrangement 130 aims at regenerating energy by the electric machine 140 in the trailer 120 to an as large extent as possible when the towing vehicle 110 cannot regenerate any energy. Yet, limitations have to be made with regard to driving conditions for ascertaining safe driving.

[0057] The control arrangement 130 is configured to detect a brake force requirement of the vehicle combination 100.

[0058] The brake force requirement of the vehicle combination 100 may be obtained via a communication interface between the towing vehicle 110 and the trailer 120, for example triggered by the driver pressing the braking pedal and / or by activating a secondary brake such as a retarder of the towing vehicle 110, and / or regeneration in case the towing vehicle 110 has regenerative capacity. The brake force requirement may also, or alternatively be obtained by detecting activation of a Downhill Speed Control functionality of the towing vehicle 110.

[0059] The communication interface between the towing vehicle 110 and the trailer 120 may comprise a wired or wireless communication interface. An example of a wired communication interface is a Controller Area Network (CAN) bus, a Media Oriented Systems Transport (MOST) bus, Ethernet, or similar. However, the communication may alternatively be made over a wireless communication interface comprising, or at least be inspired by WiFi, Bluetooth etc., or alternatively via Vehicle-to-Vehicle (V2V) communication e.g. based on Dedicated Short-Range Communications (DSRC) devices. DSRC works in 5.9 GHz band with bandwidth of 75 MHz.

[0060] Alternatively, the brake force requirement may comprise a sensor detection of a force caused by the trailer 120 pushing on the joint 101 , 111 in the driving direction of the vehicle combination 100. The second coupling device member 111 of the trailer 120 may comprise a sensor, configured for the sensor detection.

[0061] The control arrangement 130 may be communicatively connected to the sensor and may, based on the sensor measurements determine that the towing vehicle 110 is braking and estimate magnitude of the braking force requirement of the vehicle combination 100.

[0062] The control arrangement 130 is also configured to estimate regeneration capacity of the towing vehicle 110, for example via the wired or wireless communication interface between the towing vehicle 110 and the trailer 120, if any.

[0063] The control arrangement 130 may for example enquire whether the towing vehicle 110 is a BEV vehicle or not, and when it is, enquiring charging level of the batteries at the towing vehicle 110.

[0064] In case there is no communication interface between the towing vehicle 110 and the trailer 120, the regeneration capacity of the towing vehicle 110 may be estimated indirectly and a portion of insecurity may to have be accepted.

[0065] For example, in a conservative approach, it may be assumed that the towing vehicle 110 lacks regeneration capacity at all when the towing vehicle 110 is not capable of communication.

[0066] In another embodiment, the trailer 120 may comprise an image sensor, communicatively connected to the control arrangement 130. By capturing an image of the behind of the towing vehicle 110, the license plate on the vehicle may be identified and interpreted by an image recognition software running on the control arrangement 130. A check may then be made against a vehicle register onboard the trailer 120, or external to the trailer 120, for example in a public vehicle register, via a wireless communication interface. A confirmation that the towing vehicle 110 is a BEV could thereby be made, and an estimation of the remaining charging capacity of the vehicle battery of the towing vehicle 110 may be made based on time passed since the latest charging stop / vehicle stop exceeding a threshold time assumed to be a charging stop.

[0067] In case the towing vehicle 110 is foreign, the analyses may be made in two steps. Firstly, determination of country origin of the towing vehicle 110 based on image analyses of the license plate may be made. Secondly, a check for extracting vehicle data from the vehicle register of that country may be made.

[0068] Other options, for example in case of driving out of internet connection, may comprise image analyses of the captured image for detecting an exhaust pipe of the towing vehicle 110, possibly by an infra-red (IR) sensor. However, presence of an exhaust pipe does not necessarily preclude regeneration capacity of the towing vehicle 110 in case of being a hybrid vehicle. Actually, a hot / active exhaust pipe on a hybrid towing vehicle 110 may rather indicate that the batteries are empty and regenerative braking of the trailer 120 is to be currently suspended. Some puzzling may have to be made together with other pieces of information concerning the regeneration capacity of towing vehicle 110.

