Honda Giken Kogyo Kabushiki Kaisha

Honda Giken Kabushiki Kaisha

Yorihisa Yamamoto

Takashi Nishimori

Yutaka Nishi

Hiroyuki Tokunaga

Shizuo Yagi

Makoto Kawai

Yoshiaki Hirosawa

Hideki Machino

Haruhiko Yoshikawa

Mitsuya Serizawa

Kenichi Nakamura

Makoto Otabe

Ichiro Harada

Hiroshi Tanaka

Shohei Matsuda

Nobuyoshi Asanuma

Yutaka Horiuchi

Hiroshi Sekine

Kiyotaka Hayashi

Hideki Kubonoya

Etsumi Handa

Shintaro Yokoyama

Atsushi Itakagi

Atsushi Itagaki

Yuuichi Okada

Kenichi Nakamuna

In a vehicle steering control system, a manual steering input is assisted by a powered actuating steering torque which is given by K(.gamma.-t.sub.d .multidot.d .gamma./dt), where y is a detected yaw rate, K and t.sub.d are coefficients which depend on a vehicle speed, and d/dt denotes a time derivative. The detected yaw rate contributes to reducing the yaw rate of the vehicle. In particular, the coefficient t.sub.d is positive in value in a low speed range, and substantially linearly decreases with the vehicle speed, becoming negative at a certain intermediate vehicle speed. Thus, in a high speed range, when the vehicle is steered in one direction either by external disturbances or by a manual steering input, the detected yaw rate and the change rate of the yaw rate both contribute to the reduction of the yaw rate. However, in a low speed range, when the vehicle is steered in one direction, the detected yaw rate contributes to the reduction of the yaw rate but the change rate of the yaw rate contributes to the increase of the yaw rate. Thus, in a high speed range, the vehicle is made highly immune against external disturbances and the effort required for the manual steering of the vehicle is increased with the increase in the change rate of the yaw rate. Conversely, in a low speed range, the stability of the vehicle is of no concern, and the effort required for the manual steering of the vehicle is decreased with the increase in the change rate of the yaw rate.

Vehicle steering control system

According to the invention, there is provided is a vehicle steering system which can improve the resistance of a vehicle against external disturbances such as crosswind, and can prevent the operability of the steering system from being seriously affected by a failure in a part of the system related to the generation of steering reaction such as a lateral acceleration sensor, a yaw rate sensor or a reaction control unit. Because the assisting steering torque continues to be produced even when a failure has occurred in a part related to the generation of steering reaction. Therefore, a fail-safe feature can be obtained, and unnecessary loss of the operability of the steering system can be avoided. By reducing the assisting steering torque from the normal level, which is effective when the sensors are operating normally, at such a time, the driveability of the steering system similar to that under the normal condition can be ensured.

Vehicle steering system

In a vehicle steering control system, an actuating torque is applied to steerable wheels according to a steering torque applied to a steering wheel in a conventional manner, and an additional actuating torque is applied to the steering wheel by an electric motor according to lateral dynamic conditions of the vehicle so as to control the lateral stability of the vehicle even in the presence of external interferences such as crosswind. Such external interferences are detected as a lateral dynamic condition of the vehicle such as the yaw rate of the vehicle, and the steering control system produces a steering reaction which counteracts such a lateral dynamic condition by applying the additional actuating torque to the steerable wheels so that the vehicle may maintain a straight course in spite of such external interferences without requiring any intentional efforts by the vehicle operator. A torque steer arising from the drive force applied to power driven steerable wheels can be also controlled as one form of external disturbances. In particular, by amplifying the steering reaction torque when the drive force is great, it is possible to favorably control the influences of a torque steer under any operation conditions.

In a vehicle steering control system, an actuating torque is applied to steerable wheels according to a steering torque applied to a steering wheel in a conventional manner, and an additional actuating torque is applied to the steering wheel by an electric motor according to lateral dynamic conditions of the vehicle so as to control the lateral stability of the vehicle even in the presence of external interferences such as crosswind. Such external interferences are detected as a lateral dynamic condition of the vehicle such as the yaw rate of the vehicle, and the steering control system produces a steering reaction which counteracts such a lateral dynamic condition by applying the additional actuating torque to the steerable wheels so that the vehicle may maintain a straight course in spite of such external interferences without requiring any intentional efforts by the vehicle operator. In particular, by suppressing the additional actuating torque in an understeer condition, the handling of the vehicle can be improved.

