WO2019053022A1

WO2019053022A1 - System and method for a trailer towable by a vehicle

Info

Publication number: WO2019053022A1
Application number: PCT/EP2018/074511
Authority: WO
Inventors: Jeremy Greenwood
Original assignee: Jaguar Land Rover Limited
Priority date: 2017-09-15
Filing date: 2018-09-11
Publication date: 2019-03-21
Also published as: GB2566490A; GB201714852D0

Abstract

The present invention provides a system for use in a trailer towable by a vehicle. The system comprising a trailer external lighting arrangement, energy storage means configured to supply electric power to the trailer external lighting arrangement, and an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means. The system also comprises a controller configured to receive a wireless control signal from the vehicle and/or a control signal from the trailer, and to send a control signal to operate the trailer external lighting arrangement in dependence on the received vehicle wireless signal and/or the received trailer signal.

Description

SYSTEM AND METHOD FOR A TRAILER TOWABLE BY A VEHICLE

TECHNICAL FIELD The present disclosure relates to a system and method for a trailer towable by a vehicle. Aspects of the invention relate to a system, to a method, and to a trailer.

BACKGROUND It is a regulatory requirement for a trailer that is towed by a vehicle to be fitted with external lighting. In particular, this may include sidelights, stop lamps, an illuminated number plate, indicators etc.

Conventionally, such trailer external lighting is connected to corresponding external lighting on the tow vehicle by means of wiring. This can involve connecting plug-and- socket connectors that are located under a bumper of the vehicle, which can be awkward to reach for the user and can result in dirt on the bumper being passed onto the user. These connections can also be unreliable. It is an aim of the present invention to address disadvantages associated with the prior art.

SUMMARY OF THE INVENTION According to an aspect of the present invention there is provided a system for use in a trailer towable by a vehicle. The system comprises a trailer external lighting arrangement and energy storage means configured to supply electric power to the trailer external lighting arrangement. The system also comprises an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means. The system also comprises a controller configured to receive a wireless control signal from the vehicle and/or a control signal from the trailer, and to send a trailer external lighting control signal to operate the trailer external lighting arrangement in dependence on the received vehicle wireless control signal and/or the received trailer control signal.

The present invention is advantageous in that true wireless control of the trailer external lighting arrangement is provided, i.e. no wiring connections need to be established between the trailer and tow vehicle. That is, there is no wiring link between the trailer and vehicle needed to operate the trailer external lighting arrangement. Although wireless control of a trailer external lighting arrangement has been proposed previously, these have needed a power source on the trailer requiring a feed from the tow vehicle, thus meaning that true wireless control is not achieved. The trailer energy storage means of the present invention does not need a feed from the tow vehicle, but rather its charge is replenished via regenerative braking energy from the electric motor(s). It is envisaged that the energy storage means, e.g. a battery, would be of a relatively significant size, in particular large enough to absorb sufficient braking energy from the electric motor(s), which may be several kilowatts per hour. This would then provide power for the trailer external lighting arrangement for a relatively large period of time even when the vehicle and trailer are not moving (and therefore not providing additional regenerative braking energy to replenish the energy storage means). The received wireless control signal may include data relating to operation of an external lighting arrangement of the vehicle.

The energy storage means may be configured to supply electric power to at least one further trailer electrical component.

The at least one further trailer electrical component may include at least one of a recovery trailer winch component, a trailer interior lighting arrangement, a trailer refrigeration unit, a trailer tyre pressure sensor, a trailer radiator unit, one or more trailer vision sensors, one or more trailer ultrasonic sensors, and one or more trailer radar sensors.

The system may comprise an energy storage management subsystem configured to control operation of the energy storage means. The controller may be configured to determine a minimum allowable state of charge of the energy storage means in dependence on received energy storage means state of charge data, and the controller may be configured to notify the energy storage management subsystem of the determined minimum allowable state of charge.

The received energy storage means state of charge data may include data from the at least one further trailer electrical component.

