TWI655435B - Velocity estimating device, velocity estimating method, and computer program product thereof - Google Patents

Abstract

A vehicle speed estimating device is carried on a vehicle. The vehicle speed estimating device comprises a memory unit and a microprocessor. The memory unit stores a computer program. The microprocessor is electrically connected to the memory unit and can read the computer program to execute the vehicle speed estimating method. The vehicle speed estimation method slip value calculation step, the wheel speed weight value calculation step, the acceleration weight value calculation step, and the vehicle speed estimation value calculation step, by calculating the slip value, excluding the tire with excessive slip value, and imparting the wheel speed sensing value And the acceleration sensing value is weighted, and the vehicle speed can be estimated more accurately. Thus, the estimated speed can be adapted to various driving situations and can be provided to autonomous driving to prevent injury due to errors in vehicle speed estimation.

Description

Vehicle speed estimating device, vehicle speed estimating method, and computer program product thereof

The present invention relates to the field of vehicles, and more particularly to a vehicle speed estimating device, a vehicle speed estimating method, and a computer program product thereof.

At present, the speedometer of the vehicle dashboard usually refers to the average value of the plurality of wheel speeds to calculate the current speed to provide the driver with the acceleration, braking, and turning. However, in fact, the way to calculate the speed of the vehicle is not accurate enough. For example, in gravel or a road with a high sand content, all tires will have a slight degree of slippage, and the average wheel speed will be faster than the actual speed. Or when driving on the general road surface, the tires are uneven due to the road surface. When a certain tire is slipped due to special beating, the wheel speed of the slipping tire is very fast, and the vehicle speed calculated by the average value of the wheel speed is affected by the wheel speed. Not accurate. Vehicle-mounted devices that require higher-accuracy vehicle speed calculation results, such as airbag detonators, can not directly use the above-mentioned wheel speed average to calculate the vehicle speed in order to operate correctly.

In addition, with the development of self-driving cars, the automatic driving system makes an appropriate judgment on the acceleration and deceleration or turning according to the condition of the front object and the surrounding conditions of the road, and the dependence on the accurate calculation of the vehicle speed is getting higher and higher. The average speed value is only provided in a rough calculation of the vehicle speed, which is gradually insufficient. In particular, the self-driving car judges the person without the driver, and if the vehicle speed is judged to be wrong, it is likely to cause a collision, which may result in passenger casualties. Therefore, the precise estimation of the speed of the vehicle depends more on the improvement of the new calculation speed technology.

The method of estimating the speed of the vehicle has also developed an acceleration gauge to calculate the vehicle speed. However, the current acceleration gauge is limited to the straight-line driving direction, and its calculation method is integrated. The slight error may cause the calculation of the vehicle speed to be significant over time. Error. In addition, there is also a GPS method for measuring the speed of the vehicle. However, the positioning accuracy of a general-purpose GPS navigation device has its congenital error limit, which results in a large calculation of vehicle speed error, and the price of a high-precision GPS device may exceed the price of the vehicle, does not conform to the configuration cost, and may still be weathered. When there is a disability or inaccuracy due to the influence of terrain such as a tunnel.

In order to solve the technical problems faced by the prior art, the present invention provides a vehicle speed estimating device, a vehicle speed estimating method, and a computer program product therefor. The vehicle speed estimating device of the present invention is carried on a vehicle, the vehicle includes a plurality of tires, and the vehicle speed estimating device includes a microprocessor. The microprocessor can execute the vehicle speed estimation method; the computer program can also be stored in the memory unit, the microprocessor is electrically connected to the memory unit and can read the computer program to execute the vehicle speed estimation method. The vehicle speed estimating method of the present invention includes a slip value calculating step, a wheel speed weight value calculating step, an acceleration weight value calculating step, and a vehicle speed estimated value calculating step.

The slip value calculation step of the present invention is to calculate a plurality of slip values corresponding to the tires according to the plurality of wheel speed sensing values and the previous vehicle speed estimation values, wherein each wheel speed sensing value refers to Corresponding to the tire speed at the time of the tire. The wheel speed weight value calculating step is to calculate a wheel speed weight value corresponding to each tire according to the slip value and the slip average value, wherein the slip average value is an average value of the slip values. The acceleration weight value calculation step is to calculate the acceleration weight value according to the acceleration sensing value, wherein the acceleration sensing value refers to the acceleration value of the vehicle in the straight direction direction. The vehicle speed estimation value calculating step is based on the wheel speed sensing values, the previous vehicle speed estimation values, the acceleration sensing values, the wheel speed weight values, the acceleration weight values, and the time difference to calculate the current vehicle speed estimation value.

The method for estimating the speed of the vehicle according to the above steps of the present invention can be written into a computer program for storage in a storage medium or downloaded through a network platform to be sold as a computer program product. The computer program product of the present invention can be loaded by a computer device to perform and calculate an estimate of the vehicle's current vehicle speed. The computer program product includes at least a first code, a second code, a third code, and a fourth code to respectively perform a slip value calculation step, a wheel speed weight value calculation step, an acceleration weight value calculation step, and a vehicle speed Estimated value calculation steps.

