GB2512897A

GB2512897A - A method for reducing the risk of motor vehicle collision damage

Info

Publication number: GB2512897A
Application number: GB1306518.0A
Authority: GB
Inventors: Themi Philemon Petridis; Nils Schloesser
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2013-04-10
Filing date: 2013-04-10
Publication date: 2014-10-15
Also published as: DE102014206248A1; CN104097591B; CN104097591A; GB201306518D0

Abstract

A method and system for reducing the risk of damage to an object 10, 11 mounted on a rear of a motor vehicle 1 having a rear parking system 3, 8 during a reversing manoeuvre is disclosed. If an object such as a carrier 10 or bicycle 11 carried by the carrier 10 are sensed by a sensing system 2, 9 to be in position, a calibration for the rear parking system 3, 8 is adjusted to increase the distance from the rear of the vehicle 1 that an obstruction to the rear of the motor vehicle 1 is indicated by the rear parking system 3, 8 as being a high collision risk.

Description

A Method for Reducing the Risk of Motor Vehicle Collision Damage This invention relates to a motor vehicle and in particular to a method for reducing the risk of damage to an object carried on a rear end cf the mctcr vehicle.

It is known from, for example US Patent 4,830,250 and FR-A-2,531,669 to provide an aftermarket rack or carrier that can be fitted to a motor vehicle for carrying an object such as a bicycle on a rear end of a motor vehicle. It is a problem with such a carrier that the carrier and an cbject carried by the carrier will overhang cr protrude from the rear end of the motor vehicle.

Therefore, if a cycle carrier has been fitted to the rear of a vehicle, the ability of a rear parking system to accurately indicate to the driver a safe distance to an object when reversing, will be reduced. The feedback from sensors forming part of the rear parking system will be erroneous because they are calibrated to provide an output indicating the proximity of an obstruction to the rear end of the vehicle and not the proximity of the obstruction to an object carried by such a carrier. This means that the carrier or cycles might hit an object during a reversing manoeuvre whilst the parking sensors indicate that it is still safe to reverse.

It is an object of this invention to provide a method and apparatus to overcome the problems associated with the use of such a rear mounted carrier and, in particular, to prevent accidental collision damage to such a carrier and/or an object carried by the carrier.

According to a first aspect of the invention there is provided a method for reducing the risk of damage during a reversing manoeuvre to an object mounted on a rear end of a motor vehicle having a rear parking system wherein the method comprises checking whether an object is mounted on the rear of the motor vehicle and, if an object is confirmed to be so mounted, adjusting the calibration of the rear parking system to allow for the protrusion of the object.

Adjusting the calibration of the rear parking system may comprise adjusting the calibration so that a high collision risk is indicated for an obstruction spaced further away from a reference point at the rear end of the motor vehicle than the distance from the reference point indioated as being a high collision risk when a standard calibration is used.

Adjusting the calibration of the rear parking system may comprise automatically adjusting the calibration of the rear parking system so that an obstruction spaced from the rear end of the motor vehicle by a distance estimated to be equivalent to a distance the cbject is predicted to protrude from the rear end plus a safety margin will be indicated as being a high collision risk.

The safety margin may be the distance an obstruction spaced from the rear end of the motor vehicle is indicated as being a high collision risk when using the standard calibration.

Adjusting the calibration cf the rear parking system may comprise manually adjusting the distance from the rear end of the motor vehicle indicated as being a high collision risk.

A driver of the motor vehicle may be provided with an opportunity to choose whether or not to use an adjusted calibration for the rear parking system.

If the driver chooses not to use an adjusted calibration for the rear parking system, a standard calibration for the motor vehicle may be used.

The method may further comprise warning the driver if an object is in positicn on the rear cf the motor vehicle and the driver has chosen not to use the adjusted calibration.

The object may be one of a bicycle carrier mounted on the rear of the motor vehicle and one or more bicycles carried by a carrier mounted on the rear of the motor vehicle.

