Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/17—Using electrical or electronic regulation means to control braking
  • B60T8/1701—Braking or traction control means specially adapted for particular types of vehicles
  • B60T8/1708—Braking or traction control means specially adapted for particular types of vehicles for lorries or tractor-trailer combinations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
  • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
  • B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
  • B60W40/114—Yaw movement
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/17—Using electrical or electronic regulation means to control braking
  • B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/24—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to vehicle inclination or change of direction, e.g. negotiating bends
  • B60T8/248—Trailer sway, e.g. for preventing jackknifing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
  • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
  • B60W30/02—Control of vehicle driving stability
  • B60W30/04—Control of vehicle driving stability related to roll-over prevention
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T2230/00—Monitoring, detecting special vehicle behaviour; Counteracting thereof
  • B60T2230/06—Tractor-trailer swaying

Definitions

• the present invention relates to a method for predicting instability in a vehicle-trailer combination and particularly, but not exclusively to a vehicle-trailer combination comprising a motor vehicle towing a trailer attached to the vehicle at a hitch point. Aspects of the invention relate to a method, a control module, an engine control unit, a system and a vehicle. BACKGROUND
• Vehicle-trailer combinations typically act as damped systems in which the magnitude of a damping co-efficient associated with the system dictates the rate at which oscillations of the trailer decay after it has been displaced from a neutral position behind the towing vehicle, e.g. by a gust of wind.
• the greater the vehicle's road speed the lower the damping co-efficient of the vehicle-trailer system becomes.
• the system becomes increasingly unstable as velocity increases. This means that the faster the vehicle travels, the greater the tendency for dangerous and uncontrollable trailer oscillations to occur.
• This problem is exacerbated by the fact that, in recent years, increasingly stringent vehicle emissions regulations have resulted in a decrease in average vehicle weight and studies have shown that this decrease in vehicle weight has had an adverse effect on vehicle stability, particularly when towing a trailer.
• ESC Electronic Stability Control
• ESP Electronic Stability Programs
• DSC Dynamic Stability Control
• controlling trailer instability using this method relies on the trailer oscillating to such an extent that the movement of the trailer begins to cause the vehicle to yaw. If the trailer is lightweight relative to the vehicle, this may not occur until the trailer is oscillating at an undesirable level which may cause damage to the trailer and/or its load. Furthermore, in the case of a relatively light trailer, oscillations which may cause damage to goods being transported in the trailer may occur without the driver of the towing vehicle being able to detect through the steering wheel that such oscillations are occurring. Also, it may be much harder to rectify the problem if trailer oscillation builds up too much prior to detection.
• a method of predicting instability in a vehicle-trailer combination comprising monitoring a vehicle direction related parameter and monitoring a trailer direction related parameter.
• the method further comprises comparing the vehicle direction related parameter with the trailer direction related parameter to determine a response of the trailer direction to the vehicle direction over time in order to define a response trend, and determining an instability event in dependence on a change in the response trend.
• the method advantageously detects trailer instability as soon as it starts to develop, and in advance of a critical instability event.
• the method provides a computationally simple means for detecting trailer instability which relies on detection of only two parameters in real time. The method is therefore a far simpler alternative to modelling the vehicle-trailer system as a whole.
• an alarm to be generated in advance of critical instability, which allows time for corrective action to be taken by either the driver or by automatic processes, to prevent critical instability from developing which may otherwise result in a loss of control of the vehicle.
• the alarm may be used to activate an ESC system in order to prevent a critical instability event.
• the method may comprise outputting an alarm signal in dependence on making a positive determination of an instability event.
• the method may comprise outputting the alarm signal to a driver of the vehicle to indicate the onset of a trailer instability.
• Comparing the vehicle direction related parameter with the trailer direction related parameter may comprise defining an artificial vector based on the vehicle direction related parameter and the trailer direction related parameter.
• Determining the response of the trailer may comprise calculating the argument of the vector.
• Defining a response trend may comprise monitoring the argument of the vector over time.
• the instability event may be determined as a result of an unexpected change of direction of the argument.
• the vehicle direction related parameter may be the steering wheel angle.
