Method for ascertaining an erroneous pulse signal when measuring the speed of a vehicle

Abstract

The invention relates to a method for ascertaining an erroneous pulse signal when measuring the speed of a vehicle, in particular a single-track vehicle, such as an e-bike, said vehicle having a pulse-based speed sensor on a wheel. The method has the steps of: - detecting a first, second, third, and fourth pulse signal using the pulse-based speed sensor, - determining a first difference between the points in time of the second and first pulse signal, determining a second difference between the points in time of the third and second pulse signal, and determining a third difference between the points in time of the fourth and third pulse signal, - ascertaining whether the third pulse signal was detected too early or too late by at least comparing the first and / or the second difference with at least one first threshold, and - ascertaining the third pulse signal type by at least comparing the third and the second difference with at least one second threshold.

Description

[0001]R. 403015 - 1 - Description Title Method for determining an erroneous pulse signal during a speed measurement of a vehicle The invention relates to a method for determining an erroneous pulse signal during a speed measurement of a vehicle, in particular a single-track vehicle such as an e-bike. The invention further relates to a vehicle, in particular a single-track vehicle such as an e-bike, with a pulse-based speed sensor on a wheel, wherein the vehicle is designed to determine erroneous pulse signals during a speed measurement of the vehicle. Although generally applicable to vehicles, the invention is described with reference to e-bikes. State of the art In vehicles, in particular single-track vehicles such as e-bikes, it has become known to measure the speed of the vehicle using a magnetic field sensor. For this purpose, a permanent magnet is attached to the rear wheel. When driving, theWheel, so that the magnet rotates past the magnetic field sensor on the bicycle at regular intervals. This can detect the passage and output a pulse signal. The speed of the eBike can then be calculated from the wheel circumference and the time offset between two pulses. R. 403015 - 2 - During a ride, magnetic influences from iron bridges, power poles, or an electric drive unit on the bicycle can disrupt the detection device, so that additional false pulses are measured, or correct or valid pulses are not detected. This could result in the speed sensor measuring an incorrect speed. However, eBikes in particular require a permanently accurate speed sensor, since the drive assistance of the eBike depends on the current speed. Disclosure of the Invention In one embodiment, the present invention provides a method for determining an erroneousPulse signal during a speed measurement of a vehicle, in particular a single-track vehicle such as an e-bike, wherein the vehicle has a pulse-based speed sensor on a wheel, comprising the steps of: - detecting a first, second, third and fourth pulse signal by means of the pulse-based speed sensor, - determining a first difference between the times of the second and the first pulse signal, determining a second difference between the times of the third and the second pulse signal and determining a third difference between the times of the fourth and the third pulse signal, - determining whether the third pulse signal was detected too early or too late based on at least one comparison of the first and / or the second difference with at least one first threshold value, and - determining a type of the third pulse signal based on at least one comparison of the third and the second difference with at least one secondThreshold. In one embodiment, the present invention provides a vehicle, in particular a single-track vehicle such as an e-bike, with a pulse-based speed sensor on a wheel, wherein the vehicle is designed to detect faulty pulse signals during a speed measurement of the vehicle, comprising: - a detection unit designed to detect a first, second, third, and fourth pulse signal by means of the pulse-based speed sensor, - a determination device designed to determine a first difference between the times of the second and the first pulse signal, determine a second difference between the times of the third and the second pulse signal, and determine a third difference between the times of the fourth and the third pulse signal, - a first determination unit designed to determine whether the third pulse signal was detected too early or too late, based onat least one comparison of the first and / or the second difference with at least one first threshold value, and - a second determination unit, designed to determine a type of the faulty third pulse signal based on at least one comparison of the third and the second difference with at least one second threshold value. One of the advantages achieved thereby is that it is easy to recognize whether a pulse signal is faulty. A faulty pulse signal is, in particular, a delayed or premature pulse signal or a missing or additional pulse signal. A further advantage is that the type of the faulty