JP2016137893A - Vehicle speed determination system, stability control system, and saddle-riding type vehicle having stability control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine vehicle speed when turning by a steering operation.SOLUTION: A vehicle speed determination system is a speed determination system for a vehicle having a front wheel and a rear wheel. The vehicle speed determination system includes: a wheel speed sensor 35 for detecting wheel speed Vof the front wheel; and a computing unit 200 which determines vehicle speed V(r) at a rear wheel ground point on the basis of difference of the vehicle speed generating between a front wheel ground point and the rear wheel ground point due to difference between a traveling trace of the front wheel and a traveling trace of the rear wheel, and on the basis of the wheel speed Vof the front wheel.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a vehicle speed determination system for a bank that is banked when traveling on a curve, a stability control system for such a vehicle, and a saddle-ride type vehicle including the same.

  Motorcycle attitude control technology (vehicle stability control technology) represented by traction control system (TCS) and anti-lock brake system (ABS) includes wheel speeds obtained from the difference in wheel speed between the front wheels and the rear wheels. Generally, “slip amount” or “slip rate” is used.

The slip ratio λ is typically expressed by the following equation.
λ = (V−V _r ) / V ... When braking λ = (V-V _r ) / V _r ... When driving

The slip amount can be expressed by, for example, (V−V _r ).

Here, V is the vehicle speed, and _Vr is the wheel speed of the rear wheel (drive wheel). In general, the “vehicle speed” is a moving speed of the vehicle with respect to the road surface. The “wheel speed” is a tangential speed on the outer peripheral surface of the wheel when the wheel rotation axis is used as a reference. Wheel speed is proportional to "wheel rotation speed (number of rotations per unit time)" and "wheel rotation radius" and is generally expressed by the product of "wheel rotation angular speed" and "wheel rotation radius". The The unit of wheel speed is, for example, “km / hour”, but is not limited thereto. According to the above equation, when the vehicle speed V is equal to the rear wheel speed V _r , the slip ratio λ and the slip amount are equal to zero.

  As an attitude control technique (vehicle stability control technique) for a motorcycle, Patent Document 1 discloses a brake hydraulic pressure control device for a motorcycle. The control device includes wheel speed sensors that detect the wheel speeds of the front and rear wheels, and controls the braking force adjusting device based on the wheel speeds detected by the wheel speed sensors.

JP 2008-126988 A

In the attitude control technology (vehicle stability control technology) for motorcycles, conventionally, the vehicle speed is obtained by detecting the wheel speed of the front wheel that is not the driving wheel. Specifically, assuming that the front wheel speed is V _f , V = V _f is considered to hold, and the vehicle speed V in the above equation for calculating the slip ratio or slip amount is equal to the wheel speed V _f of the front wheel. Substituting measurements has been done.

  Moreover, the control apparatus of patent document 1 is equipped with the wheel speed sensor which detects the wheel speed of each wheel before and behind, and controls a braking force adjustment apparatus based on the wheel speed which each wheel speed sensor detected. In this control device, the vehicle speed is estimated from the front wheel speed detected by the front wheel speed sensor. The brake fluid pressure of the brake device is adjusted according to the speed difference between the estimated vehicle speed and the rear wheel speed detected by the rear wheel speed sensor.

  Thus, according to the prior art, the vehicle speed V is a measured value of the wheel speed of the front wheel or an estimated value based on the wheel speed of the front wheel. All of the above methods for determining the vehicle speed V are based on the assumption that the vehicle body is traveling straight. However, the saddle riding type vehicle can bank the vehicle during a curve run.

  The present invention provides a vehicle speed determination system, a stability control system, and a saddle-ride type vehicle including the same that can solve the above-described problems.

  The vehicle speed determination system of the present invention is a vehicle speed determination system for a vehicle having front wheels and rear wheels, and includes a wheel speed sensor that detects a wheel speed of the front wheels, a travel locus of the front wheels, and a travel locus of the rear wheels. And a calculator for determining the vehicle speed at the rear wheel ground point based on the difference in vehicle speed generated between the front wheel ground point and the rear wheel ground point due to the difference and the wheel speed of the front wheel.

  The vehicle speed determination system of the present invention has the above-described configuration, so that the front wheel grounding point can be obtained even when the wheel speed of the front wheel does not coincide with the vehicle speed at the rear wheel grounding point due to the “inner / outer wheel difference” during curve traveling. The vehicle speed at the rear wheel ground contact point can be determined from the wheel speed of the front wheel based on the difference in vehicle speed generated between the rear wheel ground contact point and the rear wheel ground contact point. Thereby, it is possible to provide a vehicle speed determination system that can estimate the vehicle speed during curve driving.

  The stability control system of the present invention is a stability control system for a vehicle having a front wheel and a rear wheel, and includes a first wheel speed sensor that detects a wheel speed of the front wheel and a second wheel that detects a wheel speed of the rear wheel. Based on the speed sensor, the difference in vehicle speed generated between the front wheel grounding point and the rear wheel grounding point due to the difference between the traveling locus of the front wheel and the traveling locus of the rear wheel, and the wheel speed of the front wheel An arithmetic unit that determines the vehicle speed at the rear wheel ground contact point, and a longitudinal force that is a sum of longitudinal forces acting on the front wheel or the rear wheel based on vehicle speeds at the front wheel rear contact point and the rear wheel ground contact point. And a longitudinal force control unit for adjusting the absolute value.

  The stability control system of the present invention has the above-described configuration, so that the front wheel grounding point can be obtained even when the wheel speed of the front wheel does not coincide with the vehicle speed at the rear wheel grounding point due to the “inner / outer wheel difference” during curve traveling. The vehicle speed at the rear wheel ground contact point can be determined from the wheel speed of the front wheel based on the difference in vehicle speed generated between the rear wheel ground contact point and the rear wheel ground contact point. Further, a longitudinal force control unit that adjusts the absolute value of the longitudinal force based on the vehicle speed at the rear wheel contact point determined as described above is provided. Thereby, it is possible to provide a stable control system capable of estimating the vehicle speed particularly during curve traveling.

  A saddle-ride type vehicle of the present invention includes the above-described stability control system.

  Since the saddle-ride type vehicle according to the present invention includes the above-described stability control system, it is possible to provide a saddle-ride type vehicle equipped with a stability control system that can estimate the vehicle speed during curve traveling.

  According to the vehicle speed determination system of the present invention, even if a wheel speed difference occurs between the front and rear wheels due to a difference in the locus (traveling locus) drawn on the road surface by the contact points of the front wheels and the rear wheels, The vehicle speed at the contact point can be obtained by calculation. As a result, when the vehicle speed determination system of the present invention is applied to a vehicle stability control system, vehicle control is realized based on the vehicle speed at the contact point of each wheel and without being affected by the difference between the inner and outer wheels of the front and rear wheels. It becomes possible.

