GB2342630A

GB2342630A - Indicator for reversing articulated vehicles

Info

Publication number: GB2342630A
Application number: GB9822234A
Authority: GB
Inventors: Vincent Shepherd; Peter William Ingledew; Andrew Belton
Original assignee: BELTON TECHNOLOGICAL SERVICES
Current assignee: BELTON TECHNOLOGICAL SERVICES
Priority date: 1998-10-12
Filing date: 1998-10-12
Publication date: 2000-04-19
Anticipated expiration: 2018-10-12
Also published as: GB2342630B; GB9822234D0

Abstract

The invention relates to apparatus for indicating to a driver the relative position of the towing and towed parts of an articulated vehicle. The relative positions are measured by a sensor EXTERNAL 5K POT ON TOW HITCH and these are converted by digital circuitry (U1, U2) to give a positional indication (LEDs D1-D20). An audible indication (BZ1) may alternatively, or additionally, be provided. The position of a trailer relative to a towing vehicle is then indicated to the driver by the illumination of the LEDs. Different indications, for example different colours, can be used to convey the size of the angle. The limits on the display, i.e. the relationship between the relative angle and the display, may be adjusted by a user.

Description

REVERSING ARTICULATED VEHICLES The present invention relates to vehicles having an articulated part, such as an articulated truck but also, for example, a car and trailer or car and caravan.

Both novice and experienced drivers alike have difficulty reversing articulated vehicles.

The direction in which the trailer part of the vehicle turns is often counter-intuitive with respect to the driver's operation of the steering wheel. At best, this can result in having to attempt the reversing manoeuvre a number of times with attendant frustration and embarrassment. At worst, if the towed and the towing parts of the vehicle should come into contact, serious damage can result. In particular, when the towed part of the vehicle is out of sight of the driver (for example, a low trailer attached to a car), it can be very difficult indeed to perform a satisfactory reversing manoeuvre.

It is an object of the present invention to provide apparatus to warn a driver of dangerous relative positioning of a towed part and a towing part of a vehicle or between a towing vehicle and a towed vehicle.

According to the present invention, there is provided apparatus for indicating the angle of the towed vehicle relative to a towing vehicle, whereby the towed vehicle is coupled to the towing vehicle by a rotational coupling, the apparatus comprising means for sensing a variation in angle between the towing vehicle and the towed vehicle and means for converting that variation into an indication for a driver of a towing vehicle.

In its simplest form the invention may comprise a visual or audible alarm which indicates that the angle between the towed vehicle and the towing vehicle has exceeded a predetermined threshold. Alternatively, or in addition, a continual indication of the current angle may be given. If this variation is, for example, provided by a series of LEDs (light emitting diodes) then the colour of the LEDs could change according to the magnitude of the angle. Where an audible warning is included, the identity, tone or volume of the signal may vary in accordance with the magnitude of the angle.

The apparatus may also be equipped with indicator means that operate when the vehicle is travelling forwards. Sometimes the driver of a towing vehicle can be unaware that a towed vehicle is oscillating ("slewing") from side to side. In this case the threshold of an alarm can be set at a much lower level.

The present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure la shows a view, partly in section, of a schematic diagram illustrating the concept of part of the invention; Figure lb shows a perspective view of a ball hitch and a tow-hitch fitted with an angular sensor in accordance with an embodiment of the invention; Figure 2 shows an analogue indicator circuit for use with the arrangement shown in Figure 1 ; Figure 3 shows a simplified digital indicating circuit for use with the arrangement shown in Figure 1 ; and Figure 4 shows a full circuit diagram of a digital embodiment of the present invention.

Figure la shows a schematic arrangement 10 which illustrates the principle behind part of an embodiment of the present invention. A ball hitch 12 is attached to a car or other towing vehicle C in conventional manner (not shown). The ball hitch 12 is engaged with a tow-hitch 14 held in place by a latch 16 as is conventional and attached to a trailer T. The ball hitch 12 is provided with a hollow 18 along its central, vertical axis.

Within this hollow 18 is the shaft of a potentiometer 20 whose body is fixed at the lower end of the ball hitch 12. At the opposite end of the potentiometer shaft from the potentiometer 20 is a fitting 22, for example in the shape of a hexagon. The fitting 22 is arranged to co-operate with a gap 24 in the tow-hitch 14. The fitting 22 and gap 24 can be of any suitable type such that they engage when the tow-hitch 14 is fitted to the tow-ball 12. It may be convenient, for example, to provide a taper to the fitting 22 so that as the tow-hitch 14 is lowered onto the tow-ball 12, any slight angular mis-match between the fitting 22 and the gap 24 is corrected.

