Speed measurement and collision protection using time-of-flight sensing

Abstract

Embodiments of the present disclosure relate to speed measurement and collision protection using time-of-flight sensing. A rotational speed of an object is measured using a time-of-flight sensor configured to detect one or more elements of the object passing a given location. The time-of-flight sensor is further mounted on a single-rider vehicle configured to protect the single-rider vehicle from a collision by making a time-of-flight measurement of a relative speed between the single-rider vehicle and an obstacle.

Description

[0001] CLAIM

[0002] This application claims priority to European Patent Application No. 20160028.5 filed on February 28, 2020, the contents of which are incorporated herein in its entirety by reference to the maximum extent legally permitted. TECHNICAL FIELD

[0003] The present disclosure relates generally to the measurement of the displacement speed of, for example, a vehicle, and of the rotational speed of, for example, a wheel. BACKGROUND

[0004] Wheels are equipped to various so-called single-seater or single-person vehicles, also called personal or single-person transportation vehicles. A vehicle is called single-person when it is designed to displace a single person at a time. Single-person vehicles can be equipped with electric motors to propel the vehicle.

[0005] Wheels are also equipped to various sports training equipment, such as bicycles called exercise bikes.

[0006] There is a need to measure the speed of single-person vehicles.

[0007] There is a need to ensure the safety of the persons using single-person vehicles. In particular, there is a need to limit the risk of collisions.

[0008] There is a need to measure the rotational speed of rotating objects, such as wheels, in particular of single-person vehicles, or of sports training equipment.

[0009] There is a need in the art to overcome all or part of the drawbacks of the known methods and devices for measuring the rotational speed of an object and / or for measuring the displacement speed of a vehicle.

[0010] There is a need in the art to overcome all or part of the drawbacks of the known single-person vehicles. SUMMARY

[0011] In an embodiment, a method for measuring the rotational speed of an object is provided, comprising time-of-flight detection of one or more elements of said object passing through a given position.

[0012] An embodiment provides a device for measuring the rotational speed of an object, the device being configured to implement time-of-flight detection of one or more elements of said object passing through a given position.

[0013] According to an embodiment, said object is a wheel and said one or more elements comprise one or more spokes of the wheel. Alternatively, said one or more elements are attached to one or more spokes of the wheel.

[0014] According to an embodiment, the wheel is a wheel of a single-person vehicle or of a sports training device, and the speed of the single-person vehicle or device is communicated based on the measured rotational speed.

[0015] According to an embodiment, the value representative of the rotational speed is measured by using a given number (greater than or equal to 2) of time intervals between said detections, the given number being preferably strictly comprised between 3 and 10 times the number of said one or more elements.

[0016] According to an embodiment, the sensor is: fixedly secured to an element fixed with respect to said location and oriented towards said location; or fixedly secured to said object oriented towards an element fixed with respect to said location at said passing.

[0017] According to an embodiment, the time-of-flight sensor is contained in an integrated circuit package.

[0018] According to an embodiment, the device is configured to distinguish, preferably at a periodically repeated time, the presence or absence of an element in front of the detector and at a distance from the detector less than a threshold, said detection including a detection of a switch from said absence to said presence and / or from said presence to said absence.

[0019] An embodiment provides a single-person vehicle or sports training device comprising a device such as defined above.

[0020] According to an embodiment, the single-person vehicle or sports training device comprises an arm comprising a bearing or a rotation axis of said object, said fixed element being a part of the arm or being attached to a part of the arm.

[0021] According to a second aspect, an embodiment provides a method comprising a step of single-person vehicle collision protection, the protection step comprising a time-of-flight measurement of the relative speed between the single-person vehicle and an obstacle.

[0022] An embodiment provides a device configured to implement a single-person vehicle collision protection step, the protection step comprising a time-of-flight measurement of the relative speed between the single-seat vehicle and an obstacle, and preferably a communication of a vehicle braking signal.

[0023] According to an embodiment, the presence of the obstacle is detected by time-of-flight.

[0024] According to an embodiment, the protection step is implemented only when the distance between the obstacle and said measured optical pulse source is less than a first distance threshold, the first distance threshold being preferably less than or equal to 4 meters.

[0025] According to embodiments, the protection step is implemented when the obstacle is located at any of: inside a pulse emission cone, the cone having a half-cone angle and an axis substantially in the direction of displacement of the vehicle; and at a distance shorter than a second distance threshold, the second distance threshold being shorter than a first distance threshold; and the obstacle is any of: a single obstacle; or a closest obstacle to the vehicle among a plurality of obstacles, the half-cone angle preferably being greater than or equal to about 10 degrees and / or the second distance threshold preferably being greater than or equal to about 2 meters.

[0026] According to embodiments, the measured distance between the single-person vehicle and the obstacle is preferably repeatedly obtained at a plurality of times, the relative speed being obtained from a linear regression of the measurements over time.

[0027] According to embodiments, the vehicle braking command is applied when the measured relative speed is greater than a speed threshold, the speed threshold preferably being less than or equal to 20 km / h.

[0028] According to embodiments, the device comprises a time-of-flight distance sensor comprised in an integrated circuit package.

[0029] Embodiments provide an electric single-person vehicle comprising a device such as defined above. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above features and advantages, as well as other features and advantages, will be described in detail in the following description of specific embodiments given by way of illustration and not limitation with reference to the accompanying drawings, in which:

[0031] Figure 1 An example of a single-person vehicle of the type to which the described embodiments are applicable is schematically illustrated;

[0032] Figure 2A A cross-sectional view is shown of a part of a single-person vehicle embodiment according to the first aspect, and Figure 2B A side view is shown;

[0033] Figure 3 An embodiment of a method of measuring the rotational speed of a wheel of the single-person vehicle of Fig. 2 is shown in a simplified timing diagram;

[0034] Figure 4 An embodiment of a device configured to implement the method of Figure 3 is schematically illustrated in block diagram form;

[0035] Figure 5 An embodiment of an obstacle and a single-person vehicle according to the second aspect is schematically illustrated;

[0036] Figure 6 An embodiment of a device configured to implement the method of Figure 5embodiments of a collision avoidance device for a single-person vehicle; and

[0037] Figure 7 is shown Figure 5 is shown. DETAILED DESCRIPTION

[0038] Similar features are designated by like reference numerals in the various drawings. In particular, structural and / or functional features that are common to the various embodiments can have the same reference numerals and can be arranged with the same structural, dimensional and material properties.

