Patent Publication Number: US-2009219147-A1

Title: Object detection system

Description:
The present invention relates to object detection systems for vehicles comprising a tractor-trailer combination. The invention is particularly but not exclusively applicable to vehicles such as lorries. 
     According to an aspect of the invention there is provided an object detection system for a tractor-trailer vehicle combination comprising a sensor arrangement mounted on the trailer, the sensor arrangement being arranged to detect objects and to transmit, in the form of a wireless signal, information relating to detected objects to a receiver mounted on the tractor, the receiver being arranged to receive the wireless signal, the trailer comprising a component arranged to receive power from a power source on the tractor via a component power line which is arranged to be connected to the power source upon activation of the component, wherein the sensor arrangement is arranged to receive power from the component power line. 
     Advantageously an occupant of the tractor, e.g. driver, does not need to remember to switch the system on—it automatically powers up from the lamp power line. The system is thus a passive system. The driver can not (intentionally or unintentionally) neglect to turn the system on. 
    
    
     
       An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing in which 
         FIG. 1  shows a schematic representation of a lorry having an object detection system according to the invention. 
     
    
    
     Referring to  FIG. 1 , a lorry  10  includes a tractor  12  and a trailer  14 . The tractor  12  has a driver&#39;s cabin  16  which is where the driver sits when driving. Inside the driver&#39;s cabin is a display—in this embodiment the display is in the form of a display screen  18 . The display screen  18  is provided on a dashboard in the driver&#39;s cabin  16  such that it is in convenient view of the driver when driving. 
     A receiver in the form of a receiver antenna  20  is mounted on a rear part of the tractor  12  e.g. on a rear wall of the driver&#39;s cabin  16 . The receiver  20  is arranged to receive signals from a transmitter mounted on the trailer  14  as described in further detail below. The receiver  20  is connected to the display screen  18  by an electronic cable connection  22 . 
     The tractor  12  has a power source in the form of a battery  24  to provide electrical power to components of the lorry  10  requiring such power. For example, the ignition mechanism is powered by the battery  24 . When the driver activates the ignition mechanism for the engine of the tractor  12 , a connection is made between the ignition mechanism power feed line and the battery  24 . The receiver  20  is connected to the ignition mechanism power feed line and thus is always able to receive power when a key is correctly inserted in the tractor  12 —therefore it is also able to obtain power from the battery  24  whenever the engine is running. The connection between the receiver  20  and the ignition mechanism is via a cable running from the receiver to the ignition mechanism. The lights at the rear of the trailer  14  are also powered by the battery  24  when the tractor  12  and the trailer  14  are joined together. When the tractor  12  and trailer  14  are joined together a cable connection is made between the tractor  12  and its battery and the trailer  14  in a known manner. 
     Amongst other components, lights provided at the rear end of the trailer  14 , e.g. brake lights  26  and reversing lights  26 ′, are powered by the battery  24 . A power feed line  25  connects the battery  24  to the brake lights  26  via a connector  27  which connects electronic cables on the tractor  12  to cables on the trailer  14 . Similarly a power feed line  25 ′ connects the battery  24  via the connector  27  to the reversing lights  26 ′. Object detection sensors  28 ,  30  are mounted at a rear end of the trailer  14  on each side of the trailer  14 . The connector  27  does not include a connection for providing power to any object detection sensor. Each object detection sensor  28 ,  30  is arranged to detect whether or not there is an object within a predetermined distance of the sensor. Sensors are provided on each side of the trailer  14  so that information can be obtained regarding the position of a nearby object relative to the sides of the trailer  14 , i.e. it can be determined whether the object is towards the right side or the left side of the trailer. 
     Each sensor  28 ,  30  is connected to an electronic control unit  32  by a wire connection. In other embodiments any suitable connection may be used e.g. wireless or they may be mounted on the same circuit board. The electronic control unit  32  is further connected by a wire connection to a transmitter  34  mounted near a front end of the trailer  14 . The electronic control unit  32  is arranged to obtain information from the sensors  28 ,  30  regarding nearby objects e.g. their proximity and location. The electronic control unit  32  is also arranged to send this information to the transmitter  34  for transmission. The electronic control unit  32  also has a cable connection to the brake lights  26 , and in particular to the brake light power feed line  25  such that when the brake lights  26  are receiving power the electronic control unit  32  is able to receive power. Similarly the electronic control unit  32  has a cable connection to the reversing lights  26 ′, and in particular to the reversing light power feed line  25 ′ such that when the vehicle is reversing and the reversing lights  26 ′ are activated and receiving power, the electronic control unit  32  is also able to receive power. When the electronic control unit  32  receives power it is able to provide power to the sensors  28 ,  30  and transmitter  34 —i.e. it can receive information from the sensors  28 ,  30  and transmit this information via the transmitter  34 . The transmitter  34  is arranged to transmit a wireless signal which the receiver  20  is capable of receiving. In this embodiment the wireless signal is a RF signal—in other embodiments it may be any other suitable type of wireless signal. 