It will be readily appreciated that as the angle of the trailer T moves relative to the car C, that the shaft of the potentiometer 20 will be rotated. This provides a variable resistance signal which is fed (with amplification and screening as appropriate) to circuitry described with reference to later figures. While this figure illustrates the principle, it is of little practical utility because the coupling needs to deal with other angular differences between the car and trailer. The next figure addresses this problem.

Figure l (b) shows a practical embodiment of the sensor mounting portion of the present invention. Since the car and trailer can move (to some extent) in all these angular directions relative to one another, a more sophisticated joint than that shown in Figure 1 (a) is required to protect the angular sensor from damage. In Figure 1 (b), the ball hitch 12 and the tow hitch 14 are joined to their respective car and trailer (not shown) in conventional manner. A removable branch 15a is connected to the bracket of the ball hitch and a fixed connection 19 is made to the trailer chassis 18 (shown in broken lines). Between these two is a universal joint that provides all of the necessary degrees of freedom.

Bracket 15a is connected via a hinge 15 parallel to the axles of the car to a support 15b for the body of the potentiometer 20. The shaft of the potentiometer is attached to a connecting arm 13 which in turn is rotatably and translationally housed in a sleeve 13a.

The sleeve 13a is connected at 19 to the chassis of the trailer.

The connecting arm 13 and sleeve 13a provide rotational freedom 17 for roll at the tow hitch (i. e. rotational about the length of the car and trailer combination). The hinge 15 provides rotational freedom parallel to the axles of the car to cope with the car and trailer combination going over a hill or into a valley. Because the hinge is below the ball hitch 12 (about which the rotation occurs) allowance must also be made for movement of the car and trailer towards and away from each other. This is provided by the movement 16 of connecting arm 13 within the sleeve 13a.

To un-hitch the trailer the pivot pin of hinge 15 is removed. Because the potentiometer (or other sensor) 20 remains with the trailer, the system is disabled automatically when the vehicle is not used for towing.

In use the tow hitch 14 moves through a range of angles relative to the towing vehicle C. When the vehicle C is to the right of the trailer (not shown) the tow hitch 14 moves through the range of angles Ar and when the vehicle C is to the left of the trailer, the tow hitch 14 moves through the range of angles Al. The resistance of the potentiometer varies accordingly and is processed by circuitry discussed subsequently.

In this embodiment, the potentiometer is mounted to the trailer which means that, when not in use, it is not subjected to road dirt and water, etc. It also automatically disables the system when not in use. It is possible to mount the potentiometer on the car, preferably so that it can be stowed when not in use to protect it from damage. The potentiometer could also be replaced by another angular sensor, for example an optical angular sensor.

Figure 2 shows a block schematic diagram of a basic analogue indication circuit for use with the arrangement shown in Figure 1. The circuitry is arranged between the positive (+Ve) and negative (-Ve) rails of the vehicle electrical system. The two ends of the track of potentiometer 20 are connected to the +Ve and-Ve rails respectively, while the wiper contact is connected to a first input of a comparator 32. A reference potentiometer (trimmer) 30 also has the ends of its track connected to the +Ve and-Ve rails respectively. The wiper of the trimmer 30 is connected to a second input to comparator 32. Negative feedback is applied (not shown) around the comparator 32 to reduce the gain of the circuit, as will be apparent to the skilled person. An output of comparator 32 is connected to a first terminal of a centre-zero voltmeter 34. The remaining terminal of the centre-zero voltmeter 34 is connected to the mid-point of a potential divider comprising resistors 36 and 38. Resistors 36,38 both have resistance R and are connected in series between the +Ve and-Ve supply rails. The value R is selected to pass, for example, ten times the current required to drive voltmeter 34. This will ensure that the reference voltage midway between +Ve and-Ve provided by the resistors is not affected unduly by the voltmeter current.

The circuit of Figure 2 is very easy to calibrate. The car C and trailer T are placed in alignment (relative angle 180 ) and the trimmer 30 is adjusted until the voltmeter 34 gives a central (zero) reading. As the angle of the trailer T relative to the car C changes, so the wiper of potentiometer 20 moves, which applies a varying voltage to the first input of comparator 32. The output of comparator 32 tracks the voltage variation and provides a visual variation of trailer angle to the driver on voltmeter 34. Clearly, the voltmeter 34 may be conveniently calibrated in degrees or perhaps in green, yellow and red zones to indicate the magnitude of the angle of the trailer T relative to the car C.