According to a second aspect of the invention there is provided a detection system for detecting whether an object mounted on a rear of a motor vehicle is at risk of collision with an obstruction during a reversing manoeuvre wherein the detection system comprises a rear parking sensor system to sense whether an obstruction is present and an object detection system to detect whether an object is mounted on the rear of the motor vehicle and, if an object is sensed to be mounted on the rear of the motor vehicle, a calibration value for the rear parking system is adjusted to allow for the protrusion of the object.

Adjusting the calibration of the rear parking system may comprise adjusting the calibration so that a high collision risk is indicated for an obstruction spaced further away from a reference point at the rear end of the motor vehicle than the distance from the reference point indicated as being a high collision risk when a standard calibration is used.

The system may include an electronic controller and adjusting the calibration of the rear parking system may comprise using the electronic controller to automatically adjust the calibration of the rear parking system so that an obstruction spaced away from the rear end of the motor vehicle by a distance estimated to be equivalent to a distance the object is predicted to protrude from the rear of the motor vehicle plus a safety margin will be indicated as being a high collision risk.

The system may comprise an electronic controller and a human machine interface and adjusting the calibration of the rear parking system may comprise using driver inputs to the human machine interface to manually adjust the distance from the rear of the motor vehicle indicated as being a high collision risk.

The system may include an electronic controller and a human machine interface and the human machine interface may be used to provide a driver of the motor vehicle with an opportunity to choose whether or not to use an adjusted calibration for the rear parking system.

If the driver chooses not to use an adjusted calibration for the rear parking system, a standard calibration stored in an electronic device may be used.

If an object is in position on the rear of the motor vehicle and the driver has chosen not to use the adjusted calibration, the human machine interface may be used to warn the driver of their decision.

The object may be one of a bicycle carrier mounted on the rear end of the motor vehicle and one or more bicycles carried by a carrier mounted on the rear end of the motor vehicle.

According to a third aspect of the invention there is provided a motor vehicle having a detection system constructed in accordance with said second aspect of the invention.

The invention will now be described by way of example with reference to the accompanying drawing of which:-Fig.1 is a schematic diagram of a motor vehicle according to a third aspect of the invention has a detection system according to a second aspect of the invention; Fig.2 is a flow chart of a first embodiment of a method according to a first aspect of the invention; Fig.3 is a flow chart of a second embodiment of a method according to the first aspect of the invention; and Fig.4 is a flow chart of a third embodiment of a method according to the first aspect of the invention With reference to Fig.1 there is shown a motor vehicle 1 having a carrier 10 mounted on a rear end 7 thereof for carrying an object such as a bicycle 11 and a detection system 20. The motor vehicle 1 when moving forward travels in the direction of the arrow F' shown on Fig.l and has a source of motive power (not shown) driving the motor vehicle 1 via a transmission (not shown) having at least forward and reverse drive modes. In the case of a geared transmission the reverse drive mode is entered when a reverse gear is engaged.

The detection system 20 comprises of a primary electronic controller 30, a first sensing unit 2 operably connected to the electronic controller 30 and having an object detection sensor 9, a second sensing unit 3 operably connected to the electronic controller 30 and having a pair of reversing sensors 8, a reverse drive sensor 18, an audible output device 15 and a human machine interface (USC) 4 including a screen 5 and operator input means 6.

The first sensing unit 2 is arranged to detect using the sensor 9 whether the carrier 10 or the bicycle 11 are present on the rear of the vehicle 1. The sensor 9 can be of any suitable known type such as, for example and without limitation, an ultrasonio proximity sensor, an infra-red sensor and an optioal detector. If the signal or signals from the sensor 9 provided to sensing unit 2 indicate that at least one of the carrier 10 and the bicycle 11 is present, a corresponding signal is sent to the electronic controller 30. This could be a simple binary signal such as zero equals no carrier or bicycle present and one equals a carrier 10 and/or a bioyole 11 present or could be more complex indicating whether it is simply a carrier 10 that is present or a carrier 10 and one or more bicycles 11 that are present.

The second sensing unit 3 is arranged to detect via the sensors 8 whether there is an object located in close proximity to the rear of the motor vehicle 1. That is to say, the sensing unit 3 and the sensors 8 form a rear parking sensor system. The type of sensor 8 used and the operation of the rear parking sensor system are in most respects conventional in construction and any known type of rear parking sensor system can be used. The second sensing unit 3 is connected to the electronic controller 30.