[0039] For the sake of clarity, only steps and elements that are helpful for understanding the embodiments described herein are explained and described in detail. In particular, the single-person vehicle is not described in detail, the described embodiments being compatible with a usual single-person vehicle. Also, the so-called time-of-flight or ToF sensor is not described in detail, the described embodiments being compatible with a usual ToF sensor.

[0040] Unless otherwise stated, when referring to two elements connected together, this means a direct connection, without any intermediate element other than a conductor, and when referring to two elements connected together, this means that these two elements can be connected or coupled via one or more other elements.

[0041] In the following description, when referring to terms defining an absolute position, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or terms defining a relative position, such as the terms "above", "below", "high", "low", etc., or to terms defining a direction, such as the terms "horizontal", "vertical", etc., unless otherwise specified, refer to the direction of the drawing or to the vehicle in a normal position of use.

[0042] Unless otherwise specified, "about", "approximately", "substantially" and "nearly" mean within 10%, preferably within 5%, or, when they relate to an angle or an absolute or relative angular direction, within 10 degrees, preferably within 5 degrees.

[0043] Unless otherwise specified, when elements are said to be fixedly secured, this means that these elements are mechanically connected to each other in a fixed manner, for example, fixed to each other, or form part of the same part. In other words, these elements cannot be displaced or rotated with respect to each other.

[0044] Figure 1 An example of a single-person vehicle of the type to which the described embodiments are applicable is schematically shown.

[0045] In the illustrated example, the single-person vehicle is a scooter 100 (defined by a board 110 supported by two or three wheels) and is provided with a handle 120. In the present example, the scooter 100 has two wheels, namely a rear wheel 130 and a front wheel 140. The rear wheel 130 and / or the front wheel 140 can comprise spokes 132 and 142, respectively.

[0046] The scooter 100 is typically equipped with an electric engine, and is therefore referred to as an electric scooter.

[0047] The handle 120 continues towards the front wheel 140 by means of a stem 122. The stem 122 passes through a rotating bearing 112 fixedly secured to the board 110 and extends all the way to a fork 124 (i.e. a front fork) for holding the front wheel 140. The front fork 124 and the stem 122 are fixedly secured to each other.

[0048] The board 110 is further fixedly secured to a rear fork 114 for holding the rear wheel 130.

[0049] The handle 120 can comprise a display 126 configured to display information to a user of the scooter 100. The display 126 and the information displayed are not described in detail, as the described embodiments are compatible with a usual display and with usual information displayed.

[0050] Although the single-person vehicle example illustrated here is a scooter (e.g. an electric scooter), the application of the embodiments described below is not limited to this specific example.

[0051] Thus, in an example, the single-person vehicle is any type of vehicle comprising one of the supports provided, such as the board 110 of the scooter 100, to support at least one foot of a user, among a plurality of supports provided. The support(s) is / are supported by one or more wheels. The single-person vehicle can then comprise a handle (e.g. such as the handle 120) or can not comprise a handle. Such a single-person vehicle can be driven by an electric motor. This way of being driven by an electric motor is preferred in the case where the single-person vehicle comprises a single wheel or two wheels arranged on either side in the direction of displacement. In this case, the single-person vehicle typically comprises a gyroscopic stabilisation device, thereby forming a gyroscopic unicycle (gyro scooter) for a single wheel and a gyroscopic bicycle (gyropod) for two wheels.

[0052] In other examples not shown, the one-person vehicle is of the bicycle type, i.e. a two-wheeled vehicle, preferably guided with handlebars, one of the wheels being driven by a sprocket. The one-person vehicle can also be a tricycle, i.e. a three-wheeled vehicle, preferably guided with handlebars, one of the wheels being driven by a sprocket. The bicycle can be of the electrically assisted bicycle type, also known as e-bike. The e-bike is defined as a bicycle or tricycle propelled by an electric motor, preferably activated according to the rotation of the sprocket.

[0053] The examples of one-person vehicles described above are not limiting and the embodiments described hereinafter can be applied to any one-person vehicle whose unloaded weight is preferably less than 50 kg, more preferably less than 30 kg.

[0054] First aspect:

[0055] Figure 2A A part of an embodiment of the one-person vehicle 200 according to the first aspect is shown in a cross-sectional view Figure 2A and in a side view Figure 2B The views Figure 2A and Figure 2B match.

[0056] In the example shown, the one-person vehicle 200 comprises the same or similar elements as the scooter 100 in Figure 1 These elements are not described in more detail again. Here, only the differences between the one-person vehicle 200 and the scooter 100 are highlighted.

[0057] The part shown comprises the front wheel 140 and the front fork 124. However, the embodiments described hereinafter which apply to the front wheel 140 and the front fork 124 also apply to the rear wheel 130 and the rear fork 114.

[0058] The one-person vehicle 200 is equipped with a device 210 for measuring the rotational speed of the wheel 140. The device 210 can be coupled to a unit (i.e. circuitry) 226 of the one-person vehicle 200 by a connection 212. The connection 212 can be wired or wireless.