The invention uses the slip value calculation step and the wheel speed weight value calculation step to screen out the tire with excessive slip value, and the wheel speed weight value calculation step and the acceleration weight value calculation step to respectively transmit the wheel speed weight value And the technical method of acceleration weight value to more accurately estimate the vehicle's current speed, more suitable for estimating the exact speed of the vehicle in various situation modes. Therefore, the vehicle speed estimating device and the vehicle speed estimating method can provide the need for the vehicle distance, the fixed speed, the automatic braking, and the situational judgment to achieve a more accurate vehicle speed, and avoid the casualties caused by the rough estimated error of the vehicle speed. Therefore, the present invention can accurately estimate only the wheel speed sensing value, the acceleration sensing value and the angular velocity sensing value provided by the existing equipment of the vehicle, and does not need to add other special measuring components or high-precision GPS. Equipment, so there is no need to add additional equipment costs.

1 is a block diagram showing the unit of a vehicle speed estimating device according to an embodiment of the present invention. The vehicle speed estimating device 100 of the present embodiment is carried on the vehicle 1 and is electrically or communicably connected to the vehicle signal busbar 20 of the vehicle 1. As shown in FIG. 1, the vehicle speed estimating apparatus 100 of the present embodiment includes a microprocessor 110 and a memory unit 120, and the memory unit 120 stores a computer program 121. The microprocessor 110 is electrically connected to the memory unit 120 and can read and execute the computer program 121 therein. Here, it is merely an example, and is not limited thereto. For example, the computer program 121 may be stored in the microprocessor 110, and the speed estimation method S1 is directly executed by the microprocessor 110.

In this embodiment, the vehicle 1 is exemplified by a four-wheeled vehicle including a plurality of tires, specifically, a left front wheel 10LF, a left rear wheel 10LB, a right front wheel 10RF, and a right rear wheel 10RB. This is merely an example, however, in fact the vehicle 1 may contain more tires, for example six, eight, or twelve. Further, the vehicle signal busbar 20 provided on the vehicle 1 is electrically connected to various vehicle-mounted electronic devices such as a wheel speed receiving unit 21, an acceleration gauge 23, and a yaw angular velocity meter 25. The wheel speed receiving unit 21 receives the current wheel speed sensing value V _ij (t) on each tire, wherein _i in V _ij (t) represents the left and right tire codes, and j represents the front and rear tire codes, That is, V _ij (t) can be represented as left front tire speed V _LF (t), left rear tire speed V _LB (t), right front tire speed V _RF (t), or right rear tire speed V _RB (t). This is merely an example, and is not limited thereto, and vehicles having more tires may be arranged in other ways.

The acceleration gauge 23 of the present embodiment measures the acceleration sensing value acc(t) and outputs it to the vehicle signal busbar 20, and the acceleration sensing value acc(t) refers to the acceleration direction of the vehicle 1 at the time, for example, the acceleration of the forward direction X. value. The yaw angular velocity meter 25 of the present embodiment measures the yaw angular velocity Y(t) and outputs it to the vehicle signal busbar 20, and the yaw angular velocity Y(t) refers to the yaw angular velocity corresponding to the vehicle 1 in the forward direction X (Yaw Rate).

The vehicle speed estimating device 100 of the present embodiment communicates with the vehicle signal bus 20 to receive the wheel speed sensing value V _ij (t), the acceleration sensing value acc(t), and the yaw angular velocity Y(t). The microprocessor 110 is electrically coupled to the memory unit 120 and is capable of reading the computer program 121 to perform the steps of the following vehicle speed estimating method S1.

2 is a flow chart of a method for estimating a vehicle speed according to an embodiment of the present invention. As shown in FIG. 2, the vehicle speed estimating method S1 of the present embodiment includes at least the following steps: a slip difference calculating step S10, a wheel speed weight value calculating step S20, an acceleration weight value calculating step S30, and a vehicle speed estimated value calculating step S40.

In the present embodiment, the slip value calculation step S10 is based on a plurality of wheel speed sensing values V _ij (t) and a previous vehicle speed estimation value V _CG (t-1) to respectively calculate a plurality of tires corresponding to each tire. Slip values S _ij (t). Here, the physical meaning of the slip value S _ij (t) is representative of the degree of slip of the tire at that time, and the more severe the tire slip, the larger the slip difference S _ij (t). In the slip difference calculation step S10, the slip value S _ij (t) of the present embodiment is calculated according to the following formula: , .........(algorithm 1); and when , ......... (Formula 2).

In the present embodiment, the wheel speed weight value calculating step S20 is based on the slip value calculation step S10, and the average of the slip values S _ij (t) and the slip values S _ij (t) The value, that is, the slip average value S _mean (t), is used to calculate the wheel speed weight value K _ij (t) of each tire. In the wheel speed weight value calculation step S20 of the present embodiment, the wheel speed weight value K _ij (t) is calculated according to the following formula: , .........(algorithm 3); and when , .........(algorithm 4), where , Preferably, the numerical condition of a and b is , .

The physical meaning of the above formula 3 is that in the passing wheel speed weight value calculation step S20, the tire whose slip difference S _ij (t) is larger than the slip average value S _mean (t) is screened out, and the subsequent vehicle speed estimation is not allowed. Excessive deviation due to the impact of oversized tires. In addition, the physical meaning of the above formula 4 is that the tire whose sliding value S _ij (t) is smaller than the slip average value S _mean (t) is weighted according to the contribution of the wheel speed sensing value V _ij (t) to the overall vehicle speed. The value K _ij (t).

