Mobile vehicle

Patent metadata

Field	Value
Publication number	US-9688342-B2
Application number	US-201514804774-A
Country	US
Kind code	B2
Filing date	Jul 21, 2015
Priority date	Nov 1, 2012
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

In a mobile vehicle 1 having a vehicle body 2 , a front wheel 3 f , and a rear wheel 3 r , the steering control wheel 3 f can be steered by a steering actuator 8 about a steering axis Csf which is tilted backward. The steering actuator 8 is controlled by a control device 15 . The height a, from a ground surface 110 , of the intersection point Ef of the steering axis Csf of the steering control wheel 3 f and a virtual straight line connecting the ground contact point of the steering control wheel 3 f and the center of axle of the steering control wheel 3 f in a basic posture state of the mobile vehicle 1 is set to satisfy a prescribed condition.

First claim

What is claimed is:

1. A mobile vehicle having a vehicle body and a front wheel and a rear wheel arranged spaced apart from each other in a longitudinal direction of the vehicle body,
one of the front wheel and the rear wheel being a steering control wheel which can be steered about a steering axis tilted backward,
the mobile vehicle comprising:
a steering actuator which generates a steering force for steering the steering control wheel; and
a control device which controls the steering actuator so as to stabilize a posture of the vehicle body in accordance with at least an observed value of an inclination angle in a roll direction of the vehicle body, wherein
in a case where a state in which the front wheel and the rear wheel of the mobile vehicle are both stationary in an upright posture in contact with a ground surface and axle centerlines of the front wheel and the rear wheel extend in parallel with each other in a direction orthogonal to the longitudinal direction of the vehicle body is defined as a basic posture state,
the height a, from the ground surface, of a point of intersection of the steering axis of the steering control wheel and a virtual straight line connecting a ground contact point of the steering control wheel and the center of axle of the steering control wheel in the basic posture state is set to satisfy the following first condition:

First Condition:
in a system made up of a mass point A, which moves in a horizontal direction above the ground surface, with which the mobile vehicle comes into contact, in accordance with the inclination angle in the roll direction of the vehicle body and a steering angle of the steering control wheel, and a mass point B, which moves horizontally on the ground surface, with which the mobile vehicle comes into contact, in accordance with the steering angle of the steering control wheel, independently of the inclination angle in the roll direction of the vehicle body, the system having a mass of the mass point A, a mass of the mass point B, a height of the mass point A from the ground surface, a relationship among an inclination angle in the roll direction of the vehicle body, a steering angle of the steering control wheel, and a displacement of the mass point A, and a relationship between a steering angle of the steering control wheel and a displacement of the mass point B which are set to have dynamic characteristics equivalent to those of dynamics of the mobile vehicle in the case where the steering control wheel of the mobile vehicle being stationary on a prescribed origin in the basic posture state is steered by a steering angle δ, wherein a sum of masses of the mass point A and the mass point B is equal to an overall mass of the mobile vehicle, a height of the center of gravity of the mass point A and the mass point B is equal to an overall height of the center of gravity of the mobile vehicle, and an inertia moment about the center of gravity of the mass point A and the mass point B is equal to an overall inertia moment about the overall center of gravity of the mobile vehicle, the system being also configured such that the mass point A accelerates or decelerates in response to a first gravitational moment, generated about the origin due to a gravitational force acting on the mass point A, a second gravitational moment, generated about the origin due to a gravitational force acting on the mass point B, and a road surface reaction force moment, acting about the origin due to a road surface reaction force in the vertical direction which acts on a center of contact pressure as a point of application, on the ground surface, of a resultant force of a road surface reaction force in the vertical direction which acts on the front wheel from the ground surface and of a road surface reaction force in the vertical direction which acts on the rear wheel from the ground surface, in the case where a steering angle of the steering control wheel at a time when the steering control wheel is steered to cause a front end of the steering control wheel to turn left as the mobile vehicle in the basic posture state is seen from above is defined as a positive steering angle and in the case where a moment that causes the vehicle body to lean to the right is defined as a positive moment, the following holds:
Mp/δ>−M 2/δ

where M 2 denotes the second gravitational moment generated by movement of the mass point B at a time when the steering control wheel of the mobile vehicle being stationary on the origin in the basic posture state is steered instantaneously by the steering angle δ, and Mp denotes the road surface reaction force moment generated about the origin by movement of the center of contact pressure at the time when the steering control wheel of the mobile vehicle being stationary on the origin in the basic posture state is steered instantaneously by the steering angle δ.

2. The mobile vehicle according to claim 1 , wherein, to satisfy the first condition, the height a is set to be smaller than a first prescribed value a_sum determined by the following expression (A):
a _sum=(( h +( I/m )/ h )/( Rg +( I/m )/ h ))× Rs   (A)

where
polarity of a: a>0 in a case where the point of intersection is above the ground surface, a<0 in a case where the point of intersection is below the ground surface;
I: inertia moment of the mobile vehicle;
m: mass of the mobile vehicle;
h: height of the center of gravity of the mobile vehicle from the ground surface in the basic posture state of the mobile vehicle;
Rg ( Lr /( Lf+Lr ))× Rf +( Lf /( Lf+Lr ))× Rr;

Lf: longitudinal distance between the center of gravity of the mobile vehicle and the center of axle of the front wheel in the basic posture state of the mobile vehicle;
Lr: longitudinal distance between the center of gravity of the mobile vehicle and the center of axle of the rear wheel in the basic posture state of the mobile vehicle;
Rf: radius of curvature of a transverse cross-section of the front wheel at a ground contact point of the front wheel in the basic posture state of the mobile vehicle;
Rr: radius of curvature of a transverse cross-section of the rear wheel at a ground contact point of the rear wheel in the basic posture state of the mobile vehicle; and
Rs: one of the radii of curvature Rf and Rr that corresponds to the steering control wheel.

3. The mobile vehicle according to claim 1 , wherein the height a is set to further satisfy the following second condition:
Second Condition:
M sum/δ>− M 2/δ

where Msum denotes a sum moment of the second gravitational moment M 2 and the road surface reaction force moment Mp.

4. The mobile vehicle according to claim 3 , wherein, to satisfy the first condition and the second condition, the height a is set to be not greater than a second prescribed value a_s determined by the following expression (B):
a _ s =(( h +( I/m )/ h )/( Rg+ 2×( I/m )/ h ))× Rs   (B)

where
polarity of a: a>0 in a case where the point of intersection is above the ground surface, a<0 in a case where the point of intersection is below the ground surface;
I: inertia moment of the mobile vehicle;
m: mass of the mobile vehicle;
h: height of the center of gravity of the mobile vehicle from the ground surface in the basic posture state of the mobile vehicle;
Rg ( Lr /( Lf+Lr ))× Rf +( Lf /( Lf+Lr ))× Rr;

Lf: longitudinal distance between the center of gravity of the mobile vehicle and the center of axle of the front wheel in the basic posture state of the mobile vehicle;
Lr: longitudinal distance between the center of gravity of the mobile vehicle and the center of axle of the rear wheel in the basic posture state of the mobile vehicle;
Rf: radius of curvature of a transverse cross-section of the front wheel at a ground contact point of the front wheel in the basic post

Assignees

• Honda Motor Co Ltd

Inventors

• Takenaka Toru
• Gomi Hiroshi
• Akimoto Kazushi
• Makino Hiroyuki
• Nishimura Yoichi
• Setoguchi Taihei
• Saito Naoyuki
• Muto Kenji
• Koitabashi Keisuke
• Nakabayashi Shunichi

Classifications

• B62K21/00 Primary

  Steering devices · CPC title