[0069] The properties during acceleration of a BEV and a vehicle with a combustion engine will be different. The change of gears characterising of a combustion engine may be detected by an auditive sensor and analysis of the change in rpm; perhaps in combination with an accelerometer or other similar sensor onboard the trailer 120.

[0070] Yet other options may be based on Global Positioning System (GPS) or other similar Global Navigation Satellite System (GNSS) that provide geolocation and time information to a receiver, in combination with mapping against positions of electric charging points / fuel stations, respectively. The trailer 120 may thus comprise a GPS receiver communicatively connected to the control arrangement 130. An analysis of vehicle stops / time duration of stops of the vehicle combination 100 may indicate the propulsion technology of the towing vehicle 110.

[0071] The trailer 120 may comprise wireless communicative capacity via V2V / V2X and may thereby trigger and obtain images of the towing vehicle 110 from cameras situated on other nearby and / or passing vehicles having V2V capacity, or from cameras on various infrastructure at the roadside. Based on these images, the vehicle model (BEV / combustion engine) of the towing vehicle 110 may be determined and estimation of regenerative capacity may be based there upon. Alternatively, image analyses of the captured images may detect a battery charge port, alternatively a fuel tank and / or a fuel hatch.

[0072] An advantage with V2V communication and other similar direct communication technology is that it is independent from any vehicle external communication infrastructure, for example when operating in remotely positioned mines, forests etc., where cellular communication is not available, or not available along all the route.

[0073] Also, the control arrangement 130 obtain a parameter related to current driving conditions of the trailer 120. It is desired to avoid excessive regenerative braking of the trailer 120 when there is a risk of slippery road, in particular in a curve and / or when driving in high speed.

[0074] In case the rolling friction of the trailer wheels is higher than the friction in lateral direction of the trailer wheels, a lateral force such as wind, centrifugal force during curve passage, etc., acting on the trailer 120 may cause it to dislocate laterally in relation to the towing vehicle 110; i.e. make an at least partly rotating movement around the joint 101 , 111. This kind of uncontrolled lateral movements of the trailer 120 are dangerous and may cause a severe accident, why it is desired to avoid regenerative braking (which increases the rolling friction) of the trailer 120 during driving conditions where the friction between the trailer tyres and the underneath in lateral direction is low (e.g. ice, snow etc.), and / or when a lateral force is acting on the trailer 120 (e.g. during curve taking, in particular at high speed).

[0075] Information related to friction and other parameters of current driving conditions of the trailer 120 may be obtained from the towing vehicle 110 via the communication interface. Alternatively, this information may be detected via sensors on the trailer 120 and determined by the control arrangement 130.

[0076] The current speed of the trailer 120 may be obtained from the speedometer of the towing vehicle 110 in some embodiments, via the communication interface.

[0077] Alternatively, the current speed of the trailer 120 may be calculated based on measurements made by a sensor onboard the trailer 120.

[0078] The control arrangement 130 may also obtain a parameter related to friction between the tyres of the trailer 120 and the road / underneath surface 105, for example by detecting ice, snow and / or layer of water, mud, leaked oil, wet leaves, sand and other similar friction decreasing objects on the roadway that may reduce the friction. Temperature may also influence properties of the road surface 105, for example presence of ice or snow may reduce friction in cold temperatures, while hot temperatures may cause asphalt to soften and become slippery / greasy due to the release of oils.

[0079] An optional image sensor on the trailer 120 may be configured to capture an image of the road surface 105, enabling detection of snow, ice, wet leaves, water, and various other friction reducing obstacles at the road 105, in conjunction with image recognition software, thereby detecting objects / conditions on the road surface 105 affecting friction.

