Method of calculating suggested speed range for vehicle, corresponding system and computer program product

Abstract

A method (30) of calculating a suggested speed range (42) of a vehicle is disclosed. The method includes detecting (302) a maximum speed limit effective for a section of the road on which the vehicle travels, and setting (314) an upper limit (VH) of the suggested speed range (42) to a value lower than or equal to the detected maximum speed limit. The method further includes detecting (308, 310, 312) one or more of the following parameters: i) an energy condition of a traction battery of the vehicle; ii) a temperature of one or more battery cells of a traction battery of the vehicle; and iii) power absorbed by one or more auxiliary loads of the vehicle. The method further includes setting (314) an upper limit (VH) and / or a lower limit (VL) of the suggested speed range (42) as a function of the detected parameter to increase the mileage of the vehicle.

Description

Technical Field

[0001] The present invention relates to a method and system for calculating and communicating a recommended speed range to a driver of a vehicle. Background Art

[0002] Systems of the aforementioned type are known, for example, from document US2010 / 0315218A1. This type of known system comprises a GPS receiver, an image recognition device, one or more sensors, one or more electronic processing units (processors), and a display on the vehicle dashboard. The GPS receiver and / or the image recognition device detects the legal speed limit in effect on the road on which the vehicle is traveling. The sensors detect the environmental conditions around the vehicle. The processor receives data from the GPS receiver and / or the image recognition device and from the sensors; calculates a maximum safe speed; and calculates a safe speed range as a function of the maximum safe speed and the legal speed limit. If the maximum safe speed is lower than the legal speed limit, the dashboard display screen will alert the driver, and if the maximum safe speed is lower than the legal speed limit, the safe speed range will be displayed on the speedometer.

[0003] In the known systems described above, parameters relating to consumption and range of the vehicle are not taken into account, which parameters are gaining increasing importance particularly in hybrid and electric vehicles.

[0004] Purpose of the Invention

[0005] The object of the present invention is to provide a method and a system for calculating a recommended speed range and communicating it to a driver of a vehicle, which improves driving safety and fuel consumption of the vehicle. Summary of the Invention

[0006] In one aspect, the present invention relates to a method for calculating a recommended speed range for a vehicle, which may be implemented by an electronic unit (e.g., a microprocessor or a vehicle control unit). The method comprises detecting a maximum speed limit in effect for a section of a road on which the vehicle is traveling, and setting an upper limit of the recommended speed range to a value less than or equal to the detected maximum speed limit. The method further comprises detecting one or more of the following parameters: i) an energy condition of a traction battery of the vehicle; ii) a temperature of one or more cells of the traction battery of the vehicle; and iii) power absorbed by one or more auxiliary loads of the vehicle. The method comprises setting the upper and / or lower limit of the recommended speed range as a function of the detected parameters to increase the vehicle's range.

[0007] According to another aspect, the present invention relates to a system for calculating a recommended speed range for a vehicle. The system comprises: at least one sensor configured to detect a maximum speed limit in effect for a section of a road on which the vehicle is traveling; and one or more sensors configured to detect one or more of the following parameters: i) an energy condition of the vehicle's traction battery; ii) a temperature of one or more cells of the vehicle's traction battery; and iii) power absorbed by one or more auxiliary loads of the vehicle. The system also comprises an electronic control unit configured to operate according to the method of one or more embodiments.

[0008] According to another aspect, the present invention relates to a corresponding computer program product that can be loaded into a memory of at least one processing device (e.g., a microprocessor, an electronic control unit, or a vehicle control unit) and comprises software code instructions to perform the method when the program is executed by the at least one processing device. As used herein, reference to such a computer program product is intended to be equivalent to reference to a computer-readable medium containing instructions for controlling the processing device for the purpose of coordinating the implementation of the method according to one or more embodiments. Reference to "at least one processing device" is intended to emphasize the possibility of one or more embodiments being implemented in a modular and / or distributed form. DETAILED DESCRIPTION

[0009] Further features and advantages of the invention will emerge from the following description made with reference to the accompanying drawings, provided purely by way of non-limiting example, in which:

[0010] - Figure 1 is a graph showing different energy consumption curves (energy per meter, EPM—expressed in kWh / km) of a vehicle as a function of vehicle speed (V—expressed in km / h) under four different operating conditions of the vehicle;

[0011] - Figure 2 is a graph showing the maximum safe speed (V) of a vehicle as a function of the coefficient of grip (μ – dimensionless) between the vehicle's tires and the ground in four different driving modes of the vehicle. MAX – graphs of different curves (expressed in km / h);

[0012] - Figure 3 a flowchart illustrating a method according to one or more embodiments of the present description; and

[0013] - Figure 4 A vehicle speedometer according to one or more embodiments of the present invention is shown.