     In use, a driver connects the tractor  12  to the trailer  14  and cables of the tractor  12  are connected to cables of the trailer  14  via the connector  27 . When it is desired to reverse the lorry  10  and an object is in the proximity of the reversing path then the driver needs to be alerted of the presence of the object. Initially after the tractor  12  and trailer  14  have been connected together the driver will move the lorry  10  forwards and activate the brakes. This braking operation is often used by the driver to check that the tractor and trailer are correctly connected together, that the connector  27  is correctly attached and that the trailer brake mechanism in particular is correctly connected and working. In some countries this operation must be carried out by law for safety reasons. Once the brakes are activated the brake light  26  is powered up and consequently the electronic control unit  32  also receives power. Advantageously the electronic control unit  32  is initially powered up from the brake light  26  power feed and not any other light. This is because the brake light is the first light to be activated and is activated before any significant amount of driving takes place. In this way, the object detection system is automatically operational before driving. The driver does not need to remember to activate the system. It is also a known problem that some drivers intentionally do not activate known object detections systems since they can be awkward to use. 
     The electronic control unit  32  requires very little power to transmit information via the transmitter  34 . Therefore once the brake light  26  has initially received power, the electronic control unit  32  is powered up. When the electronic control unit  32  is powered up after the trailer  14  is first attached to the tractor  12 , it generates a randomly encoded “rolling code” locking signal. This locking signal comprises an identification part which effectively provides identification of the transmitter  34 , and hence the trailer  14 , from which it is emitted. This is because the identification part of the signal is unique to a particular ECU  32  and is fixed i.e. it does not vary each time a new signal is generated. The rest of the signal does vary randomly for security reasons in accordance with well known “rolling code” systems. Each time that the connector  27  is used to attach a trailer  14  to a tractor  12 , this identification signal is generated and transmitted by the electronic control unit  32  when the brakes are first activated. The transmitter  34  is arranged to transmit the encoded locking signal under instruction from the electronic control unit  32  once the signal has been generated. After the brakes have initially been activated, then deactivated and the identification signal has been generated and transmitted, the electronic control unit  32  remains in standby mode without any further power source since it receives enough power in the initial period in which the brakes were activated to remain in this mode—the ECU  32  does not require much power to remain in the standby mode. 
     The receiver  20 , which is powered up from the ignition power feed line, receives the encoded locking signal which provides identification of the trailer  14  to which the tractor  12  (which mounts the receiver  20 ) is attached. The receiver  20  is then arranged to only receive further signals identified as originating from the transmitter  34  on the trailer  14 . This identification is possible since all further transmissions from the transmitter  34  will be signals which include the same encoded identification part. The receiver  20  has an associated memory which is arranged to store details of the identification part of the locking signal and also a processor which is arranged to compare any incoming signals to the stored identification part to ensure that only signals having this identification part are accepted for processing. In this way it is ensured that signals from transmitters other than the transmitter  34  originating from the electronic control unit  32  and the trailer  40  are not received and processed. This identification part is included in all transmissions from the transmitter  34  until the tractor  12  and trailer  14  are disconnected. Following disconnection, signals having the previously correct identification part are no longer accepted for processing (i.e. the identification part becomes invalid) and a new identification part associated with a different transmitter will be provided if and when another trailer is connected to the tractor  12 . In some embodiments when the tractor and trailer are initially joined and the identification signal is sent, the driver receives an audible or visual or audiovisual alert via the display  18  when the receiver  20  receives the identification signals. 
     As the lorry  10  is reversing, the reversing lights  26 ′ are activated and the sensor arrangement including the sensors  28 ,  30  is powered up via the connection between the power feed line  25 ′ and the battery  24 . An object comes into detection range of one of the object detection sensors  28 . In this embodiment the detection range is about 3 metres from the sensor. In other embodiments different, known sensors may be used and the detection range will vary. Whilst the sensor  28  does not detect any object (i.e. the object is outside the detection range) this information is sent to the electronic control unit  32  which does not transmit any information regarding the detection of an object via the transmitter  34 . Once an object is detected by the sensor  28  the electronic control unit  32  receives information regarding the proximity of the object and its location (according to which sensor  28 ,  30  has detected the object). This information is transmitted via the transmitter  34 . The receiver  20  receives the transmitted information and relays it to the display screen  18  where a visual indication is provided to the driver that an object has been detected within the range of detection of the sensor  28  and towards the side of the lorry  10  upon which the relevant sensor  28  is located. 
