A precipitation index estimation apparatus includes a data collection unit and an estimation processing unit. The data collection unit is configured to collect rainfall amount data detected by a rainfall amount sensor in one or more vehicles positioned on a predetermined road link within a predetermined period. The estimation processing unit is configured to estimate a precipitation index indicating an intensity of precipitation on the predetermined road link within the predetermined period, based on the collected rainfall amount data.

A precipitation index estimation apparatus includes a data collection unit and an estimation processing unit. The data collection unit is configured to collect rainfall amount data detected by a rainfall amount sensor in one or more vehicles positioned on a predetermined road link within a predetermined period. The estimation processing unit is configured to estimate a precipitation index indicating an intensity of precipitation on the predetermined road link within the predetermined period, based on the collected rainfall amount data.

A vehicle control device controls a driving device in such a manner that driving torque coincides with normal torque. The vehicle control device starts a traction control for controlling the driving device in such a manner that the driving torque coincides with suppressed torque which is smaller than the normal torque, when a predetermined traction control start condition is satisfied. The vehicle control device determines that the driver is in a non-grasp state, when an operation amount has changed to satisfy a condition in an initial determination time period. The vehicle control device starts, at an acceleration time point, an operation priority control for controlling the driving device in such a manner that the driving torque coincides with acceleration priority torque which is larger than the suppressed torque and smaller than the normal torque, if the control device had not determined that the driver was in the non-grasp state.

A vehicle control device controls a driving device in such a manner that driving torque coincides with normal torque. The vehicle control device starts a traction control for controlling the driving device in such a manner that the driving torque coincides with suppressed torque which is smaller than the normal torque, when a predetermined traction control start condition is satisfied. The vehicle control device determines that the driver is in a non-grasp state, when an operation amount has changed to satisfy a condition in an initial determination time period. The vehicle control device starts, at an acceleration time point, an operation priority control for controlling the driving device in such a manner that the driving torque coincides with acceleration priority torque which is larger than the suppressed torque and smaller than the normal torque, if the control device had not determined that the driver was in the non-grasp state.

According to one or more embodiments, a method includes computing, by a steering system, a model rack force value based on a vehicle speed, steering angle, and a road-friction coefficient value. The method further includes determining, by the steering system, a difference between the model rack force value and a load rack force value. The method further includes updating, by the steering system, the road-friction coefficient value using the difference that is determined.

According to one or more embodiments, a method includes computing, by a steering system, a model rack force value based on a vehicle speed, steering angle, and a road-friction coefficient value. The method further includes determining, by the steering system, a difference between the model rack force value and a load rack force value. The method further includes updating, by the steering system, the road-friction coefficient value using the difference that is determined.

A vehicle information calculation apparatus includes a motor torque acquisition unit, an angular acceleration acquisition unit, a contact force acquisition unit, and an inertia moment calculator. The motor torque acquisition unit acquires a torque of a motor that drives a vehicle. The angular acceleration acquisition unit acquires an angular acceleration of the motor. The contact force acquisition unit acquires a contact force of a wheel of the vehicle. The inertia moment calculator calculates an inertia moment of a rotating system of the vehicle including the wheel on the basis of the torque acquired by the motor torque acquisition unit, the angular acceleration acquired by the angular acceleration acquisition unit, the contact force acquired by the contact force acquisition unit, and a coefficient of friction between the wheel of the vehicle and a contact surface.

A vehicle information calculation apparatus includes a motor torque acquisition unit, an angular acceleration acquisition unit, a contact force acquisition unit, and an inertia moment calculator. The motor torque acquisition unit acquires a torque of a motor that drives a vehicle. The angular acceleration acquisition unit acquires an angular acceleration of the motor. The contact force acquisition unit acquires a contact force of a wheel of the vehicle. The inertia moment calculator calculates an inertia moment of a rotating system of the vehicle including the wheel on the basis of the torque acquired by the motor torque acquisition unit, the angular acceleration acquired by the angular acceleration acquisition unit, the contact force acquired by the contact force acquisition unit, and a coefficient of friction between the wheel of the vehicle and a contact surface.

Systems and methods are disclosed for estimating slipperiness of a road surface. This estimate may be obtained using an image sensor mounted on a vehicle. The estimated road slipperiness may be utilized when calculating a risk index for the road, or for an area including the road. If a predetermined threshold for slipperiness is exceeded, corrective actions may be taken. For instance, warnings may be generated to human drivers that are in control of driving vehicle, and autonomous vehicles may automatically adjust vehicle speed based upon road slipperiness detected.

A tire-side device is attached to a tire included in a vehicle and applied to a tire apparatus for estimating a condition of a road surface on which the vehicle travels. The tire-side device includes: a vibration detector outputting a detection signal according to a level of vibration of the tire; a controller having a feature quantity extraction device extracting a feature quantity of the detection signal in one rotation of the tire; and a transmitter transmitting road surface data including the feature quantity extracted by the feature quantity extraction device.