SE1050393A1 - Method and system for assessing a driver's braking behavior - Google Patents

Abstract

The invention relates to a method for assessing a driver's braking of a vehicle, comprising determining when a braking cycle begins; determining the time tengbrake when the vehicle's engine brake is used during the braking cycle; determining the time tshift for gear changes during the braking cycle; determining when the braking cycle ends; determining the total time ttotal for said braking cycle; processing ttotal and tengbrake with respect to tshift according to predetermined rules, and calculating a braking assessment value BA based on processed values for tengbrake and ttotal. The invention relates also to a system for assessing a driver's braking of a vehicle.

Description

15 20 25 30 2 heavy vehicles, the driver can reduce the wear on brake pads, brake discs, etc. that are associated with the use of the brake discs. If e.g. only the service brake is used when a heavily loaded vehicle is driving on a long downhill slope, this can result in catastrophic consequences due to overheated brake pads, brake drums and / or brake pads. The use of auxiliary brakes should therefore be encouraged to make the driver's use of them more frequent.

Not all vehicles are equipped with all available auxiliary brakes.

For example, hydraulic retarder is not always used, depending on its cost.

However, the exhaust brake, which is also an auxiliary brake, is usually available on a heavy vehicle. The problem with evaluating the driver's use of the exhaust brake, and thus encouraging the driver to use it, however, is that exhaust brake use in many countries is illegal, often at certain times of the day, as it sounds loud when used. It is also difficult to estimate the braking force that can be obtained from the exhaust brake in different driving cases.

WO 2007/139494 describes a device for determining a driver's ability to select a braking system. The driver's use of the braking system is compared with the driver's total use of the braking systems during braking to assess the driver's ability to use the braking system. The total use of the system is measured as energy consumed or use of the system.

EP 1811481 describes a method and system for monitoring and analyzing a driver's driving style. Various parameters such as speed, vehicle speed, gear selection, etc. are monitored and used to create a driver profile that shows the driver's driving style.

The object of the invention is to achieve an improved method for evaluating the driver's ability to brake so that wear and fuel consumption is minimized, and in particular to encourage the driver to drive so that wear and fuel consumption is minimized. Summary of the Invention The object described above is achieved by a method for assessing a driver's braking behavior. The method includes: determining when a deceleration period begins; determine the time tengbrake when the vehicle's engine brake is used during the braking period; determine the time tshift for shifts during the deceleration period; determine when the deceleration period ends; determining the total time ttoiai for said deceleration period; process ttotai and tengbrake with respect to tshifi according to predetermined rules, and calculate a brake assessment value BA based on processed values for tengbmke and tens.

According to another aspect, the purpose is achieved through a system for assessing a driver's braking behavior. The system comprises a control unit connected to a first measuring unit adapted to determine when a deceleration period begins; a second measuring unit coupled to the control unit and adapted to determine the time tengbrake when the vehicle's engine brake is used during the braking period and to emit a second time signal containing tengbrake depending thereon; a third measuring unit coupled to the control unit and adapted to determine the time tshif, for shifts during the deceleration period and to emit a third time signal containing tshift depending thereon; wherein the first measuring unit is adapted to determine when the deceleration period ends and to determine the total time tens for said deceleration period and emit a first time signal containing ttotaj to the control unit accordingly, wherein the control unit is further adapted to process tens And tengbrake with respect to tshifi according to predetermined rules, and to calculate a brake assessment value BA based on processed values for tengbrake And ttotal- Through the method and the system, a way is achieved to assess a driver's ability to brake in a way so that wear and fuel consumption is minimized. This type of assessment of a driver's way of braking is very general and can be applied to many types of vehicles, such as trucks, buses, cars, without major requirements on how the vehicle is equipped. According to one embodiment, the driver can receive direct feedback on his braking behavior, and can then remedy behaviors that have a negative impact on the environment and economy.

Through constant reminders of which driving style is desired, the driver can also maintain and improve his ability between training sessions.

The driver's braking behavior can also be scored, which is a positive way to encourage competition and commitment. You can thus make the driver have fun at work while improving the driving style.