• the trailer direction related parameter may be the trailer yaw.
• a vehicle brake may be activated in response to an instability event being determined.
• a vehicle mounted camera may be used to monitor the trailer direction related parameter.
• a control module for predicting instability in a vehicle-trailer combination comprises means to receive a signal indicative of a vehicle direction related parameter, and means to receive a signal indicative of a trailer direction related parameter.
• the control module further comprises processing means arranged to compare the vehicle direction related parameter with the trailer direction related parameter, determine a response of the trailer direction to the vehicle direction over time in order to define a response trend, and determine an instability event in dependence on a change in the response trend.
• a system for predicting instability in a vehicle-trailer combination comprising a control module according to the second aspect, at least one sensor arranged to monitor the vehicle direction related parameter, and at least one sensor arranged to monitor the trailer direction related parameter.
• the at least one sensor arranged to monitor the vehicle direction related parameter may comprise a steering wheel angle sensor.
• the at least one sensor arranged to monitor the vehicle direction related parameter may comprise a vehicle yaw sensor.
• the at least one sensor arranged to monitor the trailer direction related parameter may be a vehicle mounted camera.
• the invention also extends to an engine control unit comprising a control module according to the second aspect, a vehicle comprising a control module according to the second aspect, and a vehicle comprising a system according to the third aspect.
• the invention further extends to a vehicle comprising said engine control unit.
• Figure 2 is a schematic plan view diagram of the vehicle-trailer combination of Figure 1 in a trailer yaw position;
• Figure 3 is a schematic illustration of an image viewed by a rearward facing vehicle-mounted camera where the trailer is in a neutral position;
• Figure 4 is a schematic illustration of an image viewed by the rearward facing camera where the trailer is in a yawed position
• Figure 5 is a graph plotting steering wheel angle against trailer yaw during an oscillation
• Figure 6 is an illustration of a set of results from a simulation of a vehicle-trailer combination traversing a slalom in an open-loop scenario
• Figure 7 is an illustration of a set of results from a simulation of a vehicle-trailer combination traversing a slalom in a closed-loop scenario
• Figure 8 is an illustration of a set of results from a simulation of a vehicle-trailer combination traversing an adverse road in an open-loop scenario
• Figure 9 is a flow diagram illustrating a method for predicting trailer instability according to an embodiment of the present invention.
• Figure 10 is an illustration of a set of results from a test of the method in Figure 9;
• Figure 1 1 is a schematic illustration of a control module which may be used to implement the method in Figure 9;
• Figure 12 is an illustration of a vehicle having the control module in Figure 1 1 .
• a vehicle-trailer combination 10 comprises a vehicle 12 towing an attached trailer 14.
• the vehicle-trailer combination 10 is in a neutral state where the longitudinal axis L v of the vehicle 12 is substantially aligned with the longitudinal axis L T of the trailer 14.
• the yaw angle, ⁇ of the trailer 14 relative to the vehicle 12 is at or near 0°.
• the trailer 14 may be a tendency for the trailer 14 to yaw away from the neutral position represented in Figure 1 thereby resulting in a yaw angle ⁇ which is greater than 0°.
• This tendency to yaw may result from many factors, for example, the dynamics of lane-change manoeuvres, wind gusts, sharp cornering, adverse cambers etc.
• the trailer 14 once the trailer 14 has departed from its neutral position, it will normally tend to return back towards the neutral position as the vehicle-trailer combination 10 moves forwards.
• the trailer 14 once the trailer 14 reaches the neutral position its momentum will also cause it to pass through the neutral position in a pendulum effect which results in a swaying motion of the trailer 14 relative to the vehicle 12.
• the rate at which the trailer 14 moves between a yawed position on one side of the vehicle 12 to an opposite yaw position on the other side of the vehicle 12 is the yaw frequency.
• Movement of the trailer 14 relative to the towing vehicle 12 may be determined by any suitable means.
• relative movement of the trailer 14 may be sensed by optical sensing means such as a rearward facing camera mounted on the vehicle 12 for example.
• optical sensing means such as a rearward facing camera mounted on the vehicle 12 for example.