In the present embodiment, the acceleration weight value calculation step S30 calculates the acceleration weight value K _acc (t) based on the acceleration sensing value _acc (t). In the acceleration weight value calculation step S30 of the present embodiment, the acceleration weight value K _acc (t) is calculated according to the following formula: .........(calculus 5), where Preferably, the numerical condition of c is .

The physical meaning of the above formula 5 is that in the transmission acceleration weight value calculation step S30, the contribution to the overall vehicle speed for the acceleration of the vehicle 1 in the forward direction X is given a weight value K _acc (t).

In the present embodiment, the vehicle speed estimation value calculation step S40 is based on the wheel speed sensing values V _ij (t), the previous vehicle speed estimation value V _CG (t-1), the acceleration sensing value acc(t), and the The wheel speed weight value K _ij (t), the acceleration weight value K _acc (t), and the time difference T are used to calculate the current vehicle speed estimate V _CG (t). The vehicle speed estimation in this embodiment is measured and calculated as a time difference T every other fixed time interval. The previous vehicle speed estimation value V _CG (t-1) refers to the previously calculated vehicle speed estimation value. . In the vehicle speed estimated value calculating step S40, the current vehicle speed estimated value V _CG (t) of the present embodiment is calculated according to the following formula: ......... (Equation 6).

The physical meaning of the above formula 6 is that each wheel speed sensing value V _ij (t) is separately adjusted by its wheel speed weight value K _ij (t), and the previous vehicle speed estimation value V _CG (t-1) is borrowed. It is adjusted by the acceleration weight value K _acc (t), and after adding or subtracting the vehicle speed caused by the acceleration sensing value acc(t) at that time, dividing by all the weight values mentioned above, various extreme conditions are eliminated. For example, in the case of rapid acceleration of the gravel road, the tire with excessive slip difference can be eliminated, and the wheel speed weight value K _ij (t) is reduced, and the acceleration weight value K _acc (t) is increased, so that the acceleration sensing value is obtained. Acc(t) is the main contribution to the overall vehicle speed estimation, but does not neglect the contribution of the wheel speed sensing value V _ij (t) to the vehicle speed. Therefore, the estimated vehicle speed estimated value V _CG (t) estimated by the vehicle speed estimating device of the present embodiment can be closer to the actual vehicle speed. For example, in the case of acceleration and deceleration on the slope, the acceleration sensing value acc(t) is susceptible, so that the wheel speed weight value K _ij (t) can be increased, and the acceleration weight value K _acc (t) can be decreased, thereby The sensed value V _ij (t) is the main contribution of the overall vehicle speed estimation, but does not neglect the contribution of the acceleration speed sensing acc(t) to the vehicle speed. Therefore, the estimated vehicle speed estimated value V _CG (t) estimated by the vehicle speed estimating device of the present embodiment can be closer to the actual vehicle speed.

Since the vehicle speed estimating method S1 used in the embodiment can also estimate a relatively accurate vehicle speed, it can be applied to the need of a precise vehicle speed such as a fixed distance, a fixed speed, and an automatic braking. The deviation calculated from the average value of the wheel speed or the acceleration value in the prior art is solved.

Further, in other embodiments, the vehicle speed estimating method S1 further includes a mode determining step S50, which may predetermine in which mode the vehicle speed estimation is performed in advance of the foregoing steps. In the embodiment of FIG. 2, the mode determining step S50 is based on the wheel speed sensing value V _ij (t), the wheel speed threshold V _th , the previous vehicle speed estimated value V _CG (t-1), and the vehicle speed threshold. V _CGth is compared. Determining the vehicle when all of the wheel speed sensing values V _ij (t) are smaller than the wheel speed threshold V _th and the previous vehicle speed estimation value V _CG (t-1) is less than the vehicle speed threshold V _CGth 1 is in the step-by-step mode, and the acceleration weight value K _acc (t) in the acceleration weight value calculation step is calculated according to the following formula: ......... (Equation 7).

The physical meaning of the above formula 7 is that when the wheel speed sensing value V _ij (t) and the previous vehicle speed estimation value V _CG (t-1) are both lower than the threshold value, it is determined that the vehicle 1 is in the state of just starting, and therefore, The weight of the acceleration sensing value acc(t) is zero, indicating that the influence of the uncalculated acceleration sensing value acc(t) can be ignored in this state. Since the vehicle speed deviation of the starting state caused by the acceleration sensing value acc(t) is excluded, the vehicle speed estimating method S1 can avoid the increase of the deviation value of the vehicle speed estimation over time and make the estimation of the vehicle speed more accurate.

In some embodiments, the wheel speed threshold _Vth can be between 0 and 5 kilometers per hour. Preferably, the wheel speed threshold _Vth is set between 0.05 and 3 km/hr. Since the general wheel speed judgment may have detection errors, this interval can be more accurate. More specifically, the wheel speed threshold _{Vth is} set to be between 0.1 and 1 km/h, and the interval is more likely to eliminate the problem caused by the error.

The vehicle speed threshold V _{CGth is} between 1 and 10 km / h. Preferably, the vehicle speed threshold V _CGth is between 2 and 6 km / h. This interval can further eliminate the error of the vehicle speed in the low speed state. Further, the vehicle speed threshold V _CGth is between 3 and 5 km / h. In this interval, the error of the vehicle speed in the low speed state can be eliminated.

