Alertness monitoring systems and associated methods
Embodiments of driver alertness monitoring systems, devices, and associated methods based on steering variability and/or lane variability are described herein. In one embodiment, a method for detecting alertness of a driver operating a vehicle includes recording a steering position of the vehicle with a steering sensor and transmitting the recorded steering position to a processor. With the processor, the method also includes deriving a steering variability based on the recorded steering position of the vehicle over time, calculating a lane variability based on the derived steering variability and a transfer function of the vehicle, and estimating an alertness of the driver based on both the derived steering variability and the calculated lane variability.
1. A method for detecting alertness of a driver operating a vehicle, comprising:
recording a steering position of the vehicle with a steering sensor;
transmitting the recorded steering position to a processor;
with the processor,
deriving a steering variability based on the recorded steering position of the vehicle over time;
calculating a lane variability based on the derived steering variability and a transfer function of the vehicle; and
estimating an alertness of the driver based on both the derived steering variability and the calculated lane variability.
2. The method of claim 1 wherein:
recording the steering position includes recording a steering angle of the vehicle over time;
deriving the steering variability includes deriving at least one of a standard deviation, variance, root mean square, average, percent of signal amplitudes exceeding 0.3°, percent of signal amplitudes exceeding 3°, and percent of signal amplitudes exceeding 30°;
calculating the lane variability includes calculating a lateral lane position change based on the steering variability and the transfer function of the vehicle;
estimating the alertness of the driver includes estimating an alertness of the driver based on the steering variability and the calculated lateral lane position change.
3. The method of claim 1 , further comprising:
retrieving a threshold from a memory operatively coupled to the processor; and
if the estimated alertness exceeds the retrieved threshold, issuing a warning.
4. The method of claim 1 wherein estimating the alertness of the driver includes estimating an alertness of the driver based solely on a combination of the derived steering variability and the calculated lane variability.
5. The method of claim 1 wherein estimating the alertness of the driver includes estimating an alertness of the driver based on an alertness model with the derived steering variability and the calculated lane variability as input.
6. The method of claim 1 wherein estimating the alertness of the driver includes estimating an alertness of the driver based on an alertness model with the derived steering variability and the calculated lane variability as input, and wherein the alertness model is individualized for the driver.
7. A vehicle, comprising:
a steering sensor;
a processor operatively coupled to the steering sensor;
a non-transitory computer-readable storage medium operatively coupled to the processor, the computer-readable storage medium containing instructions when executed, causing the processor to perform a method comprising:
receiving data of steering position of the vehicle from the steering sensor;
deriving a steering variability based on the received steering position of the vehicle over time; and
estimating an alertness of a driver operating the vehicle based on an alertness model with the derived steering variability as input, the alertness model incorporating a transfer function between the steering variability and a lane variability.
8. The vehicle of claim 7 wherein the alertness model is configured to combine the steering variability (ΔS) and the lane variability (ΔL) linearly to derive an alertness value (D) as follows:
D=aΔL+bΔS
where a and b are lane coefficient and steering coefficient, respectively.
9. The vehicle of claim 7 wherein the alertness model is configured to derive an alertness value (D) based on the steering variability (ΔS) as follows:
D=a ( H×ΔS )+ bΔS =( aH+b ) ΔS
where a and b are lane coefficient and steering coefficient, respectively; H is the transfer function between the steering variability and the lane variability.
10. The vehicle of claim 7 wherein the alertness model is configured to combine the steering variability and the lane variability non-linearly to derive an alertness value.
11. The vehicle of claim 7 , further comprising a feedback component operatively coupled to the processor, wherein the method performed by the processor further includes:
determining whether driving performance of the driver is adequate based on the estimated alertness and a threshold stored in the computer-readable medium;
if the driving performance of the driver is inadequate, performing at least one of the following:
causing the feedback component to issue a warning to the driver;
transmitting a warning signal to a control center and/or a dispatch;
actively controlling operation of the vehicle based on the steering variability and/or lane variability; and
initializing a speed limiter.
12. The vehicle of claim 7 wherein receiving the data of steering position of the vehicle includes receiving data of steering position of the vehicle from the steering sensor via at least one of a radio tower and a satellite link.
13. The vehicle of claim 7 wherein the processor is remote from the steering sensor.
14. The vehicle of claim 7 , further comprising a lane position sensor operatively coupled to the processor.
15. A computer system for a vehicle, comprising:
a sensing module configured to receive and convert sensor readings from a steering sensor into steering position data;
a calculation module configured to derive a steering variability based on the steering position data from the sensing module and to derive a lane variability based on the steering position data and a transfer function between the steering variability and the lane variability for the vehicle, wherein the calculation module is also configured to estimate an alertness of a driver operating the vehicle based on the derived steering variability and the lane variability; and
an analysis module configured to analyze the driver's current state of alertness based on the estimated alertness from the calculation module.
16. The computer system of claim 15 wherein:
deriving the steering variability includes deriving a percent of signal amplitudes exceeding 3°, the signal being the steering position; and
deriving the lane variability includes calculating a lateral lane position change based on the steering variability and the transfer function of the vehicle.
17. The computer system of claim 15 wherein the calculation module is configured to estimate the alertness of the driver based solely on a combination of the derived steering variability and the calculated lane variability.
18. The computer system of claim 15 , further comprising:
a database module configured to retrieve a threshold from a memory; and
the analysis module is configured to compare the estimated alertness with the retrieved threshold and issue a warning output to a display module if the estimated alertness exceeds the retrieved threshold.
19. The computer system of claim 18 , further comprising a control module operatively coupled to the calculation module and the analysis module, wherein, if the estimated alertness exceeds the retrieved threshold, the control module is configured to perform at least one of adjusting a steering operation of the vehicle based on the lane variability and initiating a speed limiter for the vehicle.
20. The computer system of claim 15 wherein the calculation module is configured to estimate an alertness of the driver based on an alertness model with the derived steering variability and lane variability as input, and wherein the alertness model is individualized for the driver.