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EP0510365A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Rear wheel steering system for vehicle
Assignee: Mazda Motor Corp
•
Filing: 1992-03-20
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Granted: —
•
Expires: 2012-03-20
Abstract
Abstract A rear wheel steering system for a vehicle including a yaw rate sensor for detecting the yaw rate of the vehicle and yaw rate feedback controller for controlling a steering angle of rear wheels so that a yaw rate detected by the yaw rate sensor is made equal to a target yaw rate, the rear wheel steering system further including a side slip angle calculator for estimating a side slip angle of the vehicle, a side slip angle controller for controlling the steering angle of the rear wheels to decrease an absolute value of the estimated side slip angle calculated by the side slip angle calculator and a fuzzy controller for controlling the steering angle of the rear wheels based on fuzzy control to decrease an absolute value of a rate of change in the detected yaw rate. This rear wheel steering system can control the steering angle of the rear wheels in a desired manner even when the lateral acceleration is high and the vehicle is turning sharply, and can improve driving stability.
Inventors
- 👤 Mitsuru Nagaoka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 22:52
CPC Classifications
B; B62; B62D; B62D7/00; B62D7/06; B62D7/14; B62D7/15; B62D7/159
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
187 words
A rear wheel steering system for a vehicle comprising turning state detecting means for physically detecting turning state of the vehicle and yaw rate feedback control means (30) for controlling a steering angle (Xr) of rear wheels (3) so that a yaw rate (Y) detected by the turning state detecting means is made equal to a target yaw rate (Yo), said rear wheel steering system further comprising a second rear wheel steering angle control means adapted for controlling the steering angle (Xr) of the rear wheels (3) based on a control mode different from that of the yaw rate feedback control means (30) and a control mode selection means (33) adapted for causing the second rear wheel steering angle control means to control the steering angle (Xr) of the rear wheels (3) when the vehicle is turning with a turning radius smaller than a first predetermined turning radius and causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when the vehicle is turning with a turning radius equal to or greater than the first predetermined turning radius.
Claim 2
Dependent Claim
84 words
A rear wheel steering system for a vehicle in accordance with Claim 1 further comprising side slip angle calculating means (34) for estimating a side slip angle (z) of the vehicle, and the second rear wheel steering angle control means being constituted as a side slip angle control means (31) adapted for controlling the steering angle (Xr) of the rear wheels (3) to decrease an absolute value of the estimated the side slip angle (z) calculated by the side slip angle calculating means (34).
Claim 3
Dependent Claim
63 words
A rear wheel steering system for a vehicle in accordance with Claim 1 wherein the second rear wheel steering angle control means is constituted as a fuzzy control means (32) adapted for controlling the steering angle (Xr) of the rear wheels (3) based on fuzzy control to decrease an absolute value of a rate of change (dY) in the detected yaw rate (Y).
Claim 4
Dependent Claim
71 words
A rear wheel steering system for a vehicle in accordance with Claim 3 wherein the fuzzy control means (32) is adapted for controlling the rear wheels (3) based on a deviation (E) between the target yaw rate (Yo) and the detected yaw rate (Y) and/or a rate of change (dE) in the deviation (E) to decrease the absolute value of the rate of change (dY) in the detected yaw rate (Y).
Claim 5
Dependent Claim
94 words
A rear wheel steering system for a vehicle in accordance with Claim 3 wherein the fuzzy control means (32) is adapted for controlling the rear wheels (3) when an absolute value of the deviation (E) between the target yaw rate (Yo) and the detected yaw rate (Y) is greater than a predetermined value (E0) and/or an absolute value of the rate of change (dE) in the deviation (E) is greater than a predetermined value (dE0) and the yaw rate feedback control means (30) is adapted for controlling the rear wheels (3) under other conditions.
Claim 6
Dependent Claim
154 words
A rear wheel steering system for a vehicle in accordance with Claim 1 further comprising a third rear wheel steering angle control means adapted for controlling the steering angle (Xr) of the rear wheels (3) based on a control mode different from those of the yaw rate feedback control means (30) and the second rear wheel steering angle control means, and the control mode selection means (33) being adapted for causing the second rear wheel steering angle control means to control the steering angle (Xr) of the rear wheels (3) when the vehicle is turning with a turning radius smaller than the first predetermined turning radius but greater than a second predetermined turning radius and causing the third rear wheels steering angle control means to control the steering angle (Xr) of the rear wheels (3) when the vehicle is turning with a turning radius equal to or smaller than the second predetermined turning radius.