[0059] In an example, the device 210 transmits the measurement of the rotational speed of the wheel 140 to the unit 226. The unit 226 can then be Figure 1The display of the scooter 100 of the type of the display 126 differs in that the display 126 receives the measurement values, calculates the speed of the single- rider vehicle 200 on the basis of the measurement values, and displays the speed of the single-rider vehicle 200. The calculation of the speed of the single-rider vehicle 200 on the basis of the rotational speed of the wheel is not described in detail herein, the described embodiment being compatible with such a usual calculation. The unit 226 can for example also be formed by a wireless electronic communication device, such as a mobile phone or a smart watch, comprising a program whose execution results in receiving the measurement values, calculating the speed of the single-rider vehicle 200 on the basis of the measurement values, and displaying the speed of the single-rider vehicle 200.

[0060] In another example, the device 210 calculates the speed of the single-rider vehicle 200 on the basis of the rotational speed of the wheel 140. The device 210 passes the speed value of the single-rider vehicle 200 to the unit 226. The unit 226 can then be a display different from the display 126 of the scooter 100, wherein the display 126 displays the speed of the single-rider vehicle 200 measured by the device 210. The unit 226 can for example also be formed by a wireless electronic communication device, such as a mobile phone or a smart watch, comprising a program whose execution results in receiving the measurement values, and displaying the speed of the single-rider vehicle 200 measured by the device 210. Figure 1

[0061] The unit 226 can also be coupled, preferably connected, to the electric motor and / or to the braking system of the single-rider vehicle 200 by a wired or wireless connection. In addition to or instead of the display of the speed of the single-rider vehicle 200, the unit 226 can take measures such as limiting the speed of the single-rider vehicle 200 on the basis of the speed of the single-rider vehicle 200. For this purpose, the unit 226 can implement any usual method of limiting the speed of a single-rider vehicle.

[0062] The device 210 comprises a time-of-flight sensor 230 or ToF sensor.

[0063] Such a ToF sensor comprises an optical pulse source and an optical receiver. When an optical pulse emitted by the source is reflected by an element of an object external to the ToF sensor, and a part of the reflected pulse is received by the receiver, the ToF sensor passes information related to the presence of the external object and / or information representative of the distance between the ToF sensor and the external object on the basis of the time elapsed between the emission and the reception of each pulse.

[0064] Preferably, the optical pulses of the ToF sensor 230 have a wavelength that is all or substantially all in the near infrared, i.e. a wavelength in the range of 700 nm to 1,500 nm, preferably in the range of 800 nm to 1,100 nm, more preferably in the range of 850 nm to 940 nm, for example equal to 940 nm or approximately 940 nm. ​

[0065] Preferably, the time-of-flight measurements or ToF measurements performed by the ToF sensor 230 are repeated periodically, each ToF measurement possibly corresponding to a plurality of pulses. Then, the frequency of the ToF measurements is preferably in the range of 50 Hz to 5 kHz, for example equal to or approximately 100 Hz, equal to or approximately 300 Hz, or also for example equal to or approximately 600 Hz. The frequency of the ToF measurements can also be greater than 5 kHz.

[0066] In the example shown, the ToF sensor 230 is fixedly secured to a portion of an arm 240 of the front fork 124. The front fork 124 can comprise another arm 245, the arm 245 being located on the other side of the wheel 140 with respect to the arm 240, symmetrically with respect to the wheel 140. More specifically, the arms 240 and 245 are arranged symmetrically with respect to a median plane of the wheel 140 orthogonal to the axis of the wheel 140.

[0067] The arm 240 forms a fixed element. In the present text, a fixed element is an element that serves as a reference to define the rotation of a rotating object, such as, in the example shown, the wheel 140. For a single-person vehicle, this element is fixed with respect to the single-person vehicle, i.e. the fixed element is fixedly secured to the single-person vehicle. Thus, the fixed element accompanies the displacement of the single-person vehicle and is fixed with respect to the rotation of the rotating object.

[0068] In the example shown, the arm 240 comprises a rotation bearing 242 for the wheel 140. The wheel 140 comprises a rotation shaft 250. The rotation shaft 250 rotates in the bearing 242. In another example not shown, the arm 240 comprises the rotation shaft of the wheel 140 and the wheel 140 comprises a rotation bearing around the rotation shaft of the wheel 140. In this other example, the rotation shaft of the wheel 140 is thus fixed.

[0069] In operation, the optical pulses of the ToF sensor 230 are generally emitted in an emission cone 260 having a central axis 262. More specifically, the emission cone 260 is delimited by a boundary defined in each plane orthogonal to the axis 262, the intensity of the pulses in each unit of surface area of this plane being equal to a given percentage of a given maximum intensity in the absence of elements or objects on the path of the pulses. The given percentage is preferably less than or equal to 10%, for example equal to 5%.

[0070] Based on the information from the ToF sensor 230, the device 210 detects the passage of a spoke 142 in front of the ToF sensor 230, i.e. the passage of a spoke 142 in the emission cone 260 at a distance from the ToF sensor 230 small enough for the passage to be detected. To this end, the ToF sensor 230 is oriented so that the spokes 142 pass one after the other through the emission cone 260 as the wheel 140 rotates. In the example shown, the ToF sensor 230 is located inside the head tube 124. In the normal use position of the single-person vehicle 200, the axis 262 is for example horizontal or substantially horizontal.

[0071] The device 210 thus detects a spoke 142 passage position 270. The position 270 is defined by the intersection between the emission cone 260 and the volume swept by the spoke 142 during the rotation of the wheel 140. The ToF sensor 230 and the position 270 are fixed relative to each other, in particular during the movement of the single-person vehicle 200. In other words, the position 270 is a fixed position relative to the single-person vehicle 200 and the detector is oriented towards the position 270.

[0072] Based on the detection of the spoke 142 passage position 270, the device 210 calculates a value representative of the rotational speed of the wheel 140. An embodiment of this calculation is detailed below in connection with Figure 3 and Figure 4 The representative value can be an analog value, or preferably a digital value. The value representative of the rotational speed of the wheel 140 is also a value representative of the displacement speed of the single-person vehicle 200. Indeed, the rotational speed of the wheel 140 and the displacement speed of the single-person vehicle 200 are in a constant ratio. This ratio is a function of the diameter of the wheel 140.

