PITCHING CONTROL DEVICE OF MOTOR VEHICLE AND CONTROL METHOD

• US 20100094495A1
• Filed: 03/04/2008
• Published: 04/15/2010
• Est. Priority Date: 03/05/2007
• Status: Abandoned Application

• Current Assignee: Yokohama National University
• Original Assignee: Yokohama National University
• Inventors: Fujimoto, Hiroshi, Satoh, Shinsuke
• Application Number:
  US12/530,115
• Publication Number:
  US 20100094495A1
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

The present invention has an object to provide a pitching control device of a vehicle that controls a pitching motion by controlling a torque of its driving wheels and a control method. In the motor vehicle that drives the driving wheels by the torque of a motor, a moment about the center of gravity of the motor vehicle is found from variations of loads applied to the wheels of the motor vehicle at the time of acceleration that include loads applied to th wheels of the motor vehicle at the time of standstill and an anti-dive force working on front wheels of the motor vehicle and an anti-lift force working on rear wheels of the motor vehicle at the time of braking by a brake. A pitch angle of the motor is computed from this moment. The motor torque of the motor is computed based on the computed pitch angle.

Claims

1. A pitching control device, in a vehicle that drives its driving wheels with a torque of a motor,

comprising:

pitch angle computing means for computing a pitch angle of the motor vehicle from a moment about the center of gravity of the motor vehicle based on loads applied to wheels of the motor vehicle at the time of standstill, loads applied to the wheels of the motor vehicle at the time of acceleration and deceleration by the motor, and variations of loads applied to the wheels of the motor vehicle by an anti-dive force working on front wheels of the motor vehicle and an anti-lift force working on rear wheels of the motor vehicle at the time of braking by a brake;

motor torque computing means for computing a motor torque of the motor based on the pitch angle; and

motor control means for controlling the motor using the motor torque.

2. The pitching control device according to claim 1,

further comprising feedback means for compensating a difference between a pitch rate derived from the pitch angle computed by the pitch angle computing means and a pitch rate of the motor vehicle.

3. The pitching control device according to claim 1,

wherein

the pitch angle computing means performs computation based on Formula (A),

$\begin{array}{c}[\mathrm{Formula}\end{array}$



1 ] θ

= - 2 



mh - m 

( β





l f 

tan 



φ

f + ( 1 - β

) 

l r 

tan 



φ

r ) Is 2 + Cs + K 

a x , ( A )

(where m;

car body weight,

h;

distance from the plane ground to the center of gravity,

l_f;

distance between the center of gravity and a front wheel shaft,

l_r;

distance between the center of gravity and a rear wheel shaft,

I;

moment of inertia about a y-axis of the car body,

C;

damper coefficient,

K;

spring constant,

β

;

braking force distributed to the front wheels,

φ

_f;

anti-dive force direction, and φ

_r;

anti-lift force direction).

4. The pitching control device according to claim 1, further comprising brake torque estimating means for estimating a brake torque, wherein

the pitch angle computing means computes an acceleration based on the brake torque.

5. The pitching control device according to claim 4,

wherein

the brake torque estimating means performs estimation considering a slip ratio.

6. The pitching control device according to claim 5,

wherein

the brake torque estimating means performs estimation considering a time variation of the slip ratio.

7. The pitching control device according to claim 4,

further comprising an acceleration sensor for measuring the acceleration of a car body of the motor vehicle,

wherein

the brake torque estimating means performs estimation using the acceleration.

8. A pitching control device, in a vehicle that drives its driving wheels by a torque of a motor,

comprising:

in a vehicle that drives its driving wheels by a torque of the motor,

an acceleration sensor for measuring an acceleration of a car body of the motor vehicle;

state feedback control means that estimates state variables including a pitch angle through a state observer using a model for computing the pitch angle from a moment about a point of the center of gravity of the motor vehicle based on the acceleration, loads applied to wheels of the motor vehicle at the time of standstill, loads applied to the wheels of the motor vehicle at the time of acceleration and deceleration, variations of loads applied to the wheels of the motor vehicle by an anti-dive force working on front wheels of the motor vehicle and an anti-lift force working on rear wheels of the motor vehicle at the time of braking by a brake, and uses estimated values of the state variables;

wheel speed control means for computing a motor torque of the motor based on a slip rate that was computed by the state feedback control means; and

motor control means for controlling the motor using the motor torque.

9. The pitching control device according to claim 8,

wherein

the wheel speed control means determines a control gain by a pole assignment technique considering only moments of inertia of the wheels, and the control gain is adjusted so that the pole may become constant to the moments of the inertia of the wheels at the time of acceleration and deceleration.

