KR20230063337A - Cycling Cadence Meter and Measuring Method Utilizing Light Round Trip Time Measureme - Google Patents

Abstract

The present invention relates to a device for measuring the number of cranks on a bicycle using round-trip time measurement of light, and includes a ToF measuring unit 32, which includes a pulse generator 24 for generating pulses and An optical transmitter (21) driven by a pulse and emitting light, an optical receiver (22) detecting the light reflected from the reflector, and a pulse generator (24) detecting the pulse generation time and the light from the optical receiver (22). It may include a timer 23 for calculating the time interval and a distance calculator 25 for calculating the distance by the following equation using the time interval transmitted from the timer 23.

Description

Apparatus for measuring the number of bicycle cranks using round trip time measurement of light { Cycling Cadence Meter and Measuring Method Utilizing Light Round Trip Time Measureme}

The present invention relates to a device for measuring the number of bicycle cranks using the measurement of the round trip time of light.

The present invention relates to a device for measuring the number of bicycle cranks using the measurement of the round trip time of light. As bicycle riding is recommended for health and the environment, cadence (per minute of crank) is an index to provide a riding method that maximizes the amount of exercise when riding a bicycle along with information such as distance traveled and speed while riding a bicycle, in addition to simply riding a bicycle. rotational speed) is important.

In order to run long distances for a long time, cyclists step on the pedals while arranging their physical strength while continuously checking the distance, speed, and cadence according to the direction they are traveling. If you train steadily to keep the cadence specified in advance according to your current speed and physical strength, you will see the effect of increasing the average speed of the bicycle, which continuously records and observes the distance, time, and cadence. and can be obtained through training.

In general, when riding a bicycle, it is often used to train people to pedal at a cadence of 90, and to train by raising a gear little by little while maintaining the cadence. For this purpose, measuring accurate cadence is very important in bicycle riding. It became.

Conventionally, in order to measure cadence, as described in Korean Patent Application No. 10-2014-0040967 'Cadence sensor and speedometer for bicycles using 3-axis accelerometer', an accelerometer module is included in the crank arm, and the error between crank rotation speed and bicycle speed is included. Even if the accelerometer module is attached to the crank arm, if you ride a bicycle for a long time, the position and direction of the accelerometer module change little by little due to the impact. There are inconveniences that must be done.

In addition, to measure the cadence, a magnet is attached to the crank of the bicycle and a magnetic force sensor is attached to the horizontal axis of the bicycle. It is provided to the passenger's mobile phone or a separate monitoring device using the same wireless communication means. Magnets and sensors can be used interchangeably. In general, the distance between the magnet and the magnetic force sensor is set to cross within several mm. However, this method also has a disadvantage in that the measurement result becomes inaccurate if the position of the magnet and the magnetic force sensor changes even a little according to the operation as a result.

In some cases, a posture detection sensor is used. The posture sensor is attached to the crank of the bicycle and measures the change in posture of the sensor as the crank rotates to calculate the number of revolutions. The posture sensor mainly uses a gravitational acceleration sensor that changes in three dimensions. Similarly, since the sensor has to be fixed anywhere on the bicycle, if the location of the sensor changes due to driving, the result may be inaccurate.

The present invention has been made to overcome the above disadvantages, and an object of the present invention is to provide a device capable of measuring cadence in a more accurate way.

In order to achieve the above object, a device for measuring the number of bicycle cranks using the round-trip time measurement of light is provided, including a ToF measuring unit 32. The ToF measuring unit 32 is a pulse generator for generating pulses ( 24), an optical transmitter driven by the generated pulse and emitting light, an optical receiver 22 that detects the light reflected from the reflector, and the time at which the pulse is generated from the pulse generator 24 and the optical receiver 22 ) and a distance calculator 25 that calculates the distance by the following equation using the time interval transmitted from the timer 23 and the time interval transmitted from the timer 23.

d= 1/2*dT/c d: distance dT: time interval c: speed of light

The optical transmitter 21 may be directed to the lower body of the cyclist.

The optical transmitter 21 transmits light toward any one of the shoes, knees, and calves of the cyclist and measures the distance from the optical transmitter 21 over time. Rotational motion can be observed.

The ToF measuring unit 32 may be attached to more than one part of the handle and the saddle.

An effective value determining unit 36 for excluding time intervals calculated by light reflected from other parts designated as reflectors may be further included.

The pulse generated by the pulse generator 24 may be several picoseconds or more and several nanoseconds or less.

The instantaneous cadence can be obtained by the following equation using the instantaneous time interval representing the same distance from two peaks in the time-distance graph.

Cadence=(t2-t1)*60

The device for measuring the number of bicycle cranks includes a charger, a front lighting device, a rear lighting device, a ground speed measuring device, a cadence measuring device, a power meter, a radar (for rear detection, detecting vehicles, etc.), a black box, a cycling computer, Components may be shared with any one or more of a navigation device and a heart rate measuring device.

There is an effect of obtaining a more accurate cadence by the device as described above.