• the vehicle 12 is provided with one or more rearward facing parking assist cameras, these may be employed for the purpose of sensing movement of the trailer 14, advantageously obviating the need for an additional camera.
• the relative movement of the trailer 14 may also be detected using ultrasonic sensors, which may conveniently be existing park-assist sensors mounted on the rear of the vehicle 12.
• the trailer yaw angle ⁇ i.e. the deviation of the trailer 14 away from the neutral position, can be detected by contactless sensors on-board the vehicle 12.
• sensors are not subjected to any mechanical wear and tear.
• other types of sensing means may be employed to detect the relative movement between the vehicle 12 and trailer 14 e.g. radar and/or a mechanical arrangement provided at the trailer hitch point such as an encoder wheel arrangement.
• movement of the trailer 14 may be sensed directly by a yaw sensor, for example an accelerometer or a gyroscope, mounted on the trailer and the sensed yaw movement communicated to the vehicle 12.
• Figures 3 and 4 illustrate how the dimensions of the trailer 14 may be used in a method of determining the yaw angle of the trailer's longitudinal axis L T relative to the vehicle's longitudinal axis L v in an embodiment where a rearward facing camera mounted on the vehicle 12 is used to determine trailer yaw.
• a registration process may be first undertaken by the driver in order to ascertain the dimensions of the trailer edges as viewed by the camera. Although these relative dimensions may be input manually into the system by the driver if desired, the camera can instead be used to register these dimensions automatically based on the image viewed.
• the dimensions registered are edges A, B, C and D of the trailer 14; however, it will be appreciated that any other dimensions of trailer 14 could instead be registered as desired.
• edges A', B', C, D' of the trailer 14 viewed by the camera will change relative to those that were viewed by the camera when the trailer 14 was in the neutral position.
• This change in the relative dimensions viewed by the camera can be readily correlated to the change in yaw angle ⁇ of the trailer 14 relative to the vehicle 12.
• This effect is amplified by the proximity of the rearward facing camera to the trailer 14 since even relatively small angular movements will result in significant changes in the relative dimensions of the trailer 14 perceived by the camera.
• the upper and lower side edges B', D' on the right-hand side of the trailer 14 appear to be lengthened as compared to how they appear in Figure 3.
• the corresponding upper and lower side edges on the left-hand side of the trailer 14, appear shortened in Figure 4 compared to how they appear in Figure 3.
• the above method of determining the trailer yaw angle is based upon a comparison of relative perceived dimensions of the trailer 14. Therefore, it may not be necessary to perform the registration when the trailer 14 is in the neutral position but it may instead be possible to perform the registration procedure when the trailer 14 is at any initial angle relative to the vehicle 12.
• the vehicle 12 is also provided with additional sensors, such as ultrasonic sensors, which also detect a value for the yaw angle ⁇ of the trailer 14.
• ultrasonic sensors are existing park-assist sensors mounted on the vehicle 12, such sensors are typically deployed at spaced locations across the rear of the vehicle 12, e.g. at optimal positions along a rear bumper of the vehicle 12.
• Each ultrasonic sensor may therefore be used to detect changes in the distance to an adjacent portion of the trailer 14 as the trailer 14 oscillates from side to side about the neutral position.
• an ultrasonic sensor disposed on one side of the hitch point detects that an adjacent portion of the trailer 14 is getting closer to the vehicle 12, whereas an ultrasonic sensor disposed on the opposite side of the hitch point detects the trailer 14 is getting further away.
• the respective signals output from the camera and the ultrasonic sensors each provide a means for measuring the yaw angle of the trailer 14 and these measurements of the yaw angle are optionally input to processing means which performs filtering and analysis of the raw yaw outputs from the sensors.
• the demand for the vehicle 12 to turn may be defined by the driver turning a steering wheel, for example.
• the wheel is turned to a maximum angle of the turn initially (although not necessarily full-lock), and then gradually returned to a neutral position which is defined when the front wheels of the vehicle 12 are aligned with L v and the steering wheel angle is 0° as the vehicle 12 approaches the desired direction of travel.
• the trailer yaw angle builds gradually to a maximum as the vehicle 12 turns, with the trailer 14 returning to alignment with the vehicle 12 a short time after the vehicle 12 settles into the desired direction of travel.