The minimum allowable state of charge may be dependent on the number of trailer electrical components to which the energy storage means supplies electrical power.

The minimum allowable state of charge may increase for an increased number of trailer electrical components to which the energy storage means supplies electrical power.

The received energy storage means state of charge data may include data from the vehicle representative of a state of a driver-selectable function within the vehicle.

The controller may be configured to transmit a wireless message to the vehicle, and the wireless message may include diagnostic data received from the trailer external lighting arrangement and/or the at least one further trailer electrical component.

The diagnostic data may include information indicative of a lighting failure in the trailer external lighting arrangement.

The diagnostic data may include information indicative of at least one of: a faulty trailer sensor; trailer tyre pressure data; parking distance control data; and, video feature data. According to another aspect of the present invention there is provided a system for use in a trailer towable by a vehicle. The system comprises at least one trailer electrical component and energy storage means configured to supply electric power to the at least one trailer electrical component. The system comprises an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means. The system also comprises a controller configured to transmit a wireless message to the vehicle, the wireless message including diagnostic data received from the at least one trailer electrical component. Again, this is advantageous in that no wiring connections need to be established between the trailer and the tow vehicle in order for diagnostic data, including video feeds from a camera, to be relayed from the trailer to the tow vehicle.

According to another aspect of the present invention there is provided a system for use in a trailer towable by a vehicle. The trailer comprises at least one trailer electrical component, energy storage means configured to supply electric power to the at least one trailer electrical component, and an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means. The system comprises a receiver configured to receive energy storage means state of charge data from the vehicle and/or the at least one trailer electrical component. The system also comprises a processor configured to determine a minimum allowable state of charge of the energy storage means in dependence on the received energy storage means state of charge data. The system also comprises a controller configured to control operation of the electric motor such that a current state of charge of the energy storage means remains greater than the determined minimum allowable state of charge. This is advantageous in that control of the trailer energy storage means can be achieved without needing to establish wiring connections between the trailer and vehicle.

According to another aspect of the present invention there is provided a method for use in a trailer towable by a vehicle. The trailer comprises a trailer external lighting arrangement, energy storage means, and an electric motor coupled to at least one wheel of the trailer. The method comprises providing regenerative braking energy from the electric motor to the energy storage means. The method also comprises supplying electric power from the energy storage means to the trailer external lighting arrangement. The method also comprises receiving a wireless control signal from the vehicle and/or a control signal from the trailer, and sending a trailer external lighting control signal to operate the trailer external lighting arrangement in dependence on the received vehicle wireless control signal and/or the received trailer control signal.

According to another aspect of the present invention there is provided a trailer for being towed by a vehicle, the trailer comprising a system as described above. According to another aspect of the present invention there is provided a non-transitory, computer-readable storage medium storing instructions thereon that when executed by one or more processors causes the one or more processors to carry out the method described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic plan view of a trailer towed by a vehicle, the trailer having a system according to an embodiment of an aspect of the invention; and,

Figure 2 shows the steps carried out by the system of Figure 1 in a method according to an embodiment of an aspect of the invention.

DETAILED DESCRIPTION

The present invention provides a controller for use in a trailer towable by a vehicle. The trailer has an electrical component, such as a trailer external lighting arrangement, and energy storage means, such as a battery, to supply electric power to the electrical component. The trailer has an axle with two wheels and at least one electric motor coupled thereto. The electric motor acts as a generator to provide regenerative braking energy to the energy storage means when the electric motor is used to provide braking torque to the trailer wheel(s). The controller receives a wireless control signal from the vehicle and sends a component control signal to operate the at least one electrical component in dependence on the received wireless signal. Figure 1 shows a schematic plan view of a trailer 10 towed by a vehicle 12. The trailer 10 is connected to the vehicle 12 by means of a hitch coupling 14. The hitch coupling 14 is in the form of a mechanical hitch joint.