(A) And (b) is a figure for demonstrating the wheel speed of the front-and-rear wheel in a motorcycle. (A) to (c) are top views schematically showing a traveling locus when the motorcycle curves while banking. (A) is a yaw rate ω _{z of} a motorcycle that runs while meandering by a steering operation, (b) is a wheel speed V _f , V _r , (c) of the front and rear wheels at that time, and is determined by the prior art. It is a graph which shows each time change of slip ratio (lambda). (A) is a graph showing a bank angle φ of a motorcycle that runs while meandering by a steering operation, and (b) is a graph showing each time change of the yaw rate ω _{z at} that time. It is a block diagram which shows the structural example of the vehicle speed determination system in embodiment of this invention. It is a block diagram which shows the other structural example of the vehicle speed determination system in embodiment of this invention. It is a block diagram which shows the further another structural example of the vehicle speed determination system in embodiment of this invention. (A) is a bank angle φ of a motorcycle running while meandering by steering operation, (b) is a yaw rate ω _{z at} that time, (c) is a wheel speed V _f , V _r of the front and rear wheels, and rear Vehicle speeds V (r) and (d) at the wheel contact points are graphs showing temporal changes of the slip ratio λ obtained by the conventional technique and the slip ratio λ ′ obtained by the present embodiment. (A) is a bank angle φ of a motorcycle that rotates in a certain direction by a steering operation, (b) is a yaw rate ω _{z at} that time, (c) is a wheel speed V _f , V _{r of} front and rear wheels, and The vehicle speed V (r) (d) at the rear wheel contact point is a graph showing the time variation of each of the slip ratio λ obtained by the conventional technique and the slip ratio λ ′ obtained by the present embodiment. 1 is a side view of a motorcycle according to an embodiment of the present invention. It is a functional block diagram which shows the structure of the stable control system which concerns on embodiment of this invention. It is explanatory drawing explaining calculation of the bank angle which concerns on embodiment of this invention. It is another explanatory drawing explaining calculation of the bank angle concerning the embodiment of the present invention. (A) is a graph which shows the detection of the skid acceleration which concerns on embodiment, (b) is a graph which shows longitudinal force reduction control with respect to the detected skid acceleration. (A) And (b) is a figure which shows the relationship between the force which generate | occur | produces on the wheel which concerns on embodiment, and a friction circle. It is a flowchart which shows the stable control which concerns on embodiment.

  In motorcycles, when driving with a large steering angle, the calculated slip rate (slip amount) may show a non-zero value even though there is no actual slip. The inventor found out the cause as a result of finding and earnest research. In other words, when traveling with a large steering angle, the front wheel speed will be greater than the rear wheel speed due to the difference between the inner and outer wheels caused by the difference in the trajectory through which the ground contact points of the front and rear wheels pass. Focusing on the fact that there is a case, it was found that the slip ratio (slip amount) deviates from the actual value. Such a problem in a motorcycle arises because the moving speed of a moving vehicle with a rotational motion cannot be defined by a single value and can have different values depending on the part of the vehicle. In other words, in a motorcycle that travels while curving, the vehicle speed at the contact point of the front wheel does not necessarily match the vehicle speed at the contact point of the rear wheel. For this reason, according to the prior art that assumes that the vehicle speed at the front wheel contact point is always equal to the vehicle speed at the rear wheel contact point, the slip ratio (slip amount) is calculated even though no slip actually occurs. The value will indicate a non-zero value.

  Hereinafter, the cause of the problem of the conventional technique will be described in detail with reference to FIGS. 1 and 2. FIGS. 1A and 1B are diagrams schematically illustrating the basic configuration of the motorcycle 1, and FIGS. 2A to 2C are schematic diagrams illustrating the traveling trajectories of the front wheels and the rear wheels of the motorcycle 1. FIG. FIG.

  As shown in FIG. 1A, the motorcycle 1 includes a front wheel 8 and a rear wheel 23. The front wheel 8 is in contact with the road surface E at the front wheel contact point f, and the rear wheel 23 is in contact with the road surface E at the front wheel contact point r. In this example, the rear wheel 23 is a driving wheel, and rotates by obtaining a driving force from a driving source such as an engine or an electric motor (not shown). On the other hand, the front wheel 8 is rotated by the frictional force received from the road surface E.

In the example shown in FIGS. 1A and 1B, the motorcycle 1 moves to the right in the drawing at the vehicle speed V by the rotation of the rear wheel 23. When the motorcycle 1 is traveling straight on the straight line of the road surface E, the vehicle speed V is equal to the wheel speed V _f of the front wheel 8. At this time, if no slip occurs in the rear wheel 23, the vehicle speed V is equal to the wheel speed V _r of the rear wheel 23. As the motorcycle 1 travels, the front wheel contact point f and the rear wheel contact point r move along the road surface E.

  Next, reference will be made to FIGS. 2 (a) to 2 (c), the front wheels 8 and the rear wheels 23 of the motorcycle 1 banked with respect to the road surface E are shown schematically along with examples of the two traveling tracks F and R, respectively. ing. FIGS. 2 (a), 2 (b), and 2 (c) schematically describe the motorcycle 1 in a process of curving while banking in three stages. When an axis perpendicular to the road surface E is used as a reference, the motorcycle 1 travels while rotating around this axis. At this time, the yaw rate of the motorcycle 1 shows a non-zero value. Here, the yaw rate is the rate of time change of the yaw angle (turning angle) and is also called the yaw angular velocity. As described later with reference to FIG. 13, the yaw rate is defined as the time derivative of the angle of rotation about the Z axis that is the vehicle body fixed axis.

  In this specification, the “front wheel traveling locus” is a locus drawn by the front wheel contact point f on the road surface E, and the “rear wheel traveling locus” is a locus drawn by the rear wheel contact point r on the road surface E. . In the drawings, the road surface E is approximated by a “plane” for simplicity, but the road surface E is not limited to a plane.

  As shown in FIGS. 2A to 2C, if there is a difference between the traveling locus F of the front wheel 8 and the traveling locus R of the rear wheel 23, the front wheel contact point that moves on the traveling tracks F and R will be described. There may also be a difference between the moving speed of f and the moving speed of the rear wheel contact point r. This is because the moving distance of the front wheel contact point f and the moving distance of the rear wheel contact point r in unit time can be different. In this specification, the moving speed of the front wheel contact point f may be referred to as “vehicle speed at the front wheel contact point”, and the moving speed of the rear wheel contact point r may be referred to as “vehicle speed at the rear wheel contact point”. This is because the vehicle speed of a motorcycle that curves while banking can have different values depending on the part of the vehicle. In this specification, the vehicle speed may be expressed as V (x) as a function of the vehicle part x. For example, “vehicle speed at the front wheel contact point” is V (f), and “vehicle speed at the rear wheel contact point” is V (f). r).

  When the motorcycle 1 is moving straight on a straight line on the road surface E, the front wheel contact point f and the rear wheel contact point r move on the same straight line, and the travel locus F of the front wheel 8 and the travel locus of the rear wheel 23. R matches. As a result, the vehicle speed V (f) at the front wheel contact point f becomes equal to the vehicle speed V (r) at the rear wheel contact point r. Conventionally, on the premise of this, the vehicle speed V (f) at the front wheel contact point f is detected by measurement, and the detected value is used as the vehicle speed V (r) at the rear wheel contact point r to determine the slip ratio of the rear wheels, etc. Was calculated. Therefore, when the deviation of the running tracks F and R as shown in FIG. 2 occurs between the front and rear wheels, the vehicle speed V (r) at the rear wheel contact point r may deviate greatly from the true value. The error of slip ratio (slip amount) became large. Therefore, in the conventional vehicle attitude control system, an early intervention or an intervention delay of slip suppression control such as TCS and ABS may occur.