[0073] It can be designed that the rotational speed of the wheel is measured by positioning the magnet and the coil so that a voltage is generated in the coil each time a spoke passes a given position. In comparison with such a rotational speed measurement, the device 210 avoids having to add a magnet attached to one of the spokes 142 and avoids electromagnetic emission that would interfere with the rotational speed measurement, usually associated with the operation of an electric motor.

[0074] Furthermore, the speed measurement implemented by the device 210 has the advantage of being independent of the color or soiled state of the spokes 142 of the wheel 140.

[0075] According to an embodiment, the emission cone 260 has a high half-cone angle, i.e. greater than 10 degrees, more preferentially greater than 20 degrees, for example equal to 27 degrees or approximately 27 degrees.

[0076] Preferably, the pulse source of the ToF sensor 230 is point-like or approximately point-like at the size scale of the single-person vehicle 200. More preferably, the emission cone 2660 has a rotational symmetry around the axis 262. Thus, the cone angle of the emission cone 260 is the cone angle of a rotational cone. As a variant, the emission cone 260 is not circular and the cone angle is defined by the largest angle formed between the generatrices of the cone.

[0077] In the variant where the pulse source is not point-like, such as the emission cone 260 defined above, the emission cone 260 can deviate from the shape of a cone at its part closest to the pulse source. Then, the cone angle of the emission cone 260 is defined as the cone part farthest from the apex.

[0078] The advantage of the high value of the cone angle of the emission cone 260 defined above, compared to the variant where the value of the cone angle of the emission cone 260 is less than such a high value, is to reduce the risk of one of the spokes 142 passing through the emission cone 260 without detecting such a passage.

[0079] According to an embodiment, the ToF sensor 230 is contained in or forms an integrated circuit package. The term integrated circuit package denotes a package, preferably compact, containing one or more integrated circuits and comprising a connection area and / or pins. The connection area and / or pins are electrically coupled to the integrated circuit and are intended to be electrically coupled, preferably soldered, to a printed circuit board PCB. For example, the ToF sensor 230 is of the type sold under the reference “ST VL53L1X”. For example, the package is small enough to be inscribed in a parallelepiped having side dimensions equal to 5 mm, 3 mm and 2 mm, for example, the package dimensions being equal to 4.5 mm, 2.5 mm and 1.56 mm, respectively.

[0080] The ToF sensor 230 contained in an integrated circuit package makes it possible to easily obtain the high value of the cone angle of the emission cone 260 as described above. In addition, the ToF sensor 230 has the advantage of being compact compared to a speed measurement device using a magnet and a coil. In particular, the ToF sensor 230 is particularly easy to install. In addition, the ToF sensor 230 can easily be located in a housing located in the arm 240 of the front fork 124. The fact of providing the ToF sensor 230 in such a housing makes it possible to easily protect the ToF sensor 230.

[0081] Figure 3 An example of implementation of the method of rotational speed measurement by the device 210 described above in connection with Figure 2 is illustrated in a simplified timing diagram. More specifically, it illustrates, as a function of time t:

[0082] - the distance D between the ToF sensor 230 and the element located in front of the ToF sensor 230;

[0083] - a binary value P representative of the absence (N) / presence (Y) of spokes 142 in front of the ToF sensor 230; and

[0084] - the number of detections (DET) of the passage of spokes 142 of a wheel 140 in front of the ToF sensor 230.

[0085] For example, the ToF sensor 230 is configured to deliver, at each pulse of the ToF sensor 230, a signal representative of:

[0086] - the absence of an element in front of the ToF sensor 230 when no element is located in front of the ToF sensor 230;

[0087] - the distance between the ToF sensor 230 and the element when a single element is located in front of the sensor; and

[0088] - the distance between the ToF sensor 230 and the closest element located in front of the ToF sensor 230 when several elements are located in front of the ToF sensor 230.

[0089] In the example illustrated, the distance D takes the value D1 when no spoke is in front of the sensor. The value D1 can correspond to the distance between the ToF sensor 230 and the arm 245 (Fig. 2). When a spoke 142 passes in front of the ToF sensor 230, the distance D takes the value D2 which is less than the value D1. The spoke 142 is then the closest element located in front of the sensor.

[0090] At times ti, preferably repeated periodically, the ToF sensor 230 emits an optical pulse and delivers a signal representative of the distance D measured by the sensor. This signal takes the value representative of the measurement of the values D1 and D2. In variants, for example, when the arm 245 (Fig. 2) is not located in the emission cone 260, the value representative of the value D2 can be replaced by any value representative of the absence of a spoke 142 in front of the ToF sensor 230.

[0091] The device 210 compares the signal delivered by the ToF sensor 230 with a value representative of a distance threshold TH. The device 210 then distinguishes between the presence or absence of an element located in front of the sensor at a distance shorter than the distance TH. In the case of regular pulses, the presence and absence are distinguished with a regular repetition number. For example, the distance threshold TH is in the range 0.5 cm to 7 cm, for example, approximately equal to 7 cm, preferably in the range 0.5 cm to 3 cm, for example, approximately equal to 3 cm.

[0092] The signal P results from a comparison between the distance measured by the time of flight and a threshold TH. During a pulse of the ToF sensor 230, the signal P takes the level N when the optical pulse occurs in the absence of a spoke 142 in front of the ToF sensor 230, and the signal P takes the level Y when a spoke 142 is in front of the ToF sensor 230. The level of the signal P is stored by the device 210, for example, between two successive pulses of the ToF sensor 230.

[0093] In the example shown, a passage of a spoke 142 in front of the ToF sensor 230 is detected (detection 310) each time the signal P switches from the level N to the level Y. In another example, a passage of a spoke 142 is detected each time the signal P switches from the level Y to the level N. The rotational speed of the wheel 140 is calculated from the detection frequency 310. The calculation of the rotational speed from the detection 310 is described below in connection with Figure 4 An embodiment of the calculation of the rotational speed from the detection 310 is described.

