Abstract: A vehicle C is provided with four wheel speed sensors VS (VSfl, VSfr, VSrl, VSrr) (wheel vibration detection means) for detecting wheel speed V (Vfl, Vfr, Vrl, Vrr) at respective four wheels W (left and right front wheels Wfl, Wfr and left and right rear wheels Wrl, Wrr). When the tire pressure is in the normal value, a tire pressure monitoring system 1 prepares vibration frequency reference spectrum data for predetermined vehicle speed bands based on the detection values of each wheel speed sensor VS. The tire pressure monitoring system 1 compares the current vibration frequency spectrum data and the vibration frequency reference spectrum data corresponding to the current vehicle speed band, and determines that the tire is underinflated if the comparison result exceeds a predetermined value.

Abstract: A radius of a corner is determined by using a corner radius calculating device based on road data and data related to position of a vehicle on the road. An actual turning radius when the vehicle enters the corner is estimated by an actual turning radius calculating device based on at least a vehicle speed and motion parameters of the vehicle, and the motion state of the vehicle is controlled by the motion state control device so that an actual turning radius of the vehicle becomes close to the radius of the corner based on a calculation by radius difference calculating device for calculating a difference between the calculated corner radius and the actual turning radius. Thus, a motion state of the vehicle at a time of traveling around the corner is properly controlled to enable the vehicle to pass the corner reliably.

Abstract: A vehicle speed measuring apparatus includes front and rear wheel side vibration detection sensors for detecting vibrations from a road surface through tires, an input section through which the vibration detection sensors input their detection values, and a processing unit for calculating vehicle speed of the vehicle based on a change pattern of the detection values inputted. When the detection values are inputted through the input section, the processing unit feature extracts a change pattern of the detection values for the respective front and rear wheel sides by excluding inherent tire influences on the detection values, executes pattern matching between the front and rear wheel sides on the basis of the feature extracted change patterns of the detection values, and obtains a time difference from a coincidence of the change patterns, and thereafter calculates vehicle speed based on the time difference and a reference distance such as a wheel base.

Abstract: A rotational speed V1 of a left front wheel T1, a rotational speed V2 of a right front wheel T2, a rotational speed V3 of a left rear wheel T3, and a rotational speed V4 of a right rear wheel T4 are detected by rotational speed sensors S1-S4, respectively. A front-wheel yaw rate ?F arising due to a rotational speed difference between the front wheels T1, T2 and a rear-wheel yaw rate ?R arising due to a rotational speed difference between the rear wheels T3, T4 are monitored. When a significant disparity between the both rotational speed differences is observed, it is determined that tire inflation pressure of any of the wheels T1-T4 has decreased. Upon detection, correction is made to an apparent yaw rate that would be observed in the properly inflated wheel as a result of steering for correction by a driver, thereby improving detection accuracy of underinflation of the tires.

Abstract: A four-wheel vehicle is equipped with rotational speed sensors S1-S4 that detect a rotational speed V1 of a left front wheel T1, a rotational speed V2 of a right front wheel T2, a rotational speed V3 of a left rear wheel T3 and a rotational speed V4 of a right rear wheel T4, respectively, and a yaw rate sensor S&ggr; that detects a yaw rate of the vehicle. An underinflation detector 1 includes a controller 2 that calculates a front-wheel yaw rate &ggr;F derived from a difference in rotational speed between the front wheels T1, T2, a rear-wheel yaw rate &ggr;R derived from a difference in rotational speed between the rear wheels T3, T4, and deviations of the yaw rates &ggr;F, &ggr;R from an actually measured value output from the yaw rate sensor S&ggr;. A rate of change of the deviation with respect to change of vehicle speed is determined to thereby detect insufficiency of inflation pressure of tires with high reliability.

Abstract: A vehicle C is provided with four wheel speed sensors VS (VSfl, VSfr, VSrl, VSrr) (wheel vibration detection means) for detecting wheel speed V (Vfl, Vfr, Vrl, Vrr) at respective four wheels W (left and right front wheels Wfl, Wfr and left and right rear wheels Wrl, Wrr). When the tire pressure is in the normal value, a tire pressure monitoring system 1 prepares vibration frequency reference spectrum data for predetermined vehicle speed bands based on the detection values of each wheel speed sensor VS. The tire pressure monitoring system 1 compares the current vibration frequency spectrum data and the vibration frequency reference spectrum data corresponding to the current vehicle speed band, and determines that the tire is underinflated if the comparison result exceeds a predetermined value.

Abstract: A radius of a corner is obtained by corner radius arithmetically operating means based on road data and an own vehicle position on the road data, then an actual turning radius when the own vehicle enters the corner is estimated by actual radius arithmetically operating means based on at least an own vehicle speed and motion parameters of the vehicle, and the motion state of the own vehicle is controlled by the motion state control means so that an actual turning radius becomes close to the radius of the corner based on a calculation by radius difference calculating means for calculating a difference between the radius arithmetically operated by the corner radius arithmetically operating means and the actual turning radius. Thus, a motion state of the vehicle at a time of traveling around the corner is properly controlled to enable the vehicle to pass the corner reliably.