10. The pitching control device according to claim 8, wherein

the pitch computing means for computing the pitch angle based on a formula (A)

$\begin{array}{c}[\mathrm{Formula}\end{array}$



2 ] θ

= - 2 



mh - m 

( β





l f 

tan 



φ

f + ( 1 - β

) 

l r 

tan 



φ

r ) Is 2 + Cs + K 

a x , ( A )

(where m;

car body weight,

h;

height from the ground plane to the center of gravity,

l_f;

distance between the center of gravity and a front wheel shaft,

l_r;

distance between the center of gravity and a rear wheel shaft,

I;

moment of inertia about a y-axis of the car body,

C;

damper coefficient,

K;

spring constant,

β

;

braking force distributed to the front wheel,

φ

_f;

anti-dive force direction, and

φ

_r;

anti-lift force direction).

11. A pitching control method, in a vehicle that drives its driving wheels by a torque of a motor,

comprising:

a pitch angle computation step of computing a pitch angle of the driving wheels from a moment about a point of the center of gravity of the motor vehicle based on loads applied to wheels of the motor vehicle at the time of standstill, load imposed on the wheels of the motor vehicle at the time of acceleration and deceleration by the motor, and variations of loads applied to the wheels of the motor vehicle by an anti-dive force working on front wheels of the motor vehicle and an anti-lift force working on rear wheels of the motor vehicle at the time of braking by a brake;

a motor torque computation step of computing a motor torque of the motor based on the pitch angle; and

a motor control step of controlling the motor using the motor torque.

12. The pitching control method according to claim 11,

further comprising a feedback control step of compensating a difference between a pitch rate derived from a pitch angle computed at the pitch angle computation step and a pitch rate of the motor.

13. The pitching control method according to claim 11,

wherein

the pitch angle computation step computes the pitch angle based on Formula (A),

$\begin{array}{c}[\mathrm{Formula}\end{array}$



3 ] θ

= - 2 



mh - m 

( β





l f 

tan 



φ

f + ( 1 - β

) 

l r 

tan 



φ

r ) Is 2 + Cs + K 

a x , ( A )

(where m;

car body weight,

h;

height from the ground plane to the center of gravity,

l_f;

distance between the center of gravity and a front wheel shaft,

l_r;

distance between the center of gravity and a rear wheel shaft,

I;

moment of inertia about a y-axis of the car body,

C;

damper coefficient,

K;

spring constant,

β

;

braking force distributed to the front wheel,

φ

_f;

anti-dive force direction, and

φ

_r;

anti-lift force direction).

14. The pitching control method according to claim 11,

further comprising a brake torque estimation step of estimating the brake torque,

wherein

the pitch angle computing means computes the acceleration based on the brake torque.

15. The pitching control method according to claim 14,

wherein

the brake torque estimation step performs estimation considering a slip ratio.

16. The pitching control method according to claim 15,

wherein

the brake torque estimation step performs estimation further considering a time variation of the slip ratio.

17. The pitching control method according to claim 14,

further comprising an acceleration measurement step of measuring an acceleration of a car body of the motor vehicle with an acceleration sensor,

wherein the brake torque estimation step performs estimation using the acceleration.

18. A pitching control method, in a vehicle that drives its driving wheels by a torque of a motor,

comprising:

an acceleration measurement step of measuring acceleration of a car body of a vehicle by an acceleration sensor;

a state feedback control step of estimating state variables including a pitch angle through a state observer using a model of computing a pitch angle from a moment about the center of gravity of the motor vehicle based on variations of loads applied to wheels of the motor vehicle by the acceleration, loads applied to the wheels of the motor vehicle at the time of standstill, loads applied to the wheels of the motor vehicle at the time of acceleration and deceleration by the motor, and an anti-dive force working on the front wheels of the motor vehicle and an anti-lift force working on the rear wheels of the motor vehicle at the time of braking by a brake, and using the estimated values of the state variables;

a wheel speed control step of computing a motor torque of the motor based on a slip ratio computed by the state feedback control means; and

a motor control step of controlling the motor using the motor torque.

19. The pitching control method according to claim 18,

wherein

the wheel speed control step determines a control gain by a pole assignment technique considering only the moments of inertia of the wheels, and the control gain is adjusted so that the pole may become constant to the moments of inertia of the wheels at the time of acceleration and deceleration.

20. The pitching control method according to claim 18,

wherein

the pitch angle computation step computes the pitch angle based on Formula (A),

$\begin{array}{c}[\mathrm{Formula}\end{array}$



4 ] θ

= - 2 



mh - m 

( β





l f 

tan 



φ

f + ( 1 - β

) 

l r 

tan 



φ

r ) Is 2 + Cs + K 

a x ( A )

(where m;

car body weight,

h;

height from the ground plane to the center of gravity,

l_f;

distance between the center of gravity and a front wheel shaft,

l_r;

distance between the center of gravity and a rear wheel shaft,

I;

moment of inertia about a y-axis of the car body,

C;

damper coefficient,

K;

spring constant,

β

;

braking force distributed to the front wheels,

φ

_f;

angle between the ground plane and an anti-dive force direction, and

φ

_r;

angle between the ground plane and an anti-lift force direction).