[0080] The friction estimation may also, or alternatively be based on an estimation of current condition of the tyres of the trailer 120. Information concerning the tyres may be stored in a database and time and / or passed distance since they were new / mounted may be calculated. Alternatively, a sensor may be directed towards the tyres of the trailer 120 and in conjunction with appropriate software of the control arrangement 130, condition of the tyres may be estimated. Type of tyres (rubber mixture; studded tyres; snow chains); number and / or width of the tyres may be determined e.g. based on image recognition of a tyre marking on the tyre. The trailer 120 may for example comprise a temperature sensor or thermometer, configured to measure road temperature / ambient temperature. Also, or alternatively, the trailer 120 may comprise an image sensor communicatively connected to the control arrangement 130. Based on captured images of the road, the control arrangement 130 may detect snow ice etc, via an image recognition program.

[0081] Friction between tyres of the trailer 120 and the road 105 may also, or alternatively be estimated by determine spin of driving wheels of the trailer 120 or detect a difference in spin of the trailer driving wheels.

[0082] The friction between the rubber tyres and the road 105 is dependent on the temperature. One reason is that the rubber of the tyres changes properties with temperature. At lower temperatures, rubber may harden, reducing its grip on the road 105. As the temperature increases, the rubber softens, which may increase its ability to deform and adapt to the road surface 105, improving grip. If the temperature is too high, the rubber may start to degrade or become overly soft, reducing the overall performance of the tyres.

[0083] Different rubber mixtures and thereby different tyres will have their optimal friction performance within different temperature intervals.

[0084] Both excessively high and low temperatures may reduce the friction between the tyres and the road 105, reducing the performance and safety of the trailer 120 during regeneration.

[0085] Current driving conditions of the trailer 120 may also comprise an estimation of curvature of the road 105 as schematically illustrated in Figure 2. The curvature may be estimated based on map data in combination with vehicle positioning for example based on GPS, etc. Another possibility may be to detect the curvature of an ahead path segment via a forwardlooking sensor in combination with image recognition software.

[0086] The control arrangement 130 may be particularly designated to implement estimation of relative position displacement between the towing vehicle 110 and the trailer 120, thereby estimating curve taking of the vehicle combination 100, based on sensor measurements. The curvature of the road 105 may alternatively be estimated based on misalignment between the towing vehicle 110 and the trailer 120. The trailer 120 may comprise one or several forward looking sensors for making measurements, thereby enabling the control arrangement 130 to determine a lateral alignment deviation abetween a longitudinal extension direction 210 of the towing vehicle 110 and the longitudinal extension direction 220 of the trailer 120. The sensor may comprise or be based on e.g., a camera, a stereo camera, an infrared camera, a video camera, monochrome, coherent light (laser); microwaves (maser); a pulsed laser light (lidar), a radar, an ultrasound device, a time-of-flight camera, or similar device, in different embodiments.

[0087] By emitting a signal (light, radio waves, sound...) to hit a rear part of the towing vehicle 110 and measure the time it takes to bounce back to the sensor on the trailer 120, the distance between the sensor and the towing vehicle 110 may be calculated. By comparing the measured distance with an expected distance (corresponding to a state when the towing vehicle 110 and the trailer 120 are longitudinally aligned), a misalignment may be detected. When the detected misalignment exceeds a threshold level, curve taking may be assumed.

[0088] In yet some embodiments, an ongoing curve taking or misalignment between the towing vehicle 110 and the trailer 120 may be estimated based on measurements made by a yaw rate sensor or a gyroscopic device configured to measure yaw rate, and angular velocity around a vertical axis of the trailer 120 and / or the towing vehicle 110. The sensor may in some embodiments be electro-mechanical, magnetic, inductive, capacitive, etc.

[0089] Thereby, a curvature of the road 105 may be determined, for example at a present path segment of the road 105, or at a path segment ahead of the vehicle combinationlOO.