Abstract: Hydroplaning detection apparatus operates to feature extract a change pattern of vibration detection values for the respective front and rear wheel sides of a vehicle by excluding inherent tire influences on the vibration detection values, to execute pattern matching between the front and rear wheel sides on the basis of the feature extracted change patterns of the detection values, to obtain a time difference from a coincidence of the change patterns, and to calculate a first vehicle speed based on the time difference and a reference distance such as a wheel base of the vehicle. The hydroplaning detection apparatus also operates to calculate a second vehicle speed based on an average value of wheel speeds detected by the rear wheel speed sensor. The hydroplaning detection apparatus determines that hydroplaning has occurred if a deviation between the first vehicle speed and the second vehicle speed is greater than a certain value.

Abstract: A rotational speed V1 of a left front wheel T1, a rotational speed V2 of a right front wheel T2, a rotational speed V3 of a left rear wheel T3, and a rotational speed V4 of a right rear wheel T4 are detected by rotational speed sensors S1-S4, respectively. A front-wheel yaw rate &ggr;F arising due to a rotational speed difference between the front wheels T1, T2 and a rear-wheel yaw rate &ggr;R arising due to a rotational speed difference between the rear wheels T3, T4 are monitored. When a significant disparity between the both rotational speed differences is observed, it is determined that tire inflation pressure of any of the wheels T1-T4 has decreased. Upon detection, correction is made to an apparent yaw rate that would be observed in the properly inflated wheel as a result of steering for correction by a driver, thereby improving detection accuracy of underinflation of the tires.

Abstract: A vehicle speed measuring apparatus includes front and rear wheel side vibration detection sensors for detecting vibrations from a road surface through tires, an input section through which the vibration detection sensors input their detection values, and a processing unit for calculating vehicle speed of the vehicle based on a change pattern of the detection values inputted. When the detection values are inputted through the input section, the processing unit feature extracts a change pattern of the detection values for the respective front and rear wheel sides by excluding inherent tire influences on the detection values, executes pattern matching between the front and rear wheel sides on the basis of the feature extracted change patterns of the detection values, and obtains a time difference from a coincidence of the change patterns, and thereafter calculates vehicle speed based on the time difference and a reference distance such as a wheel base.

Abstract: A four-wheel vehicle is equipped with rotational speed sensors S1-S4 that detect a rotational speed V1 of a left front wheel T1, a rotational speed V2 of a right front wheel T2, a rotational speed V3 of a left rear wheel T3 and a rotational speed V4 of a right rear wheel T4, respectively, and a yaw rate sensor S&ggr; that detects a yaw rate of the vehicle. An underinflation detector 1 includes a controller 2 that calculates a front-wheel yaw rate &ggr;F derived from a difference in rotational speed between the front wheels T1, T2, a rear-wheel yaw rate &ggr;R derived from a difference in rotational speed between the rear wheels T3, T4, and deviations of the yaw rates &ggr;F, &ggr;R from an actually measured value output from the yaw rate sensor S&ggr;. A rate of change of the deviation with respect to change of vehicle speed is determined to thereby detect insufficiency of inflation pressure of tires with high reliability.

Abstract: In a vehicle motion control system based on a target yaw rate scheme, a brake force computing unit brakes an outer front wheel in a controlled manner when a sign of the yaw rate has changed and the yaw rate increment has become equal to or greater than a threshold value after a counter steer action has been detected and the vehicle body slip angle has become equal to or greater than a threshold value. Thus, suppose that a vehicle travels a winding road and a counter steer action is taken. If the vehicle body slip angle and actual yaw rate increment exceed threshold values, the outer front wheel is braked. Therefore, even when the vehicle body slip angle reaches a maximum value and an attempt is made to reduce it again by a counter steer action in a similar manner as a swinging pendulum, because the increases in the yaw rate and actual yaw rate increment are predicted and monitored before the vehicle body slip angle reaches its maximum value, the vehicle is enabled to travel in a stable fashion.

Abstract: In a system for computing a road surface frictional coefficient for controlling a motion of a vehicle, the road surface frictional coefficient is estimated according to the deviation of the estimated vehicle body fore-and-aft/lateral acceleration from the actually detected vehicle body fore-and-aft/lateral acceleration, instead of estimating it directly from the tire slip ratio so that the road surface frictional coefficient is prevented from being estimated substantially higher than it actually is. In particular, by judging a sudden change in the road surface frictional coefficient only when a change in the road surface frictional coefficient, in particular an increase in the frictional coefficient, has persisted for more than a prescribed time period, an error in the estimation of the road surface frictional coefficient can be minimized, and a favorable vehicle motion control based on the estimated road surface frictional coefficient can be ensured under all conditions.