• the vehicle-trailer combination 10 is subjected to conditions which move the vehicle 12 away from the desired direction of travel, such as a sudden gust of wind or a bump in the road, this may cause both the vehicle 12 and the trailer 14 to move in an oscillatory manner as the driver tries to recover the correct direction of travel of the vehicle 12. Assuming the driver is able to recover the vehicle 12 and return the vehicle-trailer combination 10 into stable alignment, such movement of the vehicle 12 may be represented as a damped oscillation, as the vehicle 12 overshoots the correct driving direction by less each time and gradually settles back into the correct driving direction. It is noted that the overshoot of the vehicle 12 may be exacerbated by the movement of the trailer 14 behind it, particularly if the trailer 14 is relatively heavy with respect to the vehicle 12.
• the delay may either increase, indicating that the magnitude of the oscillations of the trailer 14 have begun to exceed that of the oscillations of the vehicle 12, or the delay may decrease, indicating that the trailer 14 is beginning to oscillate faster than the vehicle 12.
• a change in the relationship between the two variables may indicate that the steering wheel angle has started to change more rapidly, indicating that the driver is turning more vigorously in an effort to control the vehicle-trailer combination 10. This change in the relationship between the steering wheel angle and the trailer yaw angle, is explained more fully below with reference to figure 5.
• FIG. 5 illustrates the form of an artificial vector which is used to represent the relationship between the steering wheel angle and the trailer yaw angle.
• v x+iy
• x is the trailer yaw angle
• y is the steering wheel angle
• v is the artificial vector which represents the relationship between x and y.
• the value of a shown in the Figure 5 indicates that the steering wheel angle and the trailer yaw angle are both positive and non-zero, and the steering wheel angle is smaller than the trailer yaw angle. This suggests that the vehicle 12 has recently commenced a turning manoeuvre, and the steering wheel angle is decreasing while the trailer yaw angle is increasing, in the manner described previously. Hypothetically, if the vehicle-trailer combination 10 were to oscillate steadily and continuously, the intersection of x and y would follow the circular path indicated by the dashed line 15 in a clockwise direction. In this scenario, the value of a would decrease steadily from 90° down to 0°, and then when v crosses the x-axis the sign of the angle would switch.
• Figures 6, 7 and 8 illustrate a series of simulations of the above described behaviour of the vehicle-trailer combination 10, indicating the points at which an alarm is activated.
• Figure 6 a set of results of a first simulation of a vehicle-trailer combination 10 are shown.
• the oscillating behaviour is induced by sending the vehicle-trailer combination 10 through a slalom of cones in an open-loop scenario, i.e. with no intervention by the ESC of the towing vehicle to take corrective action.
• the trailer yaw signal follows the steering wheel angle signal as expected. For example, the first minimum for the steering wheel angle appears at -25 seconds, whereas the first minimum for the trailer yaw angle is at around 27 seconds. The two signals oscillate in this manner until at -33 seconds the trailer 14 begins to become unstable, which manifests as the steering wheel angle rising sharply in response.
• the middle graph 18 shows the results of the upper graph after the two signals have been combined into an artificial phase vector, as explained previously with reference to Figure 5.
• Figure 6 there is initially a stable period of operation, in which the phase vector monotonically decreases. This trend changes suddenly at 33 seconds, as indicated by the dashed line 20, when the direction of the phase vector reverses.
• This illustration clearly demonstrates that the point at which the system becomes unstable coincides with the point at which the phase vector which is used to represent the system changes direction. Accordingly, an alarm is activated immediately after the phase changes direction, as shown in the lowermost graph 22. As the system is open loop, the alarm has no effect, and therefore the vehicle 12 does not regain control.
• Figure 7 shows a similar set of results to those in Figure 6, with the difference being that the simulation was altered such that the vehicle was arranged to brake and decelerate in response to an alarm in order to counteract trailer instability.
• the system of Figure 7 is a closed-loop system. This is evident in the graphs (24, 26), as it is clear that although an instability develops in a similar manner to the previous simulation (at around 33 seconds), the vehicle 12 regains control and returns to stable oscillation by 40 seconds.