pulse signal can be determined, for example, a pulse signal that is too early or a missing pulse signal. The term "type" is to be understood in the broadest sense and refers, in particular in the claims, preferably in the description, to a category of the pulse signal that is the cause of the faultyPulse signal describes. For example, one type could be a premature pulse signal caused by a real acceleration, or a pulse signal caused by an additional pulse. R. 403015 - 4 - Further features, advantages, and further embodiments of the invention are described below or become apparent thereby. According to an advantageous development of the invention, the vehicle has a further speed sensor with which a substitute speed is determined. The further speed sensor can, for example, estimate the current speed based on accelerations of the vehicle or measure the current speed using a GPS system. One advantage of this is that the speed can be measured redundantly. According to a further advantageous development of the invention, the substitute speed is used for speed measurement if it is determined that the third pulse signal is too early or toowas detected too late. If it is determined that a pulse signal was received too early or too late, this means that the vehicle may be traveling at a different speed than the speed measured by the pulse-based speed sensor. In this case, the system switches to the substitute speed to improve the accuracy of the speed measurement. According to a further advantageous development of the invention, a period of time in which the substitute speed is used for speed measurement is determined based on the determined type of pulse signal. Depending on the different type of pulse signal, the pulse-based speed sensor measures an incorrect speed signal for a different length of time. For example, if a pulse is missing, the pulse-based speed sensor measures the correct speed again after two subsequent pulses. One advantage of this is that theThe substitute speed is only used for a short time. According to a further advantageous development of the invention, the differences are determined when two pulse signals, preferably five pulse signals, in particular ten pulse signals, are detected using the pulse-based speed sensor, which correspond to a minimum speed of 5 km / h, preferably 10 km / h, in particular 20 km / h. The determination of whether a pulse signal has been detected too early or too late can be inaccurate at low speeds and / or when the vehicle is starting. Therefore, a minimum speed can be defined from which pulse signals that are too early or too late are detected. One advantage of this is that it reduces the probability that a pulse signal is incorrectly determined as too early or too late. According to an advantageous development of the invention, the determination of whether the third pulse signalhas been detected too early or too late if the difference in magnitude between the first and second difference is smaller than a third threshold value. To determine pulse signals that are too early or too late, it can be required that the previous speed is approximately constant, since the interval between the pulse signals changes during strong accelerations. If the differences in the times of continuous pulse signals are sufficiently small, the acceleration is low and thus the speed is approximately constant. An advantage of this is that strong accelerations do not distort the determination of pulse signals that are too early or too late. According to an advantageous development of the invention, the determination of the differences is stopped when two valid pulse signals, preferably five valid pulse signals, in particular ten valid pulse signals, are detected using the pulse-based speed sensor, which lead to a maximum speed of 20km / h, preferably 10 km / h, in particular 5 km / h. A valid pulse signal is a pulse signal that is detected neither too early nor too late, and is also not an additional or missing pulse signal. If the vehicle speed falls below the maximum speed, the determination of the differences can be stopped, since the accuracy of the method decreases at low speeds. However, if missing pulse signals are detected, meaning the determined speed could be lower than the actual speed, the determination of the differences can still be carried out. An advantage of this is that pulse signals that are too early or too late can be determined more accurately. According to an advantageous development of the invention, the determination of the differences is stopped if at least one of the following conditions is met: R. 403015 - 6 - - the substitute speed is below a third threshold value, - the vehicle's wheelis at a standstill, - no pulse signals from the pulse-based speed sensor are detected for a certain period of time. Since the accuracy of the method may be lower at low speeds, the determination of the differences can be stopped at low speeds. An advantage of this is that the pulse signal that is too early or too late can be determined more precisely. According to an advantageous development of the invention, the at least first and / or second threshold value is set depending on the speed of the vehicle. An advantage of this is that pulse signals that are too early or too late can be reliably detected over a wide speed range. Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures. It is understood that the features mentioned above and those to be explained below not onlyin the respective specified combination, but also in other combinations or on their own, without departing from the scope of the present invention. Preferred embodiments and embodiments of the present invention are illustrated in the drawings and are explained in more detail in the following description. Fig. 1 shows, in schematic form, steps of a method according to an embodiment of the present invention; Fig. 2a-g show speed profiles of the pulse-based speed sensor according to an embodiment of the present invention; R. 403015 - 7 - Fig. 3 shows a flow chart according to an embodiment of the present invention; Fig. 4 shows a vehicle according to an embodiment of the present invention. Figure 1 shows, in schematic form, steps of a method according to an embodiment of the present invention. In a first step S1, a pulse-based speed sensor onPulse signals are detected on a wheel of a vehicle. The pulse signals correspond to a magnet on the vehicle wheel, which rotates past the pulse-based speed sensor. In a further step S2, a first difference between the times of the second and first pulse signals, a second difference between the times of the third and second pulse signals, and a third difference between the times of the fourth and third pulse signals are determined. In a further step S3, it is determined whether the third pulse signal was detected too early or too late, based on at least one comparison of the first and / or second difference with at least one first threshold value. This step can be performed when the vehicle has a certain minimum speed and the speed is approximately constant. An approximately constant speed can be assumed if the following equation applies: Δ^ ^ ⋅ ( 1 − ^ ) < Δ^^^^ < Δ^ ^ ⋅ (1 + ^ ) Where: ∆^ ^ : Second Difference: ^^^^^^^^^ ^^^ ^^^^^^^^^^ ^^^ ^^^^^^^ ^^^ ^^^^^^^ ^^^^^^^^^^^ ^^^ ^^^^^^ ^^^^^^^^^^^^^ 0.1 R. 403015 - 8 - Consequently, if the first difference lies within a tolerance interval with a permitted percentage deviation around the second difference, the pulse signals were detected at regular intervals and the speed within the three pulse signals is approximately constant. In this case, the differences can be used to determine whether the third pulse signal was too early or too late, using the following equation: Where: ^ ^ , ^ ^: ^^^^^^^^ ^^^^^^ℎ^^^, ^^^^^^^^^^^^^^ 0.1 If the first difference is greater than the second difference, the third pulse signal was detected earlier than expected, since at an approximately constant speed it is expected that the second and first differences are approximately the same. Analogously, the third pulse signal was detected too late if the first difference is smaller than the second difference. If a pulse signal was determined according to step S3 that was detected too early or too late, the type of the third pulse signal can be determined in a further step S4 based on at least one comparison of the third and second differences with at least one second threshold value.The possible cases are: A: Real acceleration B: Real deceleration C: Pulse signal actually detected too early D: Pulse signal actually detected too late E: Additional – incorrect – pulse signal detected F: Pulse signal mistakenly not detected If the third pulse signal was detected too early, cases A, C and E are possible. If the third pulse signal was actually detected too early, the distance to the fourth pulse signal is greater than expected. In particular, R. 403015 - 9 - the first difference can be larger than expected by the same factor as the third difference is smaller than expected. Thus, case C can be detected if: Δ^. ^^^ ⋅ ( 1 + ^ ^ ) < Δ^ ^^^ Where: ∆^ ^^^: ^^^^^^ ^^^^^^^^^: ^^^^^^^^^ ^^^ ^^^^^^^^^^ ^^^ ^^^^^^^ ^^^ ^^^^^^^ ^^^^^^^^^^^^^ In addition, the ratio can be checked. At constant speed and shifted pulses, Δt_(k-1)⋅2= Δt_k+Δt_(k+1) applies. This results in the condition with an additional tolerance: where p_shift is the permissible deviation in percent, for example, 0.1 = 10%. A speed-dependent parameterization is also possible here. However, if an additional – incorrect – pulse signal has been detected, the third difference will also be smaller than expected, since the additional pulse signal is detected between two regular pulses. Accordingly, the total time between the two regular pulses, i.e., the sum of the second and third differences, would have to be within a tolerance interval of the first difference. Thus, an additional pulse signal according to Type E is detected if: Δ^ ^^^ ⋅ ( 1 − ^ ^^^ ) < Δ^ ^ + Δ^ ^^^< Δ^ ^^^ ⋅ (1 + ^ ^^^ ) Where: ^ ^^^ : ^^^^^^^^ ^^^^^^ℎ^^^, ^^^^^^^^^^^^^^ 0.1 If neither of the two equations above is satisfied, this is case A, i.e., a real acceleration of the vehicle while the pulse signals are being detected. R. 403015 - 10 - If, however, the third pulse signal was detected too late, the possible types are B, D, and F. If the third pulse signal was