FIG. 3A is a graph showing the time change of the yaw rate ω _z during slalom traveling with steering operation, and FIG. 3B shows the front wheel speed V _f and the rear wheel speed V _r at that time. FIG. 3 (c) is a graph showing the time change, and FIG. 3 (c) shows the time of the slip ratio λ obtained by calculation using the front wheel speed V _f shown in FIG. 3 (b) as the vehicle speed V (r) at the rear wheel contact point. It is a graph which shows a change. The yaw rate ω _z , front wheel speed V _f, and rear wheel speed V _r are all actually measured values.

As shown in FIG. 3A, the yaw rate ω _z changes within a range of about −70 ° / second to 70 ° / second. It can be seen that as the absolute value of the yaw rate ω _z increases, the difference (V _f −V _r ) between the front wheel speed V _f and the rear wheel speed V _r increases as shown in FIG. Specifically, the difference (V _f −V _r ) reached 2.5 km / hour or more at maximum. The slip ratio λ in FIG. 3C is obtained by measuring the front wheel speed V _f and the rear wheel speed V _r in FIG. 3B with respect to the formula λ = (V _f −V _r ) / V _f . It was calculated by substituting the measured value of.

The slip ratio λ of FIG. 3C thus obtained does not reflect the actual slip ratio, and shows an excessively large value (about 20% at the maximum). This means that when the yaw rate omega _z is increased during slalom traveling, even if the slip on the rear wheel does not occur, because the front wheel speed V _f satisfies increased as compared with the rear wheel speed V _r. The reason why the front wheel speed V _f and the rear wheel speed V _r do not match during the slalom traveling is that the traveling trajectory differs between the front wheels and the rear wheels as described above.

When the vehicle travels while curving by aggressive steering operation in this way, the yaw rate ω _z greatly changes with the change in the posture of the vehicle, and the front wheel speed V _f and the rear wheel speed V _r depend on the yaw rate ω _z. And the difference has changed. Therefore, if acquired by detecting or estimating a yaw rate omega _z, based on the yaw rate omega _z, it is possible to estimate the vehicle speed V (r) of the rear wheel contact point from the front wheel speed V _f.

First, when the bank angle φ is ignored, the inventor has the following relationship between the front wheel speed V _f and the vehicle speed V (r) at the rear wheel contact point via the yaw rate ω _z. I found out. That is, it was found that the value obtained by subtracting the square of V (r) from the square of V _f is proportional to the square of the yaw rate ω _z . It was also found that this proportional constant depends on the size of the vehicle. Therefore, if there are measured values of the front wheel speed V _f and the yaw rate ω _z , the vehicle speed V (r) at the rear wheel contact point can be estimated by calculation.

During slalom running, the bank angle (roll angle) φ also changes with time as the vehicle posture changes. FIG. 4A is a graph showing the time change of the bank angle φ during slalom traveling with steering operation, and FIG. 4B is a graph showing the time change of the yaw rate ω _z at that time. FIG. 4B corresponds to FIG.

As can be seen from FIGS. 4 (a) and 4 (b), during slalom traveling with steering operation, the bank angle φ shows a time change similar to the yaw rate ω _z and changes within a range of ± 25 °. There is a difference between the bank angle φ and the yaw rate ω _z . In order to grasp the movement and posture change of the vehicle, it is effective to obtain both values of the yaw rate ω _z and the bank angle φ. In fact, if the bank angle φ is different even at the same yaw rate ω _z , the vehicle speed difference at the front and rear wheel ground contact points due to the difference in the front and rear wheel trajectory also changes. If the vehicle motion and posture change (posture angle value) are grasped, the vehicle speed V (r) at the rear wheel ground contact point can be determined with high accuracy from the front wheel speed V _f obtained by measurement.

The influence of the bank angle φ can be obtained in advance by calculation, experiment, simulation, or the like. The present inventor has found that the influence of the bank angle φ can be corrected by multiplying the yaw rate ω _z by the function f (φ) of the bank angle φ. As apparent from the above-mentioned reason, f (φ) depends on the size of the saddle-ride type vehicle (for example, the distance between the front wheel grounding point and the rear wheel grounding point), but is obtained by calculation, experiment, simulation, or the like. .

From the above, the vehicle speed V (r) at the rear wheel contact point can be determined by the following general formula using the yaw rate ω _z and the bank angle φ.

Thus, in the present invention, if there is a difference between the traveling locus F of the front wheel 8 and the traveling locus R of the rear wheel 23, the difference between the front wheel grounding point f and the rear wheel grounding point r caused by this difference. The vehicle speed V (r) at the rear wheel contact point r can be determined in consideration of the difference between the vehicle speeds. That is, the detected wheel speed V _f of the front wheel 8 is not directly used as the vehicle speed V, but the vehicle speed V (r) at the rear wheel ground point r is calculated from the detected wheel speed V _f of the front wheel 8 by calculation. The determined value of V (r) (estimated value) can be used for calculations such as the slip ratio.

When the yaw rate is substantially zero (when it is equal to or less than a preset reference value), it is not necessary to calculate the above formula 1, and the wheel speed V _{f of the} front wheels is set to the vehicle speed V (r at the rear wheel contact point. )And it is sufficient.

  Next, a basic configuration example of the vehicle speed determination system according to the present invention will be described.

  This vehicle speed determination system is a vehicle speed determination system for a vehicle having a front wheel and a rear wheel, and includes a wheel speed sensor that detects a wheel speed of the front wheel and a calculator that determines the vehicle speed at the rear wheel ground point. The computing unit determines the rear wheel based on the difference in vehicle speed generated between the front wheel contact point and the rear wheel contact point due to the difference between the front wheel travel locus and the rear wheel travel locus, and the front wheel speed. Determine the vehicle speed at the contact point. This computing unit determines the vehicle speed at the ground contact point of the rear wheel from the wheel speed of the front wheel detected by the wheel speed sensor of the front wheel, resulting from the difference between the traveling locus of the front wheel and the traveling locus of the rear wheel. The difference in vehicle speed generated between the contact point and the rear wheel contact point is used.

  The difference in vehicle speed generated between the front wheel contact point and the rear wheel contact point can be estimated by various methods. For example, an image sensor that captures the road surface and front and rear wheel contact points during traveling is provided, and an image obtained by the image sensor is processed by an image processing device, whereby the difference between the traveling locus of the front wheels and the traveling locus of the rear wheels. May actually be detected. In addition, “the difference in vehicle speed” does not mean only a simple difference between the vehicle speed at the front wheel contact point and the vehicle speed at the rear wheel contact point. For example, the square of “vehicle speed at the front wheel contact point” and “rear” It may include a difference from the square of the vehicle speed at the wheel contact point.

