Dynamic gap control for automated driving
A variety of methods, controllers and algorithms are described for controlling a vehicle to closely follow one another safely using automatic or partially automatic control. The described control schemes are well suited for use in vehicle platooning and/or vehicle convoying applications, including truck platooning and convoying controllers. In one aspect, a power plant (such as an engine) is controlled using a control scheme arranged to attain and maintain a first target gap between the vehicles. Brakes (such as wheel brakes) are controlled in a manner configured to attain and maintain a second (shorter) target gap. Such control allows a certain degree of encroachment on the targeted gap (sometimes referred to as a gap tolerance) before the brakes are actuated. The described approaches facilitate a safe and comfortable rider experience and reduce the likelihood of the brakes being actuated unnecessarily.
1. A method of controlling a first vehicle to at least partially automatically maintain separation from a second vehicle while driving, the first vehicle having a power plant and brakes, the method comprising:
automatically controlling an output of the power plant during driving in accordance with a power plant output control scheme arranged to attain and maintain a first target gap between the first and the second vehicles; and
automatically controlling the brakes during driving in accordance with a braking control scheme arranged to attain and maintain a second target gap during first selected operating conditions, the second target gap being shorter than the first target gap; and
wherein the difference between the first and second target gaps is a gap tolerance, and the gap tolerance varies at least in part based on a current actual gap between the first and second vehicles.
2. The method as recited in claim 1 wherein the power plant is an engine and the controlled brakes are wheel brakes.
3. The method as recited in claim 1 wherein the first and second target gaps are longitudinal separations between the first and second vehicles.
4. The method as recited in claim 1 wherein:
the first vehicle is a truck that includes a retarder and wheel brakes;
the retarder is controlled in accordance with the power plant output control scheme; and
the wheel brakes are controlled in accordance with the braking control scheme.
5. The method as recited in claim 1 wherein:
the first vehicle is a truck that includes a retarder;
the retarder is controlled in accordance with the power plant output control scheme when an actual gap between the first and second vehicles is greater than the second target gap; and
the retarder is controlled in accordance with the braking control scheme when the actual gap between the first and second vehicles is less than the second target gap.
6. A platoon controller for at least partially automatically controlling a host vehicle to attain and maintain a first target gap separation between the host vehicle and a second vehicle while the host vehicle is driving, the platoon controller comprising:
a torque request controller configured to determine torque requests suitable for attaining and maintaining the first target gap between the host and second vehicles while the host vehicle is driving under first selected operating conditions;
a brake request controller configured to determine brake requests suitable for attaining and maintaining a second target gap between the host and second vehicles while the host vehicle is driving under the first selected operating conditions, the second target gap being shorter than the first target gap; and
wherein during driving under the first selected operation condition, the torque request controller outputs torque requests based on the first target gap and the brake request controller outputs brake requests based on the second target gap; and
the difference between the first and second target gaps is a gap tolerance, and the gap tolerance varies at least in part based on a current actual gap between the host and second vehicles.
7. The platoon controller as recited in claim 6 wherein:
the host vehicle is a truck that includes a retarder;
the retarder is controlled in accordance with the power plant output control scheme when an actual gap between the first and second vehicles is greater than the second target gap; and
the retarder is controlled in accordance with the braking control scheme when the actual gap between the first and second vehicles is less than the second target gap.
8. The platoon controller as recited in claim 6 wherein:
the host vehicle is a truck that includes a retarder and wheel brakes;
the retarder is controlled in accordance with the power plant output control scheme; and
the wheel brakes are controlled in accordance with the braking control scheme.