GB2552251A

GB2552251A - A system for steering a trailer towards a payload

Info

Publication number: GB2552251A
Application number: GB1708251.2A
Authority: GB
Inventors: Klemensas Vilemas
Original assignee: Securi-Cabin Ltd
Current assignee: Securi-Cabin Ltd
Priority date: 2016-05-24
Filing date: 2017-05-23
Publication date: 2018-01-17
Anticipated expiration: 2037-05-23
Also published as: IE20170110A1; IE87085B1; GB201708251D0; GB2552251B

Abstract

A self-steering steering system 1 for a trailer (2, Figure 1) for towing a payload (3, Figure 1), such as a construction site cabin, with a towing vehicle (4, Figure 1) is provided. Steering system 1 communicates between a target point 5 on the payload and a coupling point (5a, Figure 1) on the trailer to automatically self-steer the trailer to the payload while reversing the trailer to correctly orient and position it under the payload for loading it on the trailer. Steering system 1 comprises a steering wheelset 11 which is movable between an operating position and a non-operating position, suitably by lowering and lifting, and which may comprise a pair of steering wheels 13, 14 connected by a sway bar 16. The signal is received using a movable signal receiver 26, which may be a potentiometer or an infra-red signal receiver and which may be mounted on a motor 32.

Description

(54) Title of the Invention: A system for steering a trailer towards a payload

Abstract Title: Trailer steering towards payload with movable signal receiver (57) A self-steering steering system 1 for a trailer (2, Figure 1) for towing a payload (3, Figure 1), such as a construction site cabin, with a towing vehicle (4, Figure 1) is provided. Steering system 1 communicates between a target point 5 on the payload and a coupling point (5a, Figure 1) on the trailer to automatically self-steer the trailer to the payload while reversing the trailer to correctly orient and position it under the payload for loading it on the trailer. Steering system 1 comprises a steering wheelset 11 which is movable between an operating position and a non-operating position, suitably by lowering and lifting, and which may comprise a pair of steering wheels 13, 14 connected by a sway bar 16. The signal is received using a movable signal receiver 26, which may be a potentiometer or an infrared signal receiver and which may be mounted on a motor 32.

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A System for Steering a Trailer towards a Payload

Introduction

This invention relates to a steering system for a towed vehicle.

Background

Towed vehicles such as trailers, machinery, mobile homes, agricultural equipment and the like (hereinafter referred to collectively as trailers) can be difficult to steer in a desired direction from the towing vehicle. Steering of the trailer can be particularly difficult during reversing operations as the direction of movement of the trailer is generally counter-intuitive to the driver of the towing vehicle.

The difficulties associated with the reverse steering and positioning of trailers is well exemplified and particularly acute in the construction industry where employee welfare and other cabins are located temporarily at construction sites. Such cabins can be delivered to construction sites via heavy goods vehicles (HGV’s). However, lifting equipment such as a crane is therefore required to unload the cabins from and load the cabins on the HGV while HGV’s and the associated lifting equipment cannot be easily manoeuvred in confined or smaller sites. The use of HGV’s and lifting equipment also increases costs. In an attempt to address these problems, cabins have been manufactured on a trailer chassis and delivered to construction sites using conventional 4X4 vehicles. However, cabins incorporating a trailer chassis are significantly more expensive to produce than conventional cabins while the trailed cabins still prove difficult to steer and manoeuvre in reverse at construction sites. In particular, cabins having built-in trailers can still be almost impossible for drivers to manoeuvre in difficult or confined situations without the guidance of a third party.

Summary

According to the invention there is provided, as set out in the appended claims, a trailer steering system for steering a trailer to a payload comprising:

a steering wheelset movable between a non-operating position and a trailer supporting position;

a communication system for communicating between the steering wheelset and 10 a payload, the communication system comprising a signal receiver for receiving a signal from a payload, and a steering mechanism for steering the wheelset towards a payload in response to a received signal.

