Controlling apparatus of steering angle of rear wheels of four-wheel steering vehicle

• US 5,274,555 A
• Filed: 08/09/1991
• Issued: 12/28/1993
• Est. Priority Date: 08/10/1990
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fukunaga, Takashi, Segawa, Akiyoshi
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/743,225
• Time in Patent Office: 872 Days
• Field of Search: 364/424.05, 280/91, 180/79.1, 180/140-143
• US Class Current: 701/42
• 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 steering angle of rear wheels of a four-wheel steering vehicle is controlled so that a quick response of an electric motor mounted in the rear wheels is achieved only when it is necessary, thereby avoiding wasteful consumption of power. In addition, a yaw rate feedback system is kept stable. When unstable vibration of the electric motor is detected, a gain to the yaw rate is adjusted.

Claims

1. A controlling apparatus for controlling a steering angle of rear wheels of a four-wheel steering vehicle by driving an electric motor coupled to said rear wheels via a reduction gear, said controlling apparatus comprising:

at least one of a steering wheel angle sensor for detecting a steering wheel angle of a steering wheel of said vehicle, a vehicle speed sensor for detecting a speed of said vehicle and a yaw rate sensor for detecting an angular velocity of rotation about a center of gravity of said vehicle;

a position detector for detecting an operational position of said electric motor;

a first interface circuit for generating a current position signal indicative of said operational position of said electric motor detected by said position detector;

an operation unit for determining a desired operational position of said electric motor based on inputs received from said at least one sensor, for determining a deviation between the desired operational position of said electric motor and said operational position indicated by said current position signal, and for generating an instruction value by applying said deviation to a proportional plus integral plus differential operation; and

,

a second interface circuit for generating a drive command to a motor driver of said electric motor according to said instruction value generated by said operation unit;

wherein said operation unit includes initializing means for setting weighing constants of said proportional plus integral plus differential operation based on response characteristics of said electric motor which are calculated from deviations between the desired operational position of said rear wheels and said operational position indicated by said current position signal while said desired operational position of said electric motor is changed in steps by intermittently operatively connecting said electric motor and said rear wheels.

2. A controlling apparatus as claimed in claim 1, wherein said initializing means of said operation unit resets said weighing constants based on said deviation each time said desired operational position of said electric motor is changed in steps until said response characteristics of said electric motor falls within a target amount.

3. A controlling apparatus for controlling a steering angle of rear wheels of a four-wheel steering vehicle, comprising:

a vehicle speed sensor for detecting a speed of said vehicle;

a yaw rate sensor for detecting an angular velocity of rotation about a center of gravity of said vehicle;

a steering wheel angle sensor for detecting a steering angle of a steering wheel of said vehicle;

an electric motor for positioning said rear wheels based on a rear wheel angle instruction signal;

a position detector for detecting an operational position of said motor; and

,

a controller including a first interface circuit for generating a current position signal indicative of said operational position detected by said position detector, an operation unit for generating said rear wheel angle instruction signal based on inputs received from said vehicle speed sensor, said yaw rate sensor, said steering wheel sensor and said position detector, and a second interface circuit for applying said rear wheel angle instruction signal to a motor driver of said electric motor;

said operation unit of said controller including means for determining a desired operational position of said electric motor based on said inputs received from said vehicle speed sensor, said yaw rate sensor and said steering wheel sensor, means for determining a deviation between said desired operational position and said operational position indicated by said current position signal, and means for calculating a value of said rear wheel angle instruction signal by subtracting a first calculated value from a second calculated value, said first calculated value corresponding to a value obtained by applying said current position signal to a proportional operation, and said second calculated value corresponding to a value obtained by applying said deviation to a proportional operation and to an integral operation and summing the results of the proportion and integral operations, and then multiplying the thus summed results by a variable which is proportional to said speed of said vehicle.

4. A controlling apparatus as claimed in claim 3, wherein said operation unit of said controller includes means for selecting a value of said variable according to whether said rear wheels are turned in a same phase or an opposite phase relative to the front wheels of said vehicle.