  In an embodiment of the present invention, the computing unit is configured to determine a difference in vehicle speed generated between the front wheel contact point and the rear wheel contact point based on the vehicle yaw rate. If the yaw rate is known, it is possible to estimate the difference in vehicle speed that occurs between the front wheel contact point and the rear wheel contact point. In order to estimate the difference in vehicle speed generated between the front wheel contact point and the rear wheel contact point, it is effective to acquire information on the bank angle φ of the vehicle as described above. Therefore, in another embodiment, a bank angle acquisition unit that acquires the bank angle φ of the vehicle is further provided, and the computing unit calculates the vehicle speed at the rear wheel contact point from the wheel speed of the front wheel based on the yaw rate and the bank angle φ. Is configured to determine.

In this specification, the terms “detection” and “acquisition” are used in principle as follows.
(1) “Detecting the physical quantity a” means obtaining information indicating the value (measured value) of the physical quantity a by measuring the physical quantity a.
(2) “Acquiring the physical quantity a” includes “detecting the physical quantity a” and includes determining the value of the physical quantity a based on information detected by a sensor or the like.

“Acquire” includes, for example, the following operations.
(2.1) Substituting the measured value into a predetermined arithmetic expression to calculate the value of the physical quantity a:
(2.2) Reading the value of the physical quantity a corresponding to the measurement value from the table or the like with reference to a table or database showing the correspondence between the measurement value and the physical quantity a:
(2.3) Estimating the value of physical quantity a from the measured value.

  For example, obtaining the yaw rate includes not only the case where the yaw rate is directly detected by the yaw rate sensor, but also the case where the computing unit obtains an estimated value of the yaw rate by calculation from the output of another attitude angle sensor or speed sensor. The same applies to physical quantities other than the yaw rate, for example, the bank angle φ.

  When the wheel speed is detected, a count value per unit time of an electric pulse output by a wheel speed sensor provided in the vicinity of the axle is usually used as the wheel speed. Although this count value is proportional to the wheel speed, since this proportional constant is not usually 1, the count value is not equal to the wheel speed value (tangential speed of the wheel outer peripheral surface) itself. However, in the equations for calculating the slip ratio λ and the slip amount, each term is a wheel speed. Therefore, if the proportional constant between the wheel speed and the count value in each term is set to the same value, the count value is set to the wheel speed. May be handled as

(Embodiment)
<Vehicle speed determination system>
Hereinafter, a basic configuration example of the vehicle speed determination system in the embodiment of the present invention will be described with reference to FIG.

  The vehicle speed determination system 100 shown in FIG. 5 includes a front wheel speed sensor 35 that detects the wheel speed of the front wheel, a gyroscope 33 that detects the yaw rate of the vehicle body, and the rear wheel contact based on the wheel speed of the front wheel and the yaw rate of the vehicle body. And an arithmetic unit 200 that acquires the vehicle speed at the point. The calculator 200 in the illustrated example includes a posture angle estimation unit 59 that estimates a posture angle (at least one of a yaw angle, a roll angle, and a pitch angle) based on the output of the gyroscope 33.

The front wheel speed sensor 35 is disposed close to the front wheel and outputs an electrical pulse at a frequency proportional to the rotational speed of the front wheel. A known wheel speed sensor can be used as the front wheel speed sensor 35. The front wheel speed calculator 55 calculates the front wheel speed V _f based on the count value per unit time of the electric pulse output from the front wheel speed sensor 35. The front wheel speed calculator 55 gives the front wheel speed V _f to the rear wheel speed calculator 56.

On the other hand, the gyroscope 33 in this example detects the yaw rate (yaw angular velocity) ω _z and the roll rate (roll angular velocity), and inputs the detected values to the posture angle estimation unit 59. The attitude angle estimation unit 59 estimates the bank angle (roll angle) φ from the yaw rate ω _z and the roll rate, and gives the yaw rate ω _z and the bank angle φ to the rear wheel vehicle speed calculation unit 56. The posture angle estimation unit 59 has a configuration (including a Kalman filter) described in Patent Document 3, for example. The posture angle estimation unit 59 may acquire various measurement values from a sensor not shown in FIG. 5 or may acquire the output of the front wheel speed sensor 35.

The rear wheel vehicle speed calculation unit 56 in the example shown in FIG. 5 stores in advance the value of f (φ) in Equation 1 as a table format or a function expression. The rear wheel speed calculator 56 calculates the vehicle speed at the rear wheel contact point based on the yaw rate ω _z and the bank angle φ obtained from the attitude angle estimator 59 and the front wheel speed V _f obtained from the front wheel speed calculator 55. V (r) is calculated.

The rear wheel slip amount calculation unit 58 receives the vehicle speed V (r) at the rear wheel contact point output from the rear wheel vehicle speed calculation unit 56 and the rear wheel speed V _r output from the rear wheel speed calculation unit 57. Calculate the slip amount or slip ratio of the rear wheels. Specifically, the difference between the vehicle speed V (r) and the rear wheel speed V _{r at the} rear wheel contact point is calculated. This difference is divided by the larger absolute value of the vehicle speed V (r) and the rear wheel speed V _r as necessary.

  The slip amount or slip ratio obtained in this way is given to the vehicle stability control system 300. The vehicle stability control system 300 may be a traction control system (TCS), an anti-lock brake system (ABS), and any other known attitude control system.

  The arithmetic unit 200 in the present embodiment can be realized by a known general-purpose digital signal processor or a dedicated signal processing circuit. The computing unit 200 may include an integrated circuit device and a memory mounted on one substrate or a plurality of substrates. The computing unit 200 may be a part of a computer that implements other functional blocks such as the rear wheel slip computing unit 58. What is important for the operation of the arithmetic unit 200 is that it is configured to execute the above-described arithmetic operation, and the hardware itself may be known.

  The vehicle speed determination system 100 may include a bank angle acquisition unit 46 as shown in FIG. In this case, since the bank angle φ is obtained from the bank angle acquisition unit 46, the posture angle estimation unit 59 shown in FIG. 5 is not essential. The bank angle acquisition unit 46 acquires a bank angle based on a detection value of a distance measuring device that measures the distance from the ground, or provides a camera that captures the front of the motorcycle 1 to detect the bank angle by image processing. A configuration may be provided.

As shown in FIG. 7, the arithmetic unit 200 may include a rear wheel speed calculator 57 that receives a signal from the rear wheel speed sensor 36 and calculates the rear wheel speed V _r . In this case, the arithmetic unit 200 receives outputs from both the front wheel speed sensor 35 and the rear wheel speed sensor 36 and outputs various “vehicle speeds” including the front wheel speed V _f and the rear wheel speed V _r. be able to. This “vehicle speed” can be used for stable control of the vehicle in addition to the calculation of the slip ratio or the slip amount.

FIG. 8A shows the bank angle φ of the motorcycle running while meandering by the steering operation, FIG. 8B shows the yaw rate ω _{z at} that time, and FIG. 8C shows the wheel speed V _{f of the} front and rear wheels. , V _r , vehicle speed V (r) at the rear wheel contact point, and FIG. 8 (d) show time variations of the slip ratio λ obtained by the prior art and the slip ratio λ ′ obtained by the present embodiment. It is a graph. The bank angle φ, the yaw rate ω _z , and the wheel speeds V _f and V _r are all actually measured values, and the vehicle speed V (r) and the slip ratios λ and λ ′ at the rear wheel contact point are calculated values. As is apparent from FIG. 8D, the slip ratio λ ′ obtained by the present embodiment is a value close to zero (up to about 5%) compared to the slip ratio λ (up to 21%) obtained by the prior art. ).