According to the present invention, there is provided a trailer steering system for steering a trailer to a payload comprising:

a communication system for communicating between the steering wheelset and 20 a payload, the communication system comprising a signal receiver for receiving a signal from a payload, a steering mechanism for steering the wheelset towards a payload in response to a received signal; and wherein the signal receiver comprises a movable signal receiver movable in 25 response to a signal.

Preferably, the steering wheelset comprises a pair of steering wheels. More preferably, the steering wheels are connected by a sway bar.

Suitably, the steering wheelset is mounted on a carriage attachable to a trailer.

Preferably, the communication system comprises a signal transmitter on a payload. More preferably, the signal transmitter comprises an IR signal transmitter and the signal receiver comprises an IR signal receiver.

Advantageously, the communication system further comprises a focusing lens for focusing an IR signal on the IR signal receiver.

Preferably, the signal receiver comprises a movable signal receiver movable in is response to a signal. More preferably, the movable signal receiver is mounted on a signal receiver motor rotatable in response to a signal. Most preferably, the signal receiver motor is communicable with a signal receiver position reader. Suitably, the receiver position reader comprises a signal receiver potentiometer or an IR signal receiver.

Preferably, the steering mechanism comprises a steering angle reader for reading the steering angle of the steering wheelset. More preferably, the steering angle reader comprises a steering angle potentiometer or an IR signal receiving steering instructor. The IR signal receiving steering instructor further comprises an IR receiver having a row of Light-Emitting Diodes (LEDs) in communication with a code reader having a row of parallel slots, and a corresponding row of LED receivers configured to be in communication with the code reader. Each row has a series of slots therein and each row is different, with each row having different spaced intervals between the slots to define a code or pattern. Ideally, the LEDs are spaced apart to match the parallel rows in the code reader and the plurality of LED receivers are spaced apart to match the arrangement of the LEDs on the IR receiver.

Advantageously, the steering mechanism comprises a hydraulically controlled steering mechanism. Preferably, the hydraulically controlled steering mechanism is connected to a steering wheelset motor.

In one embodiment, the trailer steering will have manual controls configured to override automatic steering at any time. This will be useful when cabin has been unloaded from trailer and the driver is driving away from the cabin where there may is obstructions that need to be avoided (Cabin legs for example).

In a further embodiment, the invention also extends to a trailer comprising a trailer steering system as hereinbefore defined.

Suitably, the trailer steering system is mounted on the underside of the trailer.

Preferably, the trailer is a construction site cabin trailer and the payload is a construction site cabin.

In one embodiment, the payload (i.e. cabin) is fitted with proximity sensors configured to detect when the trailer is completely clear of the payload (i.e. cabin) underside. This then resets the trailer steering system to centred position(disabling the automatic steering towards target).

In one embodiment the steering angle reader comprises a steering angle potentiometer or an IR signal receiving steering instructor comprising a row of LightEmitting Diodes (LEDs) in communication with a code reader and a corresponding row of LED receivers.

In one embodiment the signal receiver comprises a signal receiver potentiometer or an IR signal receiver comprising a row of Light-Emitting Diodes (LEDs) in communication with a code reader and a corresponding row of LED receivers configured to detect an IR signal from the trailer.

In one embodiment the IR signal receiving steering instructor is a fixed IR signal receiver.

In one embodiment the fixed IR signal receiver comprises a housing having a row of 20 sensors arranged within in a curved pattern and at least one slot positioned in front of at least one sensor.

In one embodiment the IR signal receiver is a fixed IR signal receiver.

In one embodiment the fixed IR signal receiver comprises a housing having a row of sensors arranged within in a curved pattern and at least one slot positioned in front of at least one sensor.

