BBS SPY wrote:

Forgot to mention that the deflate to lowest would keep the pressure available in the reservoir and it would hold it in diagnostic mode, thereby inhibiting any ECU control, even with power down, it would remember last mode.

jdhx wrote:

On the other point, I suspect that levelling horizontal is going to be difficult at least with any degree of automation. Unless the car has a pair of built in spirit levels (does it guys?) then how does the software know which corners to pump up and which to let down and of course the extra software would need to be added in some way.

Quote:

Unless the car has a pair of built in spirit levels (does it guys?)

When ABS systems (of which Bosch were the main pioneers) were first introduced, they were little more than systems that, via pick ups on each wheel, could measure the rotation of each wheel and thus detect differential wheel rotation. Under braking, these ABS control units could use valves to relieve driver applied pressure to locked wheels. Brake pedal stepping down in pulses. Later advents saw the ability of such systems to regulate and apply pressure themselves, achieving maximum braking on each wheel. Usually the pedal pressure was isolated and maintained, although fast pulsing could be felt

It was a natural transition for the same rotation inputs to be monitored during acceleration and the same pressure and valves used to prevent wheel spin, giving Traction control. CAN Bus technology also allowed for the ABS (& now also Traction control ECU) to tell the engine management to back off the power whenever wheel spin was detected under acceleration. Exactly the same inputs and valve control is also used in hill decent control technology, which is really just additional software routines.

As such ABS units were produced that could also provide traction control (P38 Range Rover) and HDC capabilities (Freelander 1). One of the latest and best units being the widely known Bosch 5.7 ABS systems.

However in the early 20's, Bosch, in conjunction with one of the major German manufacturers, developed a whole new technological concept, so significant, that it would in effect turn everything upside down and revolutionize the feeling and handling of cars forever. The resultant improvement in road safety was such that the German manufacturer that co developed it's biggest rival, was able to persuade a court to force them to share in the technology and there were even government web sites created to educate people to the advantages. It is reputed that cars carrying the technology were involved in 80% less accidents than non equipped models.

The development in question was the introduction of a CAN bus connected gyro sensor, mounted on a thick metal pate, centrally in the vehicle. It is so sensitive, it can measure even the slightest of G forces on a car in any direction. Coupled in a fast CAN bus connected system, this sensors input allows auto boxes to change gear without the occupants feeling anything, as well as far smoother smoother power delivery / acceleration from the engine management. So if you ever wondered how come your auto does not jerk you as it changes gear or how come your vehicle does not snap your neck, stall or jerk you no matter how badly you apply the clutch and accelerator, now you know why.

However, although this new technology provided a magic carpet ride capability, it is in the braking department that it enjoys its best achievements
.
By combining, via the CAN bus, gravitational force information, traditional wheel Rotation information (that is nowadays translated more as rotational mass at each wheel), engine torque application information, gearbox torque in and out input, and additional steering wheel angle sensor input. The control unit knows exactly what is happening to the vehicle at all times, and more importantly what user inputs are being applied. How hard the driver is accelerating or braking, at what angle they are holding the steering etc, It has, built in, a set of pre determined safe parameters, at which it knows the vehicle is under control and should the vehicle ever go to close to exceeding those, it can instantly calculate and apply correctional control over the engine management, gearbox and braking control valves to keep the car within the known safe and stable envelope. This technology is commonly known as Dynamic Stability Control (DSC).

Although keeping abreast of such technological matters is just part of my job, and i enjoy sharing my knowledge and understanding, i have to say that nothing comes close to my enjoyment of understanding the true implications and ramifications of something that is otherwise an almost un noticable change in name by those behind it.

For example if you have a Rover 75 / or MG ZT, it is fitted with a Bosch 5.7 ABS system, of which almost its entire primary function is to provide just anti lock braking. hence the ABS title, If you want traction control with that, then it has an add on module that can prevent wheel spin and talk to the engine management to tell it to back off. A sub functional add on capability.

However if you have an L322, it is fitted from introduction with a Bosch 5.7 DSC unit that looks exactly the same as in the Rover / MG. However Anti lock braking is just a sub function of this unit. It's primary role is to ensure that no matter what you do, the vehicle remains stable and safe at all times. ABS, Traction control and HDC are now such sub parts of the overall functionality that the system is now a Dynamic Stability Control unit with a sub function of ABS and not the other way round.

It happened right there in the blink of a subtle name change, but it represents so much to the likes of you and i that i always think it so sad that so few would probably ever even notice, i felt compelled to write this long post and explain, so that others may also appreciate the significance of the event.

Nowadays of course the CAN bus also ties in information and control with active dampening, active ride and suspension control systems too such as EAS. In fact while you may look at the bit of electronics attached to the hydraulic valve block and think that this is simply the ABS, It is actually now the Vehicle Dynamics module, and yes, JHDX, it sure does have the ability to tell the EAS system if the car is currently level or not. And i apologize for the long winded response, but given my understanding and knowledge of the actual technology in play, i could hardly have been justified in acknowledging it as a pair of built in spirit levels

BBS SPY wrote:

it sure does have the ability to tell the EAS system if the car is currently level or not.