[0094] The time-of-flight measurement device 210 has the advantage, compared to a speed measurement device with a magnet and a coil, that the detection of the passage of a spoke is almost insensitive to the value of the threshold TH, provided that, in the example shown, the threshold TH is between the values D1 and D2. The threshold TH is therefore easier to define than a threshold for detecting a passage based on a voltage induced by the passage of a magnet in front of a coil. The device 210 is therefore more reliable and easier to adjust.

[0095] The above has been described in connection with Figure 3 A specific example of a method for time-of-flight detection of the passage of an element, such as a spoke 142 of a wheel 140, has been described. The embodiments are not limited to this specific example and can implement any method for time-of-flight detection of the presence and / or absence of a given element in front of a ToF sensor.

[0096] Figure 4 An embodiment of the device 210 of the unicycle 200 of Figure 2 is schematically shown in the form of a block diagram.

[0097] In addition to the ToF sensor 230 described above, the device 210 comprises a sequential data processing unit 410 (PU), such as a microprocessor. The processing unit 410 can comprise a memory and / or be coupled or connected to a memory of the device 210. The memory comprises a program executed by the processing unit 410 which causes the calculation of a value SPD / RPM representative of a measured rotational speed SPD and / or of a displacement speed of the unicycle 200. Preferably, the processing unit 410 and the ToF sensor 230 are located on the same printed circuit PCB. The processing unit 410 and the ToF sensor can also be in the same printed circuit package.

[0098] Preferably, device 210 further includes a first-in-first-out (FIFO) or FIFO-type stack 420. The FIFO stack 420 has a location 422, for example, in the processing unit 410, the memory, or another memory of device 210. This other memory is preferably located on the same printed circuit as the processing unit 410 and the ToF sensor 230 (e.g., in the same package).

[0099] The FIFO stack 420 includes a given number of N0 positions. In the example shown, the FIFO stack 420 includes five positions.

[0100] In operation, at each detection 310, the duration of the time interval separating the detection 310 from the previous detection 310 is stored in the FIFO stack 420. Once the FIFO stack 420 is filled, the stack at each detection 310 contains the duration of N0 time intervals between N0+1 consecutive detections 310 formed by the considered detection 310 and N0 previous detections 310.

[0101] Then, the value SPD / RPM passed by device 210 is a value representing the ratio of a given number N0 to the sum of the durations of N0 time intervals stored in the FIFO stack 420.

[0102] In the variant, the SPD / RPM value transmitted by device 210 is calculated based on a single time interval, i.e., only based on two consecutive detections 310. Compared to this variant, the SPD / RPM value calculated from the duration of multiple time intervals is closer to the value representing the actual rotational speed; in other words, the measurement of the rotational speed and / or displacement speed of the single-person vehicle 200 is more accurate.

[0103] Preferably, the given number N0 is strictly between 3 and 10 times the number of spokes 142 of the wheel 140. Compared to variations with a given number greater than ten, the sensor response time is improved. Compared to variations with a given number less than two, the measurement accuracy is improved. Therefore, the given number N0 optimizes the trade-off between the response time of the device 210 and the accuracy of the measured rotation of the wheel 140 and / or the speed of displacement of the single-person vehicle 200.

[0104] The above text combined Figure 4 The example of device 210 is not limiting. Therefore, in other examples, device 210 may transmit, for example, a signal conveying detection information of spokes passing in front of the sensor in the form of a pulse at each detection 310, rather than a value of SPD / RPM. The signal may be transmitted to a device such as unit 226 (FIG. 2). Preferably, unit 226 is in a manner similar to the above. Figure 4 The method described above is used to calculate the rotation speed of wheel 140 and / or the displacement speed of single-person vehicle 200.

[0105] The above text combined Figure 4 The calculation of the SPD / RPM value representing the measured rotational speed is not limiting. Therefore, these embodiments are compatible with any method for calculating the rotational speed of wheel 140 and / or the displacement speed of single-person vehicle 200 based on detection 310. Preferably, the calculation is performed over a duration of multiple time intervals. For example, the calculation can be any type of moving average between rotational speed values ​​calculated during said time intervals.

[0106] Based on the advantages of Time-of-Flight (ToF) measurement frequency, as mentioned above, the ToF measurement frequency is fast enough for each pass to be detected. In a variant, the ToF measurement frequency is less than a limit, and some passes shorter than this limit are not detected. However, compared to this variant, the aforementioned sufficiently fast frequency simplifies the calculation of rotational speed.

[0107] The embodiments and variations thereof are not limited to those described above in conjunction with Figures 2 to 3. Figure 1 The example mentioned above.

[0108] Therefore, in the above embodiment, the ToF sensor is securely fixed to the fork arm. However, to measure the rotational speed of the wheel, the sensor can be attached to any arm, including the wheel's bearings or axle. The term arm refers to any element that includes a portion extending radially from the wheel axis so that the spokes pass in front of the sensor. More generally, the ToF sensor can be located on any fixed element of a single-person vehicle that allows the spokes to pass in front of the sensor.

[0109] In the above embodiment, device 210 detects the passage of a plurality of spokes 142 of wheel 140. In other embodiments, the wheel includes targets attached to one or more spokes of the wheel, or multiple targets attached to the spokes of the wheel. The passage of the target(s) is detected at a position in front of the ToF sensor. The ToF sensor is then positioned such that the target(s) passes through the emission cone of the ToF sensor during wheel rotation. In other embodiments, the wheel does not include spokes; for example, the wheel is solid, and the wheel includes one or more targets.

[0110] In the above embodiments, the ToF sensor 230 is firmly fixed to a fixed element and is oriented towards a position through which one or more elements of the wheel 140 pass. In other embodiments, the rotational speed is measured by using a ToF sensor which is firmly fixed on the wheel and is oriented towards an element which is fixed relative to the given position at each time the wheel passes through the given position. Thus, in a variant of the example of Fig. 2, the ToF sensor 230 is attached to one of the spokes 142 of the wheel 140 and the fixed element is part of the arm 240. The fixed element can also be a target which is firmly fixed to the arm 240. According to an advantage, the number of passes is thus reduced at each rotation turn, which enables to increase the measurable rotational speed for a same given measurement frequency ToF, and / or to decrease the ToF measurement frequency for a same maximum measurable rotational speed.