Figure 3 is a block schematic diagram of a first digital circuit arrangement for use with the arrangement shown in Figure 1. Power supply connections to the individual units have been omitted for clarity. As in the circuit shown in Figure 2, the potentiometer 20 has each end of its track connected to the +Ve and-Ve rails respectively. In this case, however, the wiper of potentiometer 20 is connected to analogue to digital converter (A/D) 50. In this example, it is assumed that A/D 50 is a seven-bit device which provides output values between 0 and 127. The seven bits are fed to the address lines of a look-up table (for example a ROM or any derivative thereof) 52. An eighth address line, for example the most significant bit, of look-up table 52 will be discussed below.

The seven bits from A/D 50 are coded by look-up table to provide three output lines D which supply binary signals between 0 and 7 to a decoder 54. Decoder 54 provides eight output lines corresponding to the value of D applied at its input. Each output line is connected to ground via a LED LI, L2,..... L8 and series resistors (not shown) as appropriate.

The voltage at the wiper of potentiometer 20 is converted to a digital value in A/D 50 and look-up table 52 and decoder 54 light one ofLEDs LI to L8 corresponding to the position of the trailer T relative to the car C. When the trailer T and car C are in line, or nearly so, LED L4 or LED L5 is illuminated. As the angle between them increases in one direction, LEDs L4, L3, L2 and LI are illuminated in sequence. Similarly, in the opposite direction LEDs L5, L6, L7 and L8 are also illuminated in sequence with increasing angle. The LEDs LI to L8 may conveniently be arranged in a line, or a semicircle or arc to help convey the impression of trailer angle to the driver. The colour of the LEDs may also be arranged to improve assimilation of the information.

For example, LEDs L4 and L5 could be green in colour, L2, L3, L6 and L7 could be yellow in colour, while LI and L8 could be red.

The apparatus also includes an audible alarm 60 which is connected to two further data lines D'and D"of the look-up table 52. The alarm 60 is arranged to provide two different audible alarms in response to different signals D'and D". A lower-volume or lower-pitched alarm is arranged to respond to a signal on line D'. A higher pitched and/or louder alarm is arranged to respond to a signal on line D". The alarm is arranged to indicate, at a low level, that the angle of the trailer has increased to a predetermined value but also to indicate, by way of a more urgent alarm, that a much greater angle has been achieved. In this example, the low level alarm sounds at the same time as LEDs L2, L3, L6 and L7 are illuminated. The louder or higher pitched alarm sounds at the same time as LEDs L1 or L8 are illuminated. The programming of look-up table 52 to provide this is indicated in simplified fashion as follows:

A/D O/P LED Lit Signal D Alarm Forwards Forwards Alarm 0-15 Ll 0 D"143 A 16-31 L2 1 D'144-159 A 32-47 L3 2 D'160-175 A 48-63 L4 3 176-191 NA 64-79 L5 4 192-207 NA 80-95 L6 5 D'208-223 A 96-111 L7 6 D'224-239 A 112-127 L8 7 D"240-255 A The first four columns of the table should be self-explanatory. When the output of A/D 50 is, for example, between the values 32 and 47, LED L3 will be illuminated. The output D of look-up table 52 will be 2 and the lower level alarm will sound in response to signal D'. No alarm sounds if the value of A/D output is between 48 and 79 while LEDs L4 and L5 are illuminated. The right-hand two columns of the table will now be explained.

The apparatus shown in Figure 3 also has the facility to warn a driver of a trailer slewing when travelling forwards. A wheel rotation sensor 56 provides a positive output when the vehicle is travelling forwards and a negative output when the vehicle is travelling backwards. An output of this sensor is applied, via a diode 58, to the eighth bit of the address line of look-up table 52. Consequently, when the vehicle is travelling backwards, then values of between 0 and 127 are applied to look-up table 52. When the vehicle is travelling forwards, values of between 128 and 255 are applied to the look-up table. The fifth column of the table above, therefore, gives the values applied to lookup table 52 when the vehicle is travelling forwards in response to the same angular variations as give the values in the first column of the table. The wheel rotation sensor may be replaced by a signal derived from the vehicle's reversing lights.

The portion of the look-up table between address values of 128 to 255 is arranged to illuminate the LEDs L I to L8 via the output D in the same way as discussed above.

However, when the most significant bit of look-up table 52 is high (vehicle travelling forwards) the alarm 60 is arranged to sound at every angular range other than the central pair. This is shown in column 6 of the table above. The alarm sounds ("A") in response to input values of look-up table 52 between 128 and 183, and also between input values of 200 to 255. No alarm is sounded ("NA") for the substantially straightahead position which corresponds to illumination of LED L4 and LED L5. Should this alarm sound, the driver can take anti-slewing measures, such as reducing speed.