In addition, when the wheel speed sensing value V _ij (t) of any of the tires in the starting mode is greater than the one-wheel speed starting value V _st , it is determined that the vehicle 1 leaves the starting mode, and the acceleration weight in the acceleration weight value calculating step is The value K _acc (t) returns to the above equation 5 for calculation: ,among them ......... (calculus 5).

The physical meaning indicated above is calculated in the manner of returning to the previous acceleration weight value calculation step S30 after the vehicle 1 leaves the start mode. In some embodiments, the wheel speed start value _{Vst is} recommended to be set at 0 to 5 km/ Between hours.

In other embodiments, the mode determining step S50 may be more responsive to the current yaw rate Y(t) of the vehicle 1 and the predetermined yaw rate threshold _Yth when the yaw rate Y(t) is greater than the yaw rate valve. When the value Y _th is judged, the vehicle 1 is judged to be in the curve mode, and the slip value S _ij (t) in the slip value calculation step S20 is calculated according to the following formula: , .........(algorithm 8); and when , ......... (Equation 9), where the wheel speed average value V _mean (t) is the average value of the current wheel speed sensing value V _ij (t).

The physical meaning of the above equations 8 and 9 is that when the vehicle 1 is in a turning state, if the previous vehicle speed estimation value V _CG (t-1) traveling in the straight forward direction X may cause misalignment, the average value of the wheel speed is V _mean (t) is the basis for judgment, and its calculation can be more accurate. In some embodiments, the yaw rate threshold _{Yth is} recommended to be set between 2 and 8 degrees/second.

In other embodiments, determining whether the vehicle 1 is in a turning state may also be based on whether the generated turning signal of the steering wheel lasts for a specific time, for example, 10 seconds. When the steering wheel is returned, that is, when the turning signal is stopped, the slip difference calculating step S20 is returned to the calculation formulas 1 and 2 for calculating the slip value S _ij (t) in general.

In the judging step S50, when the mode judging step S10 judges that the vehicle 1 is not in the start mode or the other state of the curve mode, it is called the normal mode. In the normal mode, the vehicle speed estimation is performed by Equations 1 to 6 in accordance with the manner of the aforementioned slip difference calculating step S10, the wheel speed weight value calculating step S20, the acceleration weight value calculating step S30, and the vehicle speed estimated value calculating step S40.

In some embodiments, the memory unit 120 can be a memory or a hard disk. The computer program 121 can be transferred to the memory unit 120 through a storage medium such as a hard disk, a compact disc, a memory card, a flash drive, or the like. In other embodiments, the computer program 121 can also be stored in the memory unit 120 via an internet or wireless network. The microprocessor 110 is electrically connected to the memory unit 120 and can read the computer program 121 to perform the respective steps of the above-described vehicle speed estimating method S1.

In some embodiments, the aforementioned slip value calculation step S10, the wheel speed weight value calculation step S20, the acceleration weight value calculation step S30, and the vehicle speed estimation value calculation step S40, or even the mode determination step S50, may be integrated. For one or more speed estimation methods to facilitate implementation. The vehicle speed estimation method can be implemented by a general vehicle driving computer or the vehicle speed estimating device 10 to estimate the vehicle speed, and can also be carried by a portable device such as a smart phone, a tablet computer, or a car navigation device. Or wireless communication is connected with the vehicle signal bus 20 on the vehicle to obtain data such as wheel speed and acceleration, and then implemented to estimate the vehicle speed.

The above-mentioned speed estimation method can be written as a computer program, stored in a storage medium, or downloaded through a network platform, and sold as a computer program product. The storage medium may be the memory unit 120 of the aforementioned vehicle-mounted device, or other hard disk drive, optical disk, memory card, flash drive, or the like. The computer program product can also be stored in a cloud server or a network platform, which can be used to connect the network to download the packet wirelessly or by wire. The computer program product of the present invention can be loaded and executed by a computer device.

In one embodiment, the computer program product includes a first code, a second code, a third code, and a fourth code. The first code executes the slip value calculation step S10 described above. The second code executes the above-described wheel speed weight value calculation step S20. The third code executes the above-described acceleration weight value calculation step S30. The fourth code executes the above-described vehicle speed estimation value calculation step S40.

In other embodiments, the computer program product further includes a fifth code, and the fifth code execution mode determining step S50 compares the wheel speed sensing value V _ij (t) with the wheel speed threshold (V _th ), And compare the previous vehicle speed estimate V _CG (t-1) with the vehicle speed threshold (V _CGth ). When the comparison conforms to the start mode, the third code requires the acceleration weight value K _acc (t) to be calculated according to the following formula: .

In other embodiments, the computer program product further includes a sixth code, and the sixth code execution mode determining step S50 compares the yaw rate Y(t) with the yaw rate threshold Y _th when the comparison is met. In the curve mode, the calculated slip value S _ij (t) in the first code is calculated according to the above equations 8, 9: , .........(algorithm 8); when , ......... (Equation 9).