actually detected too late, the distance to the fourth pulse signal is smaller than expected. In particular, the first difference can be smaller than expected by the same factor as the third difference is larger than expected. Thus, case D can be detected if: Additionally, the ratio can be checked. At constant speed and shifted pulses, Δt_(k-1)⋅2= Δt_k+Δt_(k+1) applies. This results in the condition with additional tolerance: Δ^ ^^^ ⋅ 2 ⋅ ( 1 − ^ ^^^^^ ) < Δ^ ^ + Δ^^^^ < Δ^ ^^^ ⋅ 2 ⋅ (1 + ^ ^^^^^ ) where p_shift is the permissible deviation in percent (typical value: 0.1 = 10%). Speed-dependent parameterization is also possible here. However, if a pulse signal is missing, i.e., has not been detected, the fourth pulse signal will not be detected because a pulse signal is missing between two regular pulses. Accordingly, the time between the two pulse signals before and after the missing pulse signal would have to be twice as long as the regular time between two pulse signals. Consequently, the second difference would have to be twice as high as the first difference. A missing pulse signal according to Type F can thus be detected if: Where: ^ ^^^^: ^^^^^^^^ ^^^^^^ℎ^^^, ^^^^^^^^^^^^^^ 0.3 If neither of the two above equations is satisfied, this is case B, i.e. a real deceleration of the vehicle while the pulse signals are detected. R. 403015 - 11 - Figures 2a-f show curves of the speed of the pulse-based speed sensor according to an embodiment of the present invention. If an erroneous pulse signal is detected according to steps S1 to S4, the measured speed of the pulse-based speed sensor differs from the actual speed of the vehicle. As a result, depending on the type of erroneous pulse signal, a substitute speed can be used to provide permanently accurate speed determination.Figures 2a-f each show the speed curve using the pulse-based speed sensor 205 and the equivalent speed sensor 204 for the various types of pulse signals A to F. Time is plotted on the x-axis 201 in arbitrary units, and speed is plotted on the y-axis 202 in arbitrary units. Four pulse signals are used in each case. 203a, 203b, 203b, 203d, 203e, whereby the pulse signal at time ^ ^ is detected too early or too late, except in Figure 2f, where a pulse signal is missing. Figure 2a shows the velocity curve for a real acceleration according to Type A. All pulse signals are therefore valid and are detected neither too early nor too late. The pulse signal at time ^ ^ (Reference numeral 203c) is due to the acceleration (phase I in Fig. 2a between the times ^ ^^^ , ^ ^,) was detected earlier than expected. Thus, the pulse signal could be faulty. During phase II (in Fig. 2a between the times ^ ^ , ^ ^^^, ) it cannot yet be recognized that the pulse-based speed 205 corresponds to the current speed, therefore the substitute speed 204 is used in Phase II. From Phase III (in Fig. 2a between the times ^ ^^^ , ^ ^^^, ) the speed of the pulse-based speed sensor 205 is used again. Figure 2b shows the speed curve for a real deceleration according to type B. During phase I.II (in Fig. 2b between the times ^ ^^^ , ^ ^, ) it is recognized that the second pulse signal is delayed, therefore from phase I.II R. 403015 - 12 - to phase II (in Fig.2b between the times ^ ^ , ^ ^^^, ) the replacement speed 204 is used. From phase III (in Fig. 2b between the times ^ ^^^ , ^^^^, ) the pulse-based speed 205 can be used again. Figure 2c shows the speed curve for a pulse signal detected too early according to type C, i.e., a pulse signal detected incorrectly too early. The pulse signal at time ^ ^, was detected earlier than expected. Therefore, the speed curve based on the pulse-based speed sensor 205 shows an increase in phase II.I (in Fig. 2c, the first time period between the times ^ ^ , ^ ^^^ ). In phase II.II (in Fig.2c second time period between the times ^ ^ , ^ ^^^ ) no further pulse signal is detected. Therefore, the speed of the pulse-based speed sensor 205 decreases until time ^ ^ ^^ . From the time ^ ^^^the correct speed is again measured by the pulse-based speed sensor 205. Consequently, during phases II.I to III (in Fig. 2c between the times ^ ^^^ , ^ ^^^ ) the substitute speed 204 is used. Figure 2d shows the speed curve for a pulse signal detected too late according to type D. In phase I.II (in Fig. 2d second time period between the times ^ ^ ) it is initially recognized that no pulse signal is being detected. Therefore, the speed initially decreases based on the pulse-based speed sensor. At time ^ ^^^ a regular pulse signal is detected, so that the determined speed increases using the pulse-based speed sensor 205. In phase III.II (in Fig. 2d second time period between the times ^ ^^^ , ^ ^^^) no pulse signal is detected, so that the speed of the pulse-based speed sensor 205 is again measured until the time ^ ^^^ decreases. Thus, during phases II to III.II, the substitute speed 204 is used. Figure 2e shows the speed curve with an additionally detected pulse signal according to type E. The pulse signal at time ^ ^ is additionally detected. Therefore, the speed increases abruptly based on the pulse-based speed sensor 205 before decreasing over the course of the next two pulse