[0090] The control arrangement 130 is also configured to determine a maximum allowed braking force of the trailer 120, based on the obtained parameter. The maximum allowed braking force may be based on estimation of a risk of having a friction between the tyres of the trailer 120 and the road 105, lower than a threshold friction. The threshold friction may be set to a value which assures that the tyres does not slip on the road 105, depending on the driving conditions.

[0091] The maximum allowed braking force may also, or alternatively be based on estimation of an ongoing curve passage. The maximum allowed braking force of the trailer 120 may be reduced or inhibited when any one of these conditions is fulfilled, avoiding the trailer 120 to slip in lateral direction, which may cause an accident.

[0092] The control arrangement 130 is in addition configured to provide an instruction to the electric machine 140, to apply the regenerative braking force while not exceeding the determined maximum allowed braking force. The magnitude of the applied regenerative braking force is based on the estimated regeneration capacity of the towing vehicle 110. The applied regenerative braking force of the electric machine 140 thereby depend on the detected brake force requirement of the vehicle combination 100 with reduction of the estimated regeneration capacity of the towing vehicle 110, if any, while not exceeding the determined maximum allowed braking force of the trailer 120.

[0093] The control arrangement 130 may comprise e.g., one or several Electronic Control Units (ECUs), typically a plurality of interacting ECUs. The control arrangement 130 may comprise a digital computer that controls one or more electrical systems, or electrical sub systems, of the trailer 120, based on e.g., information read from the sensors placed at various parts and in different components of the trailer 120.

[0094] Figure 3 illustrates an example of a method 300 according to an embodiment. The flow chart in Figure 3 shows the method 300 for use in trailer 110. The trailer 110 is operable to be part of a vehicle combination 100 together with a towing vehicle 110 connected to the trailer 120 via a joint 101 , 111. The towing vehicle 110 and the trailer 120 may be angularly displaced in relation to each other via the joint 101, 111.

[0095] The trailer 120 comprises an electric machine 140 configured to create a regenerative braking force by converting mechanical energy into electrical energy for storage in an electrical energy storage 150 of the trailer 120.

[0096] In order to be able to correctly create and apply the regenerative braking force, the method 300 may comprise a number of steps 301-305. However, some of these steps 301-305 may be performed in various alternative manners. Further, the described steps 301-305 may be performed in a somewhat different chronological order than the numbering suggests. The method 300 may comprise the subsequent steps:

[0097] Step 301 comprises detecting a brake force requirement of the vehicle combination 100.

[0098] The detection 301 of the brake force requirement of the vehicle combination 100 may be made based on information obtained via a communication interface between the towing vehicle 110 and the trailer 120, such as a communication bus.

[0099] In embodiments wherein there is no communication interface between the towing vehicle 110 and the trailer 120, the detection 301 of the brake force requirement of the vehicle combination 100 may comprise a sensor detection of a force caused by the trailer 120 pushing on the joint 101, 111 in the driving direction of the vehicle combination 100. By determining magnitude of the force in longitudinal direction caused by the trailer 120 pushing on the joint 101 , 111 , the brake force requirement of the vehicle combination 100 may be estimated. It may be assumed that the brake force requirement corresponds to regenerative braking of the trailer 120 resulting in eliminating the pushing force on the pressure sensor.

[0100] Step 302 comprises estimating regeneration capacity of the towing vehicle 110.

[0101] The estimation 302 of the regeneration capacity of the towing vehicle 110 may be made based on information obtained via the communication interface between the towing vehicle 110 and the trailer 120.

[0102] The regeneration capacity of the towing vehicle 110 may be estimated 302 by detecting that the towing vehicle 110 cannot perform regenerative braking and / or has insufficient regeneration capacity and / or energy storage capacity to meet the detected 301 brake force requirement of the vehicle combination 100 by regenerative braking.

[0103] Step 303 comprises obtaining a parameter related to current driving conditions of the trailer 120.