Preferred embodiments are described in the dependent claims and in the detailed description.

Brief description of the accompanying figures The invention will be described below with reference to the accompanying figures, of which: Figure 1 schematically illustrates an assessment system according to an embodiment of the invention.

Figure 2 shows a flow chart of the assessment method according to an embodiment of the invention.

Figure 3 shows a flow chart of the assessment method according to another embodiment of the invention.

Figure 4 illustrates the scoring of BA in Figure 2.

Figure 5 shows a flow chart of the assessment method according to a further embodiment of the invention.

Figure 6 shows an example of how the engine speed neng changes downhill.

Detailed Description of Preferred Embodiments of the Invention Figure 1 schematically shows a system for assessing a driver's braking behavior according to an embodiment of the invention. The system comprises a control unit which preferably comprises a processor unit for performing calculations etc. and at least one memory. The control unit is connected to a number of measuring units which are adapted to determine different variables. The first measuring unit is adapted to determine when a deceleration period begins and when it ends, and to determine the total time tens for the deceleration period and emit a first time signal containing hours. to the control unit depending thereon. Depending on the situation to be assessed, the first measuring unit is adapted to monitor and calculate various parameters and signals such as the vehicle's speed, acceleration, the vehicle's driving resistance, etc. to determine when a deceleration period begins and ends. Figure 1 schematically illustrates this as an arrow to the first measuring unit. The second measuring unit connected to the control unit is adapted to determine the time tengbrake when the vehicle's engine brake is used during the braking period, and to emit a second time signal containing tengbrake depending thereon. The inputs to the second measuring unit are according to an embodiment similar to those of the first measuring unit. The third measuring unit is adapted to determine the time tshift for shifts during the deceleration period and to emit a third time signal containing tshift depending thereon. The third measuring unit then receives, for example, information from the gear system in the vehicle about when and which gears are used. The control unit is adapted to process tens and tengbrake with respect to tshift according to predetermined rules, and to calculate a brake assessment value BA based on the processed values for tengbmke and ttoiaj. The measuring units described are, according to one embodiment, functional units that can be included in the control unit.

The control unit preferably comprises a processor unit which is adapted to perform calculations etc., and at least one memory.

According to one embodiment, the calculated brake assessment value BA is presented to the driver on a display. The value BA can, for example, be displayed as points in the form of a numerical value, or as symbols. The value BA can also be feedback audibly to the driver. According to one embodiment, the value BA can be stored in the memory in the control unit, or sent to a central unit external to the vehicle for further analysis.

According to one embodiment, the system comprises a fourth measuring unit adapted to determine the engine speed nooo during the deceleration period. The measuring unit is then adapted to receive signals from the motor that indicate the motor speed. The fourth measuring unit is illustrated in Figure 1. In this embodiment, the control unit is adapted to process tens and tooootaloo with respect to tattltt and natto according to predetermined rules, and to calculate a brake assessment value BA based on processed values for tooootalto and tens. Thus, the driver's use of the correct gear for the situation can be assessed, and the driver can get feedback on his choice of gear.

The invention also relates to a method for assessing a driver's braking behavior. The method will now be explained with reference to the flow chart in Figure 2. In a first step S21, it is determined when a deceleration period begins. This may be different depending on the braking situation to be assessed, which will be explained below. In a second step S22, the time tattootalta is determined when the engine brake of the vehicle is used during the braking period. In a third step S23, the time toltltt is determined for shifts during the deceleration period. In a fourth step S24 it is determined when the deceleration period ends, which as in step S21 may be different for different situations. In a fifth step S25, the total time of tens for the deceleration period is determined, and in a sixth step S26, tens and tattoos are processed with respect to numbers according to predetermined rules. In a seventh step S27, a brake assessment value BA is calculated based on the processed values for tengbrake and ttotal- According to one embodiment, BA is calculated according to BA = tottootalta / tiotal. In this way, a BA value between 0 and 1 is obtained, and the percentage time that the engine brake has been used can be calculated, as shown in Figure 4.