[0014] As mentioned, one or more embodiments relate to a method of calculating and communicating a recommended speed range to a driver of a vehicle as a function of vehicle ambient conditions (e.g., environmental inputs) and as a function of an energy objective, i.e., to increase the vehicle's range.

[0015] In fact, the inventors have noticed that the legal speed limit (i.e., the maximum speed imposed by the speed limit in effect on the section of road on which the vehicle is traveling) generally does not optimize the vehicle's energy consumption. Therefore, the method according to the present invention calculates a recommended speed range as a function of various parameters detected by the vehicle, such as, for example, the legal speed limit (which represents an upper limit), the vehicle's energy conditions, the grip conditions between the vehicle's tires and the ground, and optionally other environmental conditions. Once the recommended speed range has been calculated, the method involves indicating (for example, visually on a speedometer displayed on the vehicle's dashboard) this recommended speed range so that the driver can be informed of the recommended speed range to maintain safe driving conditions and, at the same time, optimize vehicle consumption.

[0016] In the remainder of this description, reference will primarily be made to electric traction vehicles (battery electric vehicles, BEV). Nevertheless, one or more embodiments may be applied in a similar manner to hybrid vehicles (hybrid electric vehicles, HEV) or vehicles with an internal combustion engine (ICE).

[0017] In order to better understand the present invention, Figure 1Different curves are shown for the vehicle's energy consumption (EPM) (in kWh / km) as a function of vehicle speed (in km / h) under four different operating conditions of the vehicle, i.e., depending on the number of auxiliary loads active during driving (such as air conditioning, heated seats, etc.). For example, in the first operating condition (continuous curve), the power absorbed by the auxiliary loads is 0 kW, i.e., there are no active auxiliary loads and the only energy absorbed from the battery is due to the electric motor used to propel the vehicle. In this first operating condition, consumption increases monotonically as vehicle speed increases, since friction increases with increasing speed. In the second operating condition (dotted curve), the power absorbed by the auxiliary loads is 0.5 kW, i.e., there are few active auxiliary loads (e.g., only one heated seat is switched on). In the third operating condition (dashed-dotted curve), the power absorbed by the auxiliary loads is 2 kW, i.e., there are more active auxiliary loads (e.g., all heated seats are switched on). In the fourth operating condition (dashed curve), the power absorbed by the auxiliary loads is 10 kW. In the second, third, and fourth operating conditions (and generally, as long as energy not used for vehicle propulsion is absorbed), the consumption curve tends to diverge towards infinity as the speed approaches zero, since the consumption of the auxiliary loads remains constant over time and leads to battery depletion even if the vehicle remains stationary. However, as the speed increases, the consumption curve tends to overlap with the curve of the first operating condition, since the consumption due to the auxiliary loads becomes increasingly negligible compared to friction. Thus, in the intermediate portion, the consumption curve exhibits a minimum, corresponding to the speed value that maximizes the vehicle's range under this particular operating condition.

[0018] Again, in order to better understand the purpose of the present invention, Figure 2 The maximum safe speed V of a vehicle is shown as a function of the coefficient of grip (μ – dimensionless) between the vehicle's tires and the ground in four different driving modes of the vehicle. MAX In general, the maximum safe speed can be set to higher values ​​as the grip coefficient increases, but the relevance varies depending on the vehicle's driving mode: the choice depends on the driver's driving style, making the grip target more or less stringent (especially in sporty driving modes where greater slip can be tolerated). For example, Figure 2The MR mode ("max range," i.e., range maximization mode—continuous curve), the GT mode ("Gran Turismo," i.e., "normal" driving mode, which is usually the default setting when starting the vehicle—dotted curve), the SP mode ("sport," i.e., a mode allowing performance more suitable for sporty driving—dashed-dotted curve), and the CO mode ("racing," i.e., a mode allowing maximum performance and greater slip, for example by excluding intervention by one or more vehicle safety controls such as ESP, TCS, etc.—dashed curve) are shown. For example, the MR range maximization mode limits the maximum speed to a value of 130 km / h, regardless of the value of the grip coefficient.

[0019] The method according to the invention therefore takes into account the maximum speed limit valid for the section of road on which the vehicle is travelling, the detected energy conditions (e.g. due to the absorption of auxiliary loads) and the detected environmental conditions (e.g. the grip coefficient) in order to calculate a speed range in which the vehicle can be driven safely while maximising the range. Once this speed range has been calculated, a corresponding indication is provided to the driver (e.g. visually on the vehicle's speedometer).

