LeftieBiker wrote:Driving home on a moderately but not especially smooth road tonight, I used the instant graph display to watch power consumption, and the results may surprise us both, PedalLogic. It appears to me that the device may indeed remedy a problem with power consumption at steady speeds, but... I don't think it's the problem that PedalLogic identifies. I used both a very steady foot and the cruise control, and the constant small jumps and dips in power consumption were virtually the same with both. Since the cruise control doesn't use the accelerator pedal (I'm assuming that this is a fly by wire system!) I believe that the issue is actually that the varying pavement height slightly but significantly increases and decreases power demand, not accelerator pedal deflection. If this device smooths out the power supply response, then it may work as advertised - just not in the exact way advertised.
You are seeing two related effects but your conclusion is incorrect. Here's what's going on:
When acceleration is controlled by the driver (i.e.
, foot on pedal), there's no question that fluctuations in power demand are caused by the imperfections in the roadway surface. This is easy to observe through data and through your own personal experience. Through data, we know that the driver's foot moves up/down about 1/10th of a second after the vehicle moves in the same axis. We can measure and time this biomechanical interaction by using an accelerometer at the pedal, tracking the data from that accelerometer, and graphing it against changes in the pedal signal caused by sympathetic movement of the driver's foot. And each time this unwanted motion happens, the ECU that controls the motor's output increases or decreases power momentarily.
But our technology isn't just a simple low-pass filter. That approach leads to an immediate and significant change in the driving experience by making changes to both the intended and unintended power requests. Instead, our system utilizes probabilistic analysis to determine whether a particular change was intended by the driver. If it wasn't, the system adjusts the signal to what it believes the driver did intend. By using the built-in driving modes, drivers can manage the threshold for--and extent of--these changes. It's not magic though: if the system is set overly aggressively, it will over correct and there will be a noticeable effect on the driving experience, but even then the the effect is usually smaller (and more enjoyable) than switching from D to Eco.
When acceleration is controlled by cruise control, you will also see spikes and drops in immediate demand, and this is also caused by the roadway--but not by the driver's foot moving on the pedal. Instead, the ECU is attempting to maintain the vehicle in a steady state in terms of speed. Imperfections in the roadway impart or take away energy from that equation, so the ECU constantly adjusts the instantaneous demand to return to the target speed--and you see the results of that constant "trimming" in the display of instantaneous energy demand.
there is a million different reasons for the constant power fluctuation you saw and you are correct in that none have to do with your foot.
If you were only referring to when Leftie was driving on cruise control, I totally agree. If you were referring to manual operation as well, I disagree. The only open question is how much power is wasted. One of the purposes of this test is to see if the real-world results of a diverse group of owners/drivers match the results generated in testing on closed courses with professional drivers. There will undoubtedly be differences and things for us to learn.
DaveinOlyWA wrote:what this device is basically "adjustable Eco" mode. Even if it works exactly as advertised you will still see a wide fluctuation of power. Road and traffic and weather and wind all will insure that.
Since we are a different approach to improving mileage than is built into your vehicle, I'm not sure that "adjustable Eco" mode fully captures what we do. In any case, our focus is reducing the fluctuations in power caused by the unintended changes of the pedal position. We do that task really, really well, resulting in an upward bump of kWh from whatever it would normally be in the climate and on the roadways that your Leaf travels.