Thursday, May 12, 2016

Jalopnik: Here's How The 2017 Honda Ridgeline's Trick Off-Roading Modes Work

Wow, best article I've seen that explains how Honda's AWD works....
by Andrew P. Collins of www.jalopnik.com

Nobody expected the 2017 Honda Ridgeline to be a hardcore off-roader. It simply lacks the low gearing and solid axles typically suited to crushing rocks. But Honda’s new pickup still holds its own over rough terrain, and here’s how. Call it “better off-roading through science.”

The Ridgeline is a novelty among American-market trucks because of the way it’s built. Pickup trucks and truly tough SUVs like the Jeep Wrangler, Mercedes G-Class, Toyota 4Runner and Land Cruiser are traditionally made by slapping a body and cargo box onto a solid steel frame.

Their main drive axles are robust straight-sticks. They also generally run part-time 4WD system manually engaged with a “low range” reduction gear providing tremendous power at very low speed.

The big benefits to that kind of configuration are durability and economy. You get great resistance against hitting rocks and strength for the twisty crucible of a heavy load or an off-road trail. It’s also cheaper to build trucks that way.

The Ridgeline has the opposite of all that.

A Most Unusual Pickup

Honda’s new truck is made with unibody construction. It’s not literally “one piece,” but the shell and body and undercarriage are all part of a holistic structural system. That theoretically makes the ride smoother through minimized vibration and better balance, reduces weight and generally provides a more stable driving experience.

The Ridgeline also runs an all-around independent suspension, which means each wheel can bounce up and down on its own with little driveshafts poking into them on angles as opposed to one thick bar running between the rear wheels.

Instead of a traditional 4WD kit with a mechanical locking differential, Honda uses advanced traction control and AWD to keep their new truck moving through muck. This is where things get interesting.
Honda calls its system “Intelligent Variable Torque Management” (i-VTM4) and explains it pretty concisely in the brochure:
“Honda i-VTM4 progressively distributes optimum torque between the front and rear axles and dynamically distributes engine torque between the left and right rear wheels, with the capacity to overdrive the outside rear wheel by 2.7 percent to create a yaw moment that improves cornering precision.”
Basically that means it maximizes efficiency by putting power to the wheel that can get the most motion out of it. As Honda continues:
“By rotating the outside rear wheel faster than the front wheels while cornering, Ridgeline’s AWD system uses torque vectoring to create a yaw moment to help turn the vehicle through the corner—reducing understeer and improving controllability. With cornering forces more evenly distributed between front and rear tires, overall cornering power is increased in all road conditions.”
Now how does the Ridgeline know how to do that? Its Vehicle Stability Assist (VSA) sensors and ECUs are constantly monitoring wheel speed, steering angle, how fast the steering angle is changing, lateral G-forces, vehicle yaw rate (slide speed), and hydraulic clutch pressure for the right and left rear axle shafts.

That hydraulic clutch, by the way, can differentiate power between the left and right rear wheel or lock them together for soft-sand type situations.
That host of motion-monitoring tech is on all the time, and theoretically optimizes the Ridgeline’s tractability on pretty much any reasonable road surface in “normal” mode.

The idea is to be completely automatic. As I wrote in my review of the whole truck, think of it like your iPhone– don’t worry about what’s behind the technological curtain, just enjoy the ease of use from the front end.

Driving Modes

However, Ridgelines with AWD will also get three dedicated off-road modes to somewhat override the system manually, activated from a button below the shifter. There’s one for “snow” (available on 2WD trucks) one for “mud” and one for “sand.”

Here’s how the driving parameters change in each mode:
Snow: The idea here is to minimize pedal travel and make launching easier. The throttle input via Drive By Wire (DBW) is made less aggressive, particularly where you first tip-in the pedal. That basically means you’re giving it less gas than you think.

Mud: “Mud” mode has an emphasis on maintaining momentum. Gain increases as you tip the throttle. Torque vectoring is shut off and more power is sent to the rear wheels. The transmission delays upshifts and traction control allows for more wheelspin.

Sand: Basically the same as “mud,” but with all the needles moved even more aggressively. It has maximum rear-bias (a Honda rep told me 70 percent) and an electronically “locked” rear differential.
How does it work in real-life? Pretty well, if you use it appropriately.

Stopping in soft stuff and then turning on “sand” mode made it a lot easier to self-extract than continuously plodding along with my foot on the floor. But if you think putting it in rear-biased “sand,” and turning off traction control as much as you can will turn the Ridgeline into a power-slider you’re mistaken.

Try to “drift” the truck like you would any other pickup; turn the computers off, saw the wheel and give it too much gas, and the Ridgeline just gets annoyed with you. It drags its face around like an overladen wheelbarrow.

But use the mode meant for the surface you’re driving on and the experience becomes remarkably idiot proof. This is what I meant when I described the truck as “another step closer to autonomous off-roading.”

Is Honda’s system a solution for hardcore rock crawlers? No way. But you knew that. If your main objective is to get from Point A to the end of your adventure without worrying about how to drive through mushy stuff, the Ridgeline’s tech will really boost your confidence.

Just don’t expect your newfound “skills” to work as well in a more primitive pickup.

So you can pretty much draw the same conclusion about the new Ridgeline’s AWD system as you can about the whole car: technologically impressive, overbearingly user-friendly, and aggressively practical. Which will hopefully help more people get out and into the world already!

If you’ve not sufficiently nerded out on this tech, I invite you to read the massively in-depth Powertrain press release Honda published this week. Until then, I’m just waiting on a longer-term Ridgeline rental so I can see just how far the system will take us.

Source;
http://truckyeah.jalopnik.com/heres-how-the-2017-honda-ridgelines-trick-off-roading-m-1775651261

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