Vehicle speed control system for automotive vehicle

A method for controlling a vehicle to bring a vehicle speed closer to a command vehicle speed, the method comprising:

• detecting whether an automatic transmission of the vehicle is put in a lockup condition;
• correcting a command drive torque by decreasing a correction quantity of the command drive torque when the automatic transmission is put in an un-lockup condition;
• and
• controlling a vehicle speed of the vehicle by commanding the vehicle to generate the corrected command drive torque.

A vehicle speed control system for a vehicle, the vehicle control system comprising:

• a vehicle speed sensor sensing a vehicle speed of the vehicle;
• a target vehicle speed setting device for setting a target vehicle speed;
• a drive system generating drive force of the vehicle;
• an automatic transmission of the vehicle having a torque converter with a lockup mechanism and being connected to said drive system;
• and
• a controller connected with said vehicle speed sensor, said target vehicle speed setting device, said drive system and said automatic transmission, said controller,
• calculating a command drive torque on the basis of the vehicle speed, the target vehicle speed, and a variation of the command vehicle speed;
• detecting whether the automatic transmission is put in a lockup condition;
• correcting the command drive torque according to the lock-up condition of the automatic transmission;
• and
• controlling said drive system so as to generate the corrected command drive torque.

A vehicle speed control system for a vehicle equipped with an automatic transmission with a torque converter, the torque converter having a lockup mechanism, the vehicle control system comprising:

• a controller configured to:
• detect whether the automatic transmission is put in an un-lockup condition;
• and
• delay a response characteristic of the vehicle speed control system when the automatic transmission is put in the un-lockup condition.