Vehicle speed control system

Claim 2

A vehicle speed control system comprising: first means for inputting a set speed in response to a driver's operation; second means for sensing an actual vehicle speed of a controlled vehicle; third means for measuring a distance of the controlled vehicle from a forward vehicle in front of the controlled vehicle; fourth means for setting a desired travel speed in accordance with the set speed, the actual speed and the distance; fifth means for controlling the actual vehicle speed to the desired travel speed; sixth means for estimating a road environment recognition characteristic for a driver of the controlled vehicle; and seventh means for determining at least one of the distance and the travel speed in accordance with the road environment recognition characteristic.

Claim 3

A vehicle speed control system as claimed in claim 1 wherein said sixth means includes means for estimating the road environment recognition characteristic in accordance with a degree of difficulty in obtaining a distant view along a forward road.

Claim 4

A vehicle speed control system as claimed in claim 1 wherein said sixth means comprises imaging means for forming an image of a forward road, edge detecting means for detecting edges in the image and determining a characteristic quantity which is a number of detected edges, and correction calculating means for determining a value of a first correction quantity corresponding to the characteristic quantity according to a first relationship between the first correction quantity and the characteristic quantity and a value of a second correction quantity corresponding to the characteristic quantity according to a second relationship between the second correction quantity and the characteristic quantity, and said seventh means includes means for determining the distance and the travel speed by addition of said first and second correction quantities to the distance and the set speed, respectively.

Claim 5

A vehicle speed control system as claimed in claim 1 wherein said sixth means comprises imaging means for forming an image of the forward road, area ratio calculating means for calculating a characteristic quantity which is a ratio of an area of at least one region having a predetermined image attribute to a total area of the image of the forward road, and correction calculating means for calculating, from the characteristic quantity, first and second correction quantities for the distance and the travel speed according to first and second predetermined relationships, and said seventh means includes means for determining the distance and the travel speed by addition of said first and second correction quantities to the distance and the set speed, respectively, said image attribute being one of a predetermined luminance level and a predetermined color.

Claim 6

A vehicle speed control system as claimed in claim 1 wherein said sixth means includes means for estimating said road environment recognition characteristic in accordance with a road parameter which is one of a road width, a road rank and a number of branch points of a road.

Claim 7

A vehicle speed control system as claimed in claim 5 wherein said sixth means is connected with an onboard navigation system, and configured to receive information on the road parameter from the onboard navigation system.

Claim 8

A vehicle speed control system as claimed in claim 5 wherein said sixth means is connected with an information communicating device for receiving information on the road parameter from a road traffic infrastructure.

Claim 9

A vehicle speed control system as claimed in claim 5 wherein said sixth means is connected with imaging means for forming an image of a forward road, and configured to obtain information on the road parameter from the image of the forward road.

Claim 10

A vehicle speed control system as claimed in claim 1 wherein said sixth means includes means for determining a standard deviation of an accelerator opening over a predetermined time interval before a start of a constant speed control, and for estimating the road environment recognition characteristic in accordance with the standard deviation.

Claim 11

A vehicle speed control system for a controlled vehicle, comprising: an input section comprising a first input subsection for sensing an actual vehicle speed of the controlled vehicle, a second input subsection for inputting a desired set speed, and a third input subsection for measuring a distance of the controlled vehicle from a vehicle ahead; an actuator section for varying the vehicle speed of the controlled vehicle in response to a control signal; a controller section for controlling the actual vehicle speed of the controlled vehicle by producing the control signal according to a control characteristic in response to input signals sent from the first, second and third input subsections; wherein the input section further comprises a fourth input subsection for collecting information on a driving environment perceived by a driver of the controlled vehicle, and the controller section is configured to determine an environment recognition characteristic quantity in accordance with the information collected by the fourth input subsection and to modify the control characteristic in accordance with the environment recognition characteristic quantity.

Claim 12

A vehicle speed control system for a controlled vehicle, comprising: an input section comprising a first input subsection for sensing an actual vehicle speed of the controlled vehicle, a second input subsection for inputting a desired set speed, and a third input subsection for measuring a distance of the controlled vehicle from a vehicle ahead; an actuator section for varying the vehicle speed of the controlled vehicle in response to a control signal; a controller section for controlling the actual vehicle speed of the controlled vehicle by producing the control signal according to a control characteristic in response to input signals sent from the first, second and third input subsections; wherein the input section further comprises a fourth input subsection for collecting information on a driving environment perceived by a driver of the controlled vehicle, and the controller section is configured to determine an environment recognition characteristic quantity in accordance with the information collected by the fourth input subsection and to modify the control characteristic in accordance with the environment recognition characteristic quantity.

Claim 13

A vehicle speed control system as claimed in claim 10 wherein the fourth input subsection comprises a device which is one of an imager for forming an electronic image of a road ahead of the controlled vehicle, a storage device for storing a road map, an onboard data communicating device for obtaining road traffic information from an outside of the vehicle, and an accelerator position sensor for sensing a position of a vehicle accelerating system operated by a driver.

Claim 14

A vehicle speed control system as claimed in claim 10 wherein the controller section is configured to determine a correction quantity in accordance with the environment recognition characteristic quantity, to determine a target travel speed in accordance with the set speed, the distance and the correction quantity and to produce the control signal so as to reduce a deviation of the actual vehicle speed from the target travel speed.

Claim 15

A vehicle speed control system as claimed in claim 12 wherein the control section is configured to determine a first parameter comprising a first term equaling the set speed supplied from the second input subsection, a second parameter comprising a first term equaling the distance measured by the third input subsection, and a third parameter comprising a first term equaling the distance measured by the third input subsection, and to set the target travel speed equal to a first target speed when the third parameter is equal to or greater than a predetermined parameter value and to a second target speed when the third parameter is smaller than the predetermined parameter value, the first target speed is dependent on the set speed and independent from the distance, the first target speed is equal to the first parameter, the second target speed is dependent on the distance and decreases as the second parameter decreases, and at least one of the first, second and third parameters further comprises a second term determined in accordance with the correction quantity.

Claim 16

A vehicle speed control system as claimed in claim 13 wherein the fourth input subsection comprises a device for collecting information on one of a visual driving environment of the vehicle and a variation of a throttle opening degree for an engine of the vehicle to determine the environment recognition characteristic quantity representing a mental attitude of the driver to the visual driving environment.

Claim 17

A vehicle speed control system as claimed in claim 13 wherein the fourth input subsection comprises a device for obtaining information on a situation of a road ahead, and the controller section is configured to determine the environment recognition characteristic quantity from the information collected by the device of the fourth input subsection.

Claim 18

A vehicle speed control system as claimed in claim 15 wherein said fourth input subsection further comprises an accelerator position sensor for determining a driver's accelerator input by sensing a condition of an accelerator system of the vehicle, and the controller section is configured to monitor variation of the driver's accelerator input, to calculate a standard deviation of the driver's accelerator input over a predetermined time interval, and to determine the recognition characteristic quantity in accordance with the standard deviation, and wherein the controller section is configured to increase the characteristic quantity as the standard deviation increases, and to decrease the vehicle speed as the characteristic quantity increases.