Abstract:
A signal apparatus for a vehicle having at least one input at which signals are received from components associated with the vehicle. The received signals comprise an indication demand signal initiated by a driver of the vehicle and a lane detection signal produced by a lane detection apparatus indicative of the position of the vehicle relative to a lane of a highway. A processing means is arranged to produce an indication signal that is dependent upon both the indication demand signal and the lane detection signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of International Application No. PCT/GB2004/001598 filed Apr. 13, 2004, the disclosures of which are incorporated herein by reference, and which claimed priority to Great Britain Patent Application No. 0308912.5 filed Apr. 17, 2003, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to improvements in signal apparatus for a vehicle, especially but not exclusively for signalling the intent of a driver during a lane change manoeuvre on a highway.  
         [0003]     A lane change on a highway having multiple lanes such as a motorway or dual carriageway requires the use of an indicator by the driver during the lane change. The indicator, usually a lamp that can produce a flashing amber light visible at the side of the vehicle in which the driver wants to turn, warns other drivers that the vehicle is changing lane. After a lane change manoeuvre is complete the driver must cancel the indicator, as a self-cancelling mechanism will not operate during such a manoeuvre in many situations. Often drivers forget to cancel the indicator, which can prove annoying to other drivers.  
         [0004]     Some attempts have been made to overcome this problem using a timer to cancel the indicator after a predetermined time or number of flashes of the indicator. This does not provide a satisfactory solution, as the driver may not have completed the manoeuvre in the predetermined time.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     According to a first aspect, the invention provides a signal apparatus for a vehicle having at least one input at which signals are received from components associated with the vehicle, the received signals comprising an indication demand signal initiated by a driver of the vehicle and a lane detection signal produced by a lane detection apparatus indicative of the position of the vehicle relative to a lane of a highway, and a processing means which is arranged to produce an indication signal that is dependent upon both the indication demand signal and the lane detection signal.  
         [0006]     The processor may be arranged to produce the indication signal following receipt of an indication demand signal and cancel the indication signal when the lane detection signal indicates that the vehicle is at an appropriate position relative to the lanes of the highway. The vehicle may be considered to be at an appropriate position relative to the lanes by determining the heading angle of the vehicle relative to the lane. Most preferably, it is considered appropriate to cancel when the vehicle is going straight ahead in the lane, i.e. by checking that the vehicle is at a heading angle of approximately zero degrees relative to the heading of the lane.  
         [0007]     Checking the heading angle allows a vehicle to cross multiple lanes without the indicator auto-cancelling the cancellation only occurring at the end of the manoeuvre when the vehicle is travelling straight along its lane.  
         [0008]     The processing means may cancel the indication signal by cancelling the indication demand signal, i.e. returning it to it original state prior to the driver initiated demand. Alternatively, a cancel signal may be produced which is combined with the indication demand signal to produce the indication signal. The combination may be by way of a logical operation, perhaps by passing both through an AND gate.  
         [0009]     The processing means may be adapted to produce an indication demand signal after a driver initiated demand which continues even after a driver has indicated that the indication signal should be cancelled. This would prevent a driver cancelling a signal before a lane change has been completed.  
         [0010]     The processing means may learn over time whether or not the indication should be cancelled after the driver has demanded that it is cancelled. For example, where a driver persistently cancels the indication before a lane change is completed, the processing means may learn this driver behaviour. On all subsequent operations of the indicator a time delay may be applied which is equal to the average time delay between a driver cancelling the demand signal and the vehicle completing the manouevere as determined from the lane detection signal.  
         [0011]     Producing an indication signal that is dependent on both the indicator demand signal and a lane change signal allows the indicator to be cancelled when a manoeuvre has been completed. In this way, the driver no longer needs to remember to cancel the indicators. It also permits an indication to be cancelled at the correct time even if the vehicle changes lanes within a bend.  
         [0012]     The processing means may comprise an electronic circuit such as an ASIC. It may, alternatively, be distributed across a multiple of electronic circuits, possibly connected across a bus or wiring loom of a vehicle. The processing means may therefore be distributed around the vehicle.  
         [0013]     According to a second aspect, the invention provides a signal apparatus which includes: a turn signal indicator, which illuminates in response to an indication signal; an indicator switch, which is operable by a user to produce an indication demand signal; a lane detection apparatus, which produces a lane detection signal indicative of the position of a vehicle relative to the lanes of a multi-lane highway; and a processor, which references the indication demand signal with the lane detection signal to generate an indication signal.  
         [0014]     The indication signal produced by the processor may activate the turn signal following receipt of an indication demand signal and cancel the indicator when the vehicle is at an appropriate position relative to the lanes of the highway as indicated by the lane detection signal.  
         [0015]     The lane detection apparatus may include a camera, which is located on the vehicle such that a portion of the highway in front of the vehicle is included within its field of view. An example of such an apparatus is known from our earlier International Patent Application number PCT/GB02/02324, published under publication number WO02/092375, the disclosures of which are incorporated by reference herein.  
         [0016]     The indicator switch may comprise a stalk, which is located close to the steering wheel of a vehicle for operation by a driver as is known in the prior art. It may produce an indication demand signal which changes state when the driver moves the stalk. The stalk may include a latch, which holds the output of the switch in either a rest state or a demand state when operated by the driver.  
