Method of steering a wheeled vehicle having at least two pairs of steerable road wheels

• US 4,418,780 A
• Filed: 06/15/1981
• Issued: 12/06/1983
• Est. Priority Date: 06/24/1980
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Ito, Hideo, Yabuta, Keiichiro
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): Weaver, Ross
• Application Number:
  US06/273,971
• Time in Patent Office: 904 Days
• Field of Search: 180/79.1, 180/140, 180/141, 180/142
• US Class Current: 180/422
• CPC Class Codes: B62D 7/1581 characterised by comprising an electrical interconnecting system between the steering control means of the different axles
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

A method of steering a wheeled vehicle having a first pair of steerable road wheels to be steered by human intervention and a second pair of steerable road wheels to be steered in response to a steering effort applied to the first pair of steerable road wheels, wherein the ratio between the angle through which the first pair of steerable road wheels is steered and the angle through which the second pair of steerable road wheels is to be steered is varied to establish a predetermined functional relationship between the ratio and a detected vehicle speed so as to eliminate the lateral slip of the vehicle when the vehicle is making a turn.

Claims

1. A method of steering a wheeled vehicle having a first pair of steerable road wheels to be steered by human intervention, a second pair of steerable road wheels to be steered in response to a steering effort applied to the first pair of steerable road wheels, a first wheel axle operatively connected to the first steerable road wheels, a second wheel axle operatively connected to the second steerable road wheels, a hydraulic drive system which is adapted to develop a fluid pressure variable with a control signal applied thereto and which is operatively connected to the second pair of steerable road wheels for driving the second pair of steerable road wheels to veer through an angle variable with the fluid pressure, and means having registered therein values respectively representative of the total sprung mass and the wheel base of the vehicle and the cornering powers of the tires of the first and second steerable road wheels, comprising the steps of

detecting the vehicle speed;

producing a first signal representative of the detected vehicle speed;

detecting the sprung mass carried by each of the first steerable road wheels and producing a second signal representative of the detected sprung mass of each of the first steerable road wheels;

determining the distance between the center of gravity of the vehicle and the center axis of said first wheel axle on the basis of the second signal;

producing a third signal representative of the distance thus determined;

detecting the sprung mass carried by each of the second steerable road wheels and producing a fourth signal representative of the detected sprung mass of each of the second steerable road wheels;

determining the distance between the center of gravity of the vehicle and the center axis of said second wheel axle on the basis of the fourth signal;

producing a fifth signal representative of the distance thus determined;

calculating the ratio k between the angle through which the second pair of steerable road wheels is to be steered to the angle through which the first pair of steerable road wheels is steered,

producing a sixth signal representative of the ratio k thus calculated; and

applying the sixth signal to said hydraulic drive system as said control signal for controlling said fluid pressure on the basis of said sixth signal,

said ratio k being calculated on the basis of the first, third, and fifth signals in accordance with the equation ##EQU6## wherein M is the total sprung mass of the vehicle as registered in said means, V is the vehicle speed represented by said first signal, a is the distance represented by said third signal, b is the distance represented by said fifth signal, C_f is the cornering power of the tire of each of said first steerable road wheels as registered in said means, C_r is the cornering power of the tire of each of said second steerable road sheels as registered in said means, and l is the wheel base of the vehicle as registered in said means.

2. A control device for controlling a steering system of a wheeled vehicle having a first pair of steerable road wheels to be steered by human intervention, a second pair of steerable road wheels to be steered in response to a steering effort applied to the first pair of steerable road wheels, a first wheel axle operatively connected to the first steerable road wheels, and a second wheel axle operatively connected to the second steerable road wheels, comprising:

a hydraulic drive system which is adapted to develop a fluid pressure variable with a control signal applied thereto and which is operatively connected to the second pair of steerable road wheels for driving the second pair of steerable road wheels to veer through an angle variable with the fluid pressure,

first means having registered therein values respectively representative of the total sprung mass and the wheel base of the vehicle and the cornering powers of the tires of the first and second steerable road wheels;

second means operative to detect the vehicle speed and to produce an output signal representative of the detected vehicle speed;

third means operative to detect the sprung mass carried by each of the first steerable road wheels and to produce a second signal representative of the detected sprung mass of each of the first steerable road wheels;

fourth means operative to determine the distance between the center of gravity of the vehicle and the center axis of said first wheel axle on the basis of the output signal from the third means and to produce an output signal representative of the distance thus determined;

fifth means operative to detect the sprung mass carried by each of the second steerable road wheels and to produce an output signal representative of the detected sprung mass of each of the second steerable road wheels;

sixth means operative to determine the distance between the center of gravity of the vehicle and the center axis of said first wheel axle on the basis of the output signal from the fifth means and to produce an output signal representative of the distance thus determined; and

seventh means responsive to the respective output signals from the second, fourth, and sixth means for calculating the ratio k between the angle through which the second pair of steerable road wheels is to be steered versus the angle through which the first pair of steerable road wheels is steered, producing an output signal representative of the ratio k thus calculated and supplying the last named signal to said hydraulic drive system as said control signal, the seventh means being operative to calculate said ratio k on the basis of said respective output signals and said values registered in said first means in accordance with the equation ##EQU7## wherein M is the total sprung mass of the vehicle as registered in said means, V is the vehicle speed represented by the output signal from said second means, a is the distance represented by the output signal from said fourth means, b is the distance represented by the output signal from said sixth means, C_f is the cornering power of the tire of each of said first steerable road wheels as registered in said means, C_r is the cornering power of the tire of each of said second steerable road wheels as registered in said first means, and l is the wheel base of the vehicle as registered in said first means.