Skyactive G - Driver Demand Acceleration Request

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Introduction

Mazda's Skyactive G platform utilises many complex and overlapping control strategies and these are still mostly undiscovered. When developing forced induction support for these vehicles we have discovered that the Skyactive platform uses a linear acceleration value to set an engine torque per gear. 

This series of maps are per gear using accel pedal and vehicle speed to set the requested linear acceleration (m/s^2), they are profiled for the correct RPM range created by the gear ratio and vehicle speed.

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Tuning the Driver Demand

The correlation between linear acceleration values and engine torque demanded can be made by using the gear/final drive ratios, vehicle weight, drag coefficients and frontal area. It gives a reasonable estimation of what the desired engine torque would be. The Axis can also be converted to show the engine speed at the achieved vehicle speed and gear.

It is not necessary to convert this over for each map and convert back but it is very useful to see by how much the linear acceleration should be adjusted to hit the desired value and not be excessive in areas where is is not required. You don't necessarily need to demand 200NM of torque a 28,000 RPM in first gear as the engine will not ever see this RPM.

You can simply multiply the driver demand acceleration at the correct RPM conversions by a set percentage to give you more acceleration request and more demanded torque.

If you wish to use the driver demand maps to try improve drive-ability and enable proper use of cruise control simply make sure the RaceROM torque Hijack is unchecked.

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