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3943 messages, Last post on Nov 02, 2009 at 9:19 AM
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Replying to: lynnkushnir (May 28, 2008 9:00 pm) VDIM is different than run-of-the-mill safety systems because it integrates all the safety subsystems and the engine into a whole and it tries to anticipate dangerous situation and proactively apply these systems in a coordinated manner. Other run-of-the-mill safety systems are not integrated, they do not work as a whole or coordinate their actions and they activate only when a dangerous event occurs. VDIM constantly senses and measures motions of the HH in x, y and z axis. It will detect a potentially dangerous situation and act preemptively to prevent a dangerous event from taking shape. It does not wait for that dangerous event to happen and then respond. It cannot overcome physics but for what it can do, it does it very well. I believe Honda/Acura, Lexus, Mercedes, BMW and Volvo offer something similar. I once tried to merge into a carpool lane with a sharp left and a simultaneous sharp stab at the throttle, the VDIM refused to do it. I now wait for a clear stretch, merge into the lane first and then accelerate when the steering was no longer at any severe turn-angle. It is a lot safer too. The VDIM also negotiates curves wonderfully along a familiar local hilly freeway. We discovered this by accident. We had it in cruise, got into a well known curve a bit fast, felt the car slowed itself and then picked up again exiting the curve; all before we could do anything except to steer. It felt precisely like what we would do but the VDIM took care of it. Of course, VDIM cannot overcome physics so I won't set cruise and race down HWY 1.
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Replying to: cdptrap (May 29, 2008 10:56 am) Well, no. VDIM is just a term newly adopted by Toyota. These systems, ABS/TC(TRAC)/BA/EBD/VSC/etc, have ALWAYS been integrated, out of pure necessaty, to prevent them from negatively interacting with each other. If you read all the theory and diagnostic procedures for VDIM and then go back a few years and read the same for the earlier system(s), then called the "Star Safety System, you will find, mostly, exacting functionality throughout. And VDIM, as good as it is, and it is REALLY good, still cannot predict the future and so it can only REACT after the fact. It would be ideal if VSC could sense that the "moment", lateral inertia, of the vehicle will exceed, "soon" exceed,the traction coefficient of the tire tread to the roadbed but in order to do that it must know the CURRENT frictional coefficient of the roadbed surface. So VSC can only REACT once traction, partially, say front or rear, is actually LOST.
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Replying to: sebemismnusa (May 29, 2008 10:40 am) "...I tried to spin out...." No, it is much more likely than otherwise that what you tested was VDIM's TC/TRAC "component". Even the RX AWD series is heavily front torque biased, 95/5, and so the vehicle is much more subject to understearing, "plowing", making it extremely difficult to "spin" at a low enough speed to be comfortable with the safety factor. My experiments ('01 AWD RX300) in this vein resulted, EVERY time, in TC/TRAC kicking in the instant I tried to accelerate quickly enough that I could then yank the stearing sideways and cause the rear end to break loose and come about. So the "beep-beep-beep" you heard was more likely an indication that VSC/TC was "in play".
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Replying to: wwest (May 29, 2008 2:33 pm) I hear what you are saying but our experience says otherwise. I have had VSC on various other types of vehicles, never thought they were useful but none of them behaved as the VDIM. Not in the Mercury, not in the Sienna, not in the Chevy and not in Honda and not in Ford. None of them ever stopped me from being able to change lane, none of them could handle a curve exactly as I had experienced. So we will continue to share our experience of VDIM being different than normal VSC. I guess we have to agree to disagree  .
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Straight from the horse's mouth: http://www.toyota.eu/06_Safety/03_understanding_active_safety/05_stability_contr- ol.aspx PLease note I do not work for Toyota, just trying to sort out the subtle but important differences of VSC vs. VDIM. Enjoy! 
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Replying to: cdptrap (May 29, 2008 9:34 pm) But then the statement continues.."too much yaw (rotation around the car's centre of gravity)" By this extended definition of "too much yaw" the only difference between VDIM and VSC becomes the addition of the variable stearing ratio coupling and its integration into the "mix". So, apparently, the VDIM system remains REACTIVE just as was/is VSC. I suspect the real difference is that the VDIM/VSC intervention is now much more noticeable by the driver due to the sudden change in stearing ratio, resistance to stearing in the "wrong" direction.
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Replying to: wwest (May 29, 2008 10:34 am) RSC, Rollover stability control. This steps in when there is risk of the SUV rolling over, which is the greatest risk for an SUV. I personally am not a fan of VSC; I prefer to manage my own turns. Of course, I'm a VERY careful driver, and my care increases as the temperature decreases.
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Replying to: stevedebi (May 30, 2008 9:57 am) The PSM in my Porsche is the ideal system IMMHO in that it waits a few hundred milliseconds to give me time to react and if I react in the correct manner, say turn inside the skid, it remains inactive. |
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Replying to: wwest (May 30, 2008 9:36 am) This is another link from Toyota that shows how VDIM does a bit more than VSC. http://www.toyota.co.jp/en/safety_presen/tech/33.html As for whether it is "proactive", I think we are actually saying the same thing but emphasizing different aspects. It is true that the VDIM must first detect the possibility of an event before taking action, so one can say it is reactive in that regard. It is also true that the VDIM can, within reason, detect an event and take corrective action even before a driver realizes something is amiss, so one can also say it is proactive in that regard. It is easier to emphasize the latter because we have experienced it. We were in a traffic jam crawling at about 30+ MPH and I simply turned the steering hard to left and pressed on the gas pedal hoping to dart-merge into a carpool lane, something I had done thousands of times in all other cars, the VDIM stopped me cold. The car would not accelerate, the steering became heavy and the turn wouldn't happen. There was 0%-risk of roll-over but the VDIM resisted the turn. If the car had turned and accelerated and then the VDIM kicked in, I would wholeheartedly agree it was reacting. In our case, the VDIM simply refused to do it. We have since learned to just turn only as much as needed and smoothly press down on the gas. The smooth movement does as much as a dart-merge but a lot safer. So in everyday driving activities, as far as a driver is concerned, the VDIM is relatively proactive. So much so that many drivers (Lexus drivers and Canadian Driver testers) call it a "nanny" or "big brother" system and ask for ways to turn it off! We decided to leave it on because as long as it makes my drive safe and comfy, I am happy. Cheers!
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Replying to: cdptrap (May 30, 2008 1:51 pm) Apparently I gave the Toyota engineers who designed these systems too much credit. I'm pretty sure the first instance of a form of VSC was on a european marque, MB or BMW, and those systems, ABS/TC/"VSC", were totally integrated from the get go. If I am reading the information in that last link correctly then Toyota has only recently realized that absent integration, FULL integration, these systems could/might interfer with each other in a negative way. I don't now know if this is still of importance but in my '01 AWD RX300 if I floor the accelerate while trying to make a really tight accelerating turn the engine goes "flat" and will not recover until I release and then reapply the accelerator a bit more slowly or lightly. And yes, these sensors can be used to detect an "out-of-whack" driving condition substantially sooner than the best and more experienced driver might using our "seat-of-the-pants" sensing capability.
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