A deceleration period can start in different ways depending on the situation of the vehicle. Next, a number of braking situations are described in which a driver can actively take measures to reduce wear and tear on the vehicle and also fuel consumption, and how these can be detected and assessed. 10 15 20 25 30 Situation A In this situation the driver actively brakes to slow down. A skilled driver consistently shifts down to contribute as much engine braking power as possible and also to avoid the engine having to idle during braking, which costs fuel. You should also not put the vehicle's gearbox in neutral during braking, except at very low speeds.

To detect and assess the driver's braking behavior in situation A, use the system explained with reference to Figure 1 and the method explained with reference to Figure 2. A braking period begins, for example, when the driver starts braking after a driving period during which the vehicle has not slowed more than a predetermined threshold value. The deceleration period is considered to end when the driver accelerates or when the vehicle's speed falls below a given threshold. The time toogolako that the engine brake is used is determined, and at e.g. coupling use is given a permitted time for switching. According to one embodiment, the rules then include that if talllfl is greater than talllflmax, which is an adjustable maximum allowable time for change, tlolal is processed according to tlolal = tlolal + taamolo, where taamolo is a predetermined time period. This is illustrated in Figure 3. The local vehicle is braked with engine brake, toogolako is increased and tlolal with taamolo. When the vehicle is shifted, tollgolako and tlolal are not increased until a maximum shifting time has elapsed, talllflmax. If the maximum time has elapsed, but no gear has been engaged yet, only tlolal is increased with toamolo.

This is repeated until a gear is engaged, or the braking period is completed.

In order for the deceleration to be assessed at all, a certain total braking time is required according to one embodiment. This may depend on the speed of the vehicle.

The driver is preferably given a BA value in the form of a score based on the time toogolako when the engine brake has been used related to the total braking time tlolal, which is illustrated in Figure 4. The expected proportion of engine brake, ie the BA value, may depend on the vehicle speed. Figure 4 illustrates the limits of the BA value with Flow (vo) and Flllgll (vo), ie the limits of the vehicle's engine braking force at a certain vehicle speed vo. When the driver's ability has been assessed, this is shown to the driver with, for example, symbols and / or points. If a particular behavior is detected, e.g. that the driver is disengaged and braked at high speeds, a tip can be shown to the driver on the display where he is encouraged not to use the clutch and instead use the engine brake.

The driver gets good grades when the speed is reduced as the driver makes consistent shifts.

No fuel injection is needed and there is less wear on the service brakes.

According to one embodiment, consideration is also given to whether the vehicle's exhaust brake is used, which has a positive effect on the driver's rating for the braking method.

Situation B In this situation, the driver wants to pour the speed of the vehicle downhill, thus ensuring that the vehicle does not increase speed. A skilled driver makes sure to downshift and maintain a higher engine speed that helps reduce wear on the brakes. In these situations, exhaust brake use is also preferable. Above all, they want to reduce the wear on the service brakes, but also reduce the risk of brake overheating, which can lead to an accident.

To detect and assess the driver's braking behavior in situation B, the method explained with reference to Figure 2 is used, with some additional method steps illustrated in Figure 5.

A deceleration period begins, for example, by the vehicle starting a downhill slope. Downhill slopes can be detected in many ways. One way is to calculate the vehicle's driving resistance based on expected acceleration at a certain engine power. All external forces on the vehicle can then be assembled in driving resistance and include i.a. gravity, rolling resistance and air resistance. The braking period is considered to end when the driver accelerates or when the vehicle's speed falls below a given threshold, or when the driving resistance falls below a certain value. 10 15 20 25 30 The driver's gear selection is analyzed during braking and two times are calculated, tmotototoma and ttotal. Figure 5 illustrates that the total is increased by taamola when the engine brake is not used, ie when no gear is engaged. Preferably, a certain time toltlttmax is also given here for shifting, just as in situation A. When a braking period has begun and the vehicle brakes, according to one embodiment the engine speed is determined nano during the braking period. ttotal and tottootalto are then processed with respect to tattltt and nano according to predetermined rules, and a brake assessment value BA is calculated based on the processed values for tattgotalta and ttotal. In this way, the assessment takes into account the speed of the engine, and also how long the driver takes for shifting.