signals. Thus, the substitute speed during phases II (in Fig. 2e between the times ^ ^ , ^ ^^^ ) and III (in Fig. 2e time period between R. 403015 - 13 - the times ^ ^^^ , ^ ^^^) is used. The same applies in the case of a double jump before the speed decreases during the next two pulse signals. Figure 2f shows a speed curve with a missing pulse signal according to type F. At the end of phase II (in Fig. 2f the first time period between the times ^ ^^^ , ^ ^ ), no pulse signal is detected. Therefore, the speed decreases based on the pulse-based speed signal until the next regular pulse signal at time ^ ^ . From the next pulse signal at time ^ ^^^ The pulse-based speed sensor can again be used to determine the speed. The substitute speed 205 is thus determined during phases I.II (in Fig. 2f, the second time period between the times ^ ^^^ , ^ ^ ) and II (in Fig. 2f between the times ^ ^ , ^ ^^^) is used. Figure 3 shows a schematic flow diagram according to an embodiment of the present invention. Initially, the detection of faulty sensors is deactivated - state 301. If the activation conditions are met, for example, a minimum speed is exceeded, the detection is activated - state 302. If the activation conditions are no longer met, the detection can be deactivated again - state 301. Subsequently, a check is carried out to determine whether the speed is approximately constant - calculation 303. If so, a check is carried out to determine whether the pulse signal was too early or too late within the tolerances - decision 304. For this purpose, the two consecutive differences in the times of three pulse signals are compared. If the first difference is greater than the second, the third pulse signal is too early, and if the first difference is smaller than the second, the pulse signal is too late.Subsequently, a third difference between the times of the third and a fourth pulse signal is used to check the type of the third pulse signal. If the pulse signal occurred too early – state 305 – a check is made to see whether the third difference is larger than the first difference in a similar ratio to how the second difference was smaller than the first difference – decision 306. If so, the pulse signal is shifted and was detected too early; this is R. 403015 - 14 - Case C – state 307. Otherwise, a check is made to see whether the sum of the third difference and the second difference approximately corresponds to the first difference – decision 308. In this case, an additional pulse signal has been detected; Case E – state 309 – otherwise, it is a real acceleration of the vehicle; Case A – state 310.If, however, the pulse signal was received too late – state 311 – a check is made to see whether the third difference is smaller than the first difference in a similar ratio to how the second difference was larger than the first difference – decision 312. If so, the pulse signal has been shifted and was detected too late; case D – state 313. Otherwise, a check is made to see whether the second difference is approximately twice as large as the first difference – decision 314. In this case, a pulse signal is missing; case F – state 315 – otherwise, the vehicle is actually decelerating; case B – state 316. In any case, a brief switch to a substitute speed is made to ensure accurate speed detection, whereby the period for which the substitute speed is used depends on the detected type. The system then waits for a stable speed signal – state 317.In this case, a fifth pulse signal can initially be awaited if neither a missing pulse signal nor a real acceleration nor a deceleration has been detected – decision 318. Furthermore, the sensor can be classified as faulty if too many pulse signals have been detected too early, too late, additionally, or missing. Figure 4 shows a vehicle according to an embodiment of the present invention. Figure 4 shows a vehicle 1, here in the form of an eBike, with a pulse-based speed sensor 6, comprising: - a detection unit 2, designed to detect a first, second, third, and fourth pulse signal by means of the pulse-based speed sensor, R.403015 - 15 - - a determination device 3, designed to determine a first difference between the times of the second and the first pulse signal, determine a second difference between the times of the third and the second pulse signal and determine a third difference between the times of the fourth and the third pulse signal, - a first determination unit 4, designed to determine whether the third pulse signal was detected too early or too late, based on at least one comparison of the first and / or the second difference with at least one first threshold value, and - a second determination unit 5, designed to determine a type of the third pulse signal based on at least one comparison of the third and the second difference with at least one second threshold value. The vehicle 1 is in particular designed to carry out steps S1 to S4 according to Figure 1.The first measuring unit 2 can be formed integrally with the pulse-based speed sensor 6. Although the present invention has been described using preferred embodiments, it is not limited thereto, but can be modified in a variety of ways.