The following method will be used to verify the aforementioned vehicle speed estimation method through actual experiments. Figure 3 (a) and Figure 3 (b) are the measurement curve comparison chart and the difference comparison chart in the first scenario; Figure 4 (a) and Figure 4 (b) are the measurement curves in the second scenario, respectively. Comparison chart and difference comparison chart; Fig. 5(a) and Fig. 5(b) are measurement curve comparison charts and difference comparison charts in the third scenario; and Fig. 6(a) and Fig. 6(b) respectively It is a comparison curve and a comparison chart of the measurement curves in the fourth scenario. Here, in FIGS. 3(a), 4(a), 5(a), and 6(a), the broken line curve indicates the time corresponding to the vehicle speed calculated by the conventional technique using the wheel speed average value. The curve and the straight line are the curves of the reference vehicle speed corresponding to the time measured by the VBOX high-precision GPS device, the dot curve is a curve indicating the corresponding time of the vehicle speed calculated by the conventional technique, and the meter curve is the aforementioned vehicle speed estimation method. The estimated speed of the vehicle corresponds to the time curve. In addition, in Fig. 3 (b), Fig. 4 (b), Fig. 5 (b) and Fig. 6 (b), the broken line curve indicates the vehicle speed and the VBOX high precision calculated by the conventional technique using the wheel speed average value. The difference between the reference vehicle speeds measured by the GPS device corresponds to the time curve. The dot curve is a curve indicating the time difference between the vehicle speed calculated by the conventional technique and the reference vehicle speed measured by the VBOX high-precision GPS device. The meter curve is a curve corresponding to the time difference between the vehicle speed estimated by the aforementioned vehicle speed estimation method and the reference vehicle speed measured by the VBOX high-precision GPS device.

As shown in Fig. 3(a) and Fig. 3(b), the first scenario refers to a situation in which the gravel road is rapidly accelerated. It can be understood that the acceleration of the gravel road will cause the tire to slip, so the slip difference of the tire is large. Therefore, the curve corresponding to the time of the vehicle speed calculated by the average wheel speed of the conventional technology and the VBOX high-precision GPS device are measured. There is a significant difference in the actual speed curve, especially during the 4 to 7 second period. In this situation, the speed of the conventional technology calculated by the acceleration gauge is relatively close to the reference vehicle speed measured by the VBOX high-precision GPS device. However, for a long time, due to the gradual accumulation of errors, the acceleration gauge is used to calculate The vehicle speed gradually deviates from the reference vehicle speed measured by the VBOX high-precision GPS device. The vehicle speed transmission weight estimated by the aforementioned vehicle speed estimation method S1 is estimated to be close to the reference vehicle speed measured by the VBOX high-precision GPS device in the entire time interval.

As shown in Fig. 4(a) and Fig. 4(b), the second scenario refers to a flat linear acceleration/deceleration scenario. From this situation, it can be seen that the curve of the corresponding speed of the vehicle speed calculated by the conventional technique is calculated by the acceleration gauge, and the error accumulates over time, so that the error will gradually increase after a certain time. The curve of the vehicle speed corresponding to the time calculated by the average speed of the wheel is relatively close to the reference speed measured by the VBOX high-precision GPS device, but there is also an error of about 2 km/h at high speed. The vehicle speed transmission weight estimated by the aforementioned vehicle speed estimation method estimates the vehicle speed in the entire time interval to be close to the reference vehicle speed measured by the VBOX high-precision GPS device.

As shown in Fig. 5(a) and Fig. 5(b), the third situation is the situation of the flat curve acceleration and deceleration. Since the acceleration of the vehicle includes the longitudinal direction (forward direction X) and the lateral acceleration when driving in a curve, since not every vehicle is equipped with a lateral acceleration gauge, the conventional technique uses the longitudinal acceleration gauge to calculate the vehicle speed corresponding to the time. The curve has a significant deviation from the reference vehicle speed measured by the VBOX high-precision GPS device, and as time passes, the amount of deviation gradually increases with time. In this situation, the curve of the vehicle speed corresponding to the time calculated by the average speed of the wheel is relatively close to the reference speed measured by the VBOX high-precision GPS device, but still maintains a certain amount of deviation. . The vehicle speed transmission weight estimated by the aforementioned vehicle speed estimation method estimates the vehicle speed in the entire time interval to be close to the reference vehicle speed measured by the VBOX high-precision GPS device.

As shown in Fig. 6(a) and Fig. 6(b), the fourth scenario is a situation in which the slope is accelerated by about 30% of the slope. Since the acceleration sensing value acc(t) is affected by the gradient, the curve of the vehicle speed corresponding time calculated by the conventional technique is significantly different from the reference vehicle speed measured by the VBOX high-precision GPS device, and with time. Accumulation, the amount of deviation gradually increases with time. In this scenario, the curve of the vehicle speed corresponding to the time calculated by the average speed of the wheel is relatively close to the reference speed measured by the VBOX high-precision GPS device, but still maintains a certain amount of deviation. The vehicle speed transmission weight estimated by the aforementioned vehicle speed estimation method estimates the vehicle speed in the entire time interval to be close to the reference vehicle speed measured by the VBOX high-precision GPS device.

In the above experiment, it was confirmed that the vehicle speed estimation method screens out the tire with excessive slip value S _ij (t) through the slip value calculation step and the wheel speed weight value calculation step, and passes the wheel speed weight value calculation step and the acceleration weight value calculation step. The wheel speed weight value K _ij (t) and the acceleration weight value K _acc (t) are given. This technique can accurately estimate the vehicle speed at the time and is more suitable for various situations. Therefore, the vehicle speed estimation method performed by the vehicle speed estimating device provides the precise vehicle speed such as the fixed driving distance, the fixed speed, and the automatic braking, and can achieve a more accurate vehicle speed estimation to avoid the casualties caused by the error of the vehicle speed estimation. . In addition, the vehicle speed estimation method can accurately estimate the wheel speed sensing value, the acceleration sensing value and the angular velocity sensing value sensed by the existing equipment of the vehicle, and does not need to add other special measuring components, without adding extra Equipment costs.