Claim 7
Dependent Claim
132 words
A rear wheels steering system for a vehicle in accordance with Claim 6 further comprising side slip angle calculating means (34) for estimating a side slip angle (z) of the vehicle, the second rear wheel steering angle control means being constituted as a side slip angle control means (31) adapted for controlling the steering angle (Xr) of the rear wheels (3) to decrease an absolute value of the estimated side slip angle (z) calculated by the side slip angle calculating means (31) and the third rear wheel steering angle control means being constituted as a fuzzy control means (32) adapted for controlling the steering angle (Xr) of the rear wheels (3) based on fuzzy control to decrease an absolute value of a rate of change (dY) in the detected yaw rate (Y).
Claim 8
Dependent Claim
71 words
A rear wheel steering system for a vehicle in accordance with Claim 7 wherein the fuzzy control means (32) is adapted for controlling the rear wheels (3) based on a deviation (E) between the target yaw rate (Yo) and the detected yaw rate (Y) and/or a rate of change (dE) in the deviation (E) to decrease an absolute value of the rate of change (dY) in the detected yaw rate (Y).
Claim 9
Dependent Claim
77 words
A rear wheel steering system for a vehicle in accordance with Claim 7 or 8 wherein the fuzzy control means (32) is adapted for controlling the rear wheels (3) when an absolute value of the deviation (E) between the target yaw rate (Yo) and the detected yaw rate (Y) is greater than a predetermined value (E0) and/or an absolute value of the rate of change (dE) in the deviation (E) is greater than a predetermined value (dE0).
Claim 10
Dependent Claim
79 words
A rear wheel steering system for a vehicle in accordance with Claim 1 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the second rear wheel steering angle control means, an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value.
Claim 11
Dependent Claim
78 words
A rear wheel steering system for a vehicle in accordance with Claim 2 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the side slip angle control means (31), an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value.
Claim 12
Dependent Claim
75 words
A rear wheel steering system for a vehicle in accordance with Claim 3 wherein the control mode selection means (33) causes the yaw rate feedback control means to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the fuzzy control means (32), an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value.
Claim 13
Dependent Claim
94 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by a control means for controlling the steering angle (Xr) of the rear wheels (3) other than the yaw rate feed back, an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value.
Claim 14
Dependent Claim
122 words
A rear wheel steering system for a vehicle in accordance with Claim 1 further comprising steering angle detecting means for detecting a steering angle of a steering wheel (1) and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when during control of the steering angle (Xr) of the rear wheels (3) by the second rear wheel steering angle control means, an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value and a sign of a rate of change in the steering angle of the steering wheel detected by the steering angle detecting means changes.
Claim 15
Dependent Claim
121 words
A rear wheel steering system for a vehicle in accordance with Claim 2 further comprising steering angle detecting means for detecting a steering angle of a steering wheel (1) and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the side slip angle control means (31), an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value and a sign of a rate of change in the steering angle of the steering wheel detected by the steering angle detecting means changes.
Claim 16
Dependent Claim
119 words
A rear wheel steering system for a vehicle in accordance with Claim 3 further comprising steering angle detecting means for detecting a steering angle of a steering wheel (1) and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the fuzzy control means (32), an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value and a sign of a rate of change in the steering angle of the steering wheel detected by the steering angle detecting means changes.
Claim 17
Dependent Claim
138 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 further comprising steering angle detecting means for detecting a steering angle of a steering wheel and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by a control means for controlling the steering angle (Xr) of the rear wheels (3) other than the yaw rate feedback control means (30), an absolute value of the detected yaw rate (Y) begins to increase and goes over its peak value and a sign of a rate of change in the steering angle of the steering wheel detected by the steering angle detecting means changes.
Claim 18
Dependent Claim
83 words
A rear wheel steering system for a vehicle in accordance with Claim 1 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the second rear wheel steering angle control means, an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate begins (Yo) to decrease.
Claim 19
Dependent Claim
82 words
A rear wheel steering system for a vehicle in accordance with Claim 2 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the side slip angle control means (31), an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) begins to decrease.
Claim 20
Dependent Claim
80 words
A rear wheel steering system for a vehicle in accordance with Claim 3 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the fuzzy control means (32), an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) begins to decrease.