The hydroplaning-occurring speed of a vehicle is estimated by detecting an amount of water on a wet road surface on which the vehicle is traveling, and estimating a speed of the vehicle at and above which a hydroplaning phenomenon can occur, based on the detected amount of water. The possibility of occurrence of a hydroplaning phenomenon of a vehicle is detected by detecting an amount of water on a wet road surface on which the vehicle is traveling, detecting the speed of the vehicle, and determining whether there is a possibility that a hydroplaning phenomenon can occur, based on the detected amount of water and the detected speed of the vehicle.

Method and device for estimating hydroplaning-occuring vehicle speed and

In a vehicle steering control system, an actuating torque is applied to steerable wheels according to a steering torque applied to a steering wheel in a conventional manner, and an additional actuating torque is applied to the steering wheel by an electric motor according to lateral dynamic conditions of the vehicle so as to control the lateral stability of the vehicle even in the presence of external interferences such as crosswind. Such external interferences are detected as a lateral dynamic condition of the vehicle such as the yaw rate of the vehicle, and the steering control system produces a steering reaction which counteracts such a lateral dynamic condition by applying the additional actuating torque to the steerable wheels so that the vehicle may maintain a straight course in spite of such external interferences without requiring any intentional efforts by the vehicle operator. By representing the vehicle with a first-order delay transfer function in regards to its lateral dynamic response for each given steering input, the vehicle operator can handle the vehicle without encountering any substantial resistance even when the steering wheel is turned briskly or at high speed.

A road surface condition-detecting system for a vehicle detects a road surface condition from road noise generated by a vehicle wheel. The road surface condition is determined based on parameter data of frequency components of the road noise, by a neural network. The road noise may be corrected by eliminating therefrom a disturbance, such as audio output and exhaust noise. A present state of the road surface condition may be determined based on at least two consecutive determinations made based on the road noise detected at regular time intervals. Exclusive neural networks may be used for respective road surface condition types. One of a plurality of neural networks provided for respective vehicle speed ranges may be selected according to an actual vehicle speed. Detected sound pressure levels of the road noise extracted by frequency analysis may be normalized within respective ranges defined by upper and lower limits set corresponding to predetermined frequency ranges before being supplied to the neural network.

Road surface condition-detecting system and anti-lock brake system

In a vehicle steering control system, an actuating torque is applied to steerable wheels according to a steering torque applied to a steering wheel in a conventional manner, and an additional actuating torque is applied to the steering wheel by an electric motor according to lateral dynamic conditions of the vehicle so as to control the lateral stability of the vehicle even in the presence of external interferences such as crosswind. Such external interferences are detected as a lateral dynamic condition of the vehicle such as the yaw rate of the vehicle, and the steering control system produces a steering reaction which counteracts such a lateral dynamic condition by applying the additional actuating torque to the steerable wheels so that the vehicle may maintain a straight course in spite of such external interferences without requiring any intentional efforts by the vehicle operator. By appropriate selection of the gain of the system for generating the additional actuating torque, this advantage can be gained without causing any excessive reaction when the vehicle is undergoing a normal turning maneuver.

Provided is a vehicle steering system which can substantially stabilize the lateral dynamic behavior of a vehicle with a simple control logic over the entire range of the vehicle speed. A steering torque proportional to a yaw rate and/or a lateral acceleration of the vehicle is applied to the steerable wheels to counteract a lateral deviation of the vehicle. To avoid the oscillatory or overshooting behavior of the control system, a damping torque is applied to the steering wheel. Thus, the counteracting steering torque is given as a mathematical function including a sum of a first term consisting of a product of a yaw rate and/or the lateral acceleration of the vehicle and a first coefficient, and a second term consisting of a product of an angular speed of the steering wheel and a second coefficient. In particular, the first coefficient and second coefficient are variable in a mutually proportional relationship so that the optimum selection of the first and second conditions can be done without any complication.