In the described embodiment, the vehicle 12 is a car having a plurality of on-board vehicle control subsystems and sensors 16. For example, the vehicle 12 includes a vehicle external lighting subsystem 18 for controlling the external vehicle lights such as head lamps, brake lights and indicator lights. The lighting subsystem 18 receives inputs from the vehicle driver via control button and actuators within the vehicle cabin, and controls the external lights to operate as demanded. For example, when the driver depresses a brake pedal of the vehicle the lighting subsystem 18 causes the vehicle brake lights to operate.

The on-board vehicle control subsystems and sensors 16 also include a human- machine interface (HMI) 20. The HMI 20 comprises a display screen in the vehicle cabin configured to provide visual warnings to the vehicle driver regarding various vehicle functions. The HMI 20 also includes input means configured to allow the vehicle driver to select various available functions within the trailer 10 and vehicle 12. The input means may be in the form of a touch screen, buttons, or levers for example. The on-board vehicle control subsystems and sensors 16 also include a vehicle braking control subsystem 22. The vehicle 12 may be fitted with a hydraulic brake circuit as is known in the art, whereby application of a brake pedal (not shown) of the vehicle 12 by the driver causes application of the vehicle's wheel brakes. The wheel brakes (not shown) can be drum brakes or disc brakes, for example. Application of the brakes may be controlled by a controller of the braking system 22.

In the described embodiment, the trailer 10 has two wheels 30, 32, one on each side of the trailer 10, which are connected by an axle 34. Each of the trailer wheels 30, 32 has an electric motor/generator or machine 36, 38 attached thereto. The electric machines 36, 38 are connected to the axle 34; however, they may be connected to the trailer 10 differently in different embodiments, for example via trailer wheel hub or frame connections. The electric machines 36, 38 are connected to, and powered by, a high-power, low-capacity battery 40 of the trailer 10. The electric machines 36, 38 may be used to apply regenerative braking or tractive torque to the wheels 30, 32 of the trailer 10. The battery 40 is of a relatively significant size in order to be capable of absorbing the regenerative braking energy, for example several kilowatts per hour, optionally 20 kilowatts per hour. In the described embodiment, the electric machines are configured to freewheel during normal driving of the trailer 10 and vehicle 12. The battery 40 is a lithium-titanate rechargeable battery: this type of battery is advantageous because of its fast charging time compared with other types of lithium- ion batteries.

The trailer 10 includes an electronic control unit (ECU) or controller 50 that is configured to receive a wireless control signal 80 from the vehicle electrical components 16. The controller 50 is also configured to receive a control signal 81 from the trailer 10, in particular from a sensor at the hitch coupling 14. Furthermore, the controller 50 is configured to receive a control signal 83a, 83b from wheel speed sensors 85a, 85b of the trailer (10). The controller 50 is configured to control one or more electrical components of the trailer 10 in dependence on one or more of the received wireless signal 80 from the vehicle 12 and the received trailer control signals 81 , 83a, 83b, as will be described below. In particular, the ECU 50 comprises a wireless receiver arranged to receive wireless signals sent from a wireless transmitter located in the tow vehicle 12. The wireless signals 80 are in the form of radio frequency signals; however, other types of wireless signals may also be useful. The wireless signals 80 may be over a low-rate wireless personal area network operating according to one of the IEEE 802-15-4 standard of protocols such as Bluetooth®, WiFi or ZigBee®. The trailer 10 includes a trailer external lighting arrangement 52 having external brake lights, indicators, etc. The external lighting arrangement 52 is connected to, and powered by, the trailer battery 40. In particular, the operation of the trailer external lighting arrangement 52 is controlled in response to control signals 82 from the controller 50. The external lighting arrangement 52 can also send data signals 82 to the ECU 50 relating to the status of the external lights.