Although the present invention has been described in connection with the exemplary embodiments of the present invention, it is understood that the invention is not to be construed as The spirit and scope of the request.

<TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> 1 </td><td> Vehicle</td><td> 10LB </td> <td> Left Rear Tire</td></tr><tr><td> 10LF </td><td> Left Front Tire</td><td> 10RB </td><td> Right Rear Tire</ Td></tr><tr><td> 10RF </td><td> right front tire</td><td> 20 </td><td> vehicle signal bus </td></tr>< Tr><td> 21 </td><td> Wheel speed receiving unit</td><td> 23 </td><td> Acceleration gauge</td></tr><tr><td> 25 < /td><td> yaw rate meter</td><td> 100 </td><td> speed estimation device</td></tr><tr><td> 110 </td><td> Microprocessor</td><td> 120 </td><td> memory unit</td></tr><tr><td> 121 </td><td> computer program</td><td > acc(t) </td><td> Acceleration Sensing Value</td></tr><tr><td> K_acc(t) </td><td> Acceleration Weight value</td><td> K_ij(t) </td><td> Wheel speed weight value</td></tr><tr><td> S1 </td ><td> Speed Estimation Method</td><td> S10 </td><td> Slip Difference Calculation Steps</td></tr><tr><td> S20 </td><td> Wheel Speed weight value calculation step </td><td> S30 </td><td> acceleration weight value calculation step </td></t r><tr><td> S40 </td><td> Speed Estimation Steps</td><td> S50 </td><td> Mode Judgment Steps</td></tr><tr> <td> S_ij(t) </td><td> slip difference</td><td> S_mean(t) </td><td > slip average </td></tr><tr><td> V_CG(t) </td><td> estimated speed at the time </td><td> V _CG(t-1) </td><td> Estimated previous speed</td></tr><tr><td> V_ij(t </td><td> Wheel speed sensing value</td><td> V_mean(t) </td><td> Wheel speed average </td></tr ><tr><td> X </td><td> Forward direction</td><td> Y(t) </td><td> yaw rate</td></tr></TBODY> </TABLE>

The above and other exemplary embodiments, advantages and features of the present invention will become more apparent from the detailed description of the exemplary embodiments of the invention. FIG. 2 is a flow chart of a method for estimating a vehicle speed according to an embodiment of the present invention; FIG. 3(a) and FIG. 3(b) are respectively a comparison chart of measurement curves and a comparison chart of difference values in the first scenario; 4(a) and Fig. 4(b) are comparison curves and comparison charts of the measurement curves in the second scenario; Figure 5(a) and Figure 5(b) are comparisons of the measurement curves in the third scenario. Figure and difference comparison chart; Figure 6 (a) and Figure 6 (b) are the measurement curve comparison chart and the difference comparison chart in the fourth scenario.

Claims (33)

