Euro: VSA

[yfin]

Ofcource it cuts power when understeer is present to control wheel spin

When my car was stock it sometimes cut power around corners if there was lots of body roll. No wheel spin. No understeer. It still did it.

But, when your going in city traffic or on the freeway is there really a need to have it off if your not trying to go as quick as you car around a corner?

No need to have it off.

[Omotesando]

Well this is starting to get interesting haha! Apparently VSA is two components , so hence it is not just just called Traction Control...


Usually the Traction Control part will cut the power when detecting there is a wheel spinning, and on a car without a helical LSD such as Euro this is usually the inside wheel during cornering, or may be both wheels when accelerating uphill, etc?? I dont know the technical details of the Traction Control on our Euro but usually they cut off Spark Plugs but keeps the fuel flowing so engine wouldnt run lean.


The other part of the VSA which controlled the oversteer or understeer is the brakes, which is applied individually when it senses one corner is losing it. I would say yfin is correct that there should be g-sensors in front and back!



But when you said that it cut power where there was lots of body roll, it was probably not the traction control but the VSA activating the brakes automatically to stabilise vehicle (I assume this latter technology is linked to the EBD system somehow) ....


Anyway with VSA on you can still get the oversteer going, trust me ! lol!!

[aaronng]

Euro's Traction control: If 1 wheel spins, it brakes the other wheel so up to 50% torque is transferred (cheap man's LSD). If both wheels spin, then it cuts the throttle. By spark plug or by fuel, I'm not sure about that.

[wynode]

The other part of the VSA which controlled the oversteer or understeer is the brakes, which is applied individually when it senses one corner is losing it.

That's not all. VSA will activate the brakes individually if you have to make any evasive manouveres. Say you have to make a sudden turn of the wheel to avoid a dog crossing the road, VSA will give you more control by applying the inside rear brake to help you turn.

I believe under/over steer is detected by a accelerometer (usually placed in the centre of the car) and the position of the steering wheel (depending on the speed). It will then apply the brakes individually if rqd.

[tknova]

That's not all. VSA will activate the brakes individually if you have to make any evasive manouveres. Say you have to make a sudden turn of the wheel to avoid a dog crossing the road, VSA will give you more control by applying the inside rear brake to help you turn.

I believe under/over steer is detected by a accelerometer (usually placed in the centre of the car) and the position of the steering wheel (depending on the speed). It will then apply the brakes individually if rqd.

Spot on! That's why i think VSA should always be on until you flick the switch turning it off.

[Omotesando]

Euro's Traction control: If 1 wheel spins, it brakes the other wheel so up to 50% torque is transferred (cheap man's LSD). If both wheels spin, then it cuts the throttle. By spark plug or by fuel, I'm not sure about that.

I think for a really good driver all this technology might not be so good afterall lol!!


Are you pretty sure about how our VSA Traction control works, by braking the individual wheel if only 1 wheels loses traction? Because even a Race Logic Traction control unit doesnt do this it just plains cuts off power, even though it allows a certain amount of slip such as 5%, 10%, etc,..

And if it does I thought it will brake the wheel that is spinning? Why does it brake the other wheel? Getting confused!!

[aaronng]

LOL, my mistake. You are right. It brakes the spinning wheel. You won't be able to feel it when it brakes the spinning wheel. But the onset of both wheels spinning is slightly delayed. Try turning from a stop with more throttle, with traction control on and off. There should be a difference.

It depends on how ABS is implemented. On older cars with ABS, the ABS system is 2 channel. One for the front left and rear right, and the 2nd for the front right and rear left. The Euro has a 4 channel system, one for each wheel. This is how it makes VSA work.

The VSA software is able to utilise the ABS channel to brake each wheel. And since traction control and VSA are PROBABLY tied to the same system (same software, deactivated by the one button), then the traction control system is not similar to a Race Logic traction control system, but more of an "option" in VSA. VSA detects wheel spin when you are turning to determine understeer or oversteer and brake the proper wheel to counter it. When you are turning and you end up spinning the inner wheel and thus end up understeering, the VSA just brakes the inner wheel so you can turn. Basically it is an LSD effect, just not as good as a real mechanical LSD. And traction control is a situation in VSA where both wheels spin when the car is going straight.. I SPECULATE that the Euro does not have a separate traction control software module, but rather it is built into the VSA system as a pre-programmed scenario.

[wynode]

On older cars with ABS, the ABS system is 2 channel. One for the front left and rear right, and the 2nd for the front right and rear left.