It will be appreciated that although the first sensing unit 2, the second sensing unit 3 and the electronic controller 30 are shown in Fig.1 as separate components they could be formed as a single central controller.

Furthermore, the audible warning device 15 could be directly connected to the second sensing unit 3 as could the HFC 4.

In a first operational embodiment the detection system operates as follows.

If the reverse drive sensor 18 indicates that a reverse drive mode has been selected, the reversing sensors 8 and the object detection sensor 9 are activated along with their respeotive sensing units 3, 2.

If the output from the object detection sensor 9 indicates that a carrier 10 or carrier 10 and bicycle 11 are not present on the rear end 7 of the motor vehicle 1, the first sensing unit 2 indicates this to the electronic controller 30 and no further action is taken. That is to say, the calibration and operation of the rear parking system is unaffected and will functional normally.

However, if the output from the object detection sensor 9 indicates that a carrier 10 or carrier and bicycle 11 is present on the rear end 7 of the motor vehicle 1, the first sensing unit 2 indicates this to the electronic controller 30.

The electronic controller 30 in response to the input from the first sensing unit 2 then automatically adjusts the calibration used by the second sensing unit 3 to account for the presence of the carrier 10 and/or the carrier 10 and a bicycle 11. That is to say, an altered or adjusted calibration is used by the second sensing unit 3 to determine whether there is an object in close proximity to the rear of the motor vehicle 1 as redefined by the presence of the carrier 10 or carrier 10 and bicycle 11.

Fig.i shows an example of one approaoh used for adjusting the calibration. In the case of a standard calibration an obstruction O is indicated as being a high risk of collision when the distance between a reference point which in this case is the rear end 7 of the motor vehicle 1 and the obstruction 0-reduces to a value less than a safety distance 0' . In the case of an adjusted calibration to allow for the carrier 10 and the bicycle 11, an obstruction 02 located a distance (StX) from the reference point namely the rear end 7 of the motor vehicle 1 will be indicated as a high collision risk. That is to say the calibration for the extent of a high collision risk zone has been inoreased from 0' for the standard calibration to (S-X) for the adjusted calibration. The value of X' in this case is the actual distance that the carrier 10 and the bicycle II protrude from the rear end 7 of the motor vehicle 1 but could be a different value that is not directly related to the actual distance that the carrier 10 and bicycle 11 protrude. For example X' could be set to allow for a worst case state when four bicycles 11 are mounted on the carrier 10.

One example of this change in calibration could be applied is given in Table 1 where Distance is the distance from the known reference point such as the position of the sensors 8, Warning 1 represents the result using a standard calibration and Warning 2 represents the result using an adjusted calibration.

Distance (m) Warning 1 Warning 2 0 to 0.35 High High 0.35 to 0.75 Medium High 0.75 to 1.15 Low Medium 1.15 to 1.55 None Low 1.55+ None None

Table 1

In this example X' = 0.4m and S = 0.35m In the case of the standard Warning 1 calibration, a high warning such as a continuous sounding of the audible warning device 15 and/or a red visual output via the screen 5 of the dM1 4 is not given until the reference point on the vehicle 1 is less than 0.35m from a detected object whereas in the case of the Warning 2 calibration used when the carrier 10 is present, the high warning is provided as soon as the reference point on the vehicle 1 is within O.75m of a detected object.

As is well known in the art, the medium and low Warnings are less frequent soundings of the audible warning device 15 and/or non-red visual outputs respectively. The types of warnings described hereinbefore are provided by way of example only and the invention is not limited to these particular types of warning.

In a second operational embodiment the deteotion system 20 operates exactly as described with reference to the first operational embodiment with the exception that prior to using the adjusted calibration for the parking sensor system the driver is given the opportunity to decide whether to use the adjusted calibration or not.

That is to say, when a carrier 10 is detected to be in position and reverse gear is selected, a message is sent to the driver via the soreen 5 of the HMI4 such as "Carrier Detected, Do you wish to select Carrier Parking Sensor Calibration".

The driver can then either use the inputs 6 to respond or if the screen 5 is a touch screen device respond via the touch screen 5. A further option is a voice activated command if the vehicle 1 is equipped with such a system as part of the dM1 4.