[0020] Figure 3A flow chart of a method 30 according to the present invention is shown. After a start step 300, the method includes a step 302, in which the vehicle detects the maximum speed limit valid for the current section of road. For example, the maximum speed limit can be detected by identifying relevant road signs via a vehicle camera and / or by satellite positioning (GPS) and using the vehicle's navigation features. Alternatively, and in a similar manner, in step 302, the vehicle can detect the minimum speed limit valid for the current section of road (e.g., provided on certain lanes of a highway section). In step 304, the vehicle detects the driving mode currently used by the driver (e.g., MR, GT, SP, or CO). In step 306, the vehicle estimates the value of the grip coefficient μ. This estimate can be made as a function of one or more detected parameters (including the environment), for example, by modifying a default value according to an algorithm that takes into account the following: wheel revolutions, longitudinal acceleration, lateral acceleration, applied drive torque, the presence and intensity of rain (which can be detected via dedicated sensors, sensors that automatically activate the vehicle's windshield wipers, or again based on GPS positioning). In step 308, the vehicle detects the instantaneous energy conditions of the high-voltage battery (i.e., the battery that provides energy for electric traction). These energy conditions may include the state of charge (SOC) of the battery and / or the state of health (SOH) of the battery. In step 310, the vehicle detects the temperature (or multiple temperatures, if equipped with multiple sensors) of the high-voltage battery cells. Optionally, in step 310, the vehicle also detects possible voltage imbalances between the high-voltage battery cells. In step 312, the vehicle detects the number and type of activated auxiliary loads (e.g., high-voltage actuators such as air conditioning compressors) and estimates the power absorbed by the active auxiliary loads. In step 314, the vehicle determines a recommended speed range as a function of the parameters detected in the previous step, and in particular complies with one or more of the following conditions:

[0021] -Upper limit V H cannot be greater than the maximum speed limit detected in step 302;

[0022] -Lower limit V L cannot be less than the minimum speed limit detected in step 302;

[0023] -Upper limit V H and the lower limit V L calculated as a function of the driving mode detected in step 304 (e.g., the speed suggested in a more eco-friendly driving mode such as MR mode will be lower than the speed suggested in a more sporty driving mode like SP mode);

[0024] -Upper limit V H Calculated as a function of the grip coefficient estimated at step 306 (eg, upper limit VH decreases with decreasing coefficient of grip and / or in the presence of precipitation on the road);

[0025] -Upper limit V H and the lower limit V L calculated as a function of the energy condition of the battery detected in step 308 (for example, if the state of charge SOC of the battery is lower, the values ​​of these limits will be lower: when the percentage of charge is 10%, the recommended speed may be equal to 90 km / h, for example, and when the percentage of charge is 20%, the recommended speed may be equal to 95 km / h);

[0026] -Upper limit V H and the lower limit V L calculated as a function of the temperature of the battery cells detected at step 310 (e.g., the higher the temperature imbalance between the different battery cells, the lower the recommended speed: when the temperature difference is 15° C., the recommended speed may be equal to 90 km / h, for example, and when the temperature difference is 10° C., the recommended speed may be equal to 95 km / h);

[0027] -Upper limit V H and the lower limit V L calculated as a function of the voltage imbalance of the battery cells detected at step 310 (e.g., the higher the voltage imbalance between the different battery cells, the lower the recommended speed: when the voltage difference is 0.3 V, the recommended speed may be equal to 90 km / h, and when the voltage difference is 0.1 V, the recommended speed may be equal to 95 km / h);

[0028] -Upper limit V H and the lower limit V L Calculated as a function of the power absorbed by the active auxiliary loads estimated in step 312 (e.g., ensuring that the recommended speed range is as follows Figure 1 The EPM curve shown is centered at its minimum).

[0029] Once the recommended speed range (i.e. upper limit V H and the lower limit V L ) has been determined, the method includes step 316, wherein the vehicle provides an indication of this recommended speed range to the driver. For example, the indication may be as follows Figure 4 The visual representation shows a (digital) speedometer 40 of a vehicle according to one or more embodiments, wherein a portion 42 of the speedometer (in the example considered here, comprised in the lower limit V equal to 70 km / h) L and an upper limit V of 110 km / h H Between) utilize coloring that is different from background, to emphasize this advice speed range to the driver.Certainly, this instruction also can be offered to the driver in other ways, for example utilize acoustic warning.

[0030] It will be appreciated that the method 30 may be kept active continuously during use of the vehicle so that as one or more of the relevant conditions change, the speed limit value V H and V L Is updated periodically.

