Requirement for mechanically attached steering

[Largechris]

Hello, we are developing a new specialist low volume vehicle which will be suitable for occasional road use.

It's been suggested that it is a legal requirement for the steering wheel to be mechanically connected to the wheels, not electrically operated etc.

Can't see a reference, is this true?

Cheers

[buggalugs]

The old Infiniti Q50 had steer by wire but with a mechanical backup link, the new Toyota bz4x and I think one of the new Lexii has optional steer by wire with a yoke thingy but not sure if that's available in this country.

[PugwasHDJ80]

I originally wrote a reply saying that it was under C&U regs 1986, but when i started looking for the reference i couldn't find it.

Instinctively i presume you're going to go through IVA as a very low volume producer, in which case the issue you may have is passing the iva test.

Page 65 of https://assets.publishing.service.gov.uk/governmen... is the relevant bit.

[GreenV8S]

I don't know what regulations would apply, but I know that there are aggricultural vehicles with purely hydraulic steering and I don't believe this prevents them from being road legal.

[Largechris]

PugwasHDJ80 said:

I originally wrote a reply saying that it was under C&U regs 1986, but when i started looking for the reference i couldn't find it.

Instinctively i presume you're going to go through IVA as a very low volume producer, in which case the issue you may have is passing the iva test.

Page 65 of https://assets.publishing.service.gov.uk/governmen... is the relevant bit.

Thanks, I was kind of drawing the same conclusion, maybe it is allowed, I did see that page 65 which talks about drive by wire systems.

[poppopbangbang]

Low volume doesn't get you out of functional safety. SBW is pretty straight forward and we've done it for all sorts of things (both electronic and hydraulic)- including autonomous but on a risk vs reward basis it's very hard to achieve the required levels of proven functional safety to reduce the liability to an acceptable level for low volume.

If it's a hydraulically driven middle hinge setup ala' agri/construction then it's a little different for obvious reasons but a motor on rack or corner unit with no mechanical hand wheel link has 75% of the effort in the functional safety and 25% of the effort in the actual system.

It would be worth a conversation with one of the several companies that offer functional safety support around embedded systems to see what their thoughts are, you won't need full ASIL-D etc. for low volume, especially IVA, but it shouldn't fail in a way that whatever you are building goes through a packed bus stop....

[Largechris]

poppopbangbang said:

Low volume doesn't get you out of functional safety. SBW is pretty straight forward and we've done it for all sorts of things (both electronic and hydraulic)- including autonomous but on a risk vs reward basis it's very hard to achieve the required levels of proven functional safety to reduce the liability to an acceptable level for low volume.

If it's a hydraulically driven middle hinge setup ala' agri/construction then it's a little different for obvious reasons but a motor on rack or corner unit with no mechanical hand wheel link has 75% of the effort in the functional safety and 25% of the effort in the actual system.

It would be worth a conversation with one of the several companies that offer functional safety support around embedded systems to see what their thoughts are, you won't need full ASIL-D etc. for low volume, especially IVA, but it shouldn't fail in a way that whatever you are building goes through a packed bus stop....

That’s great thanks will do

[donkmeister]

Another shout: vehicle converters for the disabled. Plenty of disabled people driving vans with a joystick and no mechanical back up. See how those companies get it through approval and it could read across to what you are doing (even though converted vehicle Vs new vehicle).