• the steering wheel angle starts to fluctuate with increasing amplitude as a result of the driver of the vehicle turning the steering wheel more vigorously to try to regain control.
• the middle graph 26 shows that in fact there are at least two phase changes in the artificial vector between 33 seconds and 40 seconds, as indicated by the two dashed lines 28, 30, which may be as a result of the braking. Accordingly, the lower graph 32 indicates that the alarm is activated twice 33a, 33b.
• Figure 8 relates to an enhanced adverse road simulation, in which the vehicle-trailer combination 10 is subjected to a series of adversities, denoted as (a) through to (e), which are defined as follows: (a) a pair of sidewind gusts; (b) a stretch of wavy or bumpy terrain; (c) a beam on the road accompanied by a pair of sidewind gusts; (d) a single sidewind gust; and (e) a stretch of bumpy terrain accompanied by a single sidewind gust.
• the vehicle-trailer combination 10 travels around a 90° corner between 65s and 75s.
• the trailer yaw value settles at 90°. This is because in this simulation the trailer yaw angle is measured relative to a fixed global axis, rather than relative to the vehicle 12, in accordance with ISO standards. Hence, the trailer yaw angle settles at 90° from 75s onwards, because the trailer 14 (as well as the vehicle 12) is travelling at 90° relative to its initial position.
• the process 52 is conducted by an on-board computer of the vehicle 12, although in other embodiments a dedicated control module (for example as shown in Figure 1 1 , which is described below) is provided for this purpose.
• the process 52 comprises a filtering stage 54 and an instability detection stage 56.
• the filtering stage 54 ensures that the process 52 does not incorrectly trigger an alarm during normal driving conditions by defining a minimum rate of change for the difference between the trailer yaw angle (x) and the steering wheel angle (y) prior to advancing to the instability detection stage 56.
• the process 52 begins by calculating at step 58 the rate of change (e) of the difference between the trailer yaw angle (x) and the steering wheel angle (y).
• the process determines at step 60 whether the value of e exceeds a pre-determined threshold T f . If e is below the threshold, the instability detection stage 56 is not enabled (at Step 62), and the process returns to step 58 to reiterate. If the value of e exceeds T f , the instability detection stage 56 is enabled at step 64, and the process 52 advances.
• the on-board computer then calculates at step 66 the phase of vector v in the way described above.
• the process then iterates at step 68 the calculation of the phase of vand determines a trend for the phase of v.
• the on-board computer then repeats steps 66 and 68, to see whether the trend for the phase of v remains consistent.
• step 70 an alarm is raised at step 70 to indicate trailer instability. This alarm may be used either to warn the driver, or to directly initiate corrective action such as activating the ESC system.
• Figures 6 to 8 illustrate how the phase of v may follow a trend which can be used as described above to determine whether to raise an alarm.
• the phase vector graph 18 of Figure 6 from around 22 seconds the phase follows a periodic decreasing trend, with almost three complete cycles prior to an instability developing at around 33 seconds. Therefore, during the period between 22 seconds and 33 seconds, the process 52 described above would monitor the phase vector, and would find that there is a substantially consistent trend. At 33 seconds, the trend changes, therefore the process 52 would raise an alarm at this point to indicate that instability has started to develop before a state of critical instability is reached.
• a change of phase may be calculated by taking a derivative of the signal and identifying stationary points.
• the stationary points can then be categorised by taking a second derivative, which identifies local maxima, minima and inflection points, indicating a change of direction.
• a second derivative which identifies local maxima, minima and inflection points, indicating a change of direction.
• a change of phase may be detected by, for example, continuously sampling the value of the phase, comparing each new sample with the last, and determining whether the value is increasing or decreasing. Then, when a new sample value reverses the direction of the previous samples, for example if the new sample value is higher than the previous sample value, when up to that point the sample values had been decreasing with each iteration, this indicates a change of phase.
• An algorithm could be used to perform this analysis automatically, in which case a buffer may be included to prevent anomalous results triggering false alarms. Such an algorithm may be referred to as an online derivative calculation.
