Community Forums

newmarpusher · 09-15-2017, 07:21 PM

2015 Ventana 4037.

Comfort drive has been flawless for 2.5 years.

Last night we made a 3.5 hour run out to the Hershey RV show from NJ. Lots of hills and long sweeping turns.

After a long sweeping turn, for example to the left, as I entered a straight section of road, the comfort drive would continue to hold the center with the wheel cocked to the left. I would have to fight the torque of the CD to hold the MH going straight. This would continue for about 30 sec to a min, then the wheel would re-center and hold a straight line.

This happened continuously for the 3.5 hour drive. The system was working perfectly on the previous drive last weekend.

What do you think, Ken Sherwin?

pilotspike · 09-15-2017, 10:09 PM

Accidentally bumped the sensitivity knob?

KenSherwin · 09-16-2017, 08:16 AM

The CD was working exactly correctly, just as it has always done. In crosswind or road crown, the CD slowly compensates for the steering wheel correction you have to hold in order to drive straight but it has no way to know the real path of the coach so it takes a weighted average of the last few minutes of wheel position to call straight. This assumption usually works well but a very long sweeping turn gets it confused because it decides that if you keep doing what you're doing now, you won't want to feel any torque. After all, most roads are mostly straight most of the time and those that aren't, generally wiggle in both directions so they average out.

You may have had the efforts turned heavier so it was more noticeable but it has been there since 2003.

If anybody with a CD wants to demonstrate this to themselves, on a calm day, drive in the right lane of a straight section of a 4-lane road until there is no steering wheel torque. Then switch to the left lane somewhat briskly. DON'T run into another vehicle over there, DON'T knock dishes out of the cupboard, and DON'T spill the dog off of the couch, but don't dawdle either. When you get stabilized in the left lane, you should notice that you have to hold the steering wheel 5 to 10 degrees to the right of where it was a few moments ago and you should have to hold a bit of torque on the wheel. In about a minute, you should notice that there is no torque required to hold the wheel any more, even though the wheel is turned to the right.

When you get back into the right lane, the process is reversed so that you have to hold against the changed road crown for a few seconds.

To eliminate this effect, we have to know whether the new steering wheel position is caused by a change in the road path or a change in the required side force on the tires. An inertial sensor will do this but as of now, none of your coaches have one.

Does this help?

willipaul · 09-16-2017, 08:32 AM

turning the setting to 1 would have made it easier to compensate for the confusion of the unit, until it recalibrated itself, correct ?

KenSherwin · 09-16-2017, 10:00 AM

You could turn it down if it annoyed you but I never bother. It only lasts a few seconds.

newmarpusher · 09-16-2017, 02:05 PM

Quote:

Originally Posted by KenSherwin

The CD was working exactly correctly, just as it has always done. In crosswind or road crown, the CD slowly compensates for the steering wheel correction you have to hold in order to drive straight but it has no way to know the real path of the coach so it takes a weighted average of the last few minutes of wheel position to call straight. This assumption usually works well but a very long sweeping turn gets it confused because it decides that if you keep doing what you're doing now, you won't want to feel any torque. After all, most roads are mostly straight most of the time and those that aren't, generally wiggle in both directions so they average out.

You may have had the efforts turned heavier so it was more noticeable but it has been there since 2003.

If anybody with a CD wants to demonstrate this to themselves, on a calm day, drive in the right lane of a straight section of a 4-lane road until there is no steering wheel torque. Then switch to the left lane somewhat briskly. DON'T run into another vehicle over there, DON'T knock dishes out of the cupboard, and DON'T spill the dog off of the couch, but don't dawdle either. When you get stabilized in the left lane, you should notice that you have to hold the steering wheel 5 to 10 degrees to the right of where it was a few moments ago and you should have to hold a bit of torque on the wheel. In about a minute, you should notice that there is no torque required to hold the wheel any more, even though the wheel is turned to the right.

When you get back into the right lane, the process is reversed so that you have to hold against the changed road crown for a few seconds.

To eliminate this effect, we have to know whether the new steering wheel position is caused by a change in the road path or a change in the required side force on the tires. An inertial sensor will do this but as of now, none of your coaches have one.

Does this help?

Thanks Ken!

I have noticed the effect before but never so pronounced. I guess the very long distance of the sweeping turns is what made it seem like I was fighting the straights that much longer.

Good to know I don't have an issue.