With the implementation of driverless vehicles, it cannot be under stressed how important ride comfort will be to the end of facilitating people's ability to do other things in the vehicle such as eating, working on a cellphone or computer, or sleeping. With driverless technology drive-time no longer needs to be wasted time.
However, in places like bumpy New Zealand especially, good ride comfort will be difficult if the roads are not well conditioned for smoothness. I would like to suggest what I believe may be the best way to achieve this end.
Driverless cars can be guided to follow a near-perfect line on this road, like a rail car. We can exploit this. Without too much cost, we can install a central rail along the main roads which is simply a continuous steel beam that's bent into place, so as to provide smooth curves and effectively remove all disruptive bumps on the road surface, on all main roads.
For this to work, the cars would require electronic positioning, and also electronic control of the four wheels suspension systems. This is to keep the vehicle steady and to stop it from 'rocking' over the centre axis, like a seesaw.
The central rail wheels will support 80 to 90% of the weight of the car when in cruise operation. The rail wheels will not usually provide traction for drive and braking - only weight bearing. However, a motor-in-wheel system for drive, within the rail wheels, may be desirable for heavy freight vehicles.
In my model, the rail wheels are primarily redundant. The car retracts the rail wheels to a given degree, to disperse traction to the four main wheels as required, to facilitate braking and acceleration and heavy cornering. It's important for reliability that the cars are not operationally dependant on the rail system.
-Note also, the road would be resurfaced at the points where the main 4 wheels make contact, to maximise the 'bumpless' ride. This will not be expensive as the resurfacing is minimal.
Advantages:
The central rail can be laid down relatively cheaply. Basically, it gives an economical way of perfectly smoothing the road.
Not only would the system provide exceptional ride comfort, it also avoids significant dynamic loading on the the road, and in turn reduces energy loss from the cars dampeners and greatly reduces road wear - especially from heavier freight cars.
The extra cost of making a more sophisticated vehicle to accommodate this should not be too high, considering each car will usually be a robotaxi used over and again throughout the day. The extra vehicle costs would be quickly recovered, even if those costs are say an extra $50,000 per 4-seat car.
-Note also, the electronic suspension could allow the cars to actively tilt around corners by about 10 degrees. That would be invaluable in a New Zealand context. Also, with electronic suspension the system can develop a digital map of all the imperfections in the road, and in turn manipulate the electronic suspension within the cars to maximise the response (and comfort) to the road surface in advance, before making contact with a bump.
Finally, creating excellent ride comfort makes the car a place where people are happier to be. We can then look at reducing maximum travel speeds to maybe 80 or 70 km/h, as the need to reach your destination is then not so pressing - especially if you can sleep. This would make travel much safer and extremely economical as well. (see here for my argument on this)
Concluding:
This is something we can think about today, now that we have the opportunity to do so. It's just a matter of analysing the costs to benefits, and a preliminary study could give a good indication.
I think a study on this should be done sooner, not later, because if it's clear enough that the initiative is worth the investment, then there's a lot to be said for getting our driverless system right from the beginning, to avoid wasted opportunity and costly retrofitting later.
-Andrew Atkin
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