The trailer 10 includes several other electrical sensors/subsystems/components 54 that are connected to, and powered by, the trailer battery 40. These are also referred to as further trailer electrical components 54. Collectively, the trailer external lighting arrangement 52 and the further trailer electrical components 54 are the trailer electrical components 52, 54 to be powered by the battery 40. For example, the trailer 10 includes various types of sensors including one or more radar sensors 56, ultrasonic or acoustic sensors 58, and vision sensors or cameras 60. These sensors 56, 58, 60 may perform several functions such as providing data relating to the proximity of the trailer 10 to the tow vehicle 12, to other vehicles, to road boundaries, to lane boundaries, etc., particularly when the tow vehicle 12 and trailer 10 are reversing, and for use in so-called 'Transparent Trailer' technology in which one or more cameras placed at the rear of the trailer 12 allows a video feed of the surroundings to the rear of the trailer 12 to be relayed to the driver of the tow vehicle 12.

In the case where the trailer 12 is a recovery trailer the trailer sensors and subsystems 54 may include an electrical winch 62. In particular, the winch 62 includes an electrically-operated gear assembly, powered by the battery 40, to wind or unwind a connection cable round a spool.

The trailer sensors and subsystems 54 include trailer tyre pressure sensors 64. In particular, each of the trailer wheels 30, 32 has a tyre pressure sensor coupled thereto, which is configured to monitor the pressure of the tyre of the respective wheel 30, 32.

In the case in which the trailer 12 is a caravan, for example, the trailer 12 may have one or more of interior lighting 66, a refrigerator 68, and an air-conditioning unit or radiator system 70 powered by the battery 40.

It will be appreciated that several other types of trailer electrical components 54 are possible. The trailer includes a battery management system (BMS) 42 which controls the operation of the trailer battery 40. The BMS 42 sends and receives signals 84 from the battery 40. The BMS 42 also sends and receives data 86 to and from the controller 50. In particular, the BMS 42 controls the battery 40 to power the sensors and subsystems 52, 54 based on their respective power requirements, the state of charge of the battery 40, and the control signals sent by the controller 50.

The controller 50 can be used to perform several functions associated with the operation of the trailer sensors and subsystems 52, 54. For example, the controller 50 receives the wireless control signal 80 from the vehicle external lighting arrangement 18 with data relating to the operation of the vehicle external lights. In particular, the wireless signal 80 includes information as to which of the vehicle external lights are being operated. The controller 50 then sends the electrical component control signal 82 to the trailer external lighting arrangement 52 in response to the received wireless signal 80 to cause operation of the corresponding trailer external lights. In particular, if the received wireless signal 80 includes information that the vehicle brake lights are being operated, then the controller 50 is arranged to cause the trailer external lights to operate simultaneously. The battery 40 supplies the trailer external lighting arrangement 52 with charge to operate the trailer external lights as needed. The battery 40 is provided with, and stores, charge sufficient to power the trailer external lights as needed by the electric motors 36, 38. In particular, the electric motors 36, 38 provide regenerative braking torque to the trailer wheels 30, 32 to assist the vehicle brakes to cause braking of the trailer 10 and vehicle 12. This also helps to ensure the stability of the combination of the trailer 10 and vehicle 12.

This operation of the trailer external lighting arrangement is advantageous in that no wiring connections are needed between the trailer 10 and vehicle 12 to either: connect the vehicle external lighting arrangement 18 to the trailer external lighting arrangement 52; or, connect the trailer external lighting arrangement 52 or battery 40 to a power supply of the vehicle 12. This is because the battery 40 providing power to the trailer external lights 52 is rechargeable via the electric motors 36, 38, which provide regenerative braking torque to the trailer wheels 30, 32, the regenerative braking torque being used to charge the battery 40. In the presently-described embodiment, the controller 50 additionally receives a signal 81 from the hitch coupling 14, in particular a sensor therein. The signal 81 can provide an indication that the vehicle 12 and the trailer 10 have become uncoupled, for example if it is determined that the vehicle 12 is no longer exerting a force on the trailer 10, or vice versa. In this case, the trailer 10 may be moving in an unrestricted manner and it would be beneficial to alert other road users to this. Therefore, if the control signal 81 indicates that the trailer 10 has become uncoupled from the vehicle 12 then the controller 50 is configured to send a control signal 82 to the trailer external lighting arrangement 52 to illuminate hazard warning lights of the arrangement 52 so as to warn other road users.