[0111] The above embodiments are described in the example where the one-person vehicle 200 is a scooter. However, the embodiments are also applicable to any one-person vehicle, in particular as defined above in connection with Figure 5 scooter, electric scooter, bicycle, tricycle, electric bicycle, gyro scooter or gyro bike, comprising a device for measuring the wheel rotation and / or the one-person vehicle displacement speed, the speed measurement comprising a time-of-flight detection of the passage of one or more elements of the wheel, such as spokes or targets, through a given position. In the absence of spokes (solid wheel) or relatively thin spokes (such as bicycle spokes), the wheel preferably comprises one or more targets and in the case of relatively thick spokes, the targets are preferably absent.

[0112] Moreover, the above method for measuring the rotational speed of a wheel, comprising a time-of-flight detection of the passage of one or more elements of the wheel through a given position, can be applied to other vehicles than one-person vehicles. More generally, the wheel of the above embodiments can be replaced by most objects which are able to rotate. Then, when the object rotates, a ToF sensor can be firmly fixed to a fixed element and oriented towards a position having one or more elements of the object passing therethrough. The ToF sensor can also be firmly fixed to the object and positioned to be oriented towards the fixed element at each time the object passes through a given position.

[0113] In particular, the rotating object can be a wheel of a sports training device, such as a fitness bicycle. Then, the device is preferably equipped with a display or coupled to a display through a wired or wireless connection. In operation, the display provides an indication to the user of the device in the form of a speed, representative of the physical effort expended by the user.

[0114] Second aspect:

[0115] Figure 1An embodiment of a one-person vehicle 500 and an obstacle 510, e.g. a truck, according to the second aspect is schematically illustrated.

[0116] The obstacle 510 can be any element or object that can collide with the one-person vehicle 500 and / or its user and cause an accident, such as another vehicle, or any living being, e.g. an animal or a human.

[0117] In the illustrated example, the one-person vehicle 500 comprises the same or similar elements as the scooter 100 in Vehicle displacement speed The elements are not described in further detail. Here, only the differences between the one-person vehicle 500 and the scooter 100 are highlighted.

[0118] The one-person vehicle 500 comprises a collision protection device 520 or a collision protection device 520. Preferably, the collision protection device 520 is located at the front of the one-person vehicle 500. In the illustrated example, the collision protection device 520 is attached to the handle 120 or the display 126. In other examples, the collision protection device 520 can also be attached to the pole 122.

[0119] The collision protection device 520 comprises a ToF sensor 522, as defined above in connection with Fig. 2, i.e. the device is configured to deliver information about the presence of an object outside the ToF sensor and / or information representative of the distance between the ToF sensor and the external object by means of a time-of-flight measurement of optical pulses.

[0120] Preferably, the wavelength of the optical pulses of the ToF sensor 522 is all or substantially all in the near infrared, i.e. the wavelength is in the range 700 nm to 1,500 nm, preferably in the range 940 nm to 1,500 nm, more preferably equal to 940 nm or approximately 940 nm.

[0121] Preferably, the ToF measurements performed by the ToF sensor 522 are repeated periodically and each ToF measurement can correspond to a plurality of pulses. Then, the frequency of the ToF measurements is preferably in the range 1 Hz to 100 Hz, for example equal to 30 Hz or approximately 30 Hz. Although, for comparison, the frequency of the ToF measurements can also be greater than 100 Hz, the selection of a ToF measurement frequency less than 100 Hz enables to improve the accuracy of the measurements.

[0122] In operation, the optical pulses of the ToF sensor 522 are generally emitted in an emission cone 530 having an axis 532. More specifically, the emission cone 530 is delimited by a boundary defined by points in each plane orthogonal to the axis 532, where the intensity of the pulses is equal to a given percentage of the maximum intensity of the pulses per unit of surface area of the plane in the absence of an obstacle on the path of the pulses. The given percentage is preferably less than or equal to 10%, for example equal to 5%.

[0123] The ToF sensor 522 is preferably oriented towards the front of the one-person vehicle 500, i.e. the axis 532 is substantially parallel to the displacement direction or longitudinal direction of the one-person vehicle 500, within 30 degrees, preferably within 15 degrees. When one or more obstacles are located on the path of the one-person vehicle 500, the obstacle(s) are then located in front of the ToF sensor 522, i.e. in the emission cone 530. The ToF sensor thus detects the presence of the obstacle(s) 510 located on the path of the one-person vehicle 500. If the obstacle is alone in front of the sensor, the ToF sensor 522 delivers information representative of the distance between the sensor and the obstacle, or if there are several obstacles in front of the sensor, the information representative of the distance between the sensor and the closest obstacle to the sensor.

[0124] In operation, when an obstacle is located in the emission cone 530, the anti-collision device 520 determines, on the basis of the information delivered by the ToF sensor 522, a measure of the relative speed between the one-person vehicle 500 and the obstacle. An example of calculation of the measured speed is shown below in connection with 7. The anti-collision device 520 takes countermeasures aimed at avoiding a collision as a function of the measured relative speed value.

[0125] Preferably, when the measure of the relative speed between the one-person vehicle 500 and the obstacle 510 is greater than a threshold value, the anti-collision device 520 delivers a signal S for braking the one-person vehicle 500. To this end, more preferably, the one-person vehicle 500 is an electric vehicle equipped with a braking device 540, for example a device for braking the rear wheels 130 of the one-person vehicle 500. The braking device 540 receives the signal S and causes the one-person vehicle 500 to stop or slow down. The braking makes it possible to avoid a collision with the obstacle.

