Method and system for controlling shifting of a vehicle in cruise control
View Patent ↗Methods and systems are presented for improving performance of a vehicle operating in a cruise control mode where a controller adjusts torque output from a vehicle to maintain vehicle speed within a desired range while preventing the unnecessary downshifts. The methods and systems include adapting a vehicle dynamics model and a vehicle fuel consumption model that provide input to nonlinear model predictive controller.
1. A vehicle system, comprising:
a vehicle including a motive torque source;
a transmission coupled to the motive torque source; and
a controller in the vehicle, the controller including executable instructions stored in non-transitory memory, wherein the controller is configured to:
sense a vehicle speed;
provide a torque command to the motive torque source responsive to an output of an adaptive nonlinear model predictive cruise control routine, the torque command determined based on a shape of a vehicle fuel consumption model; and
operate the motive torque source to output a powertrain torque, the powertrain torque constrained below a powertrain torque threshold, where the transmission downshifts responsive to the powertrain torque equal to or greater than the powertrain torque threshold at the sensed vehicle speed.
2. The vehicle system of claim 1 , wherein the controller is further configured to adapt the vehicle fuel consumption model.
3. The vehicle system of claim 1 , wherein the controller is further configured to: in response to a convex fuel consumption model, operating the transmission in a forward gear; and, in response to a non-convex fuel consumption model, operate the transmission in a neutral state.
4. The vehicle system of claim 1 , wherein the controller is further configured to output a pulse shaped torque to the motive torque source responsive to a convex fuel consumption model.
5. The vehicle system of claim 1 , wherein the motive torque source includes an engine, and constraining the powertrain torque below the powertrain torque threshold comprises constraining an engine air flow to less than a threshold.
6. A vehicle system, comprising:
a vehicle including a motive torque source;
a transmission coupled to the motive torque source, the transmission including a neutral state and a forward gear; and
a controller in the vehicle, the controller including executable instructions stored in non-transitory memory, wherein the controller is configured to:
sense a vehicle speed;
provide a torque command to the motive torque source responsive to an output of an adaptive nonlinear model predictive cruise control routine;
operate the motive torque source to output a powertrain torque, the powertrain torque constrained below a powertrain torque threshold, where the transmission downshifts responsive to the powertrain torque equal to or greater than the powertrain torque threshold at the sensed vehicle speed;
in response to a convex fuel consumption model, operate the transmission in the forward gear; and
in response to a non-convex fuel consumption model, operate the transmission in the neutral state.
7. The vehicle system of claim 6 , where the powertrain torque is constrained by adjusting a spark advance.
8. The vehicle system of claim 6 , where the controller is further configured to maintain the vehicle speed between an upper vehicle speed threshold and a lower vehicle speed threshold.
9. The vehicle system of claim 8 , where the controller is further configured to operate the motive torque source to output the powertrain torque greater than the powertrain torque threshold responsive to the vehicle speed less than the lower vehicle speed threshold.
10. The vehicle system of claim 9 , where the powertrain torque threshold is determined based on a transmission shift schedule stored in the non-transitory memory of the controller.
11. A vehicle cruise control method, comprising:
receiving vehicle information from one or more sensors to a controller;
sensing the vehicle speed;
providing a torque command responsive to output of an adaptive nonlinear model predictive cruise control routine executed by the controller, the torque command determined based on a shape of a vehicle fuel consumption model, the torque command constrained to a value less than a powertrain torque threshold, where a transmission downshifts responsive to the torque command equal to or greater than the powertrain torque threshold at the sensed vehicle speed; and
adjusting a torque actuator of a motive torque source responsive to the torque command.
12. The method of claim 11 , further comprising downshifting the transmission responsive to the vehicle speed less than a lower vehicle speed threshold.
13. The method of claim 12 , further comprising, in response to a convex fuel consumption model, operating the transmission in a forward gear; and, in response to a non-convex fuel consumption model, operating the transmission in a neutral state.
14. The method of claim 12 , further comprising, when the vehicle fuel consumption model is non-convex,
in response to a vehicle speed increasing to an upper vehicle speed threshold, adjusting a gear selection to a neutral state, adjusting the torque actuator to deliver an idle torque, and coasting the vehicle, and
in response to the vehicle speed decreasing to the lower vehicle speed threshold, adjusting the gear selection to a forward gear, adjusting the torque actuator to deliver a torque greater than the idle torque, and accelerating the vehicle.