Adaptive dynamic model for automated vehicle

An operating system for an automated vehicle includes a failure-detector and a controller. The failure-detector detects a component-failure on a host-vehicle. Examples of the component-failure include a flat-tire and engine trouble that reduces engine-power. The controller operates the host-vehicle based on a dynamic-model. The dynamic-model is varied based on the component-failure detected by the failure-detector.

TECHNICAL FIELD OF INVENTION

This disclosure generally relates to an operating system for an automated vehicle, and more particularly relates to a system that varies or adjusts a dynamic-model used to operate the vehicle to compensate for a component-failure of a component of the vehicle.

BACKGROUND OF INVENTION

It is known to use a dynamic-model of a host-vehicle to assist with the operation of the host-vehicle. For example, the dynamic model may indicate when brakes should be applied to prevent a collision, or a safe speed for an upcoming curve. However, if there is a component failure of the host-vehicle such as a flat-tire, the dynamic-model may no longer be suitable to operate the host-vehicle.

SUMMARY OF THE INVENTION

In accordance with one embodiment, an operating system for an automated vehicle is provided. The system includes a failure-detector and a controller. The failure-detector detects a component-failure on a host-vehicle. The controller operates the host-vehicle based on a dynamic-model. The dynamic-model is varied based on the component-failure detected by the failure-detector.

DETAILED DESCRIPTION

FIG. 1illustrates a non-limiting example of an operating system10, hereafter referred to as the system10. The system10is suitable for use by an automated vehicle, a host-vehicle12for example. As used herein, the term automated vehicle may apply to instances when the host-vehicle12is being operated in an automated-mode14, i.e. a fully autonomous mode, where a human-operator (not shown) of the host-vehicle12may do little more than designate a destination in order to operate the host-vehicle12. However, full automation is not a requirement. It is contemplated that the teachings presented herein are useful when the host-vehicle12is operated in a manual-mode16where the degree or level of automation may be little more than providing an audible or visual warning to the human-operator who is generally in control of the steering, accelerator, and brakes of the host-vehicle12. For example, the system10may merely assist the human-operator as needed to avoid interference with and/or a collision with, for example, an object such as another-vehicle, a pedestrian, or a road sign.

The system10includes a failure-detector20that detects a component-failure22of a component on the host-vehicle12.FIG. 1illustrates the failure-detector20as being integrated into or part of a controller24of the system10; however this is not a requirement. It is contemplated that the failure-detector20could be part of a separate engine-control-module (ECM) or a body-control-module (BCM) of the host-vehicle12, and the failures could be communicated to the controller24on a data-buss of the host-vehicle12, e.g. via a controller-area-network (CAN) buss. Non-limiting examples component failures of vehicle components whose failure could affect the operation of the host-vehicle12include, but are not limited to, a flat-tire26, an engine-fault28(fuel-injector failure, engine-sensor failure), a perception-sensor failure (e.g. camera, radar, lidar; not shown), an anti-wheel-lock-sensor failure (not shown), a vehicle-accelerometer failure (not shown), an exterior-light failure (e.g. headlight or taillight; not shown), a low fluid level (oil, coolant, windshield-washer-fluid), and the like.

The controller24may include a processor (not specifically shown) such as a microprocessor or other control circuitry such as analog and/or digital control circuitry including an application specific integrated circuit (ASIC) for processing data as should be evident to those in the art. The controller24may include memory (not specifically shown), including non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM) for storing one or more routines, thresholds, and captured data. The one or more routines may be executed by the processor to perform steps for operating the host-vehicle12as described herein.

The controller24operates the host-vehicle12, e.g. controls steering and acceleration/braking, based on a dynamic-model30. As used herein, the dynamic-model30represents a dynamic characterization of how the host-vehicle12will respond to various situations or stimuli. For example, the dynamic-model30may be used to predict a stopping-distance of the host-vehicle12based on information about traction-conditions (e.g. wet vs. dry roadway), roadway-slope (e.g. uphill/downhill vs. level), and the like. Prior examples of dynamic-models presume that all components on the vehicle being modeled are operating within normal parameters. For example, the prior dynamic-models presume that the tire-pressures in the tires of the vehicle are within some nominal range. However, if a flat-tire occurred, the prior dynamic-models are not particularly useful as they don't adapt to changes in dynamic behavior of the vehicle due to the flat-tire. The system10described herein is an improvement over the prior examples of dynamic-models because the dynamic-model30of the host-vehicle12is varied based on the component-failure22detected by the failure-detector20.

FIG. 2illustrates a non-limiting example of a traffic-scenario32that the host-vehicle12, which is equipped with the system10, may encounter. In this example, the host-vehicle12has recently turned onto a roadway34from a side-road36. By way of example and not limitation, the dynamic-model30(FIG. 1) for the host-vehicle12may specify a maximum-acceleration38of the host-vehicle12that is considered prior to turning onto the roadway34so as to not interfere with an approaching-vehicle40. That is, the system10may use the dynamic-model30to predict if the act of the host-vehicle12turning onto the roadway34will force the approaching-vehicle40to slow-down or decelerate an undesirable amount to avoid a collision with the host-vehicle12. However, if there is something wrong with the engine of the host-vehicle12, the host-vehicle12may not be able to accelerate at a rate comparable to the maximum-acceleration38.