Claim 21
Dependent Claim
100 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 wherein the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by a control means for controlling the steering angle (Xr) of the rear wheels (3) other than the yaw rate feedback control means (30), an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) begins to decrease.
Claim 22
Dependent Claim
113 words
A rear wheel steering system for a vehicle in accordance with Claim 1 wherein in changing the control means for controlling the steering angle (Xr) of the rear wheels (3) between the yaw rate feedback control means (30) and the second rear wheel steering angle control means, the control means determines whether or not an amount of change in the steering angle (Xr) of the rear wheels (3) is greater than a predetermined limit value and when it is, controls the steering angle (Xr) of the rear wheels (3) so that the amount of change in the steering angle (Xr) of the rear wheels (3) is made equal to the predetermined limit value.
Claim 23
Dependent Claim
112 words
A rear wheel steering system for a vehicle in accordance with Claim 2 wherein in changing the control means for controlling the steering angle (Xr) of the rear wheels (3) between the yaw rate feedback control means (30) and the side slip angle control means (31), the control means determines whether or not an amount of change in the steering angle (Xr) of the rear wheels (3) is greater than a predetermined limit value and when it is, controls the steering angle (Xr) of the rear wheels (3) so that the amount of change in the steering angle (Xr) of the rear wheels (3) is made equal to the predetermined limit value.
Claim 24
Dependent Claim
110 words
A rear wheel steering system for a vehicle in accordance with Claim 3 wherein in changing the control means for controlling the steering angle (Xr) of the rear wheels (3) between the yaw rate feedback control means (30) and the fuzzy control means (32), the control means determines whether or not an amount of change in the steering angle (Xr) of the rear wheels (3) is greater than a predetermined limit value and when it is, controls the steering angle (Xr) of the rear wheels (3) so that the amount of change in the steering angle (Xr) of the rear wheels (3) is made equal to the predetermined limit value.
Claim 25
Dependent Claim
122 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 wherein in changing the control means for controlling the steering angle (Xr) of the rear wheels (3) between the yaw rate feedback control means (30) and the other control means for controlling the steering angle (Xr) of the rear wheels (3) the control means determines whether or not an amount of change in the steering angle (Xr) of the rear wheels (3) is greater than a predetermined limit value and when it is, controls the steering angle (Xr) of the rear wheels (3) so that the amount of change in the steering angle (Xr) of the rear wheels (3) is made equal to the predetermined limit value.
Claim 26
Dependent Claim
51 words
A rear wheel steering system for a vehicle in accordance with Claims 22 to 25 further comprising lateral acceleration detecting means for detecting a lateral acceleration (GL) and the predetermined limit value being increased as an absolute value of the lateral acceleration (GL) detected by the lateral acceleration detecting means increases.
Claim 27
Dependent Claim
44 words
A rear wheel steering system for a vehicle in accordance with Claims 22 to 25 further comprising road surface friction coefficient detecting means for detecting a road surface friction coefficient, and the predetermined limit value being increased as the road surface friction coefficient decreases.
Claim 28
Dependent Claim
58 words
A rear wheel steering system for a vehicle in accordance with Claims 22 to 25 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the predetermined limit value being increased as an absolute value of a rate of change in the steering angle detected by the steering angle detecting means increases.
Claim 29
Dependent Claim
75 words
A rear wheel steering system for a vehicle in accordance with Claim 25 wherein the predetermined limit value used when the control means for controlling the steering angle (Xr) of the rear wheels (3) is to be changed from the yaw rate feedback control means (30) to the side slip angle control means (31) is set smaller than the predetermined limit value used when the control means is to be changed between other control means.
Claim 30
Dependent Claim
98 words
A rear wheel steering system for a vehicle in accordance with Claims 1 to 3 and 7 to 9 further comprising steering rate restricting means adapted for restricting a steering rate of the rear wheels (3) so as to steer the rear wheels (3) at a steering rate lower than a steering rate calculated by the yaw rate feedback control means (30), when, during increase of an absolute value of the detected yaw rate (Y), an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) exceeds a predetermined value.
Claim 31
Dependent Claim
136 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 wherein further comprising steering angle detecting means for detecting a steering angle of a steering wheel and steering angle restricting means (35) adapted for restricting a steering rate of the rear wheels (3) so as to steer the rear wheels (3) at a steering rate lower than a steering rate calculated by the control means selected by the control mode selection means (33) when, during increase of an absolute value of the detected yaw rate (Y) after a change in a sign of a rate of change in the steering angle detected by the steering angle detecting means, an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) exceeds a predetermined value.