1 to 5 are views for illustrating an embodiment according to the present invention

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 are views respectively showing one embodiment of a cadence measuring device according to the present invention. In FIG. 1, the cadence measuring device 11 is attached to the saddle side, and in FIG. 2, it is attached to the handle side. The cadence measuring device 11 according to the present invention uses Time of Flight (ToF) of light to avoid that the position of the sensor changes and the measured value is affected by driving.

Since light has a constant speed and good linearity, it can be treated as a constant, so if only the time interval is accurately measured, the distance the light has moved during that time can be easily measured. In other words, when a rider sits on a bicycle and pedals, the pedal draws a circle according to the rotation of the crank, and parts such as the user's shoes or calves also make a circular motion according to the movement of the pedals. Cadence is measured while continuously measuring the circular motion of the

1, the cadence measuring device 11 is attached to the back of the saddle by a separate fixing device, and the optical transmitter 21 and the optical receiver 22 are directed toward the crank. and measure the distance to the reflector by analyzing the time interval with the pulse returning from the reflector such as the occupant's shoe, knee or calf. In FIG. 1, the reflector may be a shoe or calf of a cyclist, and in FIG. 2, the reflector may be a knee of the rider or a region around the knee. In the drawing, the round red dot represents the part where the pulse is reflected. Although it does not draw a concentric circle as shown, it moves in a similar closed curve. In addition, light can be transmitted and received at much shorter intervals than shown in the drawings, and what is shown in the drawings is merely exemplary.

In this way, if light pulses are repeatedly transmitted and received at intervals much shorter than the speed at which the occupant steps on the pedal, a graph of the distance over time can be drawn as shown in FIG. 3. The number of peaks or peaks per minute The number of is the cadence you want to find. Cadence can be calculated even from one peak. Assuming that the shape of the peak remains constant, the formula for expressing cadence in RPM is as follows.

Cadence=(t2-t1)*60

Even if the pace is slightly disturbed while pedaling, the overall graph is continuously generated, so even if the instantaneous cadence is obtained, the difference in cadence is not large, and the moment when the instantaneous cadence bounces can be immediately confirmed on the graph as shown in FIG. 3.

Pulses emitted from the optical transmitter 21 may be reflected from other parts than the reflector, but since the shape of the graph is usually kept constant as the graph continues to be drawn, pulses reflected from other parts deviate greatly from the graph. can be ignored That is, as shown in the drawing, since a curve of a similar shape is formed, the effective numerical range at a specific measurement moment does not deviate greatly from the measured value at the previous measurement moment, so it is very limited, so values outside a certain range can be ignored.

In particular, the optical transmission unit may be configured using a laser capable of focusing in a narrow area. As in the example of FIG. 6 , the ToF focused on a specific position of a pedaling shoe can receive a meaningful reflection signal only when the shoe is present at a specific position, as shown in the graph of FIG. 6 , and receive signals below the noise level at other positions. there will be In this way, a received signal with a high noise ratio according to crank rotation can be obtained, and a more accurate cadence measurement value can be derived.

In addition, although cadence measuring devices are installed on the front and rear surfaces in FIGS. 1 and 2, respectively, accuracy can be further improved by installing a plurality of cadence measuring devices and taking only invalid values by comparing values with each other. The cadence measurement device 11 may be installed on the front and rear and used to verify whether each other's current measured values are valid, or the values of the two devices may be averaged and used.

In addition, since the cadence measuring device 11 according to the present invention continues to observe and measure the movement of the reflector even if there is some movement in the mounting position of the cadence measuring device due to driving, if only the movement of the reflector can be measured, the position Even if there is a change in , it is not a big problem.

4 is a diagram showing the modules of the device according to the present invention, and FIG. 5 is a diagram showing the operation of the ToF measuring unit 32 in more detail. In FIG. 4, the wireless communication transmission/reception unit 33 can communicate with the passenger's cell phone to leave driving records such as speed and location, and can serve to communicate with a plurality of ToF measuring units 32 connected wirelessly. there is. If necessary, the data can be transmitted to the cycling computer for more comprehensive data collection and analysis. The ToF measurement unit 32 measures the time interval between the optical transmitter and the optical receiver in order to calculate the cadence, and the effective value determination unit 36 removes an invalid value from the measured time interval. The control unit 31 analyzes the change in distance information transmitted from the ToF measurement unit 32 to calculate the cadence and manages the operation of the entire module. The display unit 34 enables display of cadence information transmitted by wire or wirelessly if necessary, the power supply unit 35 supplies power, and the other bicycle assistance devices 36 connect the front and rear bicycle assistance devices with power. They share space and can be configured as a unit. By including the GPS and delivering the movement route information to the controller, the movement route of the bicycle can be displayed and stored. Various auxiliary devices can be used for other bicycles, such as a charger, front lighting device, rear lighting device, ground Speed measuring device, cadence measuring device, power meter, radar (for rear view, detecting vehicles, etc.), black box, cycling computer, navigation, heart rate measuring device, etc. can be used, and these devices can be used on the front handlebar or saddle of the bicycle. ,Post, crank, wheel, etc. are installed separately, and each device requires a separate power supply device, and a communication function is also required to send measurement data generated by each device to a monitoring device with a receiving function. However, since it is not efficient in terms of cost and space utilization to separately provide a power supply or communication device for each device, it is advantageous to integrate various devices.

