JP2014162260A - Stability evaluation system and stability evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stability evaluation system in which a position of a grounding point of a vehicle during traveling can be recognized and stability of the vehicle during traveling can be evaluated, taking into consideration behavior of the steering subject body of the vehicle.SOLUTION: The stability evaluation system of the invention evaluates the stability of a vehicle during traveling on a traveling surface, and comprises: a barycenter sensor which is arranged so as to specify the composite barycenter position of the vehicle and the steering subject body steering the vehicle; a grounding point sensor which can specify the grounding point where the vehicular wheel touches the running surface and is arranged so as to detect the rotation plane including the rotation center of the wheel and the center axial line that passes the rotation center and is vertical to the rotation plane; and a stability evaluation device which calculates the composite barycenter position based on the measurement data by the barycenter sensor, calculates the grounding point based on the measurement data by the grounding point sensor and provides at least the composite barycenter position and the grounding point as stability evaluation indices of the vehicle.

Description

  The present invention relates to a stability evaluation system and a stability evaluation method for evaluating the stability of a vehicle traveling on a traveling surface.

  2. Description of the Related Art Conventionally, it has been considered that a two-wheeled vehicle represented by a bicycle can travel straight without being tilted by maneuvering so that the center of gravity is always on the ground line of the front and rear wheels (see, for example, Non-Patent Document 1). Although the ground line changes with time according to the steering state of the bicycle, it is possible to steer the bicycle without falling down by always having the center of gravity on the ground line at each time point.

  In addition, a method has been proposed in which a motorcycle model is developed and eigenvalue analysis is performed from the results obtained by simulation to evaluate the mechanical stability of the motorcycle during travel (for example, Non-Patent Document 2). reference). According to the method described in Non-Patent Document 2, it is possible to analyze the mechanical stability of the motorcycle during traveling based on the relationship between the natural vibration during traveling of the motorcycle and the traveling speed.

Takio Oya, “Kinematics for Bicycles”, Report from JST, p.1-8, 1978, No.2 R. S. Sharp, “The Stability and Control of Motorcycles”, Journal Mechanical Engineering Science, Vol. 13, No. 5, 1971

  However, with the method described in Non-Patent Document 1, it has been difficult to grasp the position of the ground contact point of the traveling vehicle. Further, in the method described in Non-Patent Document 2, the behavior of the vehicle maneuvering subject is approximately modeled and input to the simulation model, and the stability of the vehicle during traveling is considered in consideration of the actual behavior of the vehicle maneuvering subject. Could not be evaluated.

  Therefore, an object of the present invention made in view of such circumstances is to grasp the position of the grounding point of the traveling vehicle and to evaluate the stability of the traveling vehicle in consideration of the behavior of the driving subject of the vehicle. An object of the present invention is to provide a stability evaluation system and a stability evaluation method.

  A stability evaluation system according to the present invention that achieves the above object is a stability evaluation system for evaluating the stability of a vehicle that is traveling on a traveling surface, wherein the combined center of gravity position of the vehicle and the control subject that controls the vehicle is provided. A center-of-gravity sensor arranged so as to be able to identify, a grounding point sensor capable of identifying a grounding point that is a point where a wheel of the vehicle is in contact with the traveling surface, a rotating surface including a center of rotation of the wheel, and the rotation A grounding point sensor disposed so as to be able to detect a central axis perpendicular to the rotation plane through the center, and calculating the composite barycentric position based on measurement data by the barycentric sensor, and the grounding point sensor And a stability evaluation device that calculates the ground contact point based on measurement data obtained by the above and provides at least the combined center of gravity position and the ground contact point as a stability evaluation index of the vehicle. It is intended to.

  With the stability evaluation system according to the present invention, it is possible to grasp the position of a grounding point of a traveling vehicle and to evaluate the stability of the traveling vehicle in consideration of the behavior of the subject of the vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, while grasping | ascertaining the position of the grounding point of the vehicle during driving | running | working, the stability of the vehicle during driving | running can be evaluated in consideration of the behavior of the control subject of a vehicle.