According to one embodiment, said predetermined rules include comparing naog with limit values nattottlott and nattolow for the engine speed, where nattottlott is an upper limit value and nattolotl is a lower limit value. This achieves a way of assessing the driver's choice of gear.

According to another embodiment, the rules include that if the night toll is greater than the night toll lot, ttotal is processed fi gt ttotal = ttotal + tsample And tengbrake a fi gt tengbrake = tengbrake + tsample-

If the nano is less than or equal to the night light, check according to one embodiment if the driver uses the exhaust brake during the braking period. If this is the case, and nano is greater than nattoaxttattatatotalta, ttotal is processed according to ttotal = ttotal + taatttola, and tattgotalta according to tattootaka = tattgotalta + taatttola, where nightgoxltattatotaka is a speed limit value related to the exhaust brake. If the control unit receives a signal indicating that the vehicle's exhaust brake has been used during the braking period and the nano is larger than the exhaust brake, ttotal emigt ttotal = ttotal + tsamplel is processed and tengbrake engngt tengbrake = tattootalta + toamola. In this way, the driver's use of the exhaust brake during the braking period can also be evaluated. 10 15 20 25 30 10 According to an embodiment so if neng is greater than nenglow and less nenghigh, tens are processed according to tens = tsample + ttolal and tengbfake according to tengbfake = tengbfake + tsample (neng-nenglovn / (nenghigh-nengbw) _ The driver thus brakes, but the gear selection is not the best for the situation, so downshifting is suitable, and according to one embodiment, this is suggested by the seducer in the display, a suitable gear can then be calculated and suggested.

If the total engine braking force Fengbrake at the recommended engine speed nengreq is greater than the total braking force Ftotbrake, no lower gear is required and no action is taken as the driver should not be advised to brake more than necessary. Braking more than necessary is of course unnecessary and ultimately costs fuel. The total braking force Ftotbrake is thus including service brakes. The recommended engine speed nengreq is a threshold value that, for example, indicates the minimum engine speed required to actively reduce the vehicle's speed during engine braking.

If the total engine braking force Fengbrake at the recommended engine speed nengreq is less than or equal to the total braking force Ftotbrake, and / or if neng is less than or equal to nenglow, is processed according to an embodiment tt0ta | according to tens = tt0ta | + tsamme, where tsample is, as previously mentioned, a predetermined time period. Preferably, downshifting to the driver is now suggested. Here, too, a suitable gear can be calculated and suggested.

Figure 6 shows an example of how the vehicle's speed varies during a period of time when the driver wants to keep the speed on a downhill slope, ie situation B. The figure also shows when the vehicle's exhaust brake is on or off during the same period of time. Table 1 shows how ttota | and tengbmke will be calculated i.a. depending on the driver's gear selection during the time period t. 10 ll TabeH1 Time period Description Measures tt Engine brakes - speeds higher than notioiiioti tens = tens + toatitola, tengbrake: tengbrake + tsample t; Engine brakes - speeds less than tens = tens + taaiitola nenghigh men Greater than nenglow ttotal = tsample * (neng'nenglow) l (nenghigmnenglow) to Engine brakes - speeds less than natiolow tens = tens + toatitola t4 Gears (maxi permitted time) to Engine brakes - speeds higher than notiotiioti tiotal = tiotal + toatitola, tengbrake: tengbrake + tsample to Motor brakes - speeds less than tiotal = tiotal + taaiitola nenghigh men Greater than nenglow ttotal = tsample * (neng'nenglow) l (nenglow) t; Exhaust brakes - speeds greater than tens = tens + toatitola, nellgexhasutbrake tengbrake: tengbrake + tsample to Exhaust brakes - speeds less or equal tens = tens + toaiitola with nengexhasutbrake ttotal = tsample * (neng'nenglow) l Engine brakes ) naootiioii but greater than natiolow tg Engine brakes - speeds less than natiglow tens = tioial + toamola toatitola are according to one embodiment as much as the respective time period tt-tg in the different situations above.