The steering system of the invention can be used with towed vehicles ranging from trailers to mobile homes but is particularly useful for transporting site cabins such as employee welfare cabins to construction sites. A single trailer fitted with the steering system of the invention can be used to meet transport requirements for a fleet of cabins e.g. cabins can be manufactured without built-in trailers and can be easily transported as required using the trailers of the invention. In addition, the self-steering steering system of the invention enables drivers of towing vehicles to retrieve cabins without requiring the assistance of third parties - even where blind spots occur. The use of a single trailer of the invention for multiple cabins also results in significant cost savings.

The steering system of the invention is autonomous and independent of the steering wheel of the towing vehicle thereby removing driver input from the positioning process while reducing susceptibility of the steering system of the invention to driver error. Moreover, as the target point on payloads is fixed by the steering system of the invention, it is not necessary for a driver to select the target point on payloads thereby further reducing the risk of driver error.

It should be understood that the signal receiver can be a receiver potentiometer or an IR signal receiver. The IR signal receiver comprises a row of Light-Emitting Diodes (LEDs) in communication with a code reader having a row of parallel slots, and a corresponding row of LED receivers configured to be in communication with the code reader. Each row has a series of slots therein and each row is different, with each row having different spaced intervals between the slots to define a code or pattern. Ideally, the LEDs are spaced apart to match the parallel rows in the code reader and the plurality of LED receivers are spaced apart to match the arrangement of the LEDs on the IR receiver. The pattern of slots on the code reader for the IR signal receiver are identical to pattern of slots on the code reader for the IR signal receiver steering instructor.

It should be understood that the steering angle reader can be a steering angle potentiometer or an IR signal receiving steering instructor. The IR signal receiving steering instructor further comprises an IR receiver having a row of Light-Emitting Diodes (LEDs) in communication with a code reader having a row of parallel slots, and a corresponding row of LED receivers configured to be in communication with the code reader. Each row has a series of slots therein and each row is different, with each row is having different spaced intervals between the slots to define a code or pattern. Ideally, the LEDs are spaced apart to match the parallel rows in the code reader and the plurality of LED receivers are spaced apart to match the arrangement of the LEDs on the IR receiver.

Brief Description of the Drawings

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

Figure 1 is schematic view from above of a trailer of the invention towed by a

4X4 vehicle in which the trailer is being automatically steered towards and under a payload in the form of an employee welfare cabin by the self-steering automatic steering system on the trailer;

Figure 2 is a side elevation of the trailer of Figure 1 detached from the towing 4X4 vehicle with the automatic self-steering wheelset in the trailer supporting position

i.e. in contact with the ground with the trailer road wheelset raised from the ground, and the cabin removed for clarity;

Figure 3 is an enlarged perspective view from above and one side of the selfsteering automatic steering system of Figure 1 during a reversing operation, and

Figure 4 is a plan view from above of the steering system of Figure 3. io Figure 5A is a view of the IR signal receiver and code reader. Figure 5B is a plan view of the code reader of the IR signal receiver and the corresponding code reader for the IR signal receiving steering instructor.

Figure 6A illustrates a plan view of a fixed IR signal receiver. Figure 6B illustrates a perspective view of the fixed IR signal receiver of Figure 6A.

Detailed Description of the Invention

Figure 1 shows a self-steering steering system in accordance with the invention generally indicated by the reference numeral 1 fitted on a trailer 2 for transporting a payload in the form of a cabin 3 with the trailer 2 being towed by a towing vehicle 4 such as a 4X4 commercial vehicle. As shall be explained more fully below, the steering system 1 on the trailer 2 is adapted to communicate between a target point 5 on the cabin 3 and a coupling point 5a on the trailer 2 to automatically self-steer the trailer 2 to the cabin 3, while reversing the trailer 2, to correctly orient and position the trailer 2 under the cabin for loading the cabin 3 on the trailer 2. The target point 5 can be a 50mm pin on the underside of the cabin 3. The cabin can be coupled to the trailer from any angle of approach. Once coupled, a turntable on the trailer chassis rotates so that the sides of the cabin are parallel to the side of trailer (direction of travel).

