STEERING SAFETY SYSTEMS AND METHODS
Improvements to steering functionality and safety thereof for a vehicle are disclosed. In particular, disclosed embodiments monitor and diagnose steering commands received by an in-vehicle controller from a remote server. The steering commands may be evaluated with respect to rationality and context. For example, a steering angle indicated by the steering command is compared to a current vehicle steering angle and/or to other steering angles indicated by preceding and/or subsequent steering commands. Based on diagnosis of the steering commands, an in-vehicle controller can permit or prevent engagement of autonomous vehicle operation, which applies the steering commands. In an autonomous mode, invalid steering commands can trigger a minimal risk condition (MRC) maneuver for the vehicle.
1 . An in-vehicle controller for an autonomous vehicle, the in-vehicle controller comprising a processor and a memory storing executable code configured to cause the in-vehicle controller to:
receive, from a remote server, a steering command that indicates a steering angle for navigation of the autonomous vehicle;
evaluate the steering command against at least two speed-dependent thresholds, the at least two speed-dependent thresholds comprising a first speed-dependent threshold with respect to a difference between the steering angle and a current vehicle steering angle and a second speed-dependent threshold with respect to a rate of change of the steering angle with one or more preceding steering commands;
determine whether the steering command is valid or not based on weighing, according to a current operation mode of the autonomous vehicle, respective flags resulting from the at least two speed-dependent thresholds; and
in accordance with the current operation mode being a manual operation mode and a determination that the steering command is not valid, transmit instructions to an in-vehicle user interface to cause the in-vehicle user interface to disable engagement of an autonomous operation mode for the autonomous vehicle via the in-vehicle user interface.
2 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
in accordance with the current operation mode being the manual operation mode and a determination that the steering command is valid, classify a steering functionality of the autonomous vehicle as healthy; and
permit engagement of the autonomous operation mode for the autonomous vehicle.
3 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
in accordance with the current operation mode being the autonomous operation mode and the determination that the steering command is not valid, trigger a maneuver for the autonomous vehicle to reach a complete stop.
4 . The in-vehicle controller of claim 3 , wherein the maneuver includes one or more locally-determined steering angles determined by the in-vehicle controller in accordance with a third speed-dependent threshold associated with the maneuver.
5 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
in accordance with the current operation mode being the autonomous operation mode and a determination that the steering command is valid, apply the steering command by transmitting instructions to a steering subsystem of the autonomous vehicle.
6 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
receive, from a sensor subsystem located in the autonomous vehicle, a vehicle speed measurement; and
determine the first speed-dependent threshold and the second speed-dependent threshold based on the vehicle speed measurement.
7 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
receive, from a sensor subsystem located in the autonomous vehicle, the current vehicle steering angle.
8 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
determine a regression fit for a plurality of steering angles indicating by the steering command and the one or more preceding steering commands; and
use a derivative of the regression fit as the rate of change for evaluating the steering command against the second speed-dependent threshold.
9 . The in-vehicle controller of claim 1 , wherein the executable code is further configured to cause the in-vehicle controller to:
determining a number of frames in a predetermined time window in which the steering command fails to satisfy the second speed-dependent threshold; and
based on the number of frames exceeding a particular percentage of the predetermined time window, trigger an emergency maneuver for the autonomous vehicle.
10 . A method for monitoring steering operation of a vehicle, comprising:
receiving, by an in-vehicle controller from a remote server, a steering command that indicates a steering angle for navigation of the vehicle;
evaluating, by the in-vehicle controller, the steering command against at least two speed-dependent thresholds, the at least two speed-dependent thresholds comprising a first speed-dependent threshold with respect to a difference between the steering angle and a current vehicle steering angle and a second speed-dependent threshold with respect to a rate of change of the steering angle with one or more preceding steering commands;
determining, by the in-vehicle controller, whether the steering command is valid or not based on weighing, according to a current operation mode of the vehicle, respective flags resulting from the at least two speed-dependent thresholds; and
in accordance with the current operation mode being a manual operation mode and a determination that the steering command is not valid, transmitting, by the in-vehicle controller, instructions to an in-vehicle user interface to cause the in-vehicle user interface to disable engagement of an autonomous operation mode for the vehicle via the in-vehicle user interface.
11 . The method of claim 10 , further comprising:
evaluating, by the in-vehicle controller, a second steering command against the at least two speed-dependent thresholds; and
in accordance with (i) the current operation mode being an autonomous operation mode and (ii) a determination that the second steering command is not valid based on the evaluating, triggering, by the in-vehicle controller, a maneuver for the vehicle to reach a complete stop.
12 . The method of claim 11 , wherein the maneuver includes locally-determined steering angles determined by the in-vehicle controller in accordance with a third speed-dependent threshold associated with the maneuver.
13 . The method of claim 10 , further comprising:
evaluating, by the in-vehicle controller, a second steering command against the at least two speed-dependent thresholds; and
in accordance with (i) the current operation mode being an autonomous operation mode and (ii) a determination that the steering command is valid, applying, by the in-vehicle controller, the second steering command by controlling a steering subsystem of the vehicle.
14 . The method of claim 10 , further comprising:
receiving, by the in-vehicle controller from a sensor subsystem located in the vehicle, a vehicle speed measurement; and
determining, by the in-vehicle controller, the first speed-dependent threshold and the second speed-dependent threshold based on the vehicle speed measurement.
15 . The method of claim 10 , further comprising:
receiving, by the in-vehicle controller from a sensor subsystem located in the vehicle, the current vehicle steering angle.
16 . The method of claim 10 , further comprising:
determining, by the in-vehicle controller, a regression fit for a plurality of steering angles indicating by the steering command and the one or more preceding steering commands; and
evaluating, by the in-vehicle controller, the steering command against the second speed-dependent threshold using a derivative of the regression fit as the rate of change.
17 . The method of claim 10 , further comprising:
determining a number of frames in a predetermined time window in which the steering command fails to satisfy the second speed-dependent threshold; and
based on the number of frames exceeding a particular percentage of the predetermined time window, trigger an emergency maneuver for the vehicle.
18 . A non-transitory computer-readable program storage medium having code stored thereon, the code, when executed by a processor, causing the processor to implement a method comprising:
receiving, from a remote server, a steering command that indicates a steering angle for navigation of an autonomous vehicle;
evaluating the steering command against at least two speed-dependent thresholds, the at least two speed-dependent thresholds comprising a first speed-dependent threshold with respect to a difference between the steering angle and a current vehicle steering angle and a second speed-dependent threshold with respect to a rate of change of the steering angle with one or more preceding steering commands;
determining whether the steering command is valid or not based on weighing, according to a current operation mode of the vehicle, respective flags resulting from the at least two speed-dependent thresholds; and
in accordance with the current operation mode being a manual operation mode and a determination that the steering command is not valid, transmitting instructions to an in-vehicle user interface to cause the in-vehicle user interface to disable engagement of an autonomous operation mode for the vehicle via the in-vehicle user interface.
19 . The non-transitory computer-readable program storage medium of claim 18 , wherein the method further comprises:
determining a regression fit for a plurality of steering angles indicating by the steering command and the one or more preceding steering commands; and
evaluating the steering command against the second speed-dependent threshold using a derivative of the regression fit as the rate of change.
20 . The non-transitory computer-readable program storage medium of claim 18 , wherein the method further comprises:
determining a number of frames in a predetermined time window in which the steering command fails to satisfy the second speed-dependent threshold; and
based on the number of frames exceeding a particular percentage of the predetermined time window, trigger an emergency maneuver for the autonomous vehicle.