Claim 32
Dependent Claim
76 words
A rear wheel steering system for a vehicle in accordance with Claims 30 and 31 wherein the steering angle restricting means (35) stops restricting the steering rate and the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when the absolute value of the deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) begins to decrease.
Claim 33
Dependent Claim
117 words
A rear wheel steering system for a vehicle in accordance with Claims 1 to 3 and 7 to 9 further comprising steering angle restricting means (35) adapted for restricting the steering angle (Xr) of the rear wheels (3) so that an amount of steering of the rear wheels (3) becomes maximum to decrease an absolute value of the detected yaw rate (Y) when, during increase of an absolute value of the detected yaw rate (Y), an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rated (Yo) exceeds a predetermined value and an absolute value of a rate of change (dE) in the deviation (E) exceeds a predetermined value (dE0).
Claim 34
Dependent Claim
134 words
A rear wheel steering system for a vehicle in accordance with Claims 1 to 3 and 7 to 9 further comprising steering angle detecting means for detecting a steering angle of a steering wheel (1) and steering angle restricting means (35) adapted for restricting the steering angle (Xr) of the rear wheels (3) so that an amount of steering the rear wheels (3) becomes maximum to decrease an absolute value of the detected yaw rate (Y) when, during increase of an absolute value of the detected yaw rate (Y) after a change in a sign of a rate of change in the steering angle detected by the steering angle detecting means, an absolute value of a deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) exceeds a predetermined value.
Claim 35
Dependent Claim
76 words
A rear wheel steering system for a vehicle in accordance with Claims 33 and 34 wherein the steering angle restricting means (35) stops restricting the steering rate and the control mode selection means (33) causes the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when the absolute value of the deviation (E) between the detected yaw rate (Y) and the target yaw rate (Yo) begins to decrease.
Claim 36
Dependent Claim
41 words
A rear wheel steering system for a vehicle in accordance with Claims 3, 4 and 7 to 9 further comprising function correcting means for correcting a membership function of the fuzzy control means (32) in accordance with a road surface condition.
Claim 37
Dependent Claim
78 words
A rear wheel steering system for a vehicle in accordance with Claim 36 further comprising road surface friction coefficient detecting means for detecting a road surface friction coefficient, and the function correcting means being adapted for correcting the membership function of the fuzzy control means (32) so that an absolute value of the steering angle (Xr) of the rear wheels (3) increases as the road surface friction coefficient detected by the road surface friction coefficient detecting means increases.
Claim 38
Dependent Claim
72 words
A rear wheel steering system for a vehicle in accordance with Claim 36 further comprising lateral acceleration detecting means for detecting a lateral acceleration (GL), and the function correcting means being adapted for correcting the membership function of the fuzzy control means (32) so that an absolute value of the steering angle (Xr) of the rear wheels (3) increases as the lateral acceleration (GL) detected by the lateral acceleration detecting means decreases.
Claim 39
Dependent Claim
109 words
A rear wheel steering system for a vehicle in accordance with Claims 2 and 7 to 9 wherein the control mode selection means (33) is constituted so that even when the steering angle (Xr) of the rear wheels (3) is to be controlled by the side slip angle control means (31), it prevents the side slip angle control means (31) from controlling the steering angle (Xr) of the rear wheels (3) until the steering angle (Xr) calculated by the side slip angle control means (31) becomes equal to or greater than the steering angle (Xr) of the rear wheels (3) calculated by the yaw rate feedback control means (30).
Claim 40
Dependent Claim
106 words
A rear wheel steering system for a vehicle in accordance with Claims 2 and 7 to 9 wherein the control mode selection means (33) is constituted so that when the steering angle (Xr) of the rear wheels (3) which has been controlled by the yaw rate feedback control means (30) so far is controlled by the side slip angle control means (31), it causes the side slip angle control means (31) to start controlling the steering angle (Xr) of the rear wheels (3) using the steering angle (Xr) of the rear wheels (3) calculated by the yaw rate feedback control means (30) as an initial value.