         [0017]     The processor may be arranged to cancel the indication signal regardless of whether the indicator is in the rest or the demand positions.  
         [0018]     The indication signal may in a simple arrangement comprise a flag, which is raised by the processor when an indication is needed and lowered when it is not needed.  
         [0019]     According to a third aspect the invention provides a method of operating an indicator of a vehicle during a lane change manoeuvre comprising initiating the indicator when an indication demand signal is received from an indicator switch and cancelling the indicator when a signal from a lane detection apparatus indicates that the vehicle has reached an appropriate position relative to the lanes of the highway.  
         [0020]     The method may also cancel the indicator when a cancel signal is received without waiting for the lane signalling apparatus to indicate that the appropriate position has been reached. Such a signal may be received if a driver of the vehicle operates the indicator switch to cancel the indicator.  
         [0021]     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  shows a side view of a vehicle fitted with a signal apparatus according to the present invention;  
         [0023]      FIG. 2  shows a view from the interior of the vehicle of  FIG. 1 , forwards through the front window showing the road ahead; and  
         [0024]      FIG. 3  shows a flowchart depicting the method carried out in the signal apparatus of  FIGS. 1 and 2 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     The vehicle  1  shown in the accompanying drawings is fitted with a set of indicators, of which only the front left indicator  116  is shown. These are mounted in the usual fashion at each corner of the vehicle and are arranged to be illuminated in sets, with each set comprising the indicators on the left or right hand side of the vehicle  1 .  
         [0026]     In order to control the indicators  116 , an indicator stalk  108  is provided in the region of steering wheel  106 . This is of the common design where the driver of vehicle  1  signals a demand for illumination of the indicators  116  of one set or the other by pushing the indicator stalk  108  up or down for (in the example shown in  FIG. 2  of the accompanying drawings where the indicator stalk  108  is mounted on the left hand side of the steering wheel  106 ) left or right sets respectively. The indicator stalk  108  latches in position once pushed and can be reset by the driver overriding the force of the latch or by the latch being released. In an alternative embodiment, the demand for indication is stored electronically by raising or lowering one or more flags and in which case a latch is not needed and a simple tap-up tap-down switch may be used.  
         [0027]     An icon  112  is provided on dashboard  110  in view of the driver, which lights to indicate illumination of the indicators  116  and hence remind the driver that they are indicating. Indicator control means  104  detects the indictor demand and flashes the relevant set of indicators in the usual manner.  
         [0028]     The vehicle is also fitted with a video camera  100  mounted behind front window  114 , which captures images of the view of the road ahead of the vehicle  1 . This is coupled to a lane detection apparatus  102 , which analyses the captured images to detect lane boundaries such as those at the edge  120  of the road  121  or those separating lanes  122 . The lane detection apparatus  102  fits the lane markings to a curve and uses this to calculate the heading angle and offset of the vehicle  1  relative to the lane boundaries  120 ,  122 .  
         [0029]     Although the indicator control means  104  and lane detection apparatus  102  are depicted as separate entities, the skilled man will envisage that these could be combined into one module, or one or more of the control means  104  and lane detection apparatus  102  could be combined into modules controlling other vehicle functions.  
         [0030]     The indicator control means  104  also acts to cancel the flashing of the indicators  116  once a lane change has been completed. It does this by releasing the latch of the indicator stalk  108 , hence cancelling the driver&#39;s demand for indication. The method that the control means  104  uses to determine whether to cancel the driver&#39;s demand is shown in  FIG. 3  of the accompanying drawings.  
         [0031]     In a first step  200 , the control means checks whether the driver has demanded indication by use of the indicator stalk  108 . If not, then the control means need take no further action other than to ensure the icon  112  has been extinguished  208 . The method then repeats back to the first step  200 .  
         [0032]     If the driver has demanded indication, the control means  104  checks  202  whether the vehicle  1  has moved to the centre of the next lane. It does this by checking the offsets from lane boundaries measured by lane detection apparatus  102 . The vehicle  1  is determined to have changed lane once it is roughly (typically within percent) in equidistant from the lane boundaries of the next lane in the indicated direction. Until this happens, the method is restarted from first step  200  to check whether the driver is still demanding an indication.  
         [0033]     Once the control means  104  has determined that the vehicle  1  is in the correct lane, it checks  204  whether the vehicle  1  is straight in the lane. It does this by checking that the vehicle  1  is at a heading angle of approximately zero (typically within a range of 5° from zero) with respect to the lane boundaries of the new lane. This check is repeated until the vehicle  1  is straight in the lane.  
         [0034]     Once the vehicle  1  is straight, the indication may be cancelled  206 . The latch is released, although in an alternative embodiment the indicator stalk  108  may be driven into the cancelled position by a solenoid or other actuator or, in the case where the demand is stored electronically, the demand flag may be cleared. The indicator icon  112  is extinguished  208  and the method returns to the first step  200  where the control means  104  waits for the driver to indicate a demand.  
         [0035]     In a further alternative, the control means  104  records if the driver cancels the demand before the method described above would have done. If the driver consistently does this, the control means may adjust when the method cancels the demand  206  by expanding the ranges of the lane offsets and heading angles in which the vehicle  1  is determined to be straight ahead in the appropriate lane. This is subject to a maximum limit from central in the lane and within a predetermined degrees of straight-ahead.  
         [0036]     In accordance with the provisions of the parent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this inventiono may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.