Systems and methods for navigating a vehicle

1. A system for navigating a host vehicle, the system comprising:

at least one processing device programmed to:

receive, from an image capture device, at least one image representative of an environment of the host vehicle;

determine, based on at least one driving policy, a planned navigational action for accomplishing a navigational goal of the host vehicle;

analyze the at least one image to identify a target vehicle in the environment of the host vehicle;

determine a next-state distance between the host vehicle and the target vehicle that would result if the planned navigational action was taken;

determine a maximum braking capability of the host vehicle, a maximum acceleration capability of the host vehicle, and a current speed of the host vehicle, wherein the maximum braking capability of the host vehicle is determined based on at least one factor associated with a condition of the host vehicle or the environment of the host vehicle, the condition of the host vehicle comprising at least one of: a tire pressure, a brake pad condition, or a current weight of the vehicle;

determine a current stopping distance for the host vehicle based on the current maximum braking capability of the host vehicle, the current maximum acceleration capability of the host vehicle, and the current speed of the host vehicle;

determine a current speed of the target vehicle and assume a maximum braking capability of the target vehicle based on at least one recognized characteristic of the target vehicle; and

implement the planned navigational action if the determined current stopping distance for the host vehicle is less than the determined next-state distance summed together with a target vehicle travel distance determined based on the current speed of the target vehicle and the assumed maximum braking capability of the target vehicle.

2. The system of claim 1 , wherein the current stopping distance for the host vehicle includes an acceleration distance that corresponds to a distance the host vehicle can travel over a predetermined time period at the maximum acceleration capability of the host vehicle, starting from the determined current speed of the host vehicle.

3. The system of claim 2 , wherein the predetermined time period is a reaction time associated with the host vehicle.

4. The system of claim 1 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a sensed condition of a road surface.

5. The system of claim 1 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a sensed weather condition.

6. The system of claim 1 , wherein the target vehicle speed is determined based on analysis of the at least one image.

7. The system of claim 1 , wherein the target vehicle speed is determined based on analysis of an output from at least one of a LIDAR system or a RADAR system associated with the host vehicle.

8. The system of claim 1 , wherein the recognized characteristic of the target vehicle includes a vehicle type.

9. The system of claim 1 , wherein the recognized characteristic of the target vehicle is a vehicle size.

10. The system of claim 1 , wherein the recognized characteristic of the target vehicle includes a vehicle model.

11. The system of claim 1 , wherein the recognized characteristic of the target vehicle is determined based on analysis of the at least one image.

12. The system of claim 1 , wherein the at least one characteristic of the target vehicle is determined based on at least one of a LIDAR output or a RADAR output.

13. The system of claim 1 , wherein the planned navigational action includes at least one of a lane change maneuver, a merge maneuver, a passing maneuver, a follow distance reduction maneuver, or a maintain throttle action.

14. The system of claim 1 , wherein the at least one processing device is configured to implement the planned navigational action if the determined current stopping distance for the host vehicle is less, by at least a predetermined minimum distance, than the determined next-state distance summed together with a target vehicle travel distance, wherein the target vehicle travel distance is determined based on the current speed of the target vehicle and the assumed maximum braking capability of the target vehicle.

15. The system of claim 14 , wherein the predetermined minimum distance corresponds to a predetermined separation distance to be maintained between the host vehicle and other vehicles.

16. The system of claim 15 , wherein the predetermined separation distance is at least 1 meter.

17. The system of claim 1 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a number of passengers of the host vehicle.

18. The system of claim 1 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a regulation specifying a maximum allowed braking capability.

19. The system of claim 4 , wherein the sensed condition of the road surface includes a roughness of the road, a slant or slope of the road, a presence or absence of a substance or an object on the road, or a type of the road surface.

20. The system of claim 5 , wherein the sensed weather condition includes detection of precipitation, a weather condition that affects visibility, or a weather condition that may affect handling of the host vehicle.

21. A method for navigating a host vehicle, comprising:

receiving, from an image capture device, at least one image representative of an environment of the host vehicle;

determining, based on at least one driving policy, a planned navigational action for accomplishing a navigational goal of the host vehicle;

analyzing the at least one image to identify a target vehicle in the environment of the host vehicle;

determining a next-state distance between the host vehicle and the target vehicle that would result if the planned navigational action was taken;

determining a maximum braking capability of the host vehicle, a maximum acceleration capability of the host vehicle, and a current speed of the host vehicle, wherein the maximum braking capability of the host vehicle is determined based on at least one factor associated with the condition of the host vehicle or the environment of the host vehicle, the condition of the host vehicle comprising at least one of: a tire pressure, a brake pad condition, or a current weight of the vehicle;

determining a current stopping distance for the host vehicle based on the current maximum braking capability of the host vehicle, the current maximum acceleration capability of the host vehicle, and the current speed of the host vehicle;

determining a current speed of the target vehicle and assume a maximum braking capability of the target vehicle based on at least one recognized characteristic of the target vehicle; and

implementing the planned navigational action if the determined current stopping distance for the host vehicle is less than the determined next-state distance summed together with a target vehicle travel distance determined based on the current speed of the target vehicle and the assumed maximum braking capability of the target vehicle.

22. The method of claim 21 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a sensed condition of a road surface.

23. The method of claim 21 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a sensed weather condition.

24. The method of claim 21 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a number of passengers of the host vehicle.

25. The method of claim 21 , wherein the at least one factor associated with the condition of the host vehicle or the environment of the host vehicle includes a regulation specifying a maximum allowed braking capability.

26. The method of claim 22 , wherein the sensed condition of the road surface includes a roughness of the road, a slant or slope of the road, a presence or absence of a substance or an object on the road, or a type of the road surface.

27. The method of claim 23 , wherein the sensed weather condition includes detection of precipitation, a weather condition that affects visibility, or a weather condition that may affect handling of the host vehicle.

28. The system of claim 1 , wherein the at least one factor comprises an external condition of the road.