Patent ID: 8370042

Claim:
A vehicle speed control device comprising: means for calculating a control drive force for maintaining a speed of a vehicle to a set speed; and means for conducting a cruise control which makes the vehicle travel by the control drive force calculated by the calculating means, wherein the 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, wherein the conducting 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, wherein the calculating means detects at least a slope of a road on which the vehicle travels as the travel resistance, the 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, and wherein the limit range is stored in a navigation ECU; wherein the calculating means interrupts the calculation of the feedback component while the requested drive force exceeds the control drive force, and wherein the 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.