-10 -If the driver chooses not to change the calibration then the standard calibration (Warning 1 in Table 1) is used and if they choose to adjust the calibration then the adjusted calibration (Warning 2 in Table 1) is used.

Although in the first and seoond operational embodiments there are only two calibrations Standard' and Adjusted' it will be appreciated that there could be more than two calibrations.

For example, if the sensor 9 and the first sensing unit 2 are able to estimate the distanoe that the carrier 10 or carrier 10 and bicycle 11 protrude from the reference point, the adjustment of the calibration could be based upon this estimation. In this case the adjusted calibration would vary based upon the magnitude of the sensed protrusion.

As a further example there could be a first small magnitude adjusted calibration if only the carrier 10 is present and a second larger magnitude adjusted calibration if the carrier 10 and one or more bicycles 11 is present.

In a third operational embodiment the detection system operates as follows.

If the reverse drive sensor 18 indicates that a reverse drive mode has been selected, the reversing sensors 8 and the object detection sensor 9 are activated.

If the output from the object detection sensor 9 indicates that a carrier 10 or a bicycle 11 is not present on the rear end 7 of the motor vehicle 1, the first sensing unit 2 indicates this to the electronic controller 30 and no further action is taken. That is to say, the calibration and operation of the rear parking system is unaffected and will functional normally.

-11 -However, if the output from the objeot detection sensor 9 Indicates that a carrier 10 or a bicycle 11 is present on the rear of the motor vehicle 1, the first sensing unit 2 indicates this to the electronic controller 30.

The electronic controller 30 then sends a message to the driver via the screen 5 on the HMI4 such as "Rear Carrier Detected. Do You Want To Adjust Parking Sensor Calibration".

If the driver chooses not to change the calibration then the standard calibration (Warning 1 in Table 1) stored in an electronic device is used and if they chcose tc adjust the calibration then they are able to enter via the HMI 4 a value for the desired adjustment. The electronic device may form part of the electronic controller 30 or may be part of another electronic unit.

This could be in the form cf a list of cpticns such as: Carrier Only; Carrier and one bicycle; Carrier and two bicycles; etc. The driver is given the opportunity to select one of the options and a corresponding adjustment is automatically made to the calibration of the parking sensor system.

Alternatively, the driver via the HMI 4, can adjust the calibraticn used by the second sensing unit 3 to acccunt for the presence of a carrier 10 and/or carrier 10 and bicycle 11. That is to say, the driver enters a value equal to a desired increase in distance required to account for the load being carried.

For example, if the extra prctrusicn frcm the rear of the vehicle 1 due to the carrier 10 and the carried bicycle 11 is 0.75m the driver would enter 0.75 as the adjustment -12 -required and an altered or adjusted calibration corresponding to this value is then used by the second sensing unit 3 to determine whether there is an object in close proximity to the rear of the motor vehicle 1 as redefined by the presence of the carrier 10 or carrier 10 and bicycle 11. That is to say, the standard calibration distance 3' shown on Fiq.l is increased by 0.75m so that the new calibration for high risk of collision is equal to 3' plus 0.75m. It will be appreciated that with all of the adjustments made to the calibration the correction is not necessarily seen by the second sensing unit 3 in terms of an actual distance but normally in terms a change in threshold signal level required to produce a high risk of collision alert.

Information could be provided in a user manual regarding the adjustment required for various carrier and bicycle arrangements or could be obtained via an actual measurement made by a user of the motcr vehicle 1.

With reference to Fig.2 there is shown a first embodiment of a method 100 for reducing the risk of damage to an object carried on a rear part of the motor vehicle.

The method starts in box 110 which is key-on' event followed by an engine start resulting in an engine of the motor vehicle 1 running. The method advances to box 115 where it is checked whether a reverse drive mode has been selected. If reverse has not been selected, the method loops around box 115 because the rear parking system is only active in this case if the vehicle is likely to move in a rearward direction.

If reverse has been selected, the method advances to bcx 120 where it is checked whether a carrier such as a cycle rack is mounted on the rear of the motor vehicle 1.