Claim 41
Dependent Claim
164 words
A rear wheel steering system for a vehicle in accordance with Claim 40 further comprising a vehicle rate sensor/vehicle speed sensor (40) for detecting a vehicle rate/vehicle speed (V) and a lateral acceleration sensor (43) for detecting a lateral acceleration (GL), and wherein in changing the control means for controlling the steering angle (Xr) of the rear wheels (3) from the yaw rate feedback control means (30) to the side slip angle control means (31), the side slip angle control means (31) determines whether or not the vehicle rate/vehicle speed (V) detected by the vehicle rate sensor/vehicle speed sensor (40) is greater than a predetermined value and the lateral acceleration (GL) detected by the lateral acceleration sensor (43) is greater than a predetermined value, and, if they are not, controls the steering angle (Xr) of the rear wheels (3) so as to make it equal to the steering angle (Xr) of the rear wheels (3) calculated by the yaw rate feedback control means (30).
Claim 42
Dependent Claim
115 words
A rear wheel steering system for a vehicle in accordance with Claims 2 and 7 to 9 further comprising control value correcting means (38) adapted for correcting an absolute value of the steering angle (Xr) of the rear wheels (3) calculated by the side slip angle control means (31) so as to make it greater when an absolute value of a rate of change in the side slip angle (z) calculated by the side slip angle calculating means (34) is equal to or greater than a predetermined value (z0) and a sign of the rate of change in the side slip angle (z) is the same as that of the calculated side slip angle (z).
Claim 43
Dependent Claim
151 words
A rear wheel steering system for a vehicle in accordance with Claim 42 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the control value correcting means (38) being adapted for correcting the absolute value of the steering angle (Xr) of the rear wheels (3) calculated by the side slip angle control means (31) so as to become greater when an absolute value of a rate of change in the steering angle detected by the steering angle sensor (41) is not greater than a predetermined value, the absolute value of the rate of change in the side slip angle (z) calculated by the side slip angle calculating means (34) is equal to or greater than a predetermined value and the sign of the rate of change in the side slip angle (z) is the same as that of the calculated side slip angle (z).
Claim 44
Dependent Claim
143 words
A rear wheel steering system for a vehicle in accordance with Claim 1 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the second rear wheel steering angle control means, the steering wheel (1) once turned in one direction has been turned in the other direction and an absolute value of a difference between the steering angle (Xr) of the rear wheels (3) calculated by the second rear wheel steering angle control means and that calculated by the yaw rate feedback control means (30) has become equal to or smaller than a predetermined value.
Claim 45
Dependent Claim
141 words
A rear wheel steering system for a vehicle in accordance with Claim 2 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by the side slip angle control means (31), the steering wheel (1) once turned in one direction has been turned in the other direction and an absolute value of a difference between the steering angle (Xr) of the rear wheels (3) calculated by the side slip angle control means (31) and that calculated by the yaw rate feedback control means (30) has become equal to or smaller than a predetermined value.
Claim 46
Dependent Claim
135 words
A rear wheel steering system for a vehicle in accordance with Claim 3 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle of the rear wheels when, during control of the steering angle (Xr) of the rear wheels (3) by the fuzzy control means (32), the steering wheel (1) once turned in one direction has been turned in the other direction and an absolute value of a difference between the steering angle (Xr) of the rear wheels (3) calculated by the fuzzy control means (32) and that calculated by the yaw rate feedback control means (30) has become equal to or smaller than a predetermined value.
Claim 47
Dependent Claim
164 words
A rear wheel steering system for a vehicle in accordance with Claims 7 to 9 further comprising steering angle detecting means for detecting a steering angle of a steering wheel, and the control mode selection means (33) being adapted for causing the yaw rate feedback control means (30) to control the steering angle (Xr) of the rear wheels (3) when, during control of the steering angle (Xr) of the rear wheels (3) by a control means for controlling the steering angle (Xr) of the rear wheels (3) other than the yaw rate feedback control means (30), the steering wheel (1) once turned in one direction has been turned in the other direction and an absolute value of a difference between the steering angle (Xr) of the rear wheels (3) calculated by the control means other than the yaw rate feedback control means (30) and that calculated by the yaw rate feedback control means (30) has become equal to or smaller than a predetermined value.
Claim 48
Dependent Claim
43 words
A rear wheel steering system for a vehicle in accordance with Claims 44 to 47 wherein the predetermined value is increased as an absolute value of a rate of change in the steering angle (Xr) detected by the steering angle detecting means increases.
References Cited (Backward Citations)
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