It is a figure for demonstrating the stability evaluation system by one Embodiment of this invention. It is a flowchart for demonstrating the stability evaluation method by one Embodiment of this invention. It is a figure for demonstrating an example of the contact point calculation process in step S02 of FIG. It is a figure for demonstrating the positional relationship of each sensor acquired by the stability evaluation system by one Embodiment of this invention, a synthetic | combination gravity center position, and a grounding line. It is a figure for demonstrating an example of the method for calculating a course normal reaction force with the stability evaluation system by one Embodiment of this invention. It is a figure for demonstrating an example of the method for calculating a course normal reaction force with the stability evaluation system by one Embodiment of this invention. It is a figure which shows an example of the stability evaluation result of the vehicle at the time of driving | running | working by the stability evaluation system by one Embodiment of this invention. It is a figure for demonstrating an example of the calculation method of the stability evaluation parameter | index provided by the stability evaluation system by one Embodiment of this invention. It is a figure which shows an example of the time series waveform of the gravity center displacement and bank angle normalized by the stability evaluation system by one Embodiment of this invention. It is a figure which shows the Lissajous figure produced | generated based on two time series waveforms shown in FIG. It is a figure which shows an example of the stability evaluation result provided by the stability evaluation system by one Embodiment of this invention.

  Hereinafter, embodiments of a stability evaluation system and a stability evaluation method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram for explaining a stability evaluation system according to an embodiment of the present invention. In the present embodiment, the vehicle will be described as a bicycle, and the control subject will be described as a driver (human). A stability evaluation system 1 shown in FIG. 1 includes a front wheel contact point sensor 4 attached to a front wheel 3 of a bicycle 2, a rear wheel contact point sensor 6 attached to a rear wheel 5, a steering wheel steering angle sensor 7, and a stability evaluation device. 8. A steering main body gravity sensor 10 and a vehicle gravity center sensor 11 that constitute a gravity center sensor arranged so that the combined gravity center position of the bicycle 2 and the driver 9 can be specified are provided.

  The steering subject center-of-gravity sensor 10 is arranged so that the center of gravity position of the steering subject can be specified. Specifically, the control subject center-of-gravity sensor 10 is based on a known human body characteristic theory, and includes the head, chest, waist, upper arm, forearm, hand, thigh, lower leg, and foot of the operator 9. (See, for example, Ae, Yu, Yokoi, “Estimation of Body Part Inertia Characteristics of Japanese Athletes”, Biomechanism 11 (1992) 23-33). In the bicycle 2, the vehicle center of gravity sensor 11 is disposed so as to be able to specify the position of the center of gravity of the vehicle. For example, the vehicle center-of-gravity sensor 11 is attached to the handle of the bicycle 2, the frame, and the position of the center of gravity of the bicycle 2 in a stationary state (a state where the handle is straight). For the sake of clarity in FIG. 1, the steering main gravity sensor 10 is only for the steering main gravity sensor 10 attached to the head, and the vehicle gravity sensor 11 is only for the vehicle gravity sensor 11 attached to the gravity center position of the bicycle 2 in a stationary state. These are shown with reference numerals.

  The front wheel grounding point sensor 4 and the rear wheel grounding point sensor 6 are position-identifiable, and include a virtual rotation surface including the rotation center of the wheel, and a virtual center axis line passing through the rotation center and perpendicular to the rotation surface. Are attached to the front wheel 3 and the rear wheel 5, respectively. A specific mounting mode will be described in detail later with reference to FIG.

  The steering wheel steering angle sensor 7 is attached so as to be interlocked with, for example, the movement (for example, rotation) of the steering shaft (the shaft for tilting the steering wheel) of the bicycle 2 so that the steering wheel steering angle of the bicycle 2 can be detected.

  The front wheel grounding point sensor 4 and the rear wheel grounding point sensor 6, the steering main body gravity sensor 10 and the vehicle gravity center sensor 11, and the steering wheel steering angle sensor 7 are sensors that detect triaxial acceleration and angular velocity at the mounting position of each sensor. It is. Specifically, the stability evaluation system 1 senses acceleration on three axes (XYZ axis, pitch axis, roll axis, yaw axis), and integrates the detected acceleration twice over time, thereby driving The amount of displacement in three directions from the initial state at each time point can be calculated. The stability evaluation system 1 can calculate an angular change amount in three directions from the initial state at each time point during traveling by sensing the angular velocity and integrating the sensed angular velocity over time. Preferably, the stability evaluation system 1 senses geomagnetism in addition to acceleration and angular velocity, and the amount of displacement obtained from the sensed geomagnetic measurement data based on the measurement data by the sensor sensing acceleration and angular velocity. In addition, the amount of change in angle can be corrected. These sensors detect the acceleration and angular velocity of the bicycle 2 that is running, preferably by sensing changes in geomagnetism and adding them to the initial positions of the sensors that have been measured in advance. The position information of the mounting position of each sensor in 2 can be obtained.