It will be appreciated that the invention is equally -13 -applicable to any carrier fitted to the rear of the motor vehicle 1 and is not limited to a bicycle rack.

If it is determined that a carrier 10 is not fitted, the method advances to box 145 where a standard calibration is used for the rear parking system and the rear parking system operates in accordance with that calibration. The method then advances to box 155 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 120 and, if it is not, the method ends at box 195.

If in box 120 it is confirmed that a cyole rack is fitted then the method advances to box 140. In box 140 a predefined adjusted calibration for the rear parking system is selected and the rear parking system operates in accordance with that calibration. It will be appreciated that the adjusted calibration is such that an object further from the rear of the motor vehiole 1 will be indicated as being a possible collision threat than would normally be the case if the standard calibration is used. Furthermore, an object spaced away from the rear of the motor vehicle 1 by a distance estimated to be equivalent to a distance the cycle rack is likely to protrude from the rear of the motor vehicle 1 will be indicated when using the adjusted calibration as a high risk of collision.

The method then advances from box 140 to box 150 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 120 and, if it is not, the method ends at box 190.

It will be appreciated that if at any time a key-off' event occurs then the method 100 will automatically end.

-14 -With reference to Fig.3 there is shown a second embodiment of a method 200 for reducing the risk of damage to an object carried on a rear part of the motor vehicle.

The method starts in box 210 which is key-on' event followed by an engine start resulting in an engine of the motor vehicle 1 running. The method advances to box 215 where it is checked whether a reverse drive mode has been selected. If reverse has not been selected, the method loops around box 215 because the rear parking sensors are only active in this case if the vehicle is likely to move in a rearward direction.

If reverse has been selected then the method advances to box 220 where it is checked whether a carrier such as a cycle rack is mounted on the rear of the motor vehicle 1.

If it is determined that a cycle rack is not fitted the method advances to box 245 where a standard calibration is used for the rear parking system and the rear parking system operates in accordance with that calibration. The method then advances to box 255 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 220 and, if it is not, the method ends at box 295.

If in box 220 it is confirmed that a cycle rack is fitted then the method advances to box 230 where a user of the motor vehicle 1 such as a driver is given the opportunity to accept or reject the use of an adjusted calibration for the rear parking system.

If the driver rejects the use of an adjusted calibration, the method advances to box 245 where a standard calibration is used for the rear parking system and the rear parking system operates in accordance with that calibration.

In such a case a warning message may be provided to the -15 -driver to indicate that the output from the rear parking system can no longer to be relied upon.

From box 245 the method advances to box 255 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 220 and, if it is not, the method ends at box 295.

If in box 230 the driver accepts the use of an adjusted calibration for the rear parking system then the method advances to box 240. In box 240 a predefined adjusted calibration for the rear parking system is selected and the rear parking system operates in aocordance with that calibration. As before there could be more than one predefined adjusted calibration.

The adjusted calibration will indicate that an object further from the rear of the motor vehicle 1 is a possible collision threat than would normally be the oase if the standard calibration is used and an object spaced away from the rear of the motor vehicle 1 by a distance estimated to be eguivalent to a distance the cycle rack is likely to protrude from the rear of the motor vehicle 1 will be indicated as a high risk of collision.

The method then advances from box 240 to box 250 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 220 and, if it is not, the method ends at box 290.

As before, if at any time a key-off' event occurs, the method 200 will automatically end.

With reference to Fig.4 there is shown a third embodiment of a method 300 for reducing the risk of damage to an object carried on a rear part of the motor vehicle.

-16 -The method starts in box 310 which is key-on' event followed by an engine start resulting in an engine of the motor vehicle 1 running. The method advances to box 315 where it is checked whether a reverse drive mode has been selected. If reverse has not been selected the method loops around box 315 because the rear parking system is only active in this case if the motor vehicle 1 is likely to move in a rearward direction.

If reverse has been selected then the method advances to box 320 where it is checked whether a carrier such as a cycle rack is mounted on the rear of the motor vehicle 1.

If it is determined that a cycle rack is not fitted the method advances to box 345 where a standard calibration is used for the rear parking system and the rear parking system operates in accordance with that calibration. The method then advances to box 355 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 320 and, if it is not, the method ends at box 395.