A more sophisticated approach to anti-slewing measures also takes account of vehicle speed. Clearly when taking low-speed comers the alarm will sound. To avoid this potential nuisance the alarm could be arranged to sound only when a certain angle and a certain speed are exceeded.

The look-up table approach described above is also suitable for use with an angle sensor having a digital output such as an optical angle sensor. No A/D converter will then be required. Alternatively, dedicated LED driver integrated circuits may be used to provide a more sophisticated arrangement with only slight extra complexity as will now be described with reference to Figure 4.

Figure 4 shows a circuit which has a display of 20 LEDs numbered from D1 to D20.

The LEDs D1 to D10 comprise nearside indicators while the LEDs Dl 1 to D20 comprise offside indicators. The ten nearside indicators are driven by an I. C. Ul while the ten offside indicators are driven by an I. C. U2. Both of these I. C. s are dedicated LED drivers and have the following features. Pins 2 and 3 comprise the negative and positive power supply connections respectively. Pin 5 is a signal input pin and Pins 4 and 6 comprise a low end and high end resistive divider respectively. Pin 1 drives LED No. 1 and Pins 18 to 10 drive LEDs nos. 2 to 10 respectively. The drive of the LEDs is dependent upon the voltage ratio of an input signal to a reference signal. More information can be obtained from the relevant Data Sheet obtainable from R. S.

Components, PO Box 99, Corby, Northants, NN17 9RS, United Kingdom.

LEDs D3 to D18 are green, LEDs D2 and D 19 are yellow and LEDs D1 and D20 are red. LEDs D 1 and D20 indicate that a dangerous angle between the trailer and the towing vehicle has been reached on the nearside and offside respectively.

The whole circuit is powered from the reversing lamp feed of the vehicle at sockets J1- 4 and J1-3. The voltage from these sockets is regulated to 5 volt by a standard power supply unit comprising resistors R3, R4, R5, diode D21, capacitors C1, C2 and C3, and regulator 7805 (U3). The unit will consequently be powered up all of the time that the vehicle is reversing. A switch may be provided at the tow hitch so that the unit is only powered up when a trailer is attached and the same effect is provided when the potentiometer is mounted on the trailer. Alternatively a switch may be provided so that the unit can be powered up from the vehicle's electrical system only when required.

A buzzer circuit comprises buzzer BZ1, transistors Q1 and Q2, and resistors R6 and R7.

The buzzer is arranged to sound whenever LEDs Dl, D2, D19 or D20 is illuminated.

For nearside operation a signal from Pin 11 of U1 drives the transistor Q2 while for offside operation a signal from Pin 11 of U2 drives the transistor via LED D19. A resistor R11 is placed between the LED D19 and ground to ensure adequate base drive voltage for the transistor.

There are three potentiometers to adjust for the present circuit. VR3 is a centre calibrate potentiometer which is adjusted so that no LEDs are lit when the towing vehicle and the towed vehicle are directly in line with each other. Theoretically, the EXTERNAL potentiometer on the tow hitch will provide exactly 1/2 Vcc at its wiper in this situation.

However, this will not be exact in practice so centre calibrate potentiometer VR3 is adjusted until the voltage on its wiper contact exactly matches that at the output of the EXTERNAL potentiometer. This gives no net voltage difference at the input to either IC U1 or IC U2. Consequently no LEDs are illuminated.

In operation, when the trailer moves to the nearside, the output at the wiper of the EXTERNAL potentiometer will increase from Vcc/2 up towards Vcc. This applies the required voltage ratio to IC U1 to illuminate some of the LEDs D1 to D10. The outputs of the IC U1 are active-low so the other ends of each of the LEDs D 1 to D10 are wired to the 5 Volt supply (Vcc). When the trailer moves to the offside none of the LEDs D1 to D10 are illuminate because the voltage at the wiper of the EXTERNAL potentiometer is less than the reference provided at the wiper of the potentiometer VR3.

The LEDs for the offside indication are wired differently from those on the nearside.

The output Pins of the IC U2 are connected to the anodes of the LEDs rather than the cathodes. The anodes are also connected to Vcc via resistors. Therefore, when the trailer is to the nearside of the vehicle, the offside LEDs D11 to D20 are off. When the trailer is to the offside, the situation reverses and the LEDs Dl 1 to D20 are illuminated because the voltage at the wiper of the EXTERNAL potentiometer tends towards zero volt.