  The stability evaluation device 8 calculates a combined center of gravity position of the bicycle 2 and the driver 9 based on information from the control subject center of gravity sensor 10 and the vehicle center of gravity sensor 11, and the front wheel grounding point sensor 4 and the rear wheel grounding point sensor 6 are calculated. The grounding point of the bicycle 2 is calculated based on the information from. More specifically, the stability evaluation device 8 is based on the information from the front wheel grounding point sensor 4 and the rear wheel grounding point sensor 6, and the center axis 15 and rotation of the front wheel 3 and the rear wheel 5 as shown in FIG. The surface 16 is calculated, and the point at which the rotation center 16 and the projection center axis 13 vertically projected on the traveling surface 12 intersect is calculated as the ground contact point 14. Further, the stability evaluation device 8 calculates a straight line connecting the ground points for the front wheel 3 and the rear wheel 5 as a ground line.

  FIG. 2 is a flowchart for explaining a stability evaluation method according to an embodiment of the present invention. First, a measurement step of acquiring measurement data is performed by the front wheel contact point sensor 4 and the rear wheel contact point sensor 6, as well as the steering subject gravity sensor 10 and the vehicle gravity sensor 11 (step S01). Then, the stability evaluation device 8 calculates the combined center of gravity position based on the measurement data of the steering subject center-of-gravity sensor 10 and the vehicle center-of-gravity sensor 11, and measures the front wheel ground point sensor 4 and the rear wheel ground point sensor 6 sensor. An evaluation index providing step of calculating a ground contact point from the data and providing at least the combined center of gravity position and the ground contact point as a stability evaluation index of the bicycle 2 is performed (step S02).

  The stability evaluation device 8 repeats steps S01 and S02 at predetermined time intervals after the start of measurement, thereby simplifying temporal changes in the combined center of gravity position, grounding point, and grounding line of the traveling bicycle 2 and the driver 9. Can be obtained and provided.

  Hereinafter, the calculation process by the stability evaluation apparatus 8 in step S02 described above will be described in more detail.

[Contact point calculation processing]
FIG. 3 is a diagram for explaining an example of the contact point calculation process in step S02 of FIG. In this example, the rear wheel ground contact point sensor 6 is attached to the rear wheel 5 including the position where the center axis 15 of the wheel passes. Most preferably, the front wheel contact point sensor 4 and the rear wheel contact point sensor 6 are disposed at the axle center (rotation center) of the front wheel 3 and the rear wheel 5, respectively. Preferably, the front wheel grounding point sensor 4 and the rear wheel grounding point sensor 6 are mounting members that project at an equal distance from the rotation center of the wheel toward each side of the front wheel 3 and the rear wheel 5 perpendicular to the rotation surface. Mounted on (not shown). In this case, the distances from the rotating surface to the front wheel contact point sensor 4 and the rear wheel contact point sensor 6 are measured in advance. The mounting manner of the rear wheel ground contact point sensor 6 is not limited to this, and the positional relationship between the center axis 15 that is the rotational axis of the rear wheel 5 and the rotational surface 16 of the rear wheel 5 is fixed when the bicycle 2 is traveling. It is only necessary to be attached to a position that follows the center axis 15 and the rotation surface 16 (with the center axis 15 and the rotation surface 16). The front wheel contact point sensor 4 of the front wheel 3 is also arranged in the same manner.

  The stability evaluation device 8 grasps in advance the positional relationship between the center axis 15 and the rotation surface 16 of the rear wheel 5 and the rear wheel ground point sensor 6. The stability evaluation device 8 calculates the ground contact point 14 from the measurement data acquired from the rear wheel ground contact point sensor 6 at each time point during traveling from the center axis 15 and the rotation surface 16 of the rear wheel 5 at each time point. The spatial position information of is calculated. Further, the stability evaluation device 8 calculates a point where the rotating surface 16 and the projection center axis 13 obtained by vertically projecting the center axis 15 with respect to the traveling surface 12 such as the ground intersect as the ground contact point 14. The stability evaluation apparatus 8 can calculate the contact point of the front wheel 3 by performing the same calculation process for the front wheel contact point sensor 4 not shown in FIG. The calculated straight line passing through both the ground contact points of the front wheel 3 and the rear wheel 5 can be calculated as a ground line.

[Composite centroid calculation processing]
First, the stability evaluation device 8 specifies the center of gravity position of the operator 9 based on the measurement data from the steering subject center-of-gravity sensor 10, and specifies the center of gravity position of the bicycle 2 (vehicle) based on the measurement data from the vehicle center-of-gravity sensor 11. To do. The center-of-gravity position of the pilot 9 is specified by combining the measurement results of the center-of-gravity positions of the body segments based on the human body characteristics. The center-of-gravity position of the bicycle 2 was obtained by, for example, the suspension method or the weighing method (Takio Ohya, “Regarding the kinematics of the bicycle”, Report from JST, p. 1-8, 1978, No. 2). The center of gravity is determined based on the position of the center of gravity of the bicycle 2 in a stationary state and the data measured by the vehicle center of gravity sensor 11 during traveling.