As shown particularly in Figures 2 to 4, the trailer 2 is made up of a chassis 6 for supporting the cabin 3 having two road wheelsets 7 each made up of a first road wheel 8 and an oppositely disposed second road wheel 9 either side of the chassis 6. The chassis 6 is further provided with a tow bar 10 for attachment to the towing vehicle 4 in conventional fashion.

io The steering system 1 for automatically self-steering the trailer 2 to the cabin 3 is mounted on the underside of the chassis 6 and is made up of a steering wheelset 11 mounted on a plate-like carriage 12. The steering wheelset 11 is movable between a raised non-operating position and a lowered ground contacting/trailer 2 supporting operating position in which the road wheelsets 7 are raised from the ground and the trailer 2 is supported entirely on the steering wheelset 11. The steering wheelset 11 is deployable into the trailer supporting position by lowering during reversing operations.

The steering wheelset 11 is typically smaller than the road wheelset 7 and has a first steering wheel 13 and a second oppositely disposed steering wheel 14 centrally mounted with respect to the trailer coupling point 5a on the underside of the carriage 12 and connected via a steering mechanism 15. The steering mechanism 15 is made up of a sway bar 16 extending between the first and second steering wheels 13,14 and connected to the first and second steering wheels 13,14 at respective first and second control arms 17,18. The first and second steering wheels 13,14 are joined to the control arms 17,18 by respective first and second axel rods 19,20 extending from the first and second steering wheels 13,14 to the control arms 17,18. Movement of the steering wheelset 11 is effected by a hydraulic cylinder 21 mounted on the carriage 12 having a hydraulic ram 22 connected to the sway bar 16 at a hydraulic ram mounting 23. The hydraulic cylinder 21 is driven by a steering wheelset motor 24 mounted on carriage 12. Although not illustrated, the wheelset can in fact be mounted anywhere on the trailer chassis.

The steering system 1 can communicate via a communication system 25 with the io target point 5 on the cabin 3 to direct the trailer 2 to the target point 5. The communication system 25 is made up of a rotatable signal receiver 26 mounted on the carriage 12 and a signal transmitter 27 on the target point 5 for transmitting a location indicating signal 28 to the signal receiver 26. In the present embodiment, the signal receiver 26 is an infra-red (IR) signal receiver 29 and the signal transmitter 27 is an IR signal transmitter 30. However, as will be appreciated by those skilled in the art, other signal types can be employed for the communication system 25.

The IR signal receiver 29 is provided with a focusing lens 31 disposed between the IR signal receiver 29 and the IR signal transmitter 30 to ensure that the IR signal receiver

29 is focused accurately and directly on the signal 28 originating from the IR signal transmitter 30. The IR signal receiver 29 is mounted on a signal-controlled receiver motor 32 so that the IR signal receiver 29 can rotate to follow the signal 28 and hence the target point 5 during a reversing operation. The IR signal receiver 29 is also connected to a receiver position reader in the form of potentiometer 33 mounted on the carriage 12 adjacent the receiver motor 32 by a receiver belt 34 to read and record the position of the IR signal receiver 29. The position of the IR signal receiver 29 (and hence the locus of the target point 5) is communicated to a control box 35 also mounted on the carriage 12 by a receiver communication cable 36.

As part of the steering system 15, a steering angle reader in the form of a steering angle potentiometer 37 is also mounted on the carriage 12 adjacent the control arm of the first wheel 13 and is connected to the control arm 17 and first wheel 13 via steering angle belt 38 to monitor the steering angle of the wheel 13 and hence the steering wheelset 11. The steering angle is communicated to the control box 35 via a io steering wheel angle communication cable 39.