A vehicle speed estimating method for calculating a current vehicle speed estimate of a vehicle, the vehicle comprising a plurality of tires; wherein the method comprises the following steps: a slip difference calculating step, according to a plurality of wheel speed sensing values (V _ij (t)), and a previous vehicle speed estimate (V _CG (t-1)) respectively calculate a plurality of slip values (S _ij (t)) corresponding to the tires, wherein each of the wheel speed sensing The value (V _ij (t)) refers to the current tire speed of the corresponding tire; a round speed weight calculation step, based on the slip values (S _ij (t)), and a slip average (S _mean (t) )), calculating a round speed weight value (K _ij (t)) corresponding to each of the tires, wherein the slip average value (S _mean (t)) refers to the slip values (S _ij (t)) An acceleration weight calculation step of calculating an acceleration weight value (K _acc (t)) according to an acceleration sensing value ( _acc (t)), wherein the acceleration sensing value (acc(t)) refers to The vehicle direction acceleration value at the time; and a vehicle speed estimation value calculation step, based on the wheel speed sensing values (V _ij (t)), the previous vehicle speed estimation value (V _CG (t-1)), the acceleration Sensing The value (acc(t)), the wheel speed weight value (K _ij (t)), the acceleration weight value (K _acc (t)), and a time difference (T) calculate a current vehicle speed estimate (V _CG (t)). The vehicle speed estimating method according to claim 1, wherein in the slip value calculating step, the slip values (S _ij (t)) are calculated according to the following formula: when V _ij ( t ) V _CG ( t -1), And when V _ij ( t )< V _CG ( t -1), . The vehicle speed estimating method according to claim 2, wherein in the wheel speed weight value calculating step, the wheel speed weight values (K _ij (t)) are calculated according to the following formula: when S _ij ( t ) S _mean ( t ), K _ij ( t ) = 0; and when S _ij ( t ) < S _mean ( t ), K _ij ( t ) = a * S _ij ( t ) + b , where -2.5 a -0.5,0.5 b 2. The vehicle speed estimating method according to claim 1, wherein in the acceleration weight value calculating step, the acceleration weight value (K _acc (t)) is calculated according to the following formula: K _acc ( t )= c *| acc ( t )|+1, of which 3 c 50. The vehicle speed estimating method according to claim 1, wherein in the vehicle speed estimated value calculating step, the current vehicle speed estimated value (V _CG (t)) is calculated according to the following formula: The vehicle speed estimating method according to claim 1, further comprising a mode determining step of comparing the wheel speed sensing values (V _ij (t)) to less than a round speed threshold (V _th ) and comparing When the previous vehicle speed estimation value (V _CG (t-1)) is less than a vehicle speed threshold (V _CGth ), it is determined that the vehicle is in the step-by-step mode, and the acceleration weight value in the acceleration weight value calculation step is K _acc (t)) is calculated according to the following formula: K _acc ( t )=0. The vehicle speed estimating method according to claim 6, wherein the wheel speed threshold (V _th ) is between 0 and 5 km/hour, and the vehicle speed threshold (V _CGth ) is between 1 and 10 km/hour. . The vehicle speed estimating method according to claim 6, wherein when the wheel speed sensing value (V _ij (t)) of any of the tires in the starting mode is greater than a wheel speed starting value (V _st ), the vehicle is judged Leaving the starting mode, and calculating the acceleration weight value (K _acc (t)) in the acceleration weight value calculating step according to the following formula: K _acc ( t )= c *| acc ( t )|+1, where 3 c 50. The vehicle speed estimating method according to claim 8, wherein the wheel speed starting value (V _st ) is between 0 and 5 km/h. The vehicle speed estimating method according to claim 1, further comprising a mode determining step of determining when a yaw angular velocity (Y(t)) of the vehicle is greater than a yaw angular velocity threshold (Y _th ) The vehicle is in a curve mode, and the slip values (S _ij (t)) in the slip difference calculation step are calculated according to the following formula, wherein a mean speed average (V _mean (t)) refers to the time The average of these wheel speed sensing values (V _ij (t)): when V _ij ( t ) V _mean ( t ), And when V _ij ( t ) < V _mean ( t ), . The vehicle speed estimating method according to claim 10, wherein the yaw angular velocity threshold (Y _th ) is between 2 and 8 degrees/second. A vehicle speed estimating device is carried on a vehicle, the vehicle comprising a plurality of tires, the vehicle speed estimating device comprising a memory unit and a microprocessor, wherein the memory unit stores a computer program, the microprocessor is electrically connected to the memory The unit can also read the computer program to perform the following steps: a slip difference calculation step, based on a plurality of wheel speed sensing values (V _ij (t)), and a previous vehicle speed estimate (V _CG (t-1) )) respectively calculating a plurality of slip values (S _ij (t)) corresponding to the tires, wherein each of the wheel speed sensing values (V _ij (t)) refers to the current tire speed of the corresponding tire; The speed weight value calculation step calculates a round speed weight value (K _ij (t) corresponding to each tire according to the slip values (S _ij (t)) and a slip average value (S _mean (t)) ), wherein the slip mean value (S _mean (t)) refers to an average value of the slip differences (S _ij (t)); an acceleration weight value calculation step according to an acceleration sense value (acc ( t)) calculates an acceleration weighting value (K _acc (t)), wherein the acceleration sensing value (ACC (t)) means a value of the acceleration of the vehicle when a straight direction; Vehicle speed estimation value calculating step, according to the plurality of wheel speed sensed value (V _ij (t)), the previous estimated vehicle speed value _{(V CG (t-1)} ), the acceleration sensed value (acc (t)), The wheel speed weight value (K _ij (t)), the acceleration weight value (K _acc (t)), and a time difference (T) calculate a current vehicle speed estimate (V _CG (t)). The vehicle speed estimating device according to claim 12, wherein in the slip value calculating step, the slip values (S _ij (t)) are calculated according to the following formula: when V _ij ( t ) V _CG ( t -1), And when V _ij ( t )< V _CG ( t -1), . The vehicle speed estimating device according to claim 13, wherein in the wheel speed weight value calculating step, the wheel speed weight values (K _ij (t)) are calculated according to the following formula: when S _ij ( t ) S _mean ( t ), K _ij ( t ) = 0; and when S _ij ( t ) < S _mean ( t ), K _ij ( t ) = a * S _ij ( t ) + b , where -2.5 a -0.5,0.5 b 2. The vehicle speed estimating device according to claim 12, wherein in the acceleration weight value calculating