Then, the stability evaluation device 8 calculates a composite gravity center position based on the gravity center position of the driver 9 (manipulation subject), the gravity center position of the bicycle 2, and the masses of the driver 9 and the bicycle 2. An example of a specific calculation principle will be described below. First, the mass (weight) of the pilot 9 is Ma (kg), the center-of-gravity position coordinates on the arbitrarily set XYZ plane are (Xa, Ya, Za), the mass (weight) of the bicycle 2 is Mb (kg), the center of gravity Let the position coordinates be (Xb, Yb, Zb). In this case, if the combined barycentric position coordinate is (Xg, Yg, Zg), the moment in the X, Y, and Z directions should be zero at the combined barycentric position. Therefore, about the X coordinate of the composite gravity center position of the bicycle 2 and the operator 9,
Ma.g.Xa + Mb.g.Xb- (Ma + Mb) .g.Xg = 0 (g: gravitational acceleration)
Should be satisfied. Therefore, the X coordinate of the composite centroid position is
Xg = (Ma · Xa + Mb · Xb) / (Ma + Mb)
Can be calculated as
Similarly, Yg and Zg can also be calculated by the following equations.
Yg = (Ma · Ya + Mb · Yb) / (Ma + Mb)
Zg = (Ma · Za + Mb · Zb) / (Ma + Mb)

Next, the positional relationship between the ground point (ground line) and the combined center of gravity calculated by the stability evaluation device 8 will be described with reference to FIG. FIG. 4 is a diagram for explaining the positional relationship among the sensors, the combined barycentric position, and the ground line acquired by the stability evaluation device 8. The steering subject center-of-gravity sensor 10 is attached to the head, chest, waist, upper arm, forearm, hand, thigh, lower leg, and foot of the pilot 9. A straight line passing through the front wheel contact point 14A and the rear wheel contact point 14B is a ground line 18. Combined center of gravity position of the pilot and bicycle illustrated as combined center of gravity position G, illustrating the position projecting with respect to the running surface such combined center of gravity position G as the projected combined center of gravity position G _p. When attention is focused on the positional relationship between the ground line 18 and the projection combined center of gravity position G _p, when the operator goes straight by bicycle varies projection combined center of gravity position G _p to the left and right with respect to the ground line 18.

In order to make the bicycle run stably, the operator performs center of gravity movement and handle control so that the projected combined center of gravity position _Gp is on the ground line 18. Accordingly, the present inventors have a variation in the distance between the ground line 18 projected combined center of gravity position G _p (centroid displacement amount), steering angle of the bicycle, bank angle, slip angle, running like running surface reaction force We focused on the relationship with various stability evaluation indices that can be varied in the middle bicycle. Hereinafter, various calculation methods of the stability evaluation index in the stability evaluation system 1 according to the present embodiment will be described.

[Steering wheel steering angle]
The steering angle is the angle at which the steering wheel is turned. The stability evaluation device 8 can measure the steering angle by the steering angle sensor 7 that is linked to the rotational behavior of the steering shaft. The stability evaluation device 8 calculates the steering angle by integrating the angular velocity acquired from the steering angle sensor 7 with respect to time at the time of the traveling angle, with the angle in the initial state being 0 degrees.

[Bank corner]
The bank angle is an angle when the vehicle is tilted from a vertical state. In the present embodiment, the bank angle is calculated based on the inclination of the rear wheel of the bicycle. The stability evaluation device 8 uses, as a bank angle, an angle formed by the spatial position information of the rotating surface 16 calculated in Step 02 of FIG. 2 on the rear wheel 5 of the bicycle 2 and a surface perpendicular to the traveling surface 12. Can be calculated. That is, the stability evaluation apparatus 8 calculates the bank angle by subtracting the acute angle side angle formed by the rotating surface 16 and the traveling surface 12 from 90 degrees. In this way, the stability evaluation system 1 according to the present embodiment can calculate and provide the bank angle as one of the stability evaluation indexes. When the vehicle travels in a straight line, it is considered that the vehicle body becomes unstable due to the occurrence of a bank angle. Therefore, calculating the bank angle is important in evaluating the stability of the vehicle.

