Nissan introducing independent control electric steering technology; to be deployed on select Infiniti models within a year
17 October 2012
|Components of the next-generation steering system. Click to enlarge.|
Nissan Motor Co., Ltd. unveiled the first steering technology that allows independent control of a vehicle’s tire angle and steering inputs. This next-generation steering technology was developed by Nissan and will be deployed on select Infiniti models on sale within one year.
A conventional steering system directs tire movements by transmitting steering inputs to the tires via a mechanical link. Nissan’s next-generation steering technology interprets driver input via force applied to the steering wheel, which is fed to the system’s multiple redundant Electronic Control Units (ECUs). The ECUs translate this into instructions to the steering angle actuator, which causes the front wheels to turn. At the same time, the system transmits information from the road—in effect, what the wheels re feeling—from the steering angle actuator back to the ECUs. The ECUs then filter this information, passing on to the steering wheel only the feedback that the driver needs.
For example, even on a road surface with minor ridges or furrows, the driver no longer has to grip the steering wheel tightly and make detailed adjustments, so traveling on the intended path becomes easier.
The result is that the systems transmits the driver’s intentions to the wheels even faster than a mechanical system and increases the direct driving performance feel by quickly and intelligently communicating road surface feedback to the driver.
Accompanying this next-generation steering technology, Nissan has also developed a camera-based straight-line stability system to further enhance on-center driving capability. Another first, this system improves vehicle stability by making small input angle adjustments so the vehicle will accurately trace and continue as planned in the lane it is traveling.
If the vehicle direction changes due to road surface or crosswinds, the system acts to minimize the effect of these conditions resulting in reduced steering input from the driver.
Using a camera mounted above the vehicle’s rearview mirror, the system analyzes the road ahead, recognizes the lane direction, detects changes in the vehicle’s direction, and transmits this information to multiple electronic control units as electronic signals. If a discrepancy occurs, the system acts to reduce the discrepancy by controlling the opposing force to the tire angle. By reducing the frequency of detailed steering input adjustments, which are a cause of fatigue on long drives, the driver’s workload is greatly reduced.
This next-generation steering technology's high reliability is achieved by multiple ECUs. In the event a single ECU malfunctions, another ECU will instantly take control, and in extreme circumstances such as the power supply being disrupted, the backup clutch will act to connect the steering wheel and wheels mechanically, enabling continued safe travel.
Autonomous Emergency Steering System. Separately, in another steering technology development, Nissan announced its “Autonomous Emergency Steering System.”
This system offers a high level of collision avoidance capability by applying automatic braking and automatic steering in situations where a collision is imminent and evading obstacles by braking may not be effective. The system takes effect in situations where unpredictable risks arise, such as sudden intrusions onto the road in low speed zones, or when a collision at high speed is imminent due to the driver's delayed recognition of the tail end of a traffic jam.
Nissan has long worked on the development and commercialization of brake-based control technology. The company has recently promoted development of technology to deal with situations that cannot be mitigated through braking alone. In order to prevent an accident from occurring, technology is needed to identify potential obstacles. Nissan has succeeded in developing technology which, through high-precision sensing technology and on-board control technology, automatically steers the vehicle away from potential collisions, when braking alone is insufficient.
The Autonomous Emergency Steering System, using the information provided by the front-mounted radar and camera, the two left and right rear radars, and the five laser scanners attached around the vehicle, initially acts on a risk of collision that cannot be avoided by braking. Simultaneously, it checks if there is a forward zone free of obstacles and that there are no vehicles approaching from the rear, and then displays to the driver the direction that the vehicle should be steered. If the driver cannot immediately steer in that direction, the system takes over to automatically steer the vehicle to help avoid a collision.
|Click to enlarge.|
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