The device according to the present invention is easily combined with the devices mentioned above and can use several modules in common. The cadence measurement devices shown in FIGS. 1 and 2 can be manufactured integrally with the front lighting device and the rear lighting device, respectively, so that the cadence can be measured with high precision while replacing the existing front and rear lighting devices.

In FIG. 5, the timer 23 records the time at which light is emitted, and when the pulse generator 24 generates a pulse at that time, the light is emitted by the optical transmitter 21 at the same time and goes straight as much as the distance d to the reflector When it is reflected on the light and returns to the optical receiver 22 by going straight for the same distance d again, the timer 23 measures the arrival time to calculate the time interval from departure to arrival, and calculates the time interval by the distance calculator 25. The distance d to the reflector is calculated using

The distance is calculated by the formula d= 1/2*dT/c, which indicates d: distance, dT: time interval, and c: speed of light. Since the speed of light is constant, the distance is calculated immediately if only the time interval is given, and since the time interval is the time taken while moving a distance as much as 2d, only half the value is taken. The measured distance is used to draw a graph as shown in FIG. 3 using the time value and is used to measure the cadence.

The optical transmitter 21 converts electrical signals into optical signals. Various light sources such as lasers or LEDs may be used, and infrared (Infra Red Ray) frequencies that are less affected by sunlight may be used when considering outdoor use. The pulse generator 24 generates pulses at short intervals capable of driving the optical transmitter. Since the speed of light is very fast, the pulse width must be sufficiently narrow, and it is generally better to set it to 1 nsec or less. The optical receiver 22 converts an optical signal into an electrical signal and is configured to receive the wavelength band used by the optical transmitter 21. When using IR, an optical filter is used to block the influence of sunlight. It is good. The timer 23 measures the time interval of the two transmission and reception pulse signals, and the distance calculator 25 calculates the distance to the reflector using the time interval information transmitted from the timer.

11: cadence measuring device
21: optical transmitter 22: optical receiver
23: timer 24: pulse generator
25: distance calculator
32: ToF measurement unit 33: wireless communication transmission and reception unit
34: display unit 35: power supply unit
36: effective value judgment unit

Claims (9)

A device for measuring the number of bicycle cranks using light round-trip time measurement,
It includes a ToF measuring unit 32, which ToF measuring unit 32
A pulse generator 24 for generating pulses and
An optical transmitter 21 driven by the generated pulse and emitting light
an optical receiver 22 for detecting the light reflected from the reflector; and
A timer 23 that calculates an interval between the time when a pulse is generated from the pulse generator 24 and the time when light is detected from the optical receiver 22; and
A device for measuring the number of bicycle cranks using the round-trip time measurement of light, including a distance calculator 25 that calculates the distance by the following formula using the time interval transmitted from the timer 23
d = 1/2*dT/c
d: distance
dT: time interval
c: speed of light According to claim 1, the optical transmitter (21) is a device for measuring the number of bicycle cranks using the round-trip time measurement of light directed to the lower body of the bicycle rider. The method of claim 2, wherein the optical transmitter 21 transmits light toward any one of the shoes, knees, and calves of the cyclist and measures the distance from the optical transmitter 21 over time, so that while the rider steps on the pedals, A device for measuring the number of cranks on a bicycle by measuring the round-trip time of light, allowing the rotational motion of the shoe, knee, and calf to be observed.
The apparatus of claim 3, wherein the ToF measuring unit 32 is attached to at least one part of the handlebar and the saddle, and measures the number of bicycle cranks by measuring the round-trip time of light.
The method of claim 4, further comprising an effective value determining unit (36) for excluding time intervals calculated by light reflected from other parts designated as reflectors, for measuring the number of bicycle cranks using round-trip time measurement of light Device 6. The method of claim 5, wherein the Tof measurement unit 32 uses a laser capable of focusing to focus on a pre-designated position so that a reflection signal is received only when the shoe comes to the pre-designated position, and signals below the noise level are received at other positions. A device for measuring the number of bicycle cranks using round trip time measurement of
7. The device for measuring the number of bicycle cranks using light round-trip time measurement according to claim 6, wherein the pulses generated by the pulse generator (24) are several picoseconds or more and several nanoseconds or less. The method of claim 7, wherein the number of bicycle cranks is measured using the round-trip time measurement of light, in which the instantaneous cadence is obtained by the following equation using the instantaneous time interval representing the same distance from two peaks of the time-distance graph. device for
Cadence=(t2-t1)*60
The method of claim 8, wherein the device for measuring the number of bicycle cranks is a charger, a front lighting device, a rear lighting device, a ground speed measuring device, a cadence measuring device, a power meter, a radar (for rear sensing, detecting vehicles, etc.), A device for measuring the number of cranks on a bicycle by measuring the round-trip time of light, sharing a component with any one or more of a black box, a cycling computer, a navigation device, and a heart rate monitor.

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