[Slip angle]
The slip angle refers to an angle of deviation between the direction of the front wheel of the vehicle and the traveling direction of the vehicle on the traveling surface. The stability evaluation device 8 can calculate the angle formed by the traveling direction of the bicycle 2 and the rotating surface of the front wheel 3 as a slip angle. The stability evaluation device 8 acquires the traveling direction of the bicycle 2 at a certain point during traveling as the direction of a straight line connecting the grounding point at the time point and the grounding point of the front wheel 3 at any time before or after that point. To do. Then, the stability evaluation device 8 acquires the angle formed by the acquired traveling direction of the bicycle 2 and the rotation surface of the front wheel 3 at the time point as the slip angle of the bicycle 2 at the time point. In this way, the stability evaluation system according to the present embodiment can calculate the slip angle of the running vehicle, which has been very difficult to calculate in the past, as one of the stability evaluation indexes. By calculating the slip angle of the vehicle, the cornering force generated in the traveling vehicle can be estimated, and the vehicle behavior resulting from the cornering force can be predicted.

[Running reaction force]
The traveling surface reaction force refers to a force acting on the vehicle from the traveling surface. Of the traveling surface reaction force, the force component in the direction perpendicular to the traveling direction of the vehicle on the traveling surface contributes to the rollover of the vehicle and may affect the stability evaluation of the traveling vehicle. Conceivable. Based on the bank angle and the grounding line 18, the stability evaluation device 8 can calculate a force acting in a direction perpendicular to the traveling direction (hereinafter referred to as a course vertical reaction force) out of the traveling surface reaction force. it can. The calculation method of the running surface reaction force follows a known method. Specifically, strain gauges or piezoelectric elements are arranged at the four corners of the plate as the traveling surface of the vehicle, and based on the force sensed by these strain gauges or piezoelectric elements, three axes (pitch axis, The force and moment of the roll axis and yaw axis are output.

  Then, the stability evaluation device 8 calculates the course vertical reaction force from the traveling surface reaction force calculated in this way by a method described with reference to FIGS. 5A and 5B. 5A and 5B are views for explaining an example of a method for calculating the course vertical reaction force. FIG. 5A is a view of the rear wheel 5 viewed from the front of the rear wheel 5, and FIG. It is the figure seen from the top. The course vertical reaction force is a force acting perpendicularly to the traveling direction, which is obtained by decomposing the force acting from the traveling surface as described above. Due to the influence of the vertical reaction force on the course, the bicycle 2 may roll over while traveling.

For running surface reaction force calculated as described above mu, as shown in FIG. 5A, stability evaluation device 8 is first decomposed into a force parallel Myuesuaienushita _BA relative to the running surface with a bank angle theta _BA . Next, the stability evaluation device 8 calculates an angle θ _T formed by the force μ sin θ _BA and the traveling direction line 19 as shown in FIG. 5B and decomposes it into a course vertical reaction force μ sin θ _BA · sin θ _T. In this way, the stability evaluation device 8 calculates the course vertical reaction force μ sin θ _BA · sin θ _T. The stability evaluation device 8 calculates the course vertical reaction force μsinθ _BA · sinθ _T as one of the stability evaluation indexes, thereby determining how much force in the lateral direction with respect to the traveling bicycle 2 toward the traveling direction. It is possible to numerically indicate whether or not is applied. Then, the stability evaluation system 1 can analyze, for example, at what point in time the bicycle 2 that is running has a high probability of falling in the lateral direction using the course vertical reaction force.

  As described above, the stability evaluation system according to the present embodiment can calculate and provide various indexes that contribute to the stability of the running vehicle. Such a stability evaluation system can numerically evaluate the stability of a running vehicle using such an index. Hereinafter, an example of an evaluation result based on the index calculated as described above will be described with reference to FIG.

  FIG. 6 is a diagram illustrating an example of a vehicle stability evaluation result during travel by the stability evaluation system according to the embodiment of the present invention, and the displacement of the projected composite gravity center position described with reference to FIG. 4 with respect to the ground line The amount (the center of gravity displacement amount), the steering wheel steering angle fluctuation, and the bank angle fluctuation are shown. For each of them, 0 is shown on the ground line, the displacement in the right direction of the ground line toward the traveling direction of the bicycle is minus, and the displacement in the left direction is shown as plus. The time series waveform of each stability evaluation index was obtained from the time series change of the value of each stability evaluation index with the passage of travel time.

For example, based on FIG. 6, the stability of the bicycle during traveling can be evaluated as follows. First, for some external factor at time t ₁ with the center of gravity is displaced to the right side in the traveling direction, the bank angle occurs tilt the bicycle at time t ₂ across a fixed delay The numerical value is affected. Then, the operator to correct the tilt of the bicycle at time t ₂ is the cut handle in the reverse direction, the center of gravity and follows it to move in the opposite direction to the ground line. Then, following the movement of the center of gravity, the bank angle is reduced, and the inclination of the bicycle is relaxed.