9A shows a bank angle φ of a motorcycle that performs steady circular turning in a fixed direction by a steering operation, FIG. 9B shows a yaw rate ω _{z at} that time, and FIG. 9C shows front and rear wheels. The wheel speeds V _f and V _r , the vehicle speed V (r) at the rear wheel contact point, and FIG. 9D are the slip ratio λ obtained by the prior art and the slip ratio λ ′ obtained by the present embodiment. It is a graph which shows a time change. The bank angle φ, the yaw rate ω _z , and the wheel speeds V _f and V _r are all actually measured values, and the vehicle speed V (r) and the slip ratios λ and λ ′ at the rear wheel contact point are calculated values. The bank angle during turning was about 20 °, and the yaw rate was about 60 ° / second. As is apparent from FIG. 9D, the slip ratio λ ′ obtained by the present embodiment is a value close to zero (up to about 4) compared with the slip ratio λ (up to about 10%) obtained by the conventional technique. %).

  Thus, according to the vehicle speed determination system in the present embodiment, even when the vehicle speed does not match between the front wheel ground point and the rear wheel ground point, the vehicle speed at the rear wheel ground point can be obtained from the wheel speed of the front wheel. The slip ratio during curve driving can be obtained.

  As described above, the vehicle speed determination system of the present invention can be used in addition to obtaining the slip ratio or the slip amount. This is because even in a general vehicle stability control system, the vehicle speed at the ground contact point of the rear wheel during curve traveling may be required. Even when the vehicle is provided with a wheel speed sensor for the rear wheels, the rear wheels will spin on a rough road with a small friction coefficient μ, so that it is difficult to obtain the vehicle speed at the rear wheel contact point. For these reasons, the vehicle speed determination system of the present invention is useful for various vehicle stability control systems.

  In the present embodiment, “vehicle speed at the rear wheel contact point” is calculated as “vehicle speed”, but “vehicle speed at the center of gravity of the vehicle” can also be obtained by correcting the calculation formula. That is, according to the vehicle speed determination system of the present invention, it is also possible to obtain the vehicle speed at any part of the vehicle.

  Next, a motorcycle will be described as an embodiment of a saddle-ride type vehicle provided with the above vehicle speed determination system. In the following description, front and rear and left and right are based on the forward direction of the motorcycle.

1. FIG. 10 is a side view showing a schematic configuration of a motorcycle including the stability control system according to the present embodiment. The motorcycle 1 includes a main frame 2. A head pipe 3 is provided at the upper front end of the main frame 2. A steering shaft 4 is inserted through the head pipe 3. A handle 5 is connected to the upper end of the steering shaft 4. A brake lever (not shown) is disposed on the right side of the handle 5.

  A pair of extendable front forks 7 are connected to the lower end of the steering shaft 4. Thereby, the front fork 7 is swung by the rotation operation of the handle 5. A front wheel 8 is rotatably attached to the lower end of the front fork 7. The vibration of the front wheel 8 is absorbed by the expansion and contraction of the front fork 7. A front wheel brake 10 is attached to the lower end of the front fork 7, and the rotation of the front wheel 8 is braked by operating the brake lever. A front wheel cover 11 is fixed to the front fork 7 at the top of the front wheel 8.

  On the upper part of the main frame 2, a fuel tank 15 and a seat 16 are held side by side. Below the fuel tank 15, an engine 17 and a transmission 18 are held by the main frame 2. A clutch actuator 14 that connects or disconnects the clutch 13 and the clutch 13 is disposed between the engine 17 and the transmission 18. The transmission 18 includes a drive shaft 19 that outputs power generated by the engine 17. A drive sprocket 20 is connected to the drive shaft 19. The output of power generated by the engine 17 to the drive shaft 19 is connected or disconnected by the clutch 13.

  A swing arm 21 is swingably supported on the lower rear side of the main frame 2. A driven sprocket 22 and a rear wheel 23 are rotatably supported at the rear end of the swing arm 21. The rear wheel 23 is provided with a rear wheel brake 26 that is operated by a brake pedal (not shown). A chain 24 is suspended between the drive sprocket 20 and the driven sprocket 22. The power generated by the engine 17 is transmitted to the rear wheel 23 via the clutch 13, the transmission 18, the drive shaft 19, the drive sprocket 20, the chain 24, and the driven sprocket 22.

  An ECU (Electronic Control Unit) 25 that controls the operation of each part of the motorcycle 1 is provided below the seat 16. The brake pressure applied to the front wheel brake 10 and the rear wheel brake 26 is controlled by the brake modulator 38 according to the operation of the brake lever and the brake pedal. A gyroscope 33, a lateral acceleration sensor 34, a vehicle speed calculation unit 45, and a bank angle acquisition unit 46 are provided on the main frame 2.

2. Configuration of Stability Control System Next, the configuration of the stability control system for a saddle-ride type vehicle will be described with reference to FIG. FIG. 11 is a functional block diagram showing the configuration of the stability control system 31 in the present embodiment. The stability control system 31 includes a longitudinal force control unit 32, a gyroscope 33, a lateral acceleration sensor 34, a front wheel speed sensor 35, a rear wheel speed sensor 36, a throttle sensor 37, a brake modulator 38, A vehicle speed calculation unit 45 and a bank angle acquisition unit 46 are included. A configuration in which part of the stability control system 31 is included in the ECU 25 may be employed. When the longitudinal force control unit 32 detects a side slip of the front wheel 8 or the rear wheel 23, the longitudinal force control unit 32 reduces the longitudinal force of each wheel. Details will be described later.

  When the rider steers the handle 5 of the motorcycle 1 when turning a curve, the yaw rate of the motorcycle 1 changes. When the rider tilts the vehicle body of the motorcycle 1 toward the center of the curve, the roll rate and bank angle (roll angle) of the motorcycle 1 change. The gyroscope 33 in the present embodiment detects the angular velocities in the biaxial directions of the yaw and roll of the motorcycle 1. That is, the gyroscope 33 detects the yaw rate and roll rate of the motorcycle 1. The detected values of the biaxial angular velocities are sent from the gyroscope 33 to the vehicle speed calculation unit 45, the bank angle acquisition unit 46, and the longitudinal force control unit 32. The vehicle speed calculation unit 46 in the present embodiment is composed of the arithmetic unit 200 having the configuration described with reference to FIG. 7, for example, and calculates not only the vehicle speed at the front wheel contact point but also the vehicle speed at the rear wheel contact point. Can do. In this embodiment, the vehicle speed at the rear wheel contact point is determined by the above-described calculation based on the front wheel speed, the yaw rate, and the bank angle.

  The gyroscope 33 in the present embodiment corresponds to the yaw rate sensor in the present invention, and also functions as a roll rate sensor. The gyroscope 33 may be configured to detect the pitch rate in addition to the yaw rate and roll rate.