Also in the presently-described embodiment, the controller 50 receives signals 83a, 83b from trailer wheel speed sensors 85a, 85b coupled to the trailer wheels 30, 32. The wheel speed sensors 83a, 83b can be used to indicate that the speed of the trailer 10 is changing. For example, if the signals 83a, 83b indicate that the speed of the trailer 10 is decreasing then the controller 50 is configured to send a signal 82 to the trailer external lighting arrangement 52 to operate trailer brake lights of the arrangement 52. Such a feature may be operational in addition to, or instead of, the trailer brake lights being operated in response to the wireless signal 80 from the vehicle 12.

The controller 50 is also used to determine a minimum level of charge that the battery 40 should maintain in dependence on various conditions. The controller 50 receives data 88 from the trailer sensors and subsystems 54 with information as to the number of systems in addition to the trailer external lights to which the battery 40 may need to provide power. This data 88 also contains information as to the type of these additional systems and, therefore, an indication as to the levels of required power to operate the systems. The data 88 also contains information relating to which systems are currently being powered by the battery 40.

The controller 50 also receives data 86 from the BMS 42 relating to a current state of charge (SoC) of the battery 40. In addition, the controller 50 receives data 80 from the vehicle human-machine interface (HMI) 20. This data 80 may contain information relating to future use of one or more of the trailer sensors and subsystems 54. For example, in the case in which the trailer 12 is a caravan, the vehicle driver may interact with the HMI 20 to indicate that the vehicle 12 and trailer 10 will soon be stopping to pitch the caravan, e.g. overnight, and that the battery 40 will be needed to power some of the trailer systems such as the trailer interior lighting 66, the refrigerator 68, and/or the radiator system 70 for a sustained period of time without any regenerative charge being provided to the battery 40 via the electric motors 36, 38.

The controller 50 then determines a minimum SoC that the battery 40 must not fall below in dependence on the received data 80, 86, 88. For example, in a case where the battery 40 only needs to supply power to the trailer external lighting arrangement, then the determined SoC may be relatively low, for example 5% of the total capacity of the battery 40. However, if the trailer 10 includes a system that needs a significant amount of battery power to operate, such as the winch 62 for example, or if the driver has indicated that the trailer 10 will soon be parking for a significant period of time, or some other driver-selectable function, then the determined SoC may be relatively high, for example 30% of the total capacity of the battery 40. The determined minimum allowable SoC charge may increase for an increased number of electrical components 52, 54 requiring power from the battery 40. The controller 50 then notifies the BMS 42 of the determined minimum allowable SoC, and the BMS 42 is arranged to control the operation of the electric motors 36, 38 so that the battery SoC does not fall below the minimum SoC value. Note that the battery 40 must always have sufficient charge to operate the trailer external lighting arrangement when needed. Note also that instead of the controller 50 the BMS 42 may calculate the minimum allowable SoC of the battery 40 as well as controlling usage of the battery 40 to ensure that the actual SoC does not fall below the minimum allowable SoC.