The rate at which the nearside and offside LEDs illuminate in response to differing angles is set by the potentiometers VR1 and VR2. VR1 is effectively a nearside limit adjust that is set by placing the car and trailer at a relative angle which is desired to illuminate all of the LEDs. The potentiometer VR1 is then adjusted until all of the LEDs are illuminated. The gradual illumination of the LEDs at lesser angles and the operation of the buzzer BZ 1 will occur automatically under the control of IC U1. The analogous adjustment is made using VR2 to control the point at which all of the offside LEDs are illuminated. The unit is then ready for use.

While the present invention has been described with both an analogue indicator and a digital indicator comprising nine LEDs, the skilled person will readily appreciate that different indication techniques comprising different, more or fewer indicators may be applied. In particular, a purely audible system or a purely visual system can be implemented. The circuitry by which the sensor output is converted to a visual indication can be varied widely within the competence of the skilled person. The present invention extends to any part of the described arrangement whether explicitly or implicitly disclosed herein.

Claims

CLAIMS : 1. Apparatus for indicating the angle of the towed vehicle relative to a towing vehicle, whereby the towed vehicle is coupled to the towing vehicle by a rotational coupling, the apparatus comprising means for sensing a variation in angle between the towing vehicle and the towed vehicle and means for converting that variation into an indication for a driver of a towing vehicle.
2. Apparatus as claimed in Claim 1, wherein the means for sensing a variation in angle between the towing vehicle and the towed vehicle comprises an angle sensor mounted at the rotational coupling.
3. Apparatus as claimed in Claim 2, wherein the means for sensing a variation in angle between the towing vehicle and the towed vehicle comprises a potentiometer.
4. Apparatus as claimed in any one of the Claims 1 to 3, wherein the means for converting the variation into an indication for a driver provides a visual indication.
5. Apparatus as claimed in Claim 4, wherein the visual indication comprises at least two different colours in response to the angular variation.
6. Apparatus as claimed in any one of Claims 1 to 5, wherein the means for converting the variation into an indication for a driver includes an audible indication.
7. Apparatus as claimed in Claim 6, wherein the audible indication differs in response to the angular variation.
8. Apparatus as claimed in any one of the claims 1 to 7, further comprising means for sensing the direction of the towing vehicle and means for altering the angular variation at which a warning is given to the driver in response to vehicle direction.
9. Apparatus as claimed in Claim 8, wherein the warning is an audible warning.
10. Apparatus as claimed in any one of Claims 1 to 9, wherein a visual indication is given by an analogue indicator.
11. Apparatus as claimed in any one of claims 1 to 9, wherein a visual indication is given by way of digital apparatus.
12. Apparatus for indicating an angle of a towed vehicle, substantially as hereinbefore described with reference to Figures 1 and 2; Figures 1 and 3; and Figures 1 and 4 of the accompanying drawings.

12. Apparatus for indicating an angle of a towed vehicle, substantially as hereinbefore described with reference to Figures 1 and 2; Figures 1 and 3; and Figures 1 and 4 of the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS: 1. Apparatus for indicating the angle of the towed vehicle relative to a towing vehicle, whereby the towed vehicle is coupled to the towing vehicle by a rotational coupling, the apparatus comprising means for sensing a variation in angle between the towing vehicle and the towed vehicle and means for converting that variation into an indication for a driver of a towing vehicle, the apparatus further comprising means for adjusting the relationship between the variation in angle and the variation in display.

2. Apparatus as claimed in Claim 1, wherein the means for sensing a variation in angle between the towing vehicle and the towed vehicle comprises an angle sensor mounted at the rotational coupling.

3. Apparatus as claimed in Claim 2, wherein the means for sensing a variation in angle between the towing vehicle and the towed vehicle comprises a potentiometer.

4. Apparatus as claimed in any one of the Claims 1 to 3, wherein the means for converting the variation into an indication for a driver provides a visual indication.

5. Apparatus as claimed in Claim 4, wherein the visual indication comprises at least two different colours in response to the angular variation.

6. Apparatus as claimed in any one of Claims 1 to 5, wherein the means for converting the variation into an indication for a driver includes an audible indication.

7. Apparatus as claimed in Claim 6, wherein the audible indication differs in response to the angular variation.

8. Apparatus as claimed in any one of the claims 1 to 7, further comprising means for sensing the direction of the towing vehicle and means for altering the angular variation at which a warning is given to the driver in response to vehicle direction.

9. Apparatus as claimed in Claim 8, wherein the warning is an audible warning.

10. Apparatus as claimed in any one of Claims 1 to 9, wherein a visual indication is given by an analogue indicator.

11. Apparatus as claimed in any one of claims 1 to 9, wherein a visual indication is given by way of digital apparatus.