  The lateral acceleration sensor 34 detects the lateral acceleration of the body of the motorcycle 1. The detection value of the lateral acceleration is sent from the lateral acceleration sensor 34 to the longitudinal force control unit 32 and the bank angle acquisition unit 46. The front wheel speed sensor 35 detects the rotational speed of the front wheel 8. The rear wheel speed sensor 36 detects the rotational speed of the rear wheel 23. The detected rotational speeds of the front wheels 8 and the rear wheels 23 are output to the vehicle speed calculation unit 45.

  The throttle sensor 37 detects the opening of the throttle. The detected value of the throttle opening is output to the longitudinal force control unit 32. The brake modulator 38 detects the brake pressures of the front wheel brake 10 and the rear wheel brake 26 and adjusts the respective brake pressures. The detected brake pressure of each wheel is output to the longitudinal force control unit 32.

3. Next, a configuration example of the longitudinal force control unit 32 in the present embodiment will be described.

  As shown in FIG. 11, a gyroscope 33, a lateral acceleration sensor 34, a throttle sensor 37, a brake modulator 38, a vehicle speed calculation unit 45, and a bank angle acquisition unit 46 are connected to the input of the longitudinal force control unit 32. The clutch actuator 14, the brake modulator 38, the spark plug 39, the fuel injection device 40, and the throttle actuator 41 are connected to the output of the longitudinal force control unit 32.

  The longitudinal force control unit 32 includes a skid acceleration calculation unit 47, a determination unit 49, a longitudinal force reduction control unit 50, a driving force estimation unit 51, a braking force estimation unit 52, and a longitudinal force estimation unit 53. The longitudinal force control unit 32 in the present embodiment independently detects the side slip of each wheel, and performs control to reduce the longitudinal force applied to each wheel when the side slip is detected. Next, an example of an operation for determining the presence or absence of skidding will be described.

3.1 Side slip determination In order to detect the side slip of each wheel, in this embodiment, the side slip acceleration is acquired based on the vehicle speed, bank angle, lateral acceleration and yaw rate of the motorcycle 1. The vehicle speed calculation unit 45 calculates the vehicle speed of the motorcycle 1 (the vehicle speed at the front wheel contact point and the vehicle speed at the rear wheel contact point) by the above-described calculation based on the outputs of the front wheel speed sensor 35, the gyroscope 33, and the bank angle acquisition unit 46. Can be obtained. The vehicle speed obtained by the vehicle speed calculation unit 45 is output to the skid acceleration calculation unit 47. The bank angle acquisition unit 46 in the present embodiment estimates the bank angle using “vehicle speed”, but this “vehicle speed” does not have to be the vehicle speed at the rear wheel ground point, and the vehicle speed at the front wheel ground point. Good. As described above, a difference according to the yaw rate and the bank angle occurs between the vehicle speed at the rear wheel contact point and the vehicle speed at the front wheel contact point. Even if the difference is ignored, the estimation error of the bank angle can be made sufficiently small.

  The roll angle of the motorcycle 1 is input from the gyroscope 33 to the bank angle acquisition unit 46 in the present embodiment, and the lateral acceleration of the motorcycle 1 is also input from the lateral acceleration sensor 34. The bank angle acquisition unit 46 determines the bank angle of the motorcycle 1 based on these input values and “vehicle speed”. The bank angle can be obtained by various methods. For example, the bank angle (roll angle) may be estimated by the method described in Patent Document 3.

  In order to improve the estimation accuracy of the bank angle, the vehicle speed at the rear wheel ground point is calculated using the first estimated value of the bank angle, and the vehicle speed (vehicle speed at the rear wheel ground point) obtained by the calculation is used to calculate the bank speed. The corner may be re-estimated. It is possible to improve the estimation accuracy by repeating these estimations.

  With reference to FIG. 12 and FIG. 13, an example of a method for acquiring the bank angle in the present embodiment will be described.

  FIG. 12 is a diagram schematically showing acceleration generated at the center of gravity 29 of the motorcycle 1. FIG. 13 is a diagram schematically showing the angular velocity generated in the motorcycle 1, and for convenience, the vehicle body fixed axis (Z axis) passes through the center of gravity 29. This bank angle detection method is a detection method in an ideal state where the vehicle is turning at a speed V while ignoring the pitching of the vehicle body and the tire thickness in a lean with state. The lean with state is a state where the vehicle body fixed axis (Z-axis) and the upper body of the rider are in a straight line.

  As can be seen from FIG. 12, the relationship between the bank angle φ during turning, the vehicle speed V, the time derivative of Euler's yaw angle ψ, and the gravitational acceleration g is expressed by the following equation. (DΨ / dt) is a yaw rate (yaw angular velocity) that is a time derivative of the yaw angle. φ = arctan (V · (dΨ / dt) / g) (1)

As can be seen from FIG. 13, the relationship between the bank angle φ during turning, the output value ω _z of the yaw rate sensor fixed to the vehicle body, and the time derivative of the Euler yaw angle ψ is expressed by the following equation. In FIG. 13, ω _z is an angular velocity generated around an axis in the vertical direction fixed to the vehicle body (the Z axis that is the vehicle body fixed axis), and the length of the arrow indicates the size. (DΨ / dt) is an angular velocity generated around the vertical axis.
φ = arccos (ω _z / (dΨ / dt)) (2)

From the expressions (1) and (2), the following relational expression is derived.
φ = arcsin (V · ω _z / g) (3)

The side-slip acceleration calculating unit 47 calculates the side-slip acceleration generated in each wheel based on the vehicle speed V, the bank angle φ, the yaw rate, and the side acceleration. The skid acceleration is calculated by the following equation, for example. Here, dfy / dt represents the side-slip acceleration generated on the front wheel 8, dry / dt represents the side-slip acceleration generated on the rear wheel 23, and Ay represents the detection value of the side acceleration sensor 34. If is a horizontal distance between the mounting position of the lateral acceleration sensor 34 and the center of the front wheel 8, and Ir is a horizontal distance between the mounting position of the lateral acceleration sensor 34 and the center of the rear wheel 23 (see FIG. 10).
dfy / dt = −V · ω _z · secφ−g · tan φ + Ay · secφ
+ If · dω _z / dt · secφ (4)
dry / dt = −V · ω _z · secφ−g · tan φ + Ay · secφ
−Ir · dω _z / dt · secφ (5)

In addition, when detecting a roll rate and calculating a skid acceleration, it calculates by the following formula, for example. wr represents the detected value of the roll rate.
dfy / dt = −V · ω _z · secφ−g · tan φ + Ay · secφ
+ If · dω _z / dt · secφ + If · wr · ω _z · tanφ · secφ (6)
dry / dt = −V · ω _z · secφ−g · tan φ + Ay · secφ
−Ir · dω _z / dt · secφ−Ir · wr · ω _z · tan φ · secφ (7)

  The detected skid accelerations of the front wheel 8 and the rear wheel 23 are output to the determination unit 49.