The controller 50 is also used to report diagnostic issues relating to the trailer sensors and subsystems 52, 54 to the vehicle 12. For example, if there is a failure of one of the bulbs of the trailer external lighting system 52, then the system 52 send a signal 82 to the controller 50 to this effect. The controller 50 then sends a wireless signal or message 80 to the HMI 20 of the vehicle 12 indicating the bulb failure. The HMI 20 of the vehicle 12 may relay this information to the vehicle driver by means of a warning light for example. Similarly, the BMS 42 sends a signal 86 to the controller 50 indicative of the current SoC of the battery 40, this information being relayed to the vehicle HMI 20 via the wireless link 80. Furthermore, the trailer sensors and subsystems 54 may send a diagnostic signal 88 to the controller 50 with diagnostic information relating thereto. In particular, this diagnostic information can include one or more of: tyre pressure data from the tyre pressure sensors 64; video feature data (e.g. for a 'Transparent Trailer' feature) from the cameras 60; and, parking distance control data from the ultrasonic sensors 58. The controller 50 then sends the wireless signal 80 to the vehicle HMI 20 indicating the diagnostic update. As mentioned above, the controller 50 includes a wireless receiver to receive wireless messages 80 from the vehicle 12; however, the controller 50 also includes a wireless transmitter in order to send wireless messages 80 including diagnostic data to the vehicle 12. In turn, the vehicle 12 includes a wireless receiver to receive the wireless signals 80. The wireless transmitter and receiver of the controller 50 may be in the form of a wireless transceiver.

The presently described embodiment focusses on a trailer battery 40 that is used to supply power to various sensors and subsystems of the trailer 10. Clearly, this will deplete the stored charge of the battery 40. The charge of the battery 40 may be depleted or replenished in other ways. As mentioned above, the electric motors 36, 38 are used to provide regenerative braking torque to the trailer wheels 30, 32 to provide braking assistance and increased stability to the combination of the trailer 10 and vehicle 12. This regenerative braking to the trailer wheels 30, 32 will replenish the stored charge of the battery 40. In particular, the vehicle braking control system 22 senses when the vehicle brake pedal is depressed by the driver and this is communicated to the trailer 10 via the wireless signal 80. The electric motors 36, 38 then cause braking of the trailer wheels 30, 32 in response to this signal, thereby assisting with braking and stability of the combination of the vehicle 12 and trailer 10.

Also, the electric motors 36, 38 can be operated to provide drive torque to the trailer wheels 30, 32 to provide pull away assist to the vehicle 12. In such a case, utilising the electric motors 36, 38 to provide drive torque will deplete the stored charge of the battery 40. The different uses of the battery 40 are combined to ensure that a level of charge is maintained in order to carry out the required functions.

Figure 2 summarises the steps of a method 100 carried out by the system of components in the trailer 10. When the electric motors 36, 38 are used to cause braking torque to be applied to the trailer wheels 30, 32 then the electric motors 36, 38 provide regenerative braking energy to the battery 40 at step 102. This regenerated braking energy is stored in the battery 40 and used to supply 104 power to the trailer electrical components. In tandem, the controller 50 receives 106 the wireless control signal 80 from the vehicle 12, and then commands 108 the trailer external lighting arrangement 52, powered by the battery 40, to operate in accordance with the received wireless signal 80. Also in tandem, at step 1 10 the controller 50 receives signals 82, 88 indicative of diagnostic information from the trailer electric components 52, 54, and then at step 1 12 sends the wireless signal 80 including diagnostic data to the vehicle 12. The received signals 80, 82, 86, 88 from the vehicle 12 and trailer electrical components 52, 54 are also used at step 1 14 by the controller 50 or BMS 42 to determine the minimum allowable state of charge of the battery 40, and then the BMS controls the usage of the battery 40 and of the electric motors 36, 38 at step 1 16 to ensure that the current state of charge of the battery 40 does not fall below the determined minimum allowable value.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims. In the described embodiment, the electric machines 36, 38 are powered by the battery 40; however, other energy storage means, such as one or many capacitors, supercapacitor or ultracapacitors, may be used in combination with or instead of the battery. In the described embodiment, the trailer 10 has a single axle 34; however, in different embodiments the trailer 10 may have a plurality of axles connecting pairs of trailer wheels.

Claims

A system for use in a trailer towable by a vehicle, the system comprising: a trailer external lighting arrangement; energy storage means configured to supply electric power to the trailer external lighting arrangement; an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means; and, a controller configured to receive a wireless control signal from the vehicle and/or a control signal from the trailer, and to send a trailer external lighting control signal to operate the trailer external lighting arrangement in dependence on the received vehicle wireless control signal and/or the received trailer control signal.