In one embodiment, as illustrated in Figure 5A and 5B, the IR signal receiver 29 and the signal transmitter 27 is replaced with an IR signal receiver 50 and a row of LightEmitting Diodes (LEDs) 54. The IR signal receiver 50 is connected to a row of Light15 Emitting Diodes (LED) receivers 52 mounted on the carriage 12 to read and record the position of the IR signal receiver 50. The target point 5 on the cabin 3 transmits an IR signal, the receiver 50 on the carriage 12 responds and rotates until it is perpendicular to the centre of the signal being received. The row of Light-Emitting Diodes (LEDs) 54 are in communication with a code reader 56 having a plurality of rows of parallel slots 57a. Each row 57a has a series of slots therein, with each row 57a having different spaced intervals between the slots to define a code or pattern. The corresponding row of LED receivers 52 are configured to communicate with the code reader 56, which measures the angle the receiver 50 is pointing in. The wheelset 11, that is steering wheels 13, 14, also have an IR signal receiving steering instructor with a code reader 58 having a plurality of rows of parallel slots 57b. The IR signal receiving steering instructor also comprises an IR receiver having a row of LightEmitting Diodes (LEDs) in communication with a code reader 58 having a plurality of rows of parallel slots 57b, and a corresponding row of LED receivers configured to be in communication with the code reader 58 (as per the arrangement for the IR signal receiver 50).The pattern of slots 57a on the code reader 56 for the IR signal receiver 50 are identical to pattern of parallel slots 57b on the code reader 58 for the IR signal receiver steering instructor.

The code reader 56, 58 have a specific code produced by the plurality of parallel slots io 57a, 57b. Depending on how many LEDs 54 shine through the slots 57a of the code reader 56 and are picked up by the LED receivers 52, and also in what sequence they are in, this produces a code for a processor in the IR signal receiver 50. The processor instructs the hydraulic cylinder 21 through the control box 35 to move the steering wheels 13, 14, via the steering wheelset motor 24 mounted on carriage 12, to the same position on the IR signal receiving steering instructor code reader 58 as that of the code reader 46, that is, the direction the receiver 50 is pointing in is the same direction as the steering wheels 13, 14 will be facing in. The position of the IR signal receiver 50 is communicated to a control box 35 also mounted on the carriage 12 by a receiver communication cable 36. The steering angle is communicated to the control box 35 via a steering wheel angle communication cable 39.

In a further embodiment, as illustrated in Figures 6A and 6B, the IR receiver 29, 50 can be a fixed IR receiver 60. The fixed IR receiver 60 would be fixed rather than rotating to find the centre of the signal. The fixed IR receiver 60 comprises a housing

61 with a row of sensors 62 arranged within in a curved pattern and a narrow slot 64 in the housing 61 in front of the sensors 62. When the IR signal (see Arrow A) transmitted is detected by the IR receiver 60, depending on which sensor 62 in the row received the IR signal, the processor in the IR receiver 60 calculates the code position that the steering wheels 13,14 would need to move to. As described above, the position of the IR signal receiver 60 is communicated to a control box 35 also mounted on the carriage 12 by a receiver communication cable 36. The steering angle is communicated to the control box 35 via a steering wheel angle communication cable

39.

io As shall be explained more fully below, the control box 35 is in turn in connected via a control cable 40 to a hydraulic pump servo 41 to effect movement of the hydraulic ram 22 by the motor 24 to orient and self-steer the steering system 1 in response to a signal 28 received from the control box 35.

is In use, a payload such as a cabin 3 located at a height of about 1 m above ground can be loaded onto the trailer 2 attached to the towing vehicle 4 via the tow bar 10 as follows. Firstly, the IR signal transmitter 27 on the cabin 3 is activated to transmit the signal 28 and the driver of the towing vehicle 4 activates the steering system 1 to deploy the steering wheelset 11. The steering wheelset 11 is lowered hydraulically (not shown) either automatically or selectively by the driver upon commencement of a reversing manoeuvre. Lowering of the steering wheelset 11 could also performed mechanically if desired. Lowering of the steering wheelset 11 results in the road wheelsets 7 being raised from the ground so that only the steering wheelset 11 of the steering system 1 is in contact with the ground to support the trailer 1.