     Also the sensor  28  is able to provide information to the electronic control unit  32  regarding the precise distance between the object and the sensor and this information can also be relayed via the transmitter  34  to the driver. Also, the location of the object relative to the sensor  28  or a side of the trailer  14  can also be determined by the sensor  28 . This information is also relayed to the driver in the same way. The display  18  also includes an audible alert for the driver. Initially when an object is detected the audible alert is a series of short beeps. As the object becomes closer to the sensor  28  the beeps become more frequent until such time as the object is a predetermined minimum allowed distance from the sensor and the audible alert changes to a constant tone. At this point the driver should stop. In this embodiment, the visual display comprises a series of LEDs which indicate the distance of an object from the sensor and which side of the vehicle the object is detected on. 
     Advantageously this object detection system requires no additional power source on the trailer  14 . It is initially powered up automatically when the brake light is first operated after the tractor and trailer are joined together and then it uses power from the reversing power feed line during its continued operation. Therefore, no driver/user input is required to switch the system on. 
     When two lorries  10 ,  10 ′ are in close proximity and possibly both reversing together there may be a possibility of signal contamination between transmitters  34 ,  34 ′ and receivers  20 ,  20 ′. The electronic control unit  32  encodes the signal transmitted from the transmitter  34  so that it can only be read by its corresponding receiver  20  (i.e. the receiver mounted upon the tractor attached to the trailer which mounts the transmitter  34 ) and not another receiver  20 ′ mounted upon a different tractor. The electronic control unit  32 ′ performs a similar encoding operation. This is possible since the encoding system is initially activated when the trailer  14  is attached to the tractor  12  for the first time so that the receiver  20  will only receive signals from the transmitter  34  provided on the trailer  14  to which the tractor  12  is attached. When the tractor  12  and trailer  14  are first attached and the brake light is first activated the receiver  20  receives a first encoded signal as described above. The signal includes an identification part identifying the transmitter  34  (and hence trailer  14 ) from which it has originated. The receiver  20  is arranged to then only receive signals from this transmitter  34  (i.e. signals encoded with the relevant identification part) until the connector  27  is disconnected i.e. the tractor  12  and trailer  14  are disconnected. After disconnection, the receiver  20  will not receive further signals until the connector  27  is used to connect another trailer to the tractor  12 . For example, if the tractor  12  is connected to the trailer  14 ′, the receiver  20  is able to receive signals from the transmitter  34 ′. 
     Advantageously, a large number of lorries in close proximity can use the object detection system of the present invention without the possibility of a tractor receiver picking up a trailer transmission from a trailer to which it is not connected. 
     Various modifications may be made to the embodiment described above. For example, the display may be in the form of LEDs or any other suitable visual display. The audio alert may take any other suitable form. Any combination of audible, visible or both display means may be provided. 
     A single sensor at the rear of the trailer may be sufficient to detect objects. Alternatively, more than two sensors may be provided. The sensors may not provide accurate information regarding the distance between a detected object and the sensor—instead the sensor may only be able to detect whether or not the object is within a predetermined distance limit/proximity range. The sensor may also not be able to provide accurate location information—instead the driver will only have information concerning which sensor has detected the object. The driver or another operator may be able to alter the distance at which the sensor detects an object—this may vary according to various factors e.g. driver&#39;s skill/driving conditions etc. 
     The transmitter may be provided at a different location on the trailer e.g. towards the rear of the trailer nearer to the sensor(s). Communication between the sensors and electronic control unit or the control unit and transmitter or the receiver and display may be wireless. 
     The electronic control unit and sensor or electronic control unit and transmitter or all of these components may be provided in the same housing. The transmitter may be provided spaced from a rear of the trailer e.g. towards its centre. 
     In some embodiments a separate transmitter/receiver or both may be provided for the part of the system which sends the identification part of the signal and the part of the system which sends signals relating to detected objects. Some means of communication must be provided between the two parts of the system in order to ensure that signals relating to detected objects are only received and processed at the relevant receiver when they originate from the correct transmitter (and thus, trailer). 
     In some embodiments a component mounted on the trailer, other than a lamp, which is powered by a power source on the tractor may be used in conjunction with its power feed line to provide power to the, or each, electronic control unit.