Abstract: An electrically operated parking brake apparatus that includes an electric motor and a screw mechanism The screw mechanism includes a screw-threaded shaft adapted to be rotationally driven by the electric motor, and a nut member meshing with the screw-threaded shaft, the nut member being movable along the screw-threaded shaft by the rotation of the screw-threaded shaft. The parking brake apparatus also includes a transmission member connected to the nut member for transmitting a brake operating force to a wheel brake, and a rotation preventing unit for preventing the rotation of the screw-threaded shaft so as to hold the brake operating force by fixing the position of the nut member relative to the screw-threaded shaft. The rotation preventing unit in one embodiment is an electromagnetic brake for confining the screw-threaded shaft to a stationary portion of a vehicle body.

Abstract: In a vehicle motion control system based on a target yaw rate scheme, a brake force computing unit brakes an outer front wheel in a controlled manner when a sign of the yaw rate has changed and the yaw rate increment has become equal to or greater than a threshold value after a counter steer action has been detected and the vehicle body slip angle has become equal to or greater than a threshold value. Thus, suppose that a vehicle travels a winding road and a counter steer action is taken. If the vehicle body slip angle and actual yaw rate increment exceed threshold values, the outer front wheel is braked. Therefore, even when the vehicle body slip angle reaches a maximum value and an attempt is made to reduce it again by a counter steer action in a similar manner as a swinging pendulum, because the increases in the yaw rate and actual yaw rate increment are predicted and monitored before the vehicle body slip angle reaches its maximum value, the vehicle is enabled to travel in a stable fashion.

Abstract: In a system for computing a road surface frictional coefficient for controlling a motion of a vehicle, the road surface frictional coefficient is estimated according to the deviation of the estimated vehicle body fore-and-aft/lateral acceleration from the actually detected vehicle body fore-and-aft/lateral acceleration, instead of estimating it directly from the tire slip ratio so that the road surface frictional coefficient is prevented from being estimated substantially higher than it actually is. In particular, by judging a sudden change in the road surface frictional coefficient only when a change in the road surface frictional coefficient, in particular an increase in the frictional coefficient, has persisted for more than a prescribed time period, an error in the estimation of the road surface frictional coefficient can be minimized, and a favorable vehicle motion control based on the estimated road surface frictional coefficient can be ensured under all conditions.

Abstract: An electrically operated parking brake apparatus that includes an electric motor and a screw mechanism The screw mechanism includes a screw-threaded shaft adapted to be rotationally driven by the electric motor, and a nut member meshing with the screw-threaded shaft, the nut member being movable along the screw-threaded shaft by the rotation of the screw-threaded shaft. The parking brake apparatus also includes a transmission member connected to the nut member for transmitting a brake operating force to a wheel brake, and a rotation preventing unit for preventing the rotation of the screw-threaded shaft so as to hold the brake operating force by fixing the position of the nut member relative to the screw-threaded shaft. The rotation preventing unit in one embodiment is an electromagnetic brake for confining the screw-threaded shaft to a stationary portion of a vehicle body.

Abstract: The turning behavior state of a vehicle is determined by a determining device, by comparing a front wheel slip angle and a rear wheel slip angle calculated based on a lateral slip angle of a vehicle body by a wheel slip angle calculating device, with a front wheel slip angle limit value and a rear wheel slip angle limit value which are determined based on a vehicle speed detected by a vehicle speed detecting device and a friction coefficient presumed by a friction coefficient presuming device. Thus, even in a state in which the road surface friction coefficient is low, the turning behavior state of the vehicle can be detected precisely.

Abstract: A travel state of a vehicle is detected by a travel-state detecting device. A lateral slip angle of a vehicle body is calculated as a first lateral slip angle in a first lateral slip angle calculating device by integrating a differentiated value of lateral slip angle determined based on a non-linear four-wheel vehicle's motion model. A lateral slip angle of the vehicle body is calculated as a second lateral slip angle in a second lateral slip angle calculating device by a calculation in a linear two-wheel vehicle's motion model. One of the first and second lateral slip angles is selected alternatively in a selecting device in accordance with the travel state detected by the travel-state detecting device such that the second lateral slip angle is selected when the travel-state detecting device detects a state in which the vehicle is traveling straightforwardly at a low speed.

Abstract: A hydroplaning detection system comprising AM specific frequency component extraction AM, which comprises a band-pass filter for extracting signal components PS in a main frequency band corresponding to the wheel rotation speed or the vehicle speed from wheel rotation speed signals, and a band-pass filters for respectively extracting signal components PL in other frequency bands, and AM determining the occurrence of hydroplaning based on the ratio PL/PS between the signal components PS in the main frequency band and the signal components PL in other frequency bands.