If in box 320 it is confirmed that a cycle rack is fitted then the method advances to box 330 where a user of the motor vehicle 1 such as a driver is given the opportunity to accept or reject the use of an adjusted calibration for the rear parking system.

If the driver rejects the use of an adjusted calibration the method advances to box 345 where a standard calibration is used for the rear parking system and the rear parking system operates in accordance with that calibration.

In such a case a warning message may be provided to the driver to indicate that the rear parking system may no longer be trusted.

-17 -The method then advances from box 345 to box 355 to oheck whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 320 and, if it is not, the method ends at box 395.

If in box 330 the driver accepts the use cf an adjusted calibration for the rear parking system then the method advances to box 335. In box 335 the driver inputs the calibration adjustment reguired for the size of carrier and object being transported. This can be an actual offset, such as for example 0.5m, or a range of options such as 0.5m, 0.75m or carrier only, carrier and one cycle, carrier and two cycles. The calibration cf the rear parking system is then adjusted in accordance with the instructions received from the driver. The method then advances to box 340.

In box 340 the adjusted calibration for the rear parking system is selected and the rear parking system operates in accordance with that calibration. As before, the adjusted calibration will indicate that an object further from the rear of the motor vehicle 1 is a possible collision threat than would normally be the case if the standard calibration is used and an object spaced away from the rear of the motor vehicle 1 by a distance estimated to be eguivalent to a distance the cycle rack is likely to protrude from the rear of the motor vehicle 1 will be indicated as a high risk of ccllisicn. The methcd then advances from box 340 to box 350 to check whether reverse gear or a reverse drive mode is still selected, if it is, the method returns to box 320 and, if it is not, the method ends at box 390. As before, if at any time a key-off' event occurs, the method 300 will automatically end.

Therefore in summary, the soluticn presented here is tc provide a mechanism for warning the driver that if a rear cycle carrier or other obstruction is detected on a rear end -18 -of the motor vehicle, the accuracy of the rear parking sensor system may be impaired, and suggests or forces recalibration of the rear parking sensor system. The recalibration takes into account the additional effective length of the vehicle when a cycle carrier or similar device is fitted. In one example, a predefined additional distance is added automatically to the calibration of rear parking sensor system and this may take into account a worst case effective vehicle length increase such as a cycle carrier with for bicycles. In an alternative embodiment the driver can input the desired additional length manually.

To implement the invention a system is required that is able to detect a cycle carrier or similar mounted to the rear of the vehicle. One way to achieve this could be to use an ultrasonic parking sensor or equivalent device mounted at a suitable location on the rear of the vehicle that is able to detect an object fitted to the rear of the vehicle. Another way to achieve this could be to use reverse parking camera technology to detect whether a carrier is fitted. In either case, when a carrier is detected, a HMI message can be displayed asking the driver to confirm whether a cycle carrier is fitted (or if there is any other kind of obstruction) and, if the driver confirms that there is, the driver can then be offered the option to recalibrate the rear parking system. Alternatively, adjustment of the calibration could occur automatically without driver input whenever the carrier is detected.

It will be appreciated by those skilled in the art that although the invention has been described by way of example with reference to one or more embodiments it is not limited to the disclosed embodiments and that alternative embodiments could be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

-19 -Claims 1. r method for reducing the risk of damage during a reversing manoeuvre to an object mounted on a rear end of a motor vehicle having a rear parking system wherein the method oomprises cheoking whether an object is mounted on the rear of the motor vehicle and, if an object is confirmed to be so mounted, adjusting the calibration of the rear parking system to allow for the protrusion of the object.
2. I method as claimed in claim 1 wherein adjusting the calibration of the rear parking system comprises adjusting the oalibration so that a high collision risk is indicated for an obstruction spaced further away from a reference point at the rear end of the motor vehicle than the distance from the reference point indicated as being a high collision risk when a standard calibration is used.
3. I method as claimed in olaim 2 wherein adjusting the calibration of the rear parking system comprises automatically adjusting the calibration of the rear parking system so that an obstruction spaced from the rear end of the motor vehicle by a distance estimated to be eguivalent to a distance the object is predicted to protrude from the rear end plus a safety margin will be indicated as being a high collision risk.
4. I method as claimed in olaim 2 wherein the safety margin is the distance an obstruction spaced from the rear end of the motor vehicle is indicated as being a high collision risk when using the standard calibration.
5. I method as claimed in claim 1 or in claim 2 wherein adjusting the calibration of the rear parking system comprises manually adjusting the distance from the rear end of the motor vehicle indicated as being a high collision risk.