After braking, the driver's ability is scored in the same way as in situation A, but possibly with other parameters, according to figure 4. Tips can also be given afterwards to the driver on how he can handle a similar situation next time. 10 15 20 25 30 12 Situation C In this situation the driver wants to roll freely, which means that the driver does not use gas and brake. For example, this can happen on a gentle downhill slope. Here, a gear should also be engaged instead of depressing the clutch pedal or using a neutral gear. There are several reasons for this. For example. then the engine runs at idle without engaged gear, which means that fuel is consumed. The risk is often great that the extra energy obtained by rolling still has to be slowed down.

To detect and assess situation C, the method and system described with reference to Figures 1 and 2 are used. According to one embodiment, a braking period is started by calculating the driving resistance to a certain value, which indicates that the vehicle is starting a slight downhill. The deceleration period is considered to end when the driver accelerates, if the speed of the vehicle is below a given threshold value, or if the driving resistance is below a certain value.

According to one embodiment, the system is adapted to receive information about and take into account an upcoming traffic situation. This information can be obtained, for example, via radio messages that contain information about the position of the traffic situation.

The driver can then be made aware of traffic situations when the vehicle's speed should be reduced, for example a traffic accident or queue, and adjust the vehicle's speed accordingly. Information about an upcoming road situation can also be obtained via map data about the future road and the vehicle's position. The position of the vehicle can, for example, be obtained via a GPS device in the vehicle. The driver can then be made aware of traffic situations when the vehicle's speed should be reduced, for example a roundabout, a road junction, etc., and adapt the vehicle's speed to the traffic situation. A further example of a road situation is a speed limit which means that the driver must slow down the vehicle.

The driver is preferably encouraged to use the engine brake to slow down or adjust the speed for the upcoming traffic situation. As the driver only uses the engine brake during the braking period to reduce the speed, this is rewarded according to an embodiment with a maximum brake assessment value BA 10 15 20 13 and an encouraging tip shown to the driver via the display. The driver is preferably given a score based on the time tengbrake when the engine brake has been used related to the total braking time ttoiai, which is illustrated in figure 4. The expected proportion of engine brake may depend on the speed of the vehicle. When the vehicle exceeds a certain speed without a gear being engaged, a tip is preferably given via the display which encourages the driver to put in a gear alt. release the clutch pedal.

Preferably, a certain time tshiftmax is also given here for shifting, just as in situations A and B. When gear is engaged, the driver is rewarded by adding as much time tsampie to tengbrake as to tim., Which means that the calculated brake assessment value BA is higher.

The invention also relates to a computer program product, comprising computer program instructions for forcing a computer system in a vehicle to perform the steps according to the described method when the computer program instructions are run on said computer system. The invention also comprises a computer program product where the computer program instructions are stored on a medium readable by a computer system.

The present invention is not limited to the embodiments described above. Various alternatives, modifications and equivalents can be used.

Therefore, the above-mentioned embodiments do not limit the scope of the invention, which is defined by the appended claims.

Claims (18)