  As described above, according to the stability evaluation system of the present embodiment, the behavior of the bicycle and the driver for maintaining the stability of the vehicle when the bicycle is running can be numerically expressed. Furthermore, the stability evaluation system according to the present embodiment can also provide a further stability evaluation index for evaluating the stability of the bicycle based on the time series waveform as shown in FIG. Hereinafter, a further method for calculating the stability evaluation index based on the time-series waveform will be described with reference to FIG.

FIG. 7 is a diagram for explaining an example of a stability evaluation index calculation method provided by the stability evaluation system according to the embodiment of the present invention. The time series waveform shown in FIG. 7 is, for example, a time series waveform for the center of gravity displacement. Here, the average amplitude from time t _{1 to} time t _n is A _ave , the amplitude value at time t _k is A _k, and the amplitude value A representing the time series waveform shown in FIG.

  Use the amplitude value of the time-series waveform for the displacement of the center of gravity, steering wheel steering angle, bank angle, course vertical reaction force, slip angle, etc., calculated as described above, as one of the stability evaluation indices of the running bicycle. Can do.

  Further, the stability evaluation apparatus 8 according to the present embodiment can calculate a further stability evaluation index by calculating the phase difference for the time series waveform of each stability evaluation index as shown in FIG. . Hereinafter, an example of a method for calculating the phase difference will be described with reference to FIGS. FIG. 8 is a diagram showing time series waveforms of the normalized center-of-gravity displacement amount and bank angle.

The time-series waveforms shown in FIG. 8 are respectively translated in such a way that the center-of-gravity displacement amount and bank angle time-series waveforms as shown in FIG. It is normalized to be 1. Here, each time-series waveform y ₂ of the time-series waveform y ₁ and the center of gravity displacement of the bank angle, represented by the formula.
y ₁ = A ₁ sin ωt
y ₂ = A ₂ sin (ωt + δ)
Here, A ₁ is a bank angular amplitude value, A ₂ is a gravity center displacement amplitude value, ω is an angular frequency, t is time, and δ is a phase difference. For example, A ₁ and A ₂ can be given as the maximum amplitude values of the bank angle amplitude value and the centroid displacement amplitude value when traveling in an arbitrary section, respectively.

Then, the following formula is obtained from the above formula, and the Lissajous figure shown in FIG. 9 is obtained.
y ₁ / A ₁ = sinωt
y ₂ / A ₂ = sin (ωt + δ)
Here, since it is difficult to perform the averaging process on the elliptical area S defined by the Lissajous figure, in the stability evaluation apparatus 8 according to the present embodiment, for example, the average of the distances x _i from y ₁ = y ₂ The value is calculated by the following formula and is defined as the phase difference PD.

  Thus, according to the stability evaluation system 1 according to the present embodiment, time series waveforms of two stability evaluation indexes selected from the displacement of the center of gravity, the steering angle of the steering wheel, the bank angle, the course vertical reaction force, the slip angle, and the like. Can be calculated and provided as a further stability evaluation index. Hereinafter, an example of the stability evaluation result by the stability evaluation system 1 according to the present embodiment will be described with reference to FIG.

  FIG. 10 is a diagram illustrating an example of a stability evaluation result provided by the stability evaluation system 1 according to an embodiment of the present invention. The horizontal axis represents the amplitude value of the center of gravity displacement, and the vertical axis represents the center of gravity displacement−bank angle phase difference. Here, the stability evaluation index calculated based on the data of one driver traveling straight on four types of bicycles A to D is shown. The amplitude value of the center-of-gravity displacement amount is the amplitude value (mm) of the distance between the combined center-of-gravity position projected on the traveling surface and the ground line, and the smaller this value is, the easier the vehicle travels straight. Can be said to be a good bicycle. The center-of-gravity displacement-bank angle phase difference is an index representing the operability of the bicycle. That is, it can be said that the larger the value is, the longer the time until the influence of the movement of the center of gravity reaches the change of the bank angle, and the slower the response. Conversely, the smaller the value of the center of gravity displacement amount−bank angle phase difference, the faster the bicycle can be said to be.

  That is, the bicycle A is a bicycle that has a high course holding ability and a slow response. On the other hand, the bicycle D is a bicycle that has a relatively low course retention but has a quick response to operations. Bicycles B and C are bicycles that exhibit characteristics between bicycles A and D. The operability of these bicycles was in good agreement with the experience of operation when the driver actually traveled straight on bicycles A to D.