-20 -
6. A method as olaimed in any of claims 3 to 5 wherein a driver of the motor vehicle is provided with an opportunity to ohoose whether or not to use an adjusted calibration for the rear parking system.
7. A method as claimed in claim 6 wherein, if the driver ohooses not to use an adjusted calibration for the rear parking system, a standard calibration for the motor vehicle is used.
8. A method as claimed in claim 6 or in claim 7 wherein the method further comprises warning the driver if an object is in position on the rear of the motor vehicle and the driver has chosen not to use the adjusted calibration.
9. A method as claimed in any of claims 1 to 8 wherein the object is one of a bicycle carrier mounted on the rear of the motor vehicle and one or more bicycles carried by a carrier mounted on the rear of the motor vehicle.
10. A detection system for detecting whether an object mounted on a rear of a motor vehicle is at risk of collision with an obstruction during a reversing manoeuvre wherein the detection system comprises a rear parking sensor system to sense whether an obstruction is present and an object detection system to detect whether an object is mounted on the rear of the motor vehicle and, if an object is sensed to be mounted on the rear of the motor vehicle, a calibration value for the rear parking system is adjusted to allow for the protrusion of the object.
11. A system as claimed in claim 10 wherein adjusting the calibration of the rear parking system comprises adjusting the calibration so that a high collision risk is -21 -indicated for an obstruction spaced further away from a reference point at the rear end of the motor vehicle than the distance from the reference point indicated as being a high collision risk when a standard calibration is used.
12. A system as claimed in claim 11 wherein the system includes an electronic controller and adjusting the calibration of the rear parking system comprises using the electronic controller to automatically adjust the calibration of the rear parking system so that an obstruction spaced away from the rear end of the motor vehicle by a distance estimated tc be equivalent tc a distance the object is predicted to protrude from the rear of the motor vehicle plus a safety margin will be indicated as being a high collision risk.
13. A system as claimed in claim 12 wherein the safety margin is the distance an obstruction spaced from the rear end of the motor vehicle is indicated as being a high collision risk when using the standard calibration.
14. A system as claimed in claim 10 or in claim 11 in which the system comprises an electronic controller and a human machine interface wherein adjusting the calibration of the rear parking system comprises using driver inputs to the human machine interface to manually adjust the distance from the rear of the motor vehicle indicated as being a high collision risk.
15. A system as claimed in any of claims 12 to 14 in which the system includes an electronic controller and a human machine interface wherein the human machine interface is used to provide a driver of the motor vehicle with an opportunity to choose whether or not to use an adjusted calibration for the rear parking system.

-22 -
16. A system as claimed in claim 15 wherein, if the driver chooses not to use an adjusted calibration for the rear parking system, a standard calibration stored in an electronic device is used.

17. A system as claimed in claim 15 or in claim 16 wherein, if an object is in position on the rear of the motor vehicle and the driver has chosen not to use the adjusted calibration, the human machine interface is used to warn the driver of their decision.18. A system as claimed in any of claims 10 to 17 wherein the object is one of a bicycle carrier mounted on the rear end of the motor vehicle and one or more bicycles carried by a carrier mounted on the rear end of the motor vehicle.
17. A motor vehicle having a detection system as claimed in any of claims 10 to
18.
19. A method for reducing the risk of damage to an object mounted on a rear of a motor vehicle having a rear parking system during a reversing manoeuvre substantially as described herein with reference to the accompanying drawing.
20. A detection system for detecting whether an object mounted on a rear of a motor vehicle is at risk of collision with an obstruction during a reversing manoeuvre substantially as described herein with reference to the accompanying drawing.
21. A motor vehicle substantially as described herein with reference to the accompanying drawing.