One area of automotive vehicle technology that is evolving rapidly is the area of autonomous or semi-autonomous drive capabilities. This is enabled through the introduction of sensors, for sensing vehicle parameters and surroundings, and actuators, for controlling different vehicle functionalities, such as steering, throttling and braking. Increased on-board data processing capabilities ties together these sensors and actuators such that the autonomous or semi-autonomous drive capabilities are enabled.
When the vehicle runs in autonomous mode, which means the driver does not perform maneuvers, it usually requires multiple data sources as inputs to perform the autonomous driving, such as detection of surrounding vehicles, traffic lanes, obstacles, data from navigation systems and so on. However, should one or more of these inputs not be available, there might not be sufficient information to perform autonomous driving. In such cases a driver-hand over may be requested in order to ensure road safety.
A previous document, U.S. Pat. No. 8,433,470, relates to a user interface for displaying an internal state of an autonomous driving system. In the event of an emergency situation identified by a control computer of the automated vehicle, it may immediately convey this information to a passenger in a variety of ways. For example, if the control computer is no longer able to control the vehicle safely, illuminated indicators may change color, to inform the user of the immediate need to take control of the steering wheel. The control computer may also send audio alerts to the passenger stating that there is an emergency and the passenger is required to take control of the steering wheel. The control computer may further use cameras to scan the passenger's eyes and/or other features. If the control computer determines that the eyes are closed or the body is slumped over (e.g. the passenger is sleeping or under the influence of drugs or alcohol), the control computer may take emergency control of the vehicle and use audible alerts to wake or otherwise get the attention of the driver.
However, during autonomous driving a vehicle driver may desire to use the time when the vehicle runs in autonomous mode, and the driver is not required to perform maneuvers, to perform other activities, e.g. resting, reading, watching a movie or similar. Being otherwise occupied will, depending on the circumstances, of course affect the vehicle driver's readiness to respond to a request to assume manual control of the vehicle.
Another previous document, U.S. Pat. No. 5,774,069, relates to an auto-drive control unit which can switch a vehicle provided with an auto-drive mode from the auto-drive mode to a manual drive mode at a desired point. The scheduled location (desired point) where the vehicle is to run in the manual drive is assumed to be a safety zone of the auto-drive lane, such as an interchange. Based on detection signals from various types of sensors, an auto-drive controller controls an actuator to perform auto-drive. A changeover switch is provided to switch between the auto-drive and manual drive. When the vehicle is running in the auto-drive mode, the current position of the vehicle is continuously detected on the basis of a signal from a GPS, and the vehicle speed is checked according to a signal from a vehicle speed sensor. After checking the location and the vehicle speed, an expected time of arrival at the destination, namely the scheduled location (desired point) where the drive should be changed to the manual drive, is calculated according to such data. According to a shifting time to complete the shift to the manual drive, timing for operating the changeover switch is determined, and a message is shown on a warning display to urge a driver to operate the switch. In one embodiment, it is judged in view of a prescribed shifting time whether or not the shift from the auto-drive mode to the manual drive mode can be completed before the vehicle has reached a destination and an appropriate measure is taken according to the judged result, so that the changeover to the manual drive can be made reliably at the desired point.
However, although alerting the driver in time, so that the changeover to the manual drive can be made reliably, the message shown on the warning display urging the driver to operate the changeover switch will potentially catch an otherwise occupied driver off guard. Being caught off guard will most likely affect the vehicle driver's readiness to respond to the request to assume manual control of the vehicle.