[0126] In a variant, the anti-collision device 520 analyzes the variation of the relative speed and acts on the speed of the one-person vehicle to avoid a collision, for example to reduce the relative speed. The fact of triggering braking when the relative speed exceeds a threshold value is much simpler compared to this variant.

[0127] Preferably, the speed threshold is less than or equal to 20 km / h, more preferably in the range 8 km / h to 15 km / h. The speed threshold makes it possible in particular to protect the one-person vehicle from a collision.

[0128] The advantage of the anti-collision device is that it allows braking earlier compared to the user triggering the brake himself in the absence of this device. A delay related to the reaction time of the user is avoided.

[0129] It can be designed that when an obstacle is detected and Figure 6Braking is triggered when the relative speed between the single-occupant vehicle 500 and the obstacle 510 is greater than a threshold value. As a comparison to triggering according to the displacement speed (absolute speed) of the single-occupant vehicle 500, triggering according to the relative speed between the single-occupant vehicle 500 and the obstacle 510 enables the user of the single-occupant vehicle 500 to follow the obstacle 510 when the obstacle 510 is displacing at a speed substantially equal to the displacement speed of the single-occupant vehicle 500, without the need to trigger braking.

[0130] Preferably, the method is implemented only for one or more obstacles located at least at a distance from the optical pulse source of the ToF sensor 522 that is closer than a first threshold value. To this end, for example, the anti-collision device 520 determines only the measured speed of these obstacles, and more preferably, the ToF sensor 522 detects only these obstacles. Preferably, the first threshold value is less than 4 meters or about less than 4 meters. Thus, triggering of braking is avoided when the user of the single-occupant vehicle 500 has time to avoid or intends to avoid the obstacle.

[0131] Preferably, the anti-collision protection method is implemented for any single obstacle that is at least partially located anywhere in the emission cone 530 and at any distance (shorter than a second threshold value) from the optical pulse source of the ToF sensor 522. When multiple obstacles are at least partially present in the emission cone 530 and at a distance from the pulse source that is less than the second threshold value, the protection method is implemented for the closest obstacle. The second threshold value is shorter than the first threshold value. Preferably, the second threshold value is greater than 2 meters or about greater than 2 meters.

[0132] Preferably, the emission cone 530 has a high half-cone angle, i.e., greater than 10 degrees, more preferably greater than 20 degrees, for example, equal to or about 27 degrees. The definition of the half-cone angle of the emission cone 530 is similar to the definition of the cone angle of the emission cone 260 (Fig. 2) in connection with Fig. 2. Preferably, the pulse source of the ToF sensor 522 is point-like or approximately point-like at the scale of the dimensions of the single-occupant vehicle 500, and / or the emission cone 530 has rotational symmetry around the axis 532.

[0133] The high value of the half-cone angle of the emission cone 530 enables avoiding the risk of collision with obstacles further away from the axis 532, compared to variants without the emission cone 530 having a half-cone angle with a high value as defined above. In particular, this enables avoiding the risk of collision with a moving obstacle that moves transversely to the longitudinal direction of the displacement of the single-occupant vehicle 500. An example of such an obstacle is a pedestrian crossing the trajectory of the single-occupant vehicle 500.

[0134] According to an embodiment, the ToF sensor 522 is contained in or forms an integrated circuit package. For example, the ToF sensor 522 is of the type sold under reference ST VL53L1X. For example, the package is small enough to be inscribed in a parallelepiped whose lateral dimensions are equal to 5 mm, 3 mm and 2 mm, for example the dimensions of the package are equal to 4.5 mm, 2.5 mm and 1.56 mm, respectively.

[0135] Such a ToF sensor included in an integrated circuit package makes it possible to easily obtain the high value of the cone angle of the emission cone 530 defined above and to easily obtain the first and second distance thresholds defined above. Moreover, advantageously, the ToF sensor included in the integrated circuit package is particularly light and easy to implement in a single-person vehicle.

[0136] Figure 5 An embodiment of a collision avoidance device 520 of a single-person vehicle 500 is schematically shown in the form of a block diagram. Figure 7

[0137] In addition to the ToF sensor 522 described above, the collision avoidance device 520 also comprises a sequential data processing unit 610 (PU), such as a microprocessor. The processing unit 610 can comprise a memory and / or be coupled or connected to a memory of the collision avoidance device 520. The memory comprises a program executed by the processing unit 610 which causes the emission of a braking signal S as a function of the relative speed between the single-person vehicle 500 and the obstacle. Preferably, the processing unit 610 and the ToF sensor 522 are located on the same printed circuit PCB. The processing unit 610 and the ToF sensor 522 can also be in the same printed circuit package.

[0138] Preferably, the collision avoidance device 520 further comprises a stack 620 of the first-in-first-out or FIFO type. The FIFO stack 620 has locations 622, for example in the processing unit 610, in a memory or in another memory of the collision avoidance device 520. This other memory is then preferably located on the same printed circuit as the processing unit 610 and the ToF sensor 522 (for example in the same package).

[0139] The FIFO stack 620 comprises a given number N0 of locations. In the example shown, the FIFO stack 620 comprises five locations.

[0140] In operation, for each pulse of the ToF sensor 522, the value of the distance between the ToF sensor 522 and the obstacle measured by the ToF sensor 522 is stored in the FIFO stack 620. When the FIFO stack 620 is full, it contains the distance values of a plurality of measurements.

[0141] Figure 6 ​A curve showing the distance between the one-person vehicle 500 and the obstacle as a function of time is shown, which is a calculation example of the relative speed measured between the one-person vehicle 500 and the obstacle. Preferably, this calculation is implemented by the processing unit 610 of the example of the anti-collision device 520. Figure 1

[0142] In this calculation example, the measured values (X1, X2, X3, X4, X5) of the distance between the one-person vehicle 500 and the obstacle at a plurality of times ti (t1,..., t5) are stored in, for example, a FIFO stack 620. Preferably, the times ti correspond to successive pulses of the ToF sensor 522. Preferably, the storage is only performed when the distance between the one-person vehicle 500 and the obstacle is less than a first distance threshold TH1. The measured relative speed value is obtained from the measured values by linear regression as a function of time.