• Figure 10 is a graph showing the results of a test of a system implementing the process described above for a real-world test. In this test, the vehicle- trailer combination 10 was driven steadily at 40mph, and impulse steering manoeuvers were performed at random intervals. As shown in Figure 10, the system successfully triggered an alarm each time an impulse steering manoeuver was performed.
• a control module 72 which may be used to implement the process 52 of Figure 9 is illustrated.
• the control module 72 is provided with a plurality of input means in the form of inputs 74, processing means in the form of a processor 76, and output means in the form of an output 78.
• the inputs 74 are arranged to receive the input signals relating to steering wheel angle and trailer yaw.
• the processor 76 is arranged to take these input signals and use them to conduct the process 52 outlined with reference to Figure 9, in order to predict a critical instability.
• the control module 72 may be arranged to use the output 78 to output a control signal to control an alarm, where the alarm may be used to alert the driver.
• the output may output a control signal to a vehicle system, such as an electronic stability control (ESC) system, to automatically take corrective action on behalf of the driver, as described previously.
• a vehicle system such as an electronic stability control (ESC) system
• ESC electronic stability control
• the control module may be provided with a single input for receiving sensor data or multiple inputs.
• the invention also extends to a vehicle 80 comprising the above described control module 72.
• the vehicle may be further provided with sensors (not shown) for the monitoring of the steering wheel angle and the trailer yaw angle.
• trailer direction related parameters for example a direct measurement of the direction of travel of the trailer 14, to predict instability.
• vehicle direction related parameters to steering wheel angle which provide an indication of the direction of travel of the vehicle 12 which could be utilised in the method for predicting instability.
• gyroscopic sensors in the vehicle 12 could be used to measure vehicle yaw, or a GPS system and/or a system which uses gyroscopic measurement to provide positioning information in the event of a temporary cut in a GPS signal could provide data for the direction of travel of the vehicle 12.
• Another possibility would be to provide a sensor in the front wheels to detect their current alignment.
• the above described embodiments of the invention offer the advantage that instability of the trailer 14 may be accurately predicted based on just two input variables, namely a variable indicating a direction of travel of the vehicle 12, and a variable indicating a direction of travel of the trailer 14. This negates any requirement to model the entire system of the vehicle-trailer combination 10, which would be far more computationally demanding.
• the previously described system detects the onset of oscillations in the vehicle-trailer system at a very early stage and in particular detects when the oscillations are about to become unstable. This allows action to be taken by the driver to prevent the oscillation developing further. Furthermore, this can be used to allow the driver to determine an optimum driving speed (one at which the warning does not activate) thereby minimising the need for braking.
• the primary output from the system is a warning given directly to the driver in order to allow the driver to take the required corrective action; however, in an alternative embodiment of the invention, the alert signal output from the system is optionally input into the vehicle's existing ESC system. This allows the ESC to automatically take corrective action on behalf of the driver.
• This approach has an advantage over existing systems in that over-braking of the vehicle wheels may be avoided.
• a system operating in accordance with this embodiment of the invention directly monitors the movement of the trailer 14 such that the alert signal is output to the ESC at a much earlier stage, and therefore corrective action may be taken earlier to prevent instability from occurring. For example, this could mean that upon detecting the early onset of oscillation, the ESC system automatically eases off the accelerator without having to apply the vehicle's brakes in order to regulate the vehicle- trailer road speed.
• the present invention offers the ability to detect instability of a trailer 14 which is very lightweight relative to the vehicle 12. In previous systems, movement of a very lightweight trailer of, for example, less than 750kg, would not have enough effect on the vehicle 12 to be detected by the ESC system, thus corrective action may not be taken at all. This could lead to goods contained in the trailer 14 becoming damaged.
• the process 52 of Figure 9 for predicting a critical instability event may be adapted for use with a multi-trailer system, in which a vehicle is towing two or more trailers in series.
• a multi-body scenario as well as trailer movement falling out of step with the movement of the vehicle (as in the single trailer system)
• Either of these situations may be detected and used to predict critical instability in a similar manner to when dealing with a single trailer.
• articulation angles between pairs of adjacent trailers may be measured and the process 52 can take two such measurements for two different pairs of trailers as the inputs.