The driver then reverses the towing vehicle 4 and hence the trailer 2 towards the cabin

3. The trailer 2 is self-steered towards the cabin 3 and, more particularly, the coupling point 5a on the trailer 2 is directed towards the target point 5 on the cabin 3 without input from the driver as follows. The transmitting signal 28 is received by the IR signal receiver 29 via the focusing lens 31. During the reversing movement, the IR signal receiver 29 follows the focused signal 28 and remains oriented and aligned towards the signal 28, and hence the target point 5 on the cabin 3, by constant rotation and realignment afforded by the receiver motor 32.

io The orientation of the IR signal receiver 29 is continuously detected by the receiver potentiometer 33 or IR signal receiver 50 and communicated to the control box 35. Simultaneously, the orientation (steering angle) of the first steering wheel 13, and hence the steering wheelset 11, is continuously detected by the steering angle potentiometer 37 or the IR signal receiving steering instructor and communicated to the control box 35. The control box 35 then compares the signals from the receiver potentiometer 33 or the IR signal receiver 50 and the steering angle potentiometer 37 or the IR signal receiving steering instructor and calculates any adjustments necessary in the steering angle to steer the trailer 2 towards the cabin 3, i.e. the IR signal receiver 29 is constantly moved/re-aligned to the centre of the focused signal 28 so that the target point 5 is constantly targeted by the coupling point 5a which results in a corresponding movement/re-alignment of the steering wheelset 11. The trailer 2 is therefore quickly automatically self-steered accurately and safely to the cabin 3 without requiring the driver to perform difficult counter-steering calculations and manoeuvres.

In the embodiment described above, signal transmitter 27 and signal receiver 29 are IR signal transmitters and receivers 30,29. However, as will be appreciated by those skilled in the art, other signal types are also suitable for use in the steering systems 1 of the invention e.g. lasers, radio signals and the like.

The steering system 1 can be retro-fitted to an existing trailer 2 or incorporated into the trailer 2 during manufacture. The steering system 1 can be provided with its own power source or source its power from the towing vehicle 4 if desired.

io In one embodiment, the trailer steering will have manual controls configured to override automatic steering at any time. This will be useful when cabin has been unloaded from trailer and the driver is driving away from the cabin where there may obstructions that need to be avoided (Cabin legs for example).

In one embodiment, the payload {i.e. cabin) is fitted with proximity sensors configured to detect when the trailer is completely clear of the payload {i.e. cabin) underside. This then resets the additional trailer steering to centred position (disabling the automatic steering towards target).

The embodiments in the invention described with reference to the drawings comprise a computer apparatus and/or processes performed in a computer apparatus. However, the invention also extends to computer programs, particularly computer programs stored on or in a carrier adapted to bring the invention into practice. The program may be in the form of source code, object code, or a code intermediate source and object code, such as in partially compiled form or in any other form suitable for use in the implementation of the method according to the invention. The carrier may comprise a storage medium such as ROM, e.g. CD ROM, or magnetic recording medium, e.g. a memory stick or hard disk. The carrier may be an electrical or optical signal which may be transmitted via an electrical or an optical cable or by radio or other means.

In the specification the terms comprise, comprises, comprised and comprising or any variation thereof and the terms include, includes, included and including or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiments herein described which may be varied in construction and detail without departing from the scope of the invention.

Claims

Claims

1. A trailer steering system for steering a trailer to a payload comprising:

a steering wheelset movable between a non-operating position and a trailer 5 supporting position;

a communication system for communicating between the steering wheelset and a payload, the communication system comprising a signal receiver for receiving a signal from a payload, a steering mechanism for steering the wheelset towards a payload in response io to a received signal; and wherein the signal receiver comprises a movable signal receiver movable in response to a signal.
2. A trailer steering system as claimed in Claim 1 wherein the steering wheelset 15 comprises a pair of steering wheels.
3. A trailer steering system as claimed in Claim 2 wherein the steering wheels are connected by a sway bar.