10 15 20 25 30 14 Patent claims A method for assessing a driver's braking behavior, characterized in that the method comprises: - determining when a braking period begins; - determine the time tengbrake when the vehicle's engine brake is used during the braking period; - determine the time tshift for shifts during the deceleration period; - determine when the braking period ends; - determining the total time tens for said deceleration period; - process tens and tengbmke with respect to tshift according to predetermined rules, and calculate a brake assessment value BA based on machined values for tengbrake And ttotal- A method according to claim 1, wherein the calculated brake assessment value BA is presented to the driver. Method according to one of the preceding claims, wherein BA is calculated according to BA = tengbrake / ttotal- A method according to any one of the preceding claims, wherein the rules comprise that: if tshift is greater than tshiftmax, which is an adjustable maximum allowable time for shifting, A method according to any one of the preceding claims, wherein the method comprises - determining the engine speed during the braking period; process tens and tengbrake with respect to tshift and neng according to predetermined rules, and calculate a brake assessment value BA based on processed values for tengbrake and ttotal - A method according to any one of the preceding claims, wherein said predetermined rules comprise comparing neng with limit values nenghigh and nengmw for the engine 10 15 20 25 30 15 speed, where noootttolt is an upper limit value and nooolow is a lower limit value. The method of claim 6, wherein the rules comprise that: if nano is greater than nootlot, ttotal is processed according to ttotal = ttotal + toatttola and taoootaka enHgt tengbrake = tengbrake + tsample if nano is greater than or equal to naoolow and less than or equal to nottotttolt processed ttotal and fi gt ttotal = tsample + ttotal ÛCh tengbrake and fi gt tengbrake = tengbrake + tsample (neng'nenglow) / (nenghigh'nenglow), Ûch if nano is less than naoolow, ttotal is processed according to ttotal = ttotal . A method according to any one of claims 5-8, wherein the method comprises that if the vehicle's exhaust brake has been used during the braking period and nano is greater than naooaxltaualbtaka, processing ttotal according to ttotal = ttotal + taamolo, and tooobtaka according to taoobtaka = toogotalto + tooxtalt + tooxto, speed limit value related to the exhaust brake. 9. A system for assessing a driver's braking behavior, characterized in that the system comprises a control unit connected to a first measuring unit adapted to determine when a braking period begins; a second measuring unit coupled to the control unit and adapted to determine the time tooootalto when the engine brake of the vehicle is used during the braking period and to emit a second time signal containing tooootalto depending thereon; a third measuring unit coupled to the control unit and adapted to determine the time tottltt for shifts during the deceleration period and to emit a third time signal containing tottltt in dependence thereof; wherein the first measuring unit is adapted to determine when the deceleration period ends and to determine the total time ttotal for said deceleration period and emit a first time signal containing ttotal to the control unit depending thereon, the control unit further adapted to process ttotal and tooootalto with respect to rules, and to calculate a brake assessment value BA based on processed tgngbfake 10 15 20 25 30 16 The system of claim 9, wherein the calculated brake assessment value BA is presented to the driver on a display. A system according to any one of claims 9 to 10, wherein BA is calculated according to BA = tengbrake l ttotal- A system according to any one of claims 9 to 11, wherein the rules comprise that: if tollllfl is greater than tolllllmox, which is an adjustable maximum allowable time for switching, A system according to any one of claims 9 to 12, wherein the system comprises a fourth measuring unit adapted to determine the engine speed noog during the deceleration period; and that the control unit is adapted to process tlolol and tongoloko with respect to tolllll and noog according to predetermined rules, and to calculate a brake assessment value BA based on processed values for toogoloko. A system according to any one of claims 9 to 13, wherein said predetermined rules comprise comparing noog with limit values nooglllgll and nooglow for the engine speed, where nooglllgl, is an upper limit value and nooglow is a lower limit value. The system of claim 14, wherein the rules comprise that: if noog is greater than nooolllgll, tlolol is processed according to tlolol = tlolol + toomolo and toogoloko a teng gt tengbrake = tengbrake + tsample if noog is greater than or equal to nooglow and less or equal to nooglllgll is processed ttotal and fi gt ttotal = tsample + ttotal ÛCh tengbrake and fi gt tengbrake = tengbrake + tsample (neng'nenglow) / (nenghigh'nenglow) A system according to any one of claims 13 to 15, wherein if the control unit receives a signal indicating that the vehicle's exhaust brake has been used during the braking period and neng is greater than nengexhaustbrake, processing tens fi gt ttotal = ttotal + tsample, Ûch tengbrake enngt tengbrake = tsample, nengexhaustbrake is a speed limit value related to the exhaust brake. A computer program product, comprising computer program instructions for causing a computer system in a vehicle to perform the steps of the method according to any one of claims 1 to 8, when the computer program instructions are run on said computer system. The computer program product of claim 17, wherein the computer program instructions are stored on a computer system readable medium.