• one articulation measurement along with the steering wheel angle may be used in the same way as in the single trailer arrangement.
• An artificial vector can then be constructed in the same way as outlined above in relation to a single trailer arrangement, and the phase of the vector can be monitored to identify a change in the trend of the phase, in order to predict a critical instability event.
• a method of predicting instability in a vehicle-trailer combination comprising: monitoring a vehicle direction related parameter; monitoring a trailer direction related parameter; comparing the vehicle direction related parameter with the trailer direction related parameter to determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determining an instability event in dependence on a change in the response trend.
• a method according to paragraph 1 comprising outputting an alarm signal in dependence on making a positive determination of an instability event.
• a method according to paragraph 2 comprising outputting the alarm signal to a driver of the vehicle to indicate the onset of a trailer instability. 4.
• comparing the vehicle direction related parameter with the trailer direction related parameter comprises defining an artificial vector based on the vehicle direction related parameter and the trailer direction related parameter. 5.
• determining the response of the trailer comprises calculating the argument of the vector.
• a method according to paragraph 5, wherein defining a response trend comprises monitoring the argument of the vector over time to identify a direction of growth of the argument of the vector.
• a control module for predicting instability in a vehicle-trailer combination comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend.
• a control module further comprising an output arranged to output a control signal to activate an alarm.
• a control module according to paragraph 13, wherein the alarm is used to activate an automatic vehicle safety system.
• a system for predicting instability in a vehicle-trailer combination comprising; a control module for predicting instability in a vehicle-trailer combination, the control module comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend; at least one sensor arranged to monitor the vehicle direction related parameter; and at least one sensor arranged to monitor the trailer direction related parameter.
• the at least one sensor arranged to monitor the vehicle direction related parameter comprises a steering wheel angle sensor.
• the at least one sensor arranged to monitor the vehicle direction related parameter comprises a vehicle yaw sensor.
• An engine control unit comprising a control module for predicting instability in a vehicle-trailer combination, the control module comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend.
• control module comprises an output arranged to output a control signal to activate an alarm.
• a vehicle comprising a control module for predicting instability in a vehicle-trailer combination, the control module comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend.
• control module comprises an output arranged to output a control signal to activate an alarm.
• a vehicle comprising a system for predicting instability in a vehicle-trailer combination, the system comprising; a control module for predicting instability in a vehicle- trailer combination, the control module comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend; at least one sensor arranged to monitor the vehicle direction related parameter; and at least one sensor arranged to monitor the trailer direction related parameter.
• the control module comprises an output arranged to output a control signal to activate an alarm.
• a vehicle according to paragraph 25, wherein the at least one sensor arranged to monitor the vehicle direction related parameter comprises a steering wheel angle sensor. 29. A vehicle according to paragraph 25, wherein the at least one sensor arranged to monitor the vehicle direction related parameter comprises a vehicle yaw sensor.
• a vehicle according to paragraph 25, wherein the at least one sensor arranged to monitor the trailer direction related parameter is a vehicle mounted camera.
• a vehicle comprising an engine control unit comprising a control module for predicting instability in a vehicle-trailer combination, the control module comprising: an input arranged to receive a signal indicative of a vehicle direction related parameter; an input arranged to receive a signal indicative of a trailer direction related parameter; and a processor arranged to: compare the vehicle direction related parameter with the trailer direction related parameter; determine a response of the trailer direction to the vehicle direction over time in order to define a response trend; and determine an instability event in dependence on a change in the response trend.
• the control module comprises an output arranged to output a control signal to activate an alarm.

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• Engineering & Computer Science (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Automation & Control Theory (AREA)
• Physics & Mathematics (AREA)
• Mathematical Physics (AREA)
• Regulating Braking Force (AREA)
• Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

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• 2013
  • 2013-05-01 GB GB1307886.0A patent/GB2513616B/en active Active
• 2014
  • 2014-04-16 WO PCT/EP2014/057723 patent/WO2014177380A1/en active Application Filing
  • 2014-04-16 EP EP14718569.8A patent/EP2991867A1/de not_active Withdrawn

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