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Steer-by-Wire?



It is still around, the mechanical connection from the steering wheel to the front wheels, apparently though, they are working on a way to do away with it. That might even make sense, in view of the enormous amount of effort being put into the steering nowadays.

Thereby, it all started off so harmlessly, with just a steering gear, two or three tie-rods and pivot-arms. Later on, the passive accident prevention was introduced, with the dished steering wheel and the removal of the rigid connection to the steering gear.

Only fairly recently did the airbag find its way into the steering wheel. The hydraulic power steering has been around for much longer, also the speed-sensitive variation. It could well have been left as it was, after the complex system was sustituted for by an electric motor.

It's almost seems that the steering wheel has just been discovered, and is now being misused as a control panel. Now that, thanks to the reduced size of the airbag space, one can find the hooter more easily, the confusion of buttons and switches on the steering wheel has made it more complicated again.

From now on, more faith was given to the electronics. This was the time of the active intervention. The driver still had control over the steering wheel, but no longer over the steering gear. It started off quite innocently, with the greater wheel movement compared with the steering wheel rotation.

One no longer lets go of the wheel, even when cornering sharply. Indeed, the steering afterwards becomes more and more independent. E.g., it starts to shudder, if one threatens to leave the lane-markings. If it carries on like this, we'll soon be having discussions with the steering, in the middle of the motorway.

Infiniti, with the expression 'Steer-by-Wire', and the hint towards aircraft technology, are trying to give the impression that the steering wheel and the front wheels are no longer mechanically connected. The safety requirements for a system like this would be immense.

After all, in the event of the electronics breaking down, the front wheels cannot simply be turned back to the straight-ahead position. It's more simple in an aircraft, because they have a triple redundancy anyhow (here: the interpretation of the system). After all, the aircraft can't simply stand still in the air.

Indeed, what's all this got to do with the Infiniti? The essential difference is shown in above picture. There you can see, in addition to the doubling of the universal joints, a thickening in the steering column, this apparently, filters out any influences from the steering to the steering wheel. Should the electronics break down, there is indeed, still a mechanical connection.

This would probably mean a pretty insensitive steering, without any feedback from the road. Under normal circumstances, the electronics would take over. This would provide, depending on the adjustment made by the driver, the respective precision. One advantage is, that the extremely differentiated judgement of the steering made by the motor car test-drivers, would finally come to an end, since now, the feel of the steering is adjustable.

The whole thing reminds us strongly of the beginnings of the SBC-brake (Sensotronic Brake Control), where there was still an emergency hydraulic connection to the front brake cylinders, the pressure from the pedal however, was given by a sort of simulator. In the Infinity Q50, the steering is, for the first time, freed from any influences.

We'll have to wait until after the test-driving has been done, to find out just how much feedback from the road there will still be. Whatever the case may be, it is now possible, to satisfy the various needs all over the world by software. Indeed, the test-drivers will have to find themselves a new hobby. 10/13

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