  Thus, according to the stability evaluation system 1 according to the present embodiment, it is possible to provide numerical data serving as an evaluation index regarding the running stability of a bicycle. As a result, it is possible to carry out bicycle running stability evaluation, which conventionally relies on sensory evaluation, using objective numerical values based on measurement data acquired by a sensor. Furthermore, according to the stability evaluation system 1 according to the present embodiment, no imaging device is required for running stability evaluation. Although the stability evaluation apparatus and method using an imaging apparatus can only evaluate the stability of a vehicle that is running within the imaging range of the imaging apparatus, according to the stability evaluation system 1 according to the present embodiment, Without limitation, the stability of the running vehicle can be evaluated.

  The vertical axis in FIG. 10 is not limited to the center-of-gravity displacement amount-bank angle phase difference, but is selected from the steering wheel steering angle, slip angle, and course vertical reaction force in addition to the center-of-gravity displacement amount and bank angle. Of course, it is also possible to calculate the phase difference for the two stability evaluation indexes and apply it as the vertical axis of the chart as shown in FIG. Similarly, for the horizontal axis in FIG. 10, it is also possible to take another stability evaluation index of the amplitude value of the centroid displacement amount.

  It will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims.

  For example, in the above-described embodiment, it has been described that the control subject is a driver (human), but the above-described stability evaluation system is constructed by replacing the control subject with any object capable of giving a driving force to the vehicle. Of course it is possible. Thereby, for example, it becomes possible to evaluate the running stability of the vehicle by a robot or the like.

  For example, although the above embodiment has been described on the assumption that the vehicle is a bicycle, it is of course possible to use a unicycle or a motorcycle as the vehicle. This makes it possible to evaluate the running stability of a unicycle or a motorcycle.

1: stability evaluation system, 2: bicycle, 3: front wheel, 4: front wheel contact point sensor, 5: rear wheel, 6: rear wheel contact point sensor, 7: steering wheel angle sensor, 8: stability evaluation device, 9 : Pilot, 10: pilot center of gravity sensor, 11: vehicle center of gravity sensor, 12: traveling plane, 13: projection center axis, 14: ground point, 15: center axis, 16: rotation plane, 18: ground line, 19: Direction line

Claims (11)