Determination unit 49 compares whether exceeds a threshold value G ₁ for side-slip acceleration input is determined in advance. As illustrated in FIG. 14 (a), when the value of the side-slip acceleration threshold G ₁ or more, it is determined that the skid in the corresponding wheel is occurring, is illustrated in FIG. 14 (b) As a result, a longitudinal force reduction control signal for reducing the longitudinal force applied to the corresponding wheel is output to the longitudinal force reduction control unit 50. The threshold value G ₁ may be set to a different value between the front wheel 8 and the rear wheel 23. Note that the sign of the side-slip acceleration indicates the left-right direction. When the sign is minus, it is compared whether or not the threshold value −G ₁ is exceeded. That is, to implement the determination of the reduction of the longitudinal force by comparing the absolute value with the threshold G ₁ of side-slip acceleration.

3.2 Longitudinal Force Estimation The driving force estimation unit 51 estimates the driving force generated in the driving wheel based on the detection value of the throttle sensor 37. In the present embodiment, since the driving wheel is the rear wheel 23, no driving force is generated on the front wheel 8. The driving force of the rear wheel 23 estimated by the driving force estimation unit 51 is output to the longitudinal force estimation unit 53.

  The braking force estimation unit 52 estimates the braking force generated in each wheel based on the brake pressure detected by the brake modulator 38. The estimated braking force of each wheel is output to the longitudinal force estimation unit 53.

  The longitudinal force estimation unit 53 calculates the longitudinal force of each wheel based on the input driving force and braking force. The calculated longitudinal force generated on each wheel is output to the longitudinal force reduction control unit 50.

3.3 Longitudinal Force Reduction The longitudinal force reduction control unit 50 performs control to reduce the longitudinal force acting on each wheel input from the longitudinal force estimation unit 53 based on the determination signal input from the determination unit 49. . When the driving force is larger than the braking force, control is performed to reduce the driving force or increase the braking force. In addition, when the braking force is greater than the driving force, control is performed to reduce the braking force or increase the driving force.

  For example, as shown in FIG. 15A, when the resultant force extends outside the friction circle and a side slip occurs in the motorcycle 1, the sum of the driving force and the braking force is reduced by reducing the braking force. Reduce some longitudinal force. As a result, the resultant force of the cornering force (lateral force) and the longitudinal force is within the friction circle, so that the side slip can be stopped. Further, as shown in FIG. 15 (b), when the control is performed so that the magnitudes of the driving force and the braking force are equal to each other, the longitudinal force becomes zero, so the range of the friction circle is assigned to the lateral force. be able to. In this way, the allowable value of the cornering force can be maximized.

  When reducing the driving force to reduce the longitudinal force, the longitudinal force reduction control unit 50 performs ignition cut control such as reducing the ignition frequency on the ignition plug 39 or performs control to delay the ignition timing. In addition to this, the driving force can be reduced by reducing or cutting the amount of fuel injected into the fuel injection device 40. Further, the driving force can be reduced by controlling the clutch actuator 14 to disengage the clutch 13. When the driving force is increased to reduce the longitudinal force, the longitudinal force reduction control unit 50 can increase the driving force by performing control to increase the fuel injection amount to the fuel injection device 40. In addition, when an electronic throttle is provided, the driving force can be increased by controlling the opening of the throttle.

  When the braking force is increased or decreased to reduce the longitudinal force, the brake modulator 38 is controlled to increase or decrease the brake pressure. Further, by closing the throttle, it is possible to generate an engine brake and increase the braking force. Conversely, when the engine brake is generated, the engine braking can be reduced by opening the throttle to reduce the braking force. The amount to increase or decrease the driving force and the braking force is controlled according to the magnitude of the longitudinal force input from the longitudinal force estimating unit 53. In this way, when a side slip occurs in each wheel, the side slip is detected independently in each wheel, and the longitudinal force of the driving force and the braking force is reduced independently in each wheel, and the allowable amount of the lateral grip force is increased. Therefore, the attitude of the motorcycle 1 can be controlled even during curve driving.

4). Longitudinal Force Reduction Control Operation Next, an example of the control operation of the longitudinal force control unit 32 will be described with reference to FIG. FIG. 16 is a flowchart illustrating an example of the longitudinal force control operation.

  When the motorcycle 1 reaches the curve, the rider travels along the curve while banking the motorcycle 1 body. The front wheel speed sensor 35 and the rear wheel speed sensor 36 always detect the wheel speeds of the front wheels 8 and the rear wheels 23, and acquire the wheel speeds of the front wheels as vehicle speeds necessary for acquiring the bank angle (step S01). The bank angle acquisition unit 46 in the present embodiment is based on the yaw rate input from the gyroscope 33 and the lateral acceleration input from the lateral acceleration sensor 34 in addition to the wheel speed described above, and the bank angle of the motorcycle 1. Is calculated (step S02).

  Next, based on the bank angle thus calculated and the yaw rate input from the gyroscope 33, the vehicle speed at the rear wheel contact point is obtained from the vehicle speed at the front wheel contact point (front wheel speed) (step S01). Thus, when the vehicle speed of the front and rear wheels is obtained, the position of the center of gravity with respect to the front and rear wheel ground contact points is clear, so the vehicle speed at the center of gravity can also be calculated. The bank angle value may be recalculated using the new vehicle speed value. If necessary, the estimation accuracy of the vehicle speed and the bank angle can be increased by repeating these steps S01 and S02.

Next, based on the vehicle speed, the bank angle, the yaw rate, and the lateral acceleration, the skid acceleration calculating unit 47 calculates the skid acceleration generated in each wheel (step S03). The calculated skid acceleration is compared with a predetermined threshold value G ₁ to determine the occurrence of skid (step S04). If the absolute value of the side-slip acceleration is the threshold value G ₁ or more, skidding the relevant wheel is determined to "there." If the absolute value of the side-slip acceleration is less than the threshold value G _1, determines that no skid to the appropriate wheel, again, the detection of the state quantities of the motorcycle 1. Note that the threshold for determining the presence or absence of skidding is not limited to the example shown in FIG.

  In parallel with steps S01 to S04, the driving force is acquired by estimating the driving force generated in each wheel (step S05). The driving force is estimated by the driving force estimating unit 51 according to the throttle opening degree of the throttle sensor 37, for example. In parallel with steps S01 to S05, the braking force is acquired by estimating the braking force generated on each wheel (step S06). The estimation of the braking force is performed by the braking force estimation unit 52 according to the brake pressure of each wheel detected by the brake modulator 38, for example.

  Based on the estimated driving force and braking force, the longitudinal force estimating unit 53 estimates the longitudinal force of the driving force and braking force generated on each wheel (step S07). Since the directions of the driving force and the braking force are opposite to each other, the longitudinal force can be estimated by subtracting the braking force from the driving force. Thereby, a longitudinal force can be acquired.

  If it is determined in the side slip determination that there is a side slip, the longitudinal force generated on the wheel determined to have a side slip is input from the longitudinal force estimation unit 53, and the longitudinal force corresponding to the magnitude of the longitudinal force is input. (Step S08). Since the reduction of the longitudinal force is controlled so that the driving force and the braking force are balanced, the driving force is increased or decreased or the braking force is increased or decreased according to the magnitude relationship between the driving force and the braking force. One example of increasing the driving force is to increase the fuel injected from the fuel injection device 40. As an example of reducing the driving force, the rear wheel 23 of the engine torque is reduced by reducing the fuel injected from the fuel device 40, stopping ignition of the spark plug 39 or delaying the ignition timing, or disconnecting the clutch actuator 14. Blocking transmission to the network. An example of the increase / decrease in braking force is an increase / decrease in brake pressure by the brake modulator 38.

