colejl

Simple question - does the steptronic box know whether the car is going up or down a hill? I suspect there's an electronic gyroscope that is used to affect the gear changing...

Anyone confirm either way?

andy545

I have definately noticed appropriate gear changes in the correct sense of an uphill or downhill road...whether it is a gyro that controls it? - don't know.

colejl

Indeed, the gears hold longer if going up hill... I mentioned this to someone else and they reckoned it was because of other factors, i.e. throttle position etc. rather than a gyro...

DXXXi

It definitely knows it is going up hill and I don't think it is becuase of throttle position or load etc. because it won't shift even if you ease up on the throttle. It is very sensitive and notices even slight inclines but I don't know what the technology behind it is.

gwf545

I think that BMW has had the ability to detect the angle of attack for some time. I recall reading in my E39 manual that the auto transmission would compensate for it.

pennetta

I have a SMG but the Steptronic was great on my previous BMW because of stuff like this.

colejl

The SMG works like this:

Driving Uphill
The SMG control unit recognises when the vehicle is driving uphill from the data from the wheel speed sensors and the accelerator pedal sensor position, and then prevents unnecessary upshifts and irritating pendulum shifts (e.g. at constantly high engine speed and foot taken from accelerator pedal).
Driving Downhill
Signals from the throttle-valve potentiometer (load signal), the wheel speed sensors (road speed) and the brake-light switch allow the SMG control unit to recognise when the vehicle is driving downhill. To maintain and increase the engine's braking effect, the SMG control unit will shift down a gear as road speed increases.

I would guess that the Steptronic works the same way...? All software controlled! (Gulp)

530E60NL

I've noticed this too and it is so naturall that I couldn't do it better myself if I had a manual.

I used to hate automatic cars because the transmission was so stupid but with my BMW it's fantastic!!!

DXXXi

The SMG works like this:

Driving Uphill
The SMG control unit recognises when the vehicle is driving uphill from the data from the wheel speed sensors and the accelerator pedal sensor position, and then prevents unnecessary upshifts and irritating pendulum shifts (e.g. at constantly high engine speed and foot taken from accelerator pedal).
Driving Downhill
Signals from the throttle-valve potentiometer (load signal), the wheel speed sensors (road speed) and the brake-light switch allow the SMG control unit to recognise when the vehicle is driving downhill. To maintain and increase the engine's braking effect, the SMG control unit will shift down a gear as road speed increases.

I would guess that the Steptronic works the same way...? All software controlled! (Gulp)
[/quote]
So it knows you are going uphill even when you ease off on the accelerator because the car starts to slow down. If it doesn't detect a change in speed, it will shift and if it detects a change, it won't. If it doesn't detect acceleration based on a (small) depression of the accelerator position, it knows the car is going up hill. Pretty smart.

Analogs

This being my business - the car does have a single axis gyro for the DSC (DTC 2005 on) - it also incorporates a tilt sensor for theft protection - the gyro(gives angular velocity ?/sec) is a single axis unit for a left/right versus steering input for calculating response to loss of lateral control - corrects through uses of opposite angle braking. The transmission uses load, and tilt sensor to determine anguilar ascend/descend. Secondarily they use a pressure sensor in the intake manifold to claculate approximate fuel for elevation loading.

java script:emoticon('')