Claims

R. 403015 - 16 - Claims 1. A method for determining an erroneous pulse signal during a speed measurement of a vehicle (1), in particular a single-track vehicle (1) such as an e-bike, wherein the vehicle (1) has a pulse-based speed sensor (6) on a wheel, comprising the steps of: - detecting (S1) a first, second, third and fourth pulse signal by means of the pulse-based speed sensor, - determining (S2) a first difference between the times of the second and the first pulse signal, determining a second difference between the times of the third and the second pulse signal and determining a third difference between the times of the fourth and the third pulse signal, - determining (S3) whether the third pulse signal was detected too early or too late, based on at least one comparison of the first and / or the second difference with at least one first threshold value,and - determining (S4) a type of the third pulse signal based on at least one comparison of the third and second differences with at least one second threshold value.

2. The method according to claim 1, wherein the vehicle (1) has a further speed sensor with which a substitute speed is determined.

3. The method according to claim 2, wherein the substitute speed is used for speed measurement if it is determined that the third pulse signal was detected too early or too late.

4. The method according to claim 3, wherein a period in which the substitute speed is used for speed measurement is determined based on the determined type of pulse signal. R. 403015 - 17 - 5. The method according to any one of claims 1-4, wherein the determination (S2) of the differences occurs when two pulse signals, preferably five pulse signals, in particular ten pulse signals, are detected using the pulse-based speed sensor, which correspond to a minimum speed of 5 km / h, preferably 10 km / h, in particular 20 km / h.

6. The method according to any one of claims 1-5, wherein the determination (S3) of whether the third pulse signal was detected too early or too late occurs when the absolute difference between the first and second differences is smaller than a third threshold value. 7.Method according to one of claims 1-6, wherein the determination of the differences (S2) is stopped when two valid pulse signals, preferably five valid pulse signals, in particular ten valid pulse signals, are detected based on the pulse-based speed sensor, which correspond to a maximum speed of 20 km / h, preferably 10 km / h, in particular 5 km / h.

8. Method according to one of claims 1-7, wherein the determination of the differences (S2) is stopped when at least one of the following conditions exists: - the substitute speed is below a third threshold value, - the wheel of the vehicle (1) is stationary, - no pulse signals from the pulse-based speed sensor are detected for a specific period of time.

9. Method according to one of claims 1-8, wherein the at least one first and / or second threshold value is determined depending on the speed of the vehicle (1). 10.Vehicle (1), in particular a single-track vehicle (1) such as an eBike, with a pulse-based speed sensor (6) on a wheel, wherein the vehicle (1) is designed to determine erroneous pulse signals during a speed measurement of the vehicle (1), comprising:. R. 403015 - 18 - - a detection unit (2) designed to detect a first, second, third and fourth pulse signal by means of the pulse-based speed sensor, - a determination device (3) designed to determine a first difference between the times of the second and the first pulse signal, determine a second difference between the times of the third and the second pulse signal and determine a third difference between the times of the fourth and the third pulse signal, - a first determination unit (4) designed to determine whether the third pulse signal was detected too early or too late, based on at least one comparison of the first and / or the second difference with at least one first threshold value, and - a second determination unit (5) designed to determine a type of the third pulse signal based on at least one comparison of the third and the second difference with at least one second threshold value.

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