In a powered vehicle steering system which produces a steering reaction for controlling the lateral movement of the vehicle, the steering reaction including a yaw rate reaction component and a steering wheel damping component, when the vehicle operator is firmly holding the steering wheel or actually turning the steering wheel, the damping component is reduced so that the effort required for turning the steering wheel may be reduced, and the vehicle operator may turn the steering wheel without any substantial effort. Conversely, if the vehicle operator is not firmly holding the steering wheel, and the steering wheel is allowed to move freely, the damping component is increased so that the lateral movement of the vehicle may be stabilized even when the vehicle is subjected to disturbances such as crosswind. Thus, the stability of the lateral movement of the vehicle and the responsiveness of the vehicle steering system can be ensured at the same time.

In a 'steer-by-wire' vehicle steering control system which steers steerable wheels with a powered actuator according to an input signal obtained from a sensor associated with a steering wheel, a secondary actuator is coupled to the steering wheel for the purpose of giving the operator of the vehicle a reaction force. The reaction force on the steering wheel not only gives a familiar sensation to the vehicle operator who is more familiar with a vehicle equipped with more conventional steering system, but also improves the driveability and stability of the vehicle since the reaction force provides information on the condition of the vehicle which aids the vehicle operator in making proper and accurate steering maneuvers.

In a 'steer-by-wire' vehicle steering control system which steers steerable wheels with a powered actuator according to an input signal obtained from a sensor associated with a steering wheel, to the end of achieving an optimum vehicle response to a steering input, a compensatory transfer function is introduced between the steering wheel and the powered steering actuator. The compensatory transfer function can be obtained by suitable manipulation of the transfer functions of the hardware involved and a desired overall transfer function. The frequency domain compensatory transfer function is transformed into a time-domain input-output relationship, and the steering mechanism is actuated accordingly as a real time operation. By suitable selection of the desired overall transfer function, it is possible to achieve a vehicle response both stable and favorable.

In a 'steer-by-wire' vehicle steering control system which steers steerable wheels with a powered actuator according to an input signal obtained from a sensor associated with a steering wheel, a secondary actuator is coupled to the steering wheel for the purpose of giving the operator of the vehicle a reaction force. The reaction force on the steering wheel is sharply increased or oscillated when a limit of the angular displacement of the steering wheel has been reached for the purpose of allowing the vehicle operator to know how far the steering wheel has been turned. The limit of the angular displacement of the steering wheel typically corresponds to the maximally steered condition of the steerable wheels.

A method for detecting malfunctioning of a digital computer of a control device which repetitively processes a main routine and, at each predetermined timing, interrupts the processing of the main routine in order to process at least one interruption routine. The method includes the steps of (a) changing the contents of a first stored data after a predetermined plurality of consecutive interrupt routines are executed, (b) setting a second stored data equal to the first stored data in processing the main routine, (c) outputting the second stored data as a signal from the digital operating circuit in processing the interruption routine, and (d) identifying a malfunction by detecting whether the contents of the second stored data outputted from the circuit remain constant for a time longer than a second predetermined time.

Program execution malfunction detecting method for an automobile

A method for controlling a stepless automatic transmission of a vehicle and an apparatus therefore automatically control the transmission ratio according to the change with respect to time of a throttle aperture and a driving condition of the vehicle. A change with respect to time of the throttle aperture is taken into account in determining the objective engine speed and the transmission ratio. An apparatus includes a throttle sensor for sensing a change with respect to time of the throttle aperture, a first allocator for allocating an objective engine speed in a condition that the change with respect to time of the throttle aperture is within a prescribed range, a second allocator for allocating an objective engine speed in a condition that the throttle aperture is opened more rapidly than a first prescribed value, a third allocator for allocating an objective engine speed in a condition that the throttle aperture is closed more rapidly than a second prescribed value, and a transmission controller for controlling a transmission ratio of the stepless automatic transmission so that an actual engine speed coincides with the objective engine speed. A method includes the steps of sensing a change with respect to time of a throttle aperture, allocating an objective engine speed according to the change with respect to time of the throttle aperture, and controlling a transmission ratio of the stepless automatic transmission so that an actual engine speed coincides with the objective engine speed.

Growing community of inventors

Saitama, Japan

Yorihisa Yamamoto