[0143] The advantage of the calculation by linear regression is that it is particularly easy to implement. However, the described embodiments are not limited to this example and any calculation capable of determining the relative speed between the vehicle and the object can be implemented based on the measured values of the distance between the vehicle and the object at a plurality of times.

[0144] Embodiments of the second aspect are described in the example where the one-person vehicle described above is a scooter. However, embodiments of the second aspect are also applicable to any one-person vehicle, in particular such as defined above in connection with ​ Thus, any one-person vehicle, such as a scooter, an electric scooter, a bicycle, a tricycle, an electric bicycle, a gyro scooter or a gyro bike, for example, can be provided comprising an anti-collision device measuring the relative speed between the one-person vehicle and an obstacle by time of flight.

[0145] Various embodiments and variants have been described. The person skilled in the art will understand that some features of these different embodiments and variants can be combined and that other variants will occur to the person skilled in the art. In particular, a one-person vehicle comprising a device according to the first aspect, i.e. configured to measure the rotational speed of a wheel of the vehicle and / or the speed of the vehicle by time of flight, can further comprise an anti-collision device according to the second aspect, i.e. measuring the relative speed between the one-person vehicle and an obstacle by time of flight.

[0146] Finally, the practical implementation of the described embodiments and variants is within the capabilities of the person skilled in the art, based on the functional indications given above.

[0147] Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the application. Accordingly, the description is not intended to limit the application. The application is limited only as defined in the following claims and the full scope of equivalents thereof.​

Claims

1. A method of measuring a rotational speed of a wheel relative to a first arm, the first and second arms being symmetrically arranged relative to a mid-plane of the wheel and orthogonal to an axis of the wheel, the wheel comprising a plurality of spokes, and the method comprising: emitting, by a ToF sensor fixed to the first arm, a plurality of optical pulses toward the second arm; reflecting some of the optical pulses from one or more spokes of a plurality of spokes of the wheel, the plurality of spokes rotating and passing between the first and second arms; detecting a time of flight of the reflected optical pulses; wherein detecting the time of flight of the reflected optical pulses comprises: generating a distance value representing a distance to the one or more spokes of the plurality of spokes of the wheel; and comparing the distance value to a distance threshold in order to detect a passage of the one or more spokes of the wheel; and wherein deriving the rotational speed comprises determining the rotational speed from the detected passage; and deriving the rotational speed from the detected time of flight.

2. The method of claim 1, further comprising communicating a linear speed of the wheel based on the derived rotational speed.

3. The method of claim 1, wherein the wheel is a wheel of a single-person vehicle or of a sports training device, and the method further comprises communicating a speed of the single-person vehicle or of the sports training device based on the derived rotational speed.

4. The method of claim 1, further comprising calculating a value representing the derived rotational speed by using a given number of time intervals greater than or equal to two between detections of time of flight of the reflected optical pulses.

5. The method of claim 4, wherein the given number is 3 to 10 times a number of the one or more spokes of the plurality of spokes of the wheel.

6. The method of claim 1, wherein the plurality of optical pulses are infrared pulses.

7. An apparatus for measuring a rotational speed of a wheel relative to a first and second arms, the first and second arms being symmetrically arranged relative to a mid-plane of the wheel and orthogonal to an axis of the wheel, the wheel comprising a plurality of spokes, and the apparatus comprising: a transmitter configured to emit a plurality of optical pulses from the first arm toward the second arm; wherein some of the optical pulses are reflected from one or more spokes of a plurality of spokes of the wheel, the plurality of spokes rotating and passing between the first and second arms; circuitry configured to detect a time of flight of the reflected optical pulses, and to derive the rotational speed from the detected time of flight; wherein the circuitry detects the time of flight of the reflected optical pulses by: generating a distance value representing a distance to the one or more spokes of the plurality of spokes of the wheel; and comparing the distance value to a distance threshold in order to detect a passage of the one or more spokes of the wheel; and wherein deriving the rotational speed comprises determining the rotational speed from the detected passage.

8. The apparatus of claim 7, wherein the circuitry is further configured to communicate a linear speed of the wheel based on the derived rotational speed.

9. The apparatus of claim 7, wherein the wheel is a wheel of a single-person vehicle or of a sports training apparatus, and wherein the circuitry is further configured to communicate a speed of the single-person vehicle or of the apparatus based on the derived rotational speed.

10. The apparatus of claim 7, wherein a value representative of the derived rotational speed is calculated by using a given number of time intervals greater than or equal to two between time-of-flight detections.

11. The apparatus of claim 10, wherein the given number is 3 to 10 times a number of the one or more spokes of the plurality of spokes of the wheel.

12. The apparatus of claim 7, wherein the emitter and circuitry form a time-of-flight sensor that is fixedly secured to an element that is fixed relative to the wheel.

13. The apparatus of claim 12, wherein the time-of-flight sensor is contained in an integrated circuit package.

14. The apparatus of claim 7, wherein the emitter and circuitry form a time-of-flight sensor that is configured to periodically distinguish, at a time, whether one or more spokes of the plurality of spokes of the wheel are present or not present at a distance less than a threshold distance in front of the time-of-flight sensor.

15. The apparatus of claim 14, wherein the detecting comprises detecting a switch from not present to present and a switch from present to not present.

16. A single-person vehicle or a sports training apparatus comprising the apparatus of claim 7.

17. The single-person vehicle or the sports training apparatus of claim 16, wherein the emitter and circuitry form a time-of-flight sensor that is fixedly secured to an element of the single-person vehicle or of the sports training apparatus.

18. The single-person vehicle or the sports training apparatus of claim 17, the first arm comprising a bearing or an axis of rotation of the wheel, and wherein the element is part of or is attached to part of the first arm.

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