[0104] The obtained 303 parameter related to current driving conditions of the trailer 120 may comprises speed and / or acceleration of the trailer 120, and / or a parameter related to friction between the tyres of the trailer 120 and the road 105, and / or a parameter related to a longitudinal alignment between the towing vehicle 110 and the trailer 120.

[0105] Step 304 comprises determining a maximum allowed braking force of the trailer 120, based on the obtained 303 parameter.

[0106] The maximum allowed braking force of the trailer 120 may be determined 304 by estimating a risk of having a friction between the tyres of the trailer 120 and the road 105, lower than a threshold friction. Also, or alternatively, the maximum allowed braking force of the trailer 120 may be determined 304 by estimating an ongoing curve passage of the vehicle combination 100.

[0107] An ongoing curve passage of the vehicle combination 100 may be estimated based on map data in combination with vehicle positioning for example based on GPS, etc., and knowledge of the vehicle destination and / or driving direction. Alternatively, the ongoing curve passage may be detected based on an image sensor, and image recognition software.

[0108] In yet other alternative embodiments, the ongoing curve passage detected and predicted by measurement of an angle a between a respective longitudinal axis 210, 220 of the towing vehicle 110 and the trailer 120, and / or angles of frontal wheels of the towing vehicle 110, as measured by an appropriate sensor.

[0109] The maximum allowed braking force of the trailer 120 may be reduced or inhibited when any one of these conditions is fulfilled.

[0110] Step 305 comprises applying a regenerative braking force of the electric machine 140 while not exceeding the determined 304 maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated 302 regeneration capacity of the towing vehicle 110.

[0111] The regenerative braking force applied 305 by the electric machine 140 may depend on the detected 301 brake force requirement of the vehicle combination 100 with reduction of the estimated 302 regeneration capacity of the towing vehicle 110, while not exceeding the determined 304 maximum allowed braking force of the trailer 120.

[0112] The above described steps 301-305 to be performed in the trailer 120 may be implemented by a computer / the control arrangement 130. The computer / control arrangement 130 may comprise processing circuitry such as, but not limited to, a processor, Central Processing Unit (CPU), a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a System-on-Chip (SoC), a programmable logic unit, a microprocessor, an application-specific integrated circuit, or any other device capable of electronically performing operations in a defined manner.

[0113] The above described method 300 may be implemented by the control arrangement 130, together with computer program product comprising instructions for performing at least some of the functions of the method steps 301-305.

[0114] The computer program product mentioned above may be a computer readable medium. The computer program may be stored in a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps 301-305 of the method 300. The computer-readable medium may be a non-transitory computer-readable medium, such as a tangible electronic, magnetic, optical, infrared, elec- tromagnetic, and / or semiconductor system, apparatus, and / or device.

[0115] The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described method 300; control arrangement 130; trailer 120; vehicle combination 100; computer program product and / or computer-readable storage medium. Various changes, substitutions and / or alterations may be made, without departing from invention embodiments as defined by the appended claims.

[0116] As used herein, the term “and / or” comprises any and all combinations of one or more of the associated listed items. The term “or” as used herein, is to be interpreted as a mathematical OR, i.e., as an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless expressly stated otherwise. In addition, the singular forms “a”, “an” and “the” are to be interpreted as “at least one”, thus also possibly comprising a plurality of entities of the same kind, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and / or “comprising”, specifies the presence of stated features, actions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and / or groups thereof. A single unit such as e.g., a processor may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid- state medium supplied together with or as part of other hardware but may also be distributed in other forms such as via Internet or other wired or wireless communication system.