[0031] As an example, one can think of a situation where the vehicle is traveling on a highway and the camera (and / or navigation system, e.g. if the camera is "blind") detects a speed limit of 130 km / h. In the absence of other influencing factors, the recommended speed range would be represented by an emphasized (e.g. colored) portion 42 of the speedometer, with a maximum V H = 130 km / h. Then, depending on the possible auxiliary loads that are subsequently activated, the upper limit V H For example, if the user only turns on one heated seat, there will be some additional consumption, which will reduce V H value (e.g., from 130 km / h to 100 km / h), and if he or she turns on two heated seats or other additional loads, then V H It may be more convenient to lower the value to a different value (higher, such as 105 km / h). Furthermore, if the estimated grip coefficient at that time indicates poor grip, the upper speed limit may be further lowered: for example, if the vehicle estimates the grip coefficient μ to be 0.5, then the recommended speed may be further lowered (e.g., to 90 km / h). Furthermore, if the vehicle detects a significant battery depletion, the upper speed limit may be further lowered: for example, the recommended speed may be further lowered (e.g., to 40 km / h).

[0032] Of course, despite the principle of the invention, the construction details and the embodiments may vary widely with respect to what has been described and illustrated purely by way of example, without thereby departing from the scope of the invention as defined in the appended claims.

Claims

1. A method (30) for calculating a recommended speed range (42) for a vehicle, comprising: - detecting (302) a maximum speed limit in force for the section of road on which the vehicle is travelling; - The upper limit (V H ) is set (314) to a value less than or equal to said detected maximum speed limit; The method (30) further comprises detecting (308, 310, 312) one or more of the following parameters: i) the energy condition of the traction battery of the vehicle; ii) the temperature of one or more cells of the traction battery of the vehicle; and iii) power absorbed by one or more auxiliary loads of the vehicle; And wherein, the method (30) further comprises setting the upper limit (V H ) and / or lower limit (V L ) is set (314) as a function of the one or more detected parameters to increase the mileage of the vehicle.

2. The method (30) according to claim 1, comprising: - detecting (302) a minimum speed limit in force for a section of road on which the vehicle is travelling; as well as - the lower limit (V L ) is set to a value greater than or equal to the detected minimum speed limit.

3. The method (30) according to claim 1 or claim 2, wherein: The maximum speed limit and / or the minimum speed limit is detected by identifying corresponding road signs by processing an image captured by a camera of the vehicle ( 302 ).

4. The method (30) according to any one of the preceding claims, wherein: The maximum speed limit and / or the minimum speed limit are detected (302) via satellite positioning of the vehicle.

5. The method (30) according to any one of the preceding claims, comprising: - detecting (312) power absorbed by one or more auxiliary loads of the vehicle; - determining a target speed value (V) of the vehicle as a function of the power absorbed by one or more auxiliary loads, at which target speed value (V) a minimum value of energy per meter (EPM) of the vehicle is obtained; and - setting (314) the upper limit (V) of the recommended speed range (42) H ) and the lower limit (V L ), so that the target speed value (V) is included in the upper limit (V H ) and the lower limit (V L )between.

6. The method (30) according to any one of the preceding claims, comprising: - detecting (304) the driving mode (MR, GT, SP, CO) currently used by the vehicle; as well as - The upper limit (V H ) and / or the lower limit (V L ) is set (314) as a function of the detected driving mode.

7. The method (30) according to any one of the preceding claims, comprising: - estimating (306) the value of the coefficient of grip (μ) between the tires of the vehicle and the road; as well as - The upper limit (V H ) and / or the lower limit (V L ) is set (314) as a function of the estimated grip coefficient (μ), in particular, the upper limit (V H ) and / or the lower limit (V L ).

8. The method (30) according to claim 7, wherein: Estimating (306) the value of the grip coefficient (μ) includes detecting precipitation and decreasing the value of the grip coefficient (μ) as the intensity of the detected precipitation increases.

9. The method (30) according to any one of the preceding claims, comprising: An indication of the recommended speed range (42) is provided to a driver of the vehicle, in particular by displaying (316) the recommended speed range (42) on a speedometer (40) of the vehicle.

10. A system for calculating a recommended speed range (42) for a vehicle, comprising: - at least one sensor configured to detect (302) a maximum speed limit in effect for a section of the road on which the vehicle is travelling; - one or more sensors configured to detect (308, 310, 312) one or more of the following parameters: i) the energy condition of the traction battery of the vehicle; ii) the temperature of one or more cells of the traction battery of the vehicle; as well as iii) power absorbed by one or more auxiliary loads of the vehicle; as well as - An electronic control unit configured to operate according to the method of any one of the preceding claims.

11. A computer program product capable of being loaded into a memory of at least one processing device and comprising software code instructions which, when the program is executed by the at least one processing device, cause the at least one processing device to perform the method according to any one of claims 1 to 9.

Images