A system according to Claim 1 , wherein the received vehicle wireless control signal includes data relating to operation of an external lighting arrangement of the vehicle.

A system according to Claim 1 or Claim 2, wherein the received trailer control signal includes an indication that the trailer has become uncoupled from the vehicle.

A system according to any previous claim, wherein the received trailer control signal includes an indication that the trailer speed is decreasing.

A system according to any previous claim, wherein the energy storage means is configured to supply electric power to at least one further trailer electrical component. A system according to any previous claim, wherein the at least one further trailer electrical component includes at least one of a recovery trailer winch component, a trailer interior lighting arrangement, a trailer refrigeration unit, a trailer tyre pressure sensor, a trailer radiator unit, one or more trailer vision sensors, one or more trailer ultrasonic sensors, and one or more trailer radar sensors.

A system according to any previous claim, the system comprising an energy storage management subsystem configured to control operation of the energy storage means.

A system according to Claim 5, the controller being configured to determine a minimum allowable state of charge of the energy storage means in dependence on received energy storage means state of charge data, and the controller being configured to notify the energy storage management subsystem of the determined minimum allowable state of charge.

A system according to Claim 6 when dependent on Claim 4, wherein the received energy storage means state of charge data includes data from the at least one further trailer electrical component.

A system according to Claim 7, wherein the minimum allowable state of charge is dependent on the number of trailer electrical components to which the energy storage means supplies electrical power.

A system according to Claim 8, wherein the minimum allowable state of charge increases for an increased number of trailer electrical components to which the energy storage means supplies electrical power.

A system according to any of Claims 6 to 9, wherein the received energy storage means state of charge data includes data from the vehicle representative of a state of a driver-selectable function within the vehicle.

A system according to any previous claim, wherein the controller is configured to transmit a wireless message to the vehicle, the wireless message including diagnostic data received from the trailer external lighting arrangement and/or the at least one further trailer electrical component.

A system according to Claim 1 1 , wherein the diagnostic data includes information indicative of a lighting failure in the trailer external lighting arrangement.

A system according to Claim 1 1 or Claim 12, wherein the diagnostic data includes information indicative of at least one of: a faulty trailer sensor; trailer tyre pressure data; parking distance control data; and, video feature data.

A system for use in a trailer towable by a vehicle, the system comprising: at least one trailer electrical component; energy storage means configured to supply electric power to the at least one trailer electrical component; an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means; and, a controller configured to transmit a wireless message to the vehicle, the wireless message including diagnostic data received from the at least one trailer electrical component.

A system for use in a trailer towable by a vehicle, the trailer comprising at least one trailer electrical component, energy storage means configured to supply electric power to the at least one trailer electrical component, and an electric motor coupled to at least one wheel of the trailer, the electric motor being configured to act as a generator to provide regenerative braking energy to the energy storage means, the system comprising: a receiver configured to receive energy storage means state of charge data from the vehicle and/or the at least one trailer electrical component; a processor configured to determine a minimum allowable state of charge of the energy storage means in dependence on the received energy storage means state of charge data; and, a controller configured to control operation of the electric motor such that a current state of charge of the energy storage means remains greater than the determined minimum allowable state of charge.

A method for use in a trailer towable by a vehicle, the trailer comprising a trailer external lighting arrangement, energy storage means, and an electric motor coupled to at least one wheel of the trailer, and the method comprising: providing regenerative braking energy from the electric motor to the energy storage means; supplying electric power from the energy storage means to the trailer external lighting arrangement; receiving a wireless control signal from the vehicle and/or a control signal from the trailer, and sending a control signal to operate the trailer external lighting arrangement in dependence on the received vehicle wireless control signal and/or the received trailer control signal.

A trailer for being towed by a vehicle, comprising a system according to any of Claims 1 to 17.

A non-transitory, computer-readable storage medium storing instructions thereon that when executed by one or more processors causes the one or more processors to carry out the method of Claim 18.