Claims

PATENT CLAIMS1 . A method (300) for use in a trailer (120), operable to be part of a vehicle combination (100) together with a towing vehicle (110) connected to the trailer (120) via a joint (101 , 111), wherein the trailer (120) comprises an electric machine (140) configured to create a regenerative braking force by converting mechanical energy into electrical energy for storage in an electrical energy storage (150) of the trailer (120); wherein the method (300) comprises the steps of: detecting (301) a brake force requirement of the vehicle combination (100); estimating (302) regeneration capacity of the towing vehicle (110); obtaining (303) a parameter related to current driving conditions of the trailer (120); determining (304) a maximum allowed braking force of the trailer (120), based on the obtained (303) parameter; applying (305) a regenerative braking force of the electric machine (140) while not exceeding the determined (304) maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated (302) regeneration capacity of the towing vehicle (110).

2. The method (300) according to claim 1 , wherein the regeneration capacity of the towing vehicle (110) is estimated (302) by detecting that the towing vehicle (110) cannot perform regenerative braking and / or has insufficient regeneration capacity and / or energy storage capacity to meet the detected (301) brake force requirement of the vehicle combination (100) by regenerative braking.

3. The method (300) according to any one of the preceding claims, wherein the step of detecting (301) the brake force requirement of the vehicle combination (100) comprises a sensor detection of a force caused by the trailer (120) pushing on the joint (101 , 111) in the driving direction of the vehicle combination (100).

4. The method (300) according to any one of the preceding claims, wherein the detection (301) of the brake force requirement of the vehicle combination (100) and the estimation (302) of the regeneration capacity of the towing vehicle (110) are made based on information obtained via a communication interface between the towing vehicle (110) and the trailer (120).

5. The method (300) according to any one of the preceding claims, wherein the obtained (303) parameter related to current driving conditions of the trailer (120) comprises speed and / or acceleration of the trailer (120), and / or a parameter related to friction be-tween the tyres of the trailer (120) and the road (105), and / or a parameter related to a longitudinal alignment between the towing vehicle (110) and the trailer (120).

6. The method (300) according to any one of the preceding claims, wherein the step of determining (304) the maximum allowed braking force of the trailer (120) comprises estimating a risk of having a friction between the tyres of the trailer (120) and the road (105), lower than a threshold friction; and / or estimating an ongoing curve passage; and wherein the maximum allowed braking force of the trailer (120) is reduced or inhibited when any one of these conditions is fulfilled.

7. The method (300) according to any one of the preceding claims, wherein the regenerative braking force applied (305) by the electric machine (140) depends on the detected (301) brake force requirement of the vehicle combination (100) with reduction of the estimated (302) regeneration capacity of the towing vehicle (110), while not exceeding the determined (304) maximum allowed braking force of the trailer (120).

8. A control arrangement (130) for use in a trailer (120) operable to be part of a vehicle combination (100) together with a towing vehicle (110) connected to the trailer (120) via a joint (101, 111), wherein the trailer (120) comprises an electric machine (140) configured to create a regenerative braking force by converting mechanical energy into electrical energy, for storage in an electrical energy storage (150) of the trailer (120); wherein the control arrangement (130) is configured to: detect a brake force requirement of the vehicle combination (100); estimate regeneration capacity of the towing vehicle (110); obtain a parameter related to current driving conditions of the trailer (120); determine a maximum allowed braking force of the trailer (120), based on the obtained parameter; provide an instruction to the electric machine (140), to apply the regenerative braking force while not exceeding the determined maximum allowed braking force, wherein the magnitude of the applied regenerative braking force is based on the estimated regeneration capacity of the towing vehicle (110).

9. A trailer (120) suitable for forming a vehicle combination (100) together with a towing vehicle (110) via a joint (101 , 111); wherein the trailer (120) comprises: an electric machine (140) configured to create a regenerative braking force by converting mechanical energy into electrical energy; an electrical energy storage (150) configured to store electrical energy; anda control arrangement (130) according to claim 8.

10. An articulated vehicle (100), comprising: a towing vehicle (110); a trailer (120) according to claim 9; a joint (101 , 111), configured to connect the trailer (120) to the towing vehicle (110).

11. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method (300) according to any one of claims 1-7.

12. A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method (300) ac- cording to any one of claims 1-7.

Images