A stability evaluation system for evaluating the stability of a vehicle traveling on a running surface,
A center-of-gravity sensor arranged so as to be able to specify a combined center-of-gravity position of the vehicle and a steering subject who controls the vehicle;
A grounding point sensor capable of specifying a grounding point that is a point where a wheel of the vehicle is in contact with the traveling surface, and a rotation surface including a rotation center of the wheel, and a perpendicular to the rotation surface through the rotation center A grounding point sensor arranged to detect the central axis line;
The composite centroid position is calculated based on measurement data from the centroid sensor, and the contact point is calculated based on measurement data from the contact point sensor, so that at least the combination centroid position and the contact point are determined for the vehicle. A stability evaluation device provided as a stability evaluation index;
A stability evaluation system comprising:   The stability evaluation system according to claim 1, wherein the center-of-gravity sensor and the contact point sensor are sensors that sense acceleration and angular velocity about three axes. The center-of-gravity sensor includes a vehicle center-of-gravity sensor capable of specifying a center-of-gravity position of the vehicle, and a steering main body center-of-gravity sensor capable of specifying a center of gravity position of the steering main body,
The stability evaluation device calculates the composite gravity center position based on measurement data obtained by the vehicle gravity sensor and the steering subject gravity sensor.
The stability evaluation system according to claim 1 or 2, wherein   The stability evaluation device calculates a spatial position of the center axis and the rotation surface during traveling based on measurement data obtained by the contact point sensor, and vertically projects the rotation surface and the traveling surface. 4. The stability evaluation system according to claim 1, wherein a point where a central axis intersects is calculated as the grounding point. 5. The vehicle is a motorcycle;
The stability evaluation apparatus includes:
A straight line connecting the grounding points calculated for the front wheel and the rear wheel of the two-wheeled vehicle is calculated as a grounding line, and a center-of-gravity displacement amount that is a distance between the grounding line and the combined center of gravity projected onto the traveling surface is calculated. Calculate or
Calculating a bank angle of the vehicle, which is an angle obtained by subtracting an angle formed by the rotating surface and the traveling surface from 90 degrees;
Providing the displacement of the center of gravity or the bank angle as a stability evaluation index of the vehicle;
The stability evaluation system according to any one of claims 1 to 4, wherein The stability evaluation apparatus includes:
Calculate the time series change of the center of gravity displacement amount and the time series change of the bank angle,
Obtain a centroid displacement amount time series waveform from the centroid displacement amount time series change, and calculate an amplitude value of the centroid displacement amount based on the centroid displacement amount time series waveform,
Obtain a bank angle time series waveform from the time series change of the bank angle, calculate the phase difference between the bank angle time series waveform and the centroid displacement amount time series waveform,
Providing the amplitude value of the center-of-gravity displacement amount and the phase difference as a stability evaluation index of the vehicle;
The stability evaluation system according to claim 5, wherein: A steering wheel steering angle sensor arranged to detect a steering wheel steering angle of the vehicle;
The stability evaluation device calculates a steering angle from measurement data obtained by the steering angle sensor, and provides the steering angle as a stability evaluation index of the vehicle.
The stability evaluation system according to any one of claims 1 to 6, wherein   The stability evaluation device calculates a traveling surface reaction force acting in a direction perpendicular to the traveling direction of the vehicle, among the traveling surface reaction forces acting on the traveling vehicle from the traveling surface, The stability evaluation system according to claim 1, wherein the running surface reaction force is provided as a stability evaluation index of the vehicle.   The stability evaluation device calculates an angle formed by the traveling direction of the vehicle and the rotating surface as a slip angle of the vehicle during travel, and provides the slip angle as a stability evaluation index of the vehicle. The stability evaluation system according to any one of claims 1 to 8, wherein A stability evaluation system for evaluating the stability of a motorcycle running on a running surface,
A center-of-gravity sensor arranged so as to be able to specify a composite center-of-gravity position of a steering subject that controls the motorcycle and the motorcycle;
A grounding point sensor capable of specifying a grounding point that is a point where a wheel of the two-wheeled vehicle is in contact with the traveling surface, and a rotation surface including a rotation center of the wheel, and a perpendicular to the rotation surface through the rotation center A grounding point sensor arranged to detect the central axis line;
A steering wheel steering angle sensor arranged to detect a steering wheel steering angle of the two-wheeled vehicle;
The composite centroid position is calculated based on the measurement data from the centroid sensor, and the contact point is calculated based on the measurement data from the contact point sensor, so that at least the combined centroid position and the contact point are the two-wheeled vehicle. A stability evaluation device provided as a stability evaluation index of
With
The stability evaluation apparatus includes:
A straight line connecting the grounding points calculated for the front wheel and the rear wheel of the two-wheeled vehicle is calculated as a grounding line, and a center-of-gravity displacement amount that is a distance between the grounding line and the combined center of gravity projected onto the traveling surface is calculated. Calculate, and
A bank angle of the two-wheeled vehicle, which is an angle obtained by subtracting an angle formed by the rotating surface and the traveling surface from 90 degrees;
Steering wheel steering angle calculated from data measured by the steering wheel steering angle sensor,
Of the traveling surface reaction force acting on the two-wheeled vehicle from the traveling surface, the traveling surface reaction force acting perpendicularly to the traveling direction of the two-wheeled vehicle, or the traveling direction of the two-wheeled vehicle and the rotating surface Calculate the slip angle of the two-wheeled vehicle that is running, based on the calculation result,
Obtaining a centroid displacement amount time-series waveform from the centroid displacement amount time-series change, calculating an amplitude value of the centroid displacement amount based on the centroid displacement amount time-series waveform; and
A time series waveform is obtained from one or two time series changes of the bank angle, the steering wheel steering angle, the traveling surface reaction force acting in a direction perpendicular to the traveling direction of the two-wheeled vehicle, and the slip angle. Calculating a phase difference for two time-series waveforms of the one or two time-series waveforms and the centroid displacement amount time-series waveform;
Providing as a stability evaluation index of the two-wheeled vehicle including at least the amplitude value and the phase difference;
A stability evaluation system. A stability evaluation method for evaluating the stability of a vehicle traveling on a running surface,
A center-of-gravity sensor disposed so as to be able to specify a combined center-of-gravity position of the vehicle and a control subject who controls the vehicle, and a ground-point sensor capable of specifying a ground point that is a point where a wheel of the vehicle is in contact with the traveling surface, A grounding point sensor disposed so as to be able to detect a rotation surface including a rotation center of the wheel and a central axis passing through the rotation center and perpendicular to the rotation surface;
A measurement step for acquiring measurement data by
The composite barycentric position is calculated based on the measurement data of the barycentric sensor, and the grounding point is calculated based on the measurement data of the grounding point sensor, and at least the synthetic barycentric position and the grounding point are determined for the vehicle. An evaluation index providing step provided as a stability evaluation index;
The stability evaluation method characterized by including.

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