I'm not sure how true that is given the front does upto 75 percent of braking. With cars like the integra Vti-r (somewhat 'older' than the euro), they run a 3 channel ABS system. 2 Channels for each of the front two wheels and 1 channel for the rear wheels.

In regards to the Euro it is true to say that traction control and VSA are both disabled by the one switch however they are both seperate systems IMO. Traction control is primarily there to cut the throttle when wheel spin is detected at the front wheels.

VSA is there to increase vehicle stability and keep the driver in control of the car. From what I have read about other manufacturers, the stability program detects under/over steer and brakes the wheels individually in order to give the driver maximum control.

Aarong, I'm not sure you if you could call VSA a 'cheap' implementation of a LSD as an LSD actively transfers power from one wheel to another depending on the level of grip. VSA can't do this.

This looks like a good thread

Anyone got some links to the EUROs stability program?

[aaronng]

I thought that since the traction control uses the same wheel spin sensors as the VSA that hardware is the same as the VSA. My argument is that traction control is not a separate unit, but one that is part of the VSA. Like a tiny software module in the VSA that has the logic "if both wheels spin and no g-sensor activity, THEN cut throttle"

Honda Japan's website for model data shows "VSA (ABS+TCS+Sideslip control), translated of course. So I tend to see the ABS, TCS and stability control as one unit.

With an open diff, if the spinning wheel is braked so that there is more resistance than the non-spinning wheel, then torque will transfer to the non-spinning wheel. It's inducing a outer wheel spin instead of an inner wheel spin.

[aaronng]

There is a description of what VSA does in situations of understeer, oversteer and wheelspin. But a babelfish of the page is difficult to understand:

The function of VSA
- At the time of oversteer control (revolution, behavior stabilization) when the involvement of the vehicle occurs
- At the time of understeer control (revolution acceleration, with respect to) road surface trace propensity when locus of the driving wheel is filled
- With respect to takeoff propensity when road surface circumstance of the takeoff control (left and right wheel is different)
- Stability improvement > at time of control < braking of braking

* As for VSA it is the system which to the last assists the brakes operation and accelerator operation etc. of the driver. Therefore, same as the vehicle which is not VSA, foreward the corner and the like sufficient deceleration is necessary, it cannot control to unreasonable driving. We request careful driving.

What I think it says:
The function of VSA:
- At the time of oversteer, the system tries to control the vehicle turn rate and stabilise the vehicle behaviour.
- At the time of understeer, the system tries to control the acceleration, (with respect to the difference in the direction of the vehicle movement on the road and the direction the tyres are pointing.
- Controls acceleration force when the road surface is different for the left and right wheels. (I think different wheel speeds)
- Stability improvement by brake control

* VSA is a system that assists in brake and accelerator operation for the driver. Therefore vehicles that are not equipped with VSA should anticipate the corners and decelerate sufficiently. It cannot control irresponsible driving (Hooning! lol). Please drive carefully.

[aaronng]

More info... Yum yum. Got this from tsx.acurazine.com where they got info from Acura about the TSX's VSA.

Originally Posted by Acura Website
Vehicle Stability Assist (VSA) adds side-slip control to the ABS and traction control. It works by controlling brake pressure, engine power or both to help maintain traction. Even if you take no action, VSA will reduce engine power and/or apply the brakes to reduce front or rear side-slip. The traction control component of VSA® uses sensors that monitor the front wheels and computer-controlled modulation of engine power and front brakes to help prevent wheel spin when starting out or accelerating. If the sensors detect excessive front-wheel spin during acceleration, the traction control function automatically closes a secondary throttle valve until wheel spin stops. This helps the TSX maintain traction during acceleration and helps the driver retain steering control, even when accelerating on slippery surfaces.

And stuff I found from www.acura.com

The traction control component of VSA® uses sensors that monitor the front wheels and computer-controlled modulation of engine power and front brakes to help prevent wheel spin when starting out or accelerating. If the sensors detect excessive front-wheel spin during acceleration, the traction control function automatically closes a secondary throttle valve until wheel spin stops. This helps the TSX maintain traction during acceleration and helps the driver retain steering control, even when accelerating on slippery surfaces.

So traction control does use the front brakes. And the only thing I can think of to use the front brakes in a situation needing traction control is when 1 wheel is spinning. If both wheels were spinning excessively, then it would be better to cut the throttle instead.

[wynode]

Interesting read that and I think you make a valid point about using the brake if one wheel is spining and cutting the throttle if both wheels are spining