Vehicle speed control device and method

• US 20090048755A1
• Filed: 07/09/2008
• Published: 02/19/2009
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Advics Company Limited (Aisin Corp.), DENSO Corporation
• Original Assignee: Advics Company Limited (Aisin Corp.), DENSO Corporation
• Inventors: Tokimasa, Mitsuhiro, Kodama, Hiroyuki, Takeda, Masayoshi, Kumabe, Hajime, Nakai, Yasuhiro, Niwa, Satoshi, Kadowaki, Kazunori, Osaki, Shintaro, Fukuda, Syotarou
• Granted Patent: US 8,370,042 B2
• Time in Patent Office: Days
• US Class Current: 701/94
• CPC Class Codes: B60K 31/00 Vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator fittings acting on two or more sub-units B60W30/14; speedometers G01P; systems or devices for controlling speed in general G05D13/00 ; in traffic anti-collision system for road vehicles G08G1/16
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2555/60 Traffic rules, e.g. speed limits or right of way
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data

Abstract

A vehicle speed control device calculates a desired axle torque for maintaining a speed of a vehicle to a set speed, and conducts cruise control. Specifically, the vehicle speed control device calculates a drive force including a feedforward component corresponding to the set speed and a travel resistance against the travel of the vehicle, and a feedback component corresponding to a deviation of the set speed from the actual speed of the vehicle as a desired axle torque. The vehicle speed control device interrupts the cruise control when a requested drive axle torque requested by an accelerator operation during the cruise control exceeds the desired axle torque, and restarts the cruise control when the requested drive axle torque becomes lower than the desired axle torque.

Claims

1. A vehicle speed control device comprising:

drive force calculating means for calculating a control drive force for maintaining a speed of a vehicle to a set speed; and

cruise control means for conducting a cruise control which makes the vehicle travel by the control drive force calculated by the drive force calculating means,

wherein the drive force calculating means calculates a drive force including a feedforward component corresponding to the set speed and a travel resistance against travel of the vehicle, and a feedback component corresponding to a deviation between the set speed and an actual speed of the vehicle as the control drive force, and

wherein the cruise control means interrupts the cruise control when accelerator operation is conducted by a driver during the cruise control, and a requested drive force requested by the accelerator operation exceeds the control drive force, and restarts the cruise control at a time when the requested drive force becomes lower than the control drive force.

2. The vehicle speed control device according to claim 1,

wherein the drive force calculating means detects at least a slope of a road on which the vehicle travels as the travel resistance.

3. The vehicle speed control device according to claim 2,

wherein the drive force calculating means checks whether a detected value of the slope is within a limit range that is defined by Law or Regulation, and uses no detected value in the calculation of the feedforward component or uses a value that is limited within the limit range.

4. The vehicle speed control device according to claim 2,

wherein the drive force calculating means conducts a filtering process for removing noises from the detected value of the slope.

5. The vehicle speed control device according to claim 4,

wherein the filtering process is conducted with a larger time constant as a deviation of a value when the detected value of the slope is filtered with a given time constant from a value that is not filtered is smaller.

6. The vehicle speed control device according to claim 1,

wherein the drive force calculating means interrupts the calculation of the feedback component while the requested drive force exceeds the control drive force.

7. The vehicle speed control device according to claim 6,

wherein the drive force calculating means calculates a proportional component and an integral component as the feedback component, restarts only the calculation of the proportional component at a time when the requested drive force becomes lower than the control drive force after exceeding the control drive force, limits the feedback component to a limit deceleration until the deceleration corresponding to the calculation result of the proportional component becomes lower than a given limit deceleration, and cancels the limit and restarts the calculation of the integral component at a time when the deceleration becomes lower than the limit deceleration.

8. The vehicle speed control device according to claim 1,

wherein the cruise control means generates a brake force in a brake device when it is determined that the speed of the vehicle cannot be reduced to the set speed by only an engine brake.

9. The vehicle speed control device according to claim 8,

wherein the cruise control means determines that the speed of the vehicle cannot be reduced to the set speed by only the engine brake when a minimum torque that can be realized by a power train is equal to or higher than a torque corresponding to the control drive force.

10. A vehicle speed control method comprising:

calculating a control drive force including a feedforward component corresponding to a set speed and a travel resistance against travel of a vehicle, and a feedback component corresponding to a deviation of the set speed from an actual speed of the vehicle, which is a control drive force for maintaining a speed of the vehicle to the set speed;

conducting a cruise control for making the vehicle travel by the control drive force;

interrupting the cruise control when an accelerator operation is conducted by a driver during the cruise control and a requested drive force that is requested by the accelerator operation exceeds the control drive force; and

restarting the cruise control at a time when the requested drive force becomes lower than the control drive force after a termination of the accelerator operation.