20
4. A trailer steering system as claimed in any of Claims 1 to 3 wherein the steering wheelset is mounted on a carriage attachable to a trailer.
5. A trailer steering system as claimed in any of Claims 1 to 4 wherein the communication system comprises a signal transmitter on a payload.
6. A trailer steering system as claimed in Claim 5 wherein the signal transmitter comprises an IR signal transmitter and the signal receiver comprises an IR signal receiver.

5
7. A trailer steering system as claimed in Claim 6 wherein the communication system further comprises a focusing lens for focusing an IR signal on the IR signal receiver.
8. A trailer steering system as claimed in Claim 1 wherein the movable signal io receiver is mounted on a signal receiver motor rotatable in response to a signal.
9. A trailer steering system as claimed in Claim 8 wherein the signal receiver motor is communicable with a signal receiver position reader.

15
10. A trailer steering system as claimed in Claim 9 wherein the signal receiver position reader comprises a signal receiver potentiometer or an IR signal receiver comprising a row of Light-Emitting Diodes (LEDs) in communication with a code reader and a corresponding row of LED receivers.

20
11. A trailer steering system as claimed in any of Claims 1 to 10 wherein the steering mechanism comprises a steering angle reader for reading the steering angle of the steering wheelset.
12. A trailer steering system as claimed in Claim 11 wherein the steering angle

25 reader comprises a steering angle potentiometer or an IR signal receiving steering instructor comprising a row of Light-Emitting Diodes (LEDs) in communication with a code reader and a corresponding row of LED receivers.
13. A trailer steering system as claimed in Claim 11 or Claim 12 wherein the 5 steering mechanism comprises a hydraulically controlled steering mechanism.
14. A trailer steering system as claimed in Claim 13 wherein the hydraulically controlled steering mechanism is connected to a steering wheelset motor.

io 15. A trailer steering system as claimed in any preceding Claim and having manual controls configured to override automatic steering at any time.

16. A trailer steering system comprising a control module configured to compare the signals from a signal receiver and a steering angle reader and configured to is calculate adjustments necessary in the steering angle to steer the wheelset towards the payload; in which the payload is fitted with proximity sensors configured to detect when the trailer is completely clear of the payload underside; and in which the signal receiver comprises a movable signal receiver movable in response to a signal.

20 17. A trailer comprising a trailer steering system as claimed in any of Claims 1 to

16.

18. A trailer as claimed in Claim 17 wherein the trailer steering system is mounted on the underside of the trailer.

19. A trailer as claimed in Claim 18 wherein the trailer is a construction site cabin trailer and the payload is a construction site cabin.

20. A trailer as claimed in Claim 16 in which the proximity sensors are configured to

5 reset the trailer steering system to centred position.

21. A trailer as claimed in Claim 16, in which the steering angle reader comprises a steering angle potentiometer or an IR signal receiving steering instructor comprising a row of Light-Emitting Diodes (LEDs) in communication with a code reader and a io corresponding row of LED receivers.

22. A trailer as claimed in Claim 16, in which the signal receiver comprises a signal receiver potentiometer or an IR signal receiver comprising a row of Light-Emitting

Diodes (LEDs) in communication with a code reader and a corresponding row of LED
15 receivers configured to detect an IR signal from the trailer.

23. A trailer as claimed in Claim 21 wherein the IR signal receiving steering instructor is a fixed IR signal receiver.
20 24. A trailer as claimed in claim 24 wherein the fixed IR signal receiver comprises a housing having a row of sensors arranged within in a curved pattern and at least one slot positioned in front of at least one sensor.
25. A trailer as claimed in claimed in claim 22 wherein the IR signal receiver is a fixed

25 IR signal receiver.
26. A trailer as claimed in claim 25 wherein the fixed IR signal receiver comprises a housing having a row of sensors arranged within in a curved pattern and at least one slot positioned in front of at least one sensor.

Intellectual

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Office

Application No: GB1708251.2