step, the acceleration weight value (K _acc (t)) is calculated according to the following formula: K _acc ( t ) = c *| acc ( t )|+1,3 c 50. The vehicle speed estimating device according to claim 12, wherein in the vehicle speed estimated value calculating step, the current vehicle speed estimated value (V _CG (t)) is calculated according to the following formula: The vehicle speed estimating device of claim 12, further comprising a mode determining step of comparing the wheel speed sensing values (V _ij (t)) to less than a wheel speed threshold (V _th ) and comparing When the previous vehicle speed estimation value (V _CG (t-1) is less than a vehicle speed threshold (V _CGth ), it is determined that the vehicle is in the step-by-step mode, and the acceleration weight value of the acceleration weight value calculation step (K _acc (t)) Calculated according to the following formula: K _acc ( t )=0. The vehicle speed estimating device according to claim 17, wherein the wheel speed threshold (V _th ) is between 0 and 5 km/h, and the vehicle speed threshold (V _CGth ) is between 1 and 10 km/h. . The vehicle speed estimating device according to claim 17, wherein when the wheel speed sensing value (V _ij (t)) of any of the tires in the starting mode is greater than a wheel speed starting value (V _st ), the vehicle is judged Leaving the starting mode, and calculating the acceleration weight value (K _acc (t)) in the acceleration weight value calculating step according to the following formula: K _acc ( t )= c *| acc ( t )|+1, where 3 c 50. The vehicle speed estimating device according to claim 19, wherein the wheel speed starting value (V _st ) is between 0 and 5 km/h. The vehicle speed estimating device according to claim 12, further comprising a mode determining step of determining when a yaw angular velocity (Y(t)) of the vehicle is greater than a yaw angular velocity threshold (Y _th ) The vehicle is in a curve mode, and the slip values (S _ij (t)) in the slip difference calculation step are calculated according to the following formula, wherein a mean speed average (V _mean (t)) refers to the time The average of these wheel speed sensing values (V _ij (t)): when V _ij ( t ) V _mean ( t ), And when V _ij ( t ) < V _mean ( t ), . The vehicle speed estimating device of claim 21, wherein the yaw rate threshold (Y _th ) is between 2 and 8 degrees/second. A computer program product capable of being loaded by an electronic device to perform and calculate an estimated speed of a vehicle at a time, the vehicle comprising a plurality of tires; wherein the computer program product comprises: a first code, which can be based on a plurality of The wheel speed sensing value (V _ij (t)) and a previous vehicle speed estimation value (V _CG (t-1)) respectively calculate a plurality of slip values (S _ij (t)) corresponding to the tires, Wherein, each of the wheel speed sensing values (V _ij (t)) refers to the current tire speed of the corresponding tire; a second code that can be based on the slip values (S _ij (t)), and a slip a mean value (S _mean (t)), which calculates a round weight weight value (K _ij (t)) corresponding to each tire, wherein the slip mean value (S _mean (t)) refers to the slip values An average value of (S _ij (t)); a third code capable of calculating an acceleration weight value (K _acc (t)) according to an acceleration sensing value ( _acc (t)), wherein the acceleration sensing value (acc(t)) refers to the acceleration value of the vehicle in the straight direction at the time; and a fourth code that can be based on the wheel speed sensing values (V _ij (t)) and the previous vehicle speed estimation value (V _CG ( T-1)), the sense of acceleration Value (acc (t)), the plurality of wheel speed weighting value (K _ij (t)), the acceleration weight value (K _acc (t)), and a time difference (T) calculated by the time the vehicle speed estimate (V _CG (t)). The computer program product of claim 23, wherein in the first code, the slip values (S _ij (t)) are calculated according to the following formula: when V _ij ( t ) V _CG ( t -1), And when V _ij ( t )< V _CG ( t -1), . The computer program product of claim 24, wherein in the second code, the wheel speed weight values (K _ij (t)) are calculated according to the following formula: when S _ij ( t ) S _mean ( t ), K _ij ( t ) = 0; and when S _ij ( t ) < S _mean ( t ), K _ij ( t ) = a * S _ij ( t ) + b , where -2.5 a -0.5,0.5 b 2. The computer program product of claim 23, wherein in the third code, the acceleration weight value (K _acc (t)) is calculated according to the following formula: K _acc ( t )= c *| acc ( t ) |+1, of which 3 c 50. The computer program product of claim 23, wherein in the fourth code, the current vehicle speed estimate (V _CG (t)) is calculated according to the following formula: The computer program product of claim 23, further comprising a fifth code, wherein the fifth code can be based on the wheel speed sensing values (V _ij (t)), a wheel speed threshold (V _th ), The previous vehicle speed estimate (V _CG (t-1), and a vehicle speed threshold (V _CGth ) are compared, when the wheel speed sensing values (V _ij (t)) are less than one wheel speed valve The value (V _th ), and when the previous vehicle speed estimation value (V _CG (t-1) is less than the vehicle speed threshold (V _CGth ), determines that the vehicle is in the step-by-step mode, and the third code is The acceleration weight value (K _acc (t)) is calculated according to the following formula: K _acc ( t )=0. The computer program product of claim 28, wherein the wheel speed threshold ( _Vth ) is between 0 and 5 km/hr, and the vehicle speed threshold (V _CGth ) is between 1 and 10 km/hour. . The computer program product of claim 29, wherein the wheel speed sensing value (V _ij (t)) of any of the tires in the starting mode of the fifth code comparison is greater than a wheel speed starting value (V _st ) When it is determined that the vehicle leaves the starting mode, the acceleration weight value (K _acc (t)) calculated at the acceleration weight value is calculated according to the following formula: K _acc ( t )= c *| acc ( t )|+1 Of which 3 c 50. The computer program product of claim 30, wherein the wheel speed start value (V _st ) is between 0 and 5 km/h. The computer program product of claim 23, further comprising a sixth code that can be based on a yaw rate (Y(t)) of the vehicle and a yaw rate threshold ( _Yth ) Performing an alignment, when the yaw rate (Y(t)) of the vehicle is greater than the yaw rate threshold ( _Yth ), determining that the vehicle is in a curve mode and at the first code The slip values (S _ij (t)) in the calculation are calculated according to the following formula, wherein the average value of the wheel speed (V _mean (t)) refers to the average of the wheel speed sensing values (V _ij (t)) at that time. Value: When V _ij ( t ) V _mean ( t ), And when V _ij ( t ) < V _mean ( t ), . The computer program product of claim 32, wherein the yaw rate threshold ( _Yth ) is between 2 and 8 degrees/second.