Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-08-28
2001-04-03
Cuchlinski, Jr., William A (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S023000, C180S168000, C180S204000, C307S009100
Reexamination Certificate
active
06212452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic steering system for a vehicle, for automatically parking the vehicle without recourse to a steering operation by a driver.
2. Description of the Prior Art
Automatic steering systems for vehicles are already known from Japanese Patent Application Laid-open Nos. 3-74256 and 4-55168 and the like. The automatic steering systems for vehicles utilize an actuator for a conventionally well-known electric power steering device, and are designed so that back parking and linear parking are automatically controlled by controlling the actuator based on the relationship between a distance of movement of the vehicle and a steering angle that has been previously stored.
In the known automatic steering system, when a driver operates a steering wheel during an automatic steering control operation and it is determined that the steering torque exceeds a previously set reference steering torque, the automatic steering control operation is discontinued.
However, there is a problem that if the determination is carried out only by comparing an output from a steering torque detecting means with the reference steering torque, the output from the steering torque detecting means may temporarily exceed the reference steering torque due to noise in the steering torque detecting means, or due to an inertial torque of the steering wheel when a tire contacts a bump in the road or a curb, or when an automatic steering operation is carried out through the actuator, and at each time, the automatic steering operation is discontinued. If the reference steering torque is set at a higher value in order to avoid such a disadvantage, there is a possibility that the automatic steering operation and the manual steering operation may interfere with each other to give a sense of incompatibility to the driver, and if the driver operates the steering wheel during the automatic steering control operation, the automatic steering control operation may not immediately be discontinued.
SUMMARY OF THE INVENTION
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to ensure that the steering operation by the driver during the automatic steering control operation, can be detected to reliably discontinue the automatic steering control operation.
To achieve the above object, there is provided an automatic steering system for a vehicle, comprising a movement locus setting means adapted to store or calculate a locus of movement of the vehicle to a target position, an actuator for steering a wheel of the vehicle, and a control means for controlling the driving of the actuator based on the locus of movement set by the movement locus setting means. The automatic steering system further includes a steering operation detecting means for detecting a steering operation by a driver, so that when the steering operation detecting means detects the steering operation by the driver for at least a predetermined time, the control means discontinues the control of the actuator based on the locus of movement.
With the above arrangement, even if the output from the steering torque detecting means is temporarily increased due to noise or due to an inertial torque generated when a tire contacts a bump in the road or a curb, the control means does not discontinue the control of the actuator based on the locus of movement. Therefore, there is not a possibility that the automatic steering operation will be discontinued against the driver's will. When the driver's steering operation has been carried out, the predetermined time corresponds to a minimum duration which at least exceeds the time and in which a steering torque is detected. The predetermined time is set at 0.1 second in the described embodiment, but can be changed.
In addition, the predetermined time is set larger than one half of an intrinsic period (T) of a steering section. With the above arrangement, the steering torque generated by the driver's steering operation can be discriminated from an inertial torque generated when a tire contacts a bump in the road or a curb.
Further, the locus of movement of the vehicle is set as a steering angle of the wheel with respect to a distance of movement of the vehicle. Thus, even if the traveling speed of the vehicle is varied, a constant locus of movement can be ensured.
The automatic steering system further includes a brake input means operated by the driver, and the driving of the actuator based on the locus of movement, is permitted only when the brake input means is being operated. With the above arrangement, when the vehicle is moved close to an obstacle, the brake input means can be immediately operated to stop the vehicle.
In addition, the steering operation detecting means detects the steering operation by the driver, when a torque inputted to a steering wheel is equal to or larger than a reference steering torque. Thus the influence of noise can be eliminated, whereby the steering operation by the driver can be reliably detected. The reference torque is a value which ensures that the steering torque generated by the driver's steering operation can be discriminated from noise or the like. The reference torque is set at 0.2 kgf-m in the described embodiment, but can be changed.
The predetermined time or the reference steering torque can be changed in accordance with the state of variation in torque inputted to the steering wheel. It is thus possible to reliably determine whether the detected torque is a torque generated by the driver's steering operation, or a torque generated due to any other factor.
The state of variation in torque is a torque variation frequency, and the predetermined time is prolonged or the reference steering torque is increased, in accordance with an increase in the torque variation frequency. In view of the fact that the torque variation frequency is larger, the torque generated due to any factor other than the driver's steering operation, can be discriminated from the torque generated by the driver's steering operation.
The automatic steering system further includes a vehicle speed detecting means for detecting the vehicle speed, and the predetermined time or the reference steering torque is changed in accordance with the vehicle speed. Thus even if an inertial torque generated when a tire contacts a bump in the road, is varied in accordance with the vehicle speed, the predetermined time or the reference steering torque is changed in accordance with the variation. Therefore, the inertial torque can be reliably discriminated from the torque generated by the driver's steering operation.
The predetermined time is prolonged or the reference steering torque is increased, in accordance with an increase in vehicle speed, and in view of the fact that the inertial torque generated when a tire contacts a bump in the road, is larger at a higher vehicle speed, the inertial torque can be further reliably discriminated from the torque generated by the driver's steering operation.
Further, the predetermined time or the reference steering torque is changed in accordance with the state of the steered wheel. Thus, even if the inertial torque generated when a tire contacts a bump in the road, is varied in accordance with the state of the steered wheel, the predetermined time or the reference steering torque is changed in accordance with the variation. Therefore, the inertial torque can be reliably discriminated from the torque generated by the driver's steering operation.
The state of the steered wheel is a steering angular speed or a steering angular acceleration, and the predetermined time is prolonged or the reference steering torque is increased, in accordance with an increase in steering angular speed or in steering angular acceleration. In view of the fact that the inertial torque is increased with an increase in steering angular speed or in steering angular acceleration, the inertial torque can be reliably discrimin
Sakai Katsuhiro
Shimizu Yasuo
Arent Fox Kintner & Plotkin & Kahn, PLLC
Beaulieu Yonel
Cuchlinski, Jr. William A
Honda Giken Kogyo Kabushiki Kaisha
LandOfFree
Automatic steering system for vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic steering system for vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic steering system for vehicle will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2502283