  Thus, according to the embodiment of the present invention, in the motorcycle 1, the vehicle speed can be acquired not only at the front wheel contact point but also at the rear wheel contact point even when turning around the curve. For this reason, the longitudinal force control unit 32 can independently control the longitudinal force of the driving force and the braking force generated on each wheel, and the posture can be controlled during curve traveling.

  In the present embodiment, when calculating the skid acceleration generated on each wheel based on the lateral acceleration, the yaw rate, the running speed, the bank angle, and the roll rate during the curve running, the skid acceleration considering the bank angle can be acquired. The accuracy of estimating the skid acceleration will be higher.

  In the motorcycle 1 according to the present embodiment, since the driving force generated parallel to the traveling direction of each wheel and the braking force are controlled to be balanced, the resultant force of the driving force and the braking force is reduced, and the wheel grip force is reduced. Since all of the allowable amount can be assigned to the cornering force, the attitude of the motorcycle 1 during curve driving can be maintained.

  The lateral acceleration of the motorcycle 1 may be detected using GPS instead of the lateral acceleration sensor 34. Further, instead of using the engine as a power source, an electric motor may be used as the power source. In this case, increase / decrease in driving force and braking force can also be controlled by increasing / decreasing motor torque.

  The saddle-ride type vehicle according to the present invention is not limited to a motorcycle but may be any vehicle that can travel in a bank. The bank angle acquisition unit may perform calculation using the detected value of the roll rate in addition to the detected values of the vehicle speed, the yaw rate, and the lateral acceleration. When the motorcycle includes a continuously variable transmission (CVT), the longitudinal force may be reduced by increasing or decreasing the torque by changing the gear ratio.

  The vehicle speed determination system of the present invention can be widely applied to saddle riding type vehicles having front wheels and rear wheels. This vehicle speed determination system can be widely used in attitude control technology for motorcycles represented by a traction control system (TCS) and an antilock brake system (ABS).

DESCRIPTION OF SYMBOLS 1 ... Motorcycle 14 ... Clutch actuator 32 ... Longitudinal force control part 33 ... Gyroscope 34 ... Lateral acceleration sensor 35 ... Front wheel speed sensor 36 ... Rear wheel speed sensor 39 ... Spark plug 40 ... Fuel injection device 45 ... Vehicle speed calculation part 46 ... Bank angle acquisition unit 47 ... Side slip acceleration calculation unit 49 ... Discrimination unit 50 ... Longitudinal force reduction control unit 51 ... Driving force estimation unit 52 ... Braking force estimation unit 55 ... Front wheel wheel speed calculation unit 57 ... Rear wheel wheel speed calculation unit 59 ... Attitude angle estimation unit 100 ... Vehicle speed determination system 200 ... Calculator 300 ... Vehicle stability control system

Claims (13)

A vehicle speed determination system for a saddle-ride type vehicle having front wheels and rear wheels and capable of running in a bank,
A wheel speed sensor for detecting a wheel speed of the front wheel;
Based on the difference between the front wheel contact point and the rear wheel contact point due to the difference between the front wheel travel locus and the rear wheel travel locus, and the front wheel speed, A calculator for determining the vehicle speed at the point;
With
The computing unit determines a difference in vehicle speed generated between a front wheel grounding point and a rear wheel grounding point based on a yaw rate around an axis fixed to the vehicle.   The vehicle speed determination system according to claim 1, further comprising a yaw rate sensor that detects a yaw rate of the vehicle. A bank angle acquisition unit for acquiring the bank angle of the vehicle;
The vehicle speed determination system according to claim 1 or 2, wherein the computing unit determines a vehicle speed at a rear wheel ground contact point from a wheel speed of a front wheel based on the yaw rate and a bank angle.   4. The vehicle speed determination system according to claim 1, wherein when the yaw rate is substantially zero, the arithmetic unit sets the wheel speed of the front wheel as the vehicle speed at the rear wheel contact point. 5. The vehicle speed at the rear wheel contact point is V (r), the front wheel speed is V _f , the vehicle bank angle is φ, the vehicle yaw rate is ω _z , and the preset function of the bank angle φ is f (φ). When
The computing unit is based on Equation 1 below:

The vehicle speed determination system according to claim 4, wherein a vehicle speed V (r) at the rear wheel contact point is calculated. A stability control system for a saddle-ride type vehicle having front wheels and rear wheels and capable of running in a bank,
A first wheel speed sensor for detecting a wheel speed of the front wheel;
A second wheel speed sensor for detecting a wheel speed of the rear wheel;
Based on the difference in vehicle speed generated between the front wheel grounding point and the rear wheel grounding point due to the difference between the traveling locus of the front wheel and the traveling locus of the rear wheel, and the wheel speed of the front wheel, A computing unit for determining the vehicle speed at the point and the rear wheel contact point;
A longitudinal force control unit that adjusts an absolute value of longitudinal force that is a sum of forces in the front-rear direction acting on the front wheel or the rear wheel, based on vehicle speeds at the front wheel contact point and the rear wheel contact point;
With
The operation unit is a stability control system that determines a difference in vehicle speed generated between a front wheel contact point and a rear wheel contact point based on a yaw rate around an axis fixed to the vehicle.   The stable control system according to claim 6, further comprising a yaw rate sensor that detects a yaw rate of the vehicle. A bank angle acquisition unit for acquiring the bank angle of the vehicle;
8. The stable control according to claim 6, wherein the computing unit determines a numerical value that defines a degree of slip of the rear wheel based on a wheel speed of the front wheel and a rear wheel and a yaw rate and a bank angle of the vehicle. system. A lateral acceleration acquisition unit that acquires lateral acceleration that is acceleration in the left-right direction acting on the vehicle,
The stability control system according to claim 8, wherein the longitudinal force control unit reduces an absolute value of longitudinal force acting on the front wheel or the rear wheel based on the lateral acceleration and the bank angle.   The longitudinal force control unit obtains side slip acceleration of the front wheel and the rear wheel based on the lateral acceleration and the bank angle, and a longitudinal force acting on the front wheel or the rear wheel according to the magnitude of the side slip acceleration. The stable control system according to claim 9, wherein the absolute value of is reduced. The lateral acceleration acquisition unit acquires the lateral acceleration based on a detection value of a lateral acceleration sensor,
The longitudinal force control unit reduces an absolute value of longitudinal force acting on the front wheel or the rear wheel based on the yaw rate, the vehicle speed at the rear wheel contact point, the lateral acceleration, and the bank angle. Stable control system as described in   The stability control system according to claim 11, wherein the longitudinal force control unit acquires a roll rate of the vehicle and reduces an absolute value of a longitudinal force acting on the front wheel or the rear wheel based on the roll rate. .   A saddle-ride type vehicle comprising the stability control system according to any one of claims 6 to 12.

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