To address this situation, the system10may include an engine-status-detector42that operates to determine if the engine of the host-vehicle12is operating normally. The engine-status-detector42may be fully embedded in an engine-control-module (ECM, not shown) that outputs codes on a data-bus to indicate the operational status of the engine, as will be recognized by those in the art. If the engine is not operating properly, the component-failure22may be characterized as an engine-fault28when the engine of the host-vehicle12is operating at reduced-power, is operating in a limp-home mode. Accordingly, the maximum-acceleration38parameter of the dynamic-model30may be decreased when the engine of the host-vehicle12is operating at a reduced-power44. As a result, the system10may decide to not turn onto the roadway34when the approaching-vehicle40is detected. As such, the dynamic-model30is varied based on the component-failure22detected by the failure-detector20.

The system10may include a tire-pressure-detector46, i.e. a tire-pressure-indicator. The component-failure22may indicate that the flat-tire26has occurred when a tire-pressure48is less than a pressure-threshold50. The pressure-threshold50may be just barely above a completely flat-tire, or may be a pressure less than the recommended-pressure for a given tire where the dynamic behavior of the host-vehicle12is noticeably affected. It is also contemplated that multiple values of the pressure-threshold50may be used to continually adjust the dynamic-model30so that the flat-tire26covers both instances of a soft-tire and completely flat-tire. How the dynamic-model30is adjusted or varied may be determined by empirical testing and/or computer modeling. In situations when the host-vehicle is being operated on the manual-mode16where a human-operator is steering the host-vehicle12, the adjustments to the dynamic model may be used by, for example, a lane-keeping-system that only operates to steer the host-vehicle when the operator allows the host-vehicle to deviate too far from the center of a travel-lane.

As a non-limiting example, if one of the front tires, e.g. the wheel72(FIG. 2), is soft or flat, the steering behavior may be asymmetrical. That is, the magnitude of change in direction of the host-vehicle12arising from a given magnitude of the steering-angle62for a left-turn may differ from that for a right-turn. For example, if the wheel72is the flat-tire26, it may take a greater magnitude of the steering-angle62to turn the host-vehicle to the right that to make the same amount of turn to the left. The dynamic-model30may be varied or adjusted to anticipate this asymmetric behavior by increasing the expected change in steering necessary to steer the host-vehicle12through an upcoming curve.

The system10may include a steering-torque-detector52that monitors the amount steering torque applied to a hand-wheel (i.e. steering-wheel, not shown) operated by a human operator, or applied by an automated steering actuator of the host-vehicle12. The component-failure22may indicate that a flat-tire26has occurred when a steering-torque54necessary to keep the host-vehicle12centered in a travel-lane56(FIG. 2) is greater than a torque-threshold58. That is, the flat-tire26may cause the host-vehicle12to ‘pull’ in one direction, so a compensating steering torque is necessary to keep the host-vehicle12traveling near the center of the travel-lane56. It is recognized that there are causes other than the flat-tire26that require a compensating steering torque to keep the host-vehicle12traveling near the center of the travel-lane56. For example, a bent or worn suspension component may cause the same effect and the dynamic-model30may be adjusted to compensate in the same manner.

The system10may include a steering-angle-detector60, and the component-failure22indicates that a flat-tire26has occurred when a steering-angle62necessary to keep the host-vehicle centered in the travel-lane56is greater than an angle-threshold64. The effect on the dynamic behavior of the host-vehicle12due to the flat-tire26may be similar to the above described idea for compensating or adjusting the dynamic-model30based on the steering-torque54. However, a commercially available example of the steering-angle-detector60may be more economical than a commercially available example of the steering-torque-detector52.

The system10may include a wheel-speed-detector66, and the component-failure22indicates that a flat-tire26has occurred when a wheel-speed68of a wheel72(FIG. 2) of the host-vehicle12does not correspond to a vehicle-speed70of the host-vehicle12. Vehicles with anti-lock or anti-skid braking systems have a wheel-speed-detector at each wheel of a vehicle. The vehicle-speed70may be determined by taking an average wheel-speed of three wheels out of the four wheels that most agree with each other, and the fourth wheel that indicates a wheel speed most different from the other three may be presumed to be flat if the difference is greater than some threshold, one kilometer-per-hour (1 kph) for example. Alternatively, the vehicle-speed70may be determined using an independent means such as radar or lidar if the host-vehicle12is so equipped.

Once the component-failure22is identified, one or aspects or characteristics of the dynamic-model30may be varied, altered, or otherwise modified so the controller24has a version of the dynamic-model30that allows the system10to anticipate how the host-vehicle12is expected to respond to various inputs such as changes in the steering-angle62, application of the brakes of the host-vehicle12, or increasing engine power to accelerate the host-vehicle12. By way of example and not limitation, the dynamic-model30may specify a maximum-curve-speed74for a curve-radius76of an upcoming curve of the travel-lane56(FIG. 2). If the component-failure22is something that reduces the ability of the host-vehicle12to safely navigate the upcoming curve, the dynamic-model30may be varied so the maximum-curve-speed74is decreased for a specified value of the curve-radius78when the component-failure22is, for example, a flat-tire26, or a broken shock-absorber or spring of the suspension-system of the host-vehicle. Similarly, the dynamic-model30may specify a braking-distance78for a vehicle-speed70of the host-vehicle12, and the braking-distance78may be increased when the component-failure22is a flat-tire26.

Accordingly, an operating system (the system10), a controller24for the system10, and a method of operating the system10is provided. The dynamic-model30provides a means for the controller24to predict the dynamic-behavior of the host-vehicle12during various transient maneuvers such as cornering and braking. However, it has been observed that some types or instances of the component-failure22can change the dynamic-behavior. To overcome this change the dynamic-model30is varied or altered so that